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1
Mortl, Amanda E. "Monitoring soil moisture and soil water salinity in the Loxahatchee floodplain". [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015734.
Testo completo
2
Klopp, Hans Walter. "Soil Salinity and Sodicity Impacts on Soil Shrinkage, Water Movement and Retention". Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27879.
Testo completoAbstract (sommario):
Saline, sodic, and saline-sodic ground waters are problematic throughout the Northern Great Plains and Red River Valley. High sodium adsorption ratio (SAR) and low electrical conductivity (EC) of soil solution and irrigation waters are known to create issues with saturated soil hydrologic conductivity. Our objective was determine the impact of saline, sodic and saline-sodic solutions on soil shrinkage and soil hydrologic properties. Soil shrinkage, water retention, and hydraulic conductivity were determined on a variety of soil textures following saturation with salt solutions of variable EC and SAR combinations. Data were fitted with simple theoretical models then model parameters statistically compared. Increasing SAR and decreasing EC of increased soil shrinkage, decreased hydraulic conductivity, and increased water retention near saturated conditions (i.e., > -100 cm H2O). Whereas saline-sodic waters resulted in the greatest rate of decline in saturated conductivity over time such as when salts would be managed without maintaining divalent cations.
3
Sabia, Roberto. "Sea surface salinity retrieval error budget within the esa soil moisture and ocean salinity mission". Doctoral thesis, Universitat Politècnica de Catalunya, 2008. http://hdl.handle.net/10803/30542.
Testo completoAbstract (sommario):
L’oceanografia per satèl•lit ha esdevingut una integració consolidada de les tècniques convencionals de monitorització in situ dels oceans. Un coneixement precís dels processos oceanogràfics i de la seva interacció és fonamental per tal d’entendre el sistema climàtic. En aquest context, els camps de salinitat mesurats regularment constituiran directament una ajuda per a la caracterització de les variacions de la circulació oceànica global. La salinitat s’utilitza en models oceanogràfics predictius, pero a hores d’ara no és possible mesurar-la directament i de forma global.
La missió Soil Moisture and Ocean Salinity (SMOS) (en català, humitat del sòl i salinitat de l’oceà) de l’Agència Espacial Europea pretén omplir aquest buit mitjançant la implementació d’un satèl•lit capaç de proveir aquesta informació sinòpticament i regular.
Un nou instrument, el Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) (en català, radiòmetre d’observació per microones per síntesi d’obertura), ha estat desenvolupat per tal d’observar la salinitat de la superfície del mar (SSS) als oceans a través de l’adquisició d’imatges de la radiació de microones emesa al voltant de la freqüència de 1.4 GHz (banda L). SMOS portarà el primer radiòmetre orbital, d’òrbita polar, interferomètric 2D i es llençarà a principis de 2009.
Així com a qualsevol altra estimació de paràmetres geofísics per teledetecció, la recuperació de la salinitat és un problema invers que implica la minimització d’una funció de cost. Per tal d’assegurar una estimació fiable d’aquesta variable, la resta de paràmetres que afecten a la temperatura de brillantor mesurada s’ha de tenir en compte, filtrar o quantificar. El producte recuperat seran doncs els mapes de salinitat per a cada passada del satèl•lit sobre la Terra.
El requeriment de precisió proposat per a la missió és de 0.1 ‰ després de fer el promig en finestres espaciotemporals de 10 dies i de 20x20.
En aquesta tesi de doctorat, diversos estudis s’han dut a terme per a la determinació del balanç d’error de la salinitat de l’oceà en el marc de la missió SMOS. Les motivacions de la missió, les condicions de mesura i els conceptes bàsics de radiometria per microones es descriuen conjuntament amb les principals característiques de la recuperació de la salinitat.
Els aspectes de la recuperació de la salinitat que tenen una influència crítica en el procés d’inversió són:
• El biaix depenent de l’escena en les mesures simulades,
• La sensibilitat radiomètrica (soroll termal) i la precisió radiomètrica,
• La definició de la modelització directa banda L
• Dades auxiliars, temperatura de la superfície del mar (SST) i velocitat del vent, incerteses,
• Restriccions en la funció de cost, particularment en el terme de salinitat, i
• Promig espacio-temporal adequat.
Un concepte emergeix directament de l’enunciat del problema de recuperació de la salinitat: diferents ajustos de l’algoritme de minimització donen resultats diferents i això s’ha de tenir en compte. Basant-se en aquesta consideració, la determinació del balanç d’error s’ha aproximat progressivament tot avaluant l’extensió de l’impacte de les diferents variables, així com la parametrització en termes d’error de salinitat.
S’ha estudiat l’impacte de diverses dades auxiliars provinents de fonts diferents sobre l’error SSS final. Això permet tenir una primera impressió de l’error quantitatiu que pot esperar-se en les mesures reals futures, mentre que, en un
altre estudi, s’ha investigat la possibilitat d’utilitzar senyals derivats de la reflectometria per tal de corregir les incerteses de l’estat del mar en el context SMOS.
El nucli d’aquest treball el constitueix el Balanç d’Error SSS total. S’han identificat de forma consistent les fonts d’error i s’han analitzat els efectes corresponents en termes de l’error SSS mig en diferents configuracions
d’algoritmes.
Per una altra banda, es mostren els resultats d’un estudi de la variabilitat horitzontal de la salinitat, dut a terme utilitzant dades d’entrada amb una resolució espacial variable creixent. Això hauria de permetre confirmar la capacitat de la SSS recuperada per tal reproduir característiques oceanogràfiques mesoscàliques.
Els principals resultats i consideracions derivats d’aquest estudi contribuiran a la definició de les bases de l’algoritme de recuperació de la salinitat.Satellite oceanography has become a consolidated integration of conventional in situ monitoring of the oceans. Accurate knowledge of the oceanographic processes and their interaction is crucial for the understanding of the climate system. In this framework, routinely-measured salinity fields will directly aid in characterizing the variations of the global ocean circulation. Salinity is used in predictive oceanographic models, but no capability exists to date to measure it directly and globally. The European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission aims at filling this gap through the implementation of a satellite that has the potential to provide synoptically and routinely this information. A novel instrument, the Microwave Imaging Radiometer by Aperture Synthesis, has been developed to observe the sea surface salinity (SSS) over the oceans by capturing images of the emitted microwave radiation around the frequency of 1.4 GHz (L-band). SMOS will carry the first-ever, polar-orbiting, space-borne, 2-D interferometric radiometer and will be launched in early 2009. Like whatsoever remotely-sensed geophysical parameter estimation, the retrieval of salinity is an inverse problem that involves the minimization of a cost function. In order to ensure a reliable estimation of this variable, all the other parameters affecting the measured brightness temperature will have to be taken into account, filtered or quantified. The overall retrieved product will thus be salinity maps in a single satellite overpass over the Earth. The proposed accuracy requirement for the mission is specified as 0.1 ‰ after averaging in a 10-day and 2ºx2º spatio-temporal boxes. In this Ph.D. Thesis several studies have been performed towards the determination of an ocean salinity error budget within the SMOS mission. The motivations of the mission, the rationale of the measurements and the basic concepts of microwave radiometry have been described along with the salinity retrieval main features. The salinity retrieval issues whose influence is critical in the inversion procedure are: • Scene-dependent bias in the simulated measurements, • Radiometric sensitivity (thermal noise) and radiometric accuracy, • L-band forward modeling definition, • Auxiliary data, sea surface temperature (SST) and wind speed, uncertainties, • Constraints in the cost function, especially on salinity term, and • Adequate spatio-temporal averaging. A straightforward concept stems from the statement of the salinity retrieval problem: different tuning and setting of the minimization algorithm lead to different results, and complete awareness of that should be assumed. Based on this consideration, the error budget determination has been progressively approached by evaluating the extent of the impact of different variables and parameterizations in terms of salinity error. The impact of several multi-sources auxiliary data on the final SSS error has been addressed. This gives a first feeling of the quantitative error that should be expected in real upcoming measurements, whilst, in another study, the potential use of reflectometry-derived signals to correct for sea state uncertainty in the SMOS context has been investigated. The core of the work concerned the overall SSS Error Budget. The error sources are consistently binned and the corresponding effects in terms of the averaged SSS error have been addressed in different algorithm configurations. Furthermore, the results of a salinity horizontal variability study, performed by using input data at increasingly variable spatial resolution, are shown. This should assess the capability of retrieved SSS to reproduce mesoscale oceanographic features. Main results and insights deriving from these studies will contribute to the definition of the salinity retrieval algorithm baseline.
4
Wong, Vanessa Ngar Lai. "The effects of salinity and sodicity on soil organic carbon stocks and fluxes /". View thesis entry in Australian Digital Theses Program, 2007. http://thesis.anu.edu.au/public/adt-ANU20080428.223144/index.html.
Testo completo
5
Ries, Mackenzie Lynn. "The Effect of Salinity on Soil Microbial Community Structure". Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31807.
Testo completoAbstract (sommario):
Soil salinity is a widespread problem that affects crop productivity. We expect that saline soils also have altered microbial community structure, soil food webs and related soil properties. To test this, we sampled field soils across four farms in eastern North Dakota that host salinity gradients. We evaluated microbial biomass carbon, phospholipid fatty acid analysis and nematode counts in moderately saline and low saline soils. Additionally, we measured soil properties that represent potential food sources and habitat characteristics that influence microbial communities. We found higher microbial group abundance in moderately saline soils than in the lower saline soils. In contrast, we found lower nematode abundances in the moderately saline soils. We also observed increased labile carbon, nitrogen, phosphorus, and water content in the moderately saline soils. Based on our results, saline soils appear to have unique soil biological characteristics, which have implications for overall soil function along salinity gradients.
6
Walworth, James, e Thomas L. Thompson. "Salinity Management and Soil Amendments for Southwestern Pecan Orchards". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2006. http://hdl.handle.net/10150/146654.
Testo completo
7
Walworth, J. L. "Salinity Management and Soil Amendments for Southwestern Pecan Orchards". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2011. http://hdl.handle.net/10150/239609.
Testo completo
8
Stong, Matthew Harold. "Development of Remote Sensing Techniques for Assessment of Salinity Induced Plant Stresses". Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194858.
Testo completoAbstract (sommario):
Salinity has been shown to reduce vegetative growth, crop quality, and yield in agricultural crops. Remote sensing is capable of providing data about large areas. This project was designed to induce salinity stress in a crop, pak choi, and thereafter monitor the response of the crop as expressed by its spectral reflectances. The project was conducted in the National Taiwan University Phytotron, and spectral data was collected using a GER 2600. Yield and soil salinity (ECe) were also measured. After three seasons of data were collected, wavelengths sensitive to salinity were selected. These wavelengths, which are within the spectral response of biochemicals produced by plants as a response to soil salinity, were used to create two indices, the Salinity Stress Index (SSI) and the Normalized Salinity Stress Index (NSSI). After creating the indices tests were conducted to determine the efficacy of these indices in detecting salinity and drought stresses as compared to existing indices (SRVI and NDVI). This project induced salinity and drought stress in a crop, pak choi, and thereafter monitored the response of the crop as expressed by its spectral reflectances. The SSI and NSSI correlated well to both ECe and marketable yield. Additionally the SSI and NSSI were found to provide statistical differences between salinity stressed treatments and the control treatment. Drought stress was not detected well by any of the indices reviewed although the SSI and NSSI indices tended to increase with drought stress and decrease with salinity stress. As a final test, specific ion toxicities of sodium and chloride were tested against the developed indices (SSI and NSSI) and existing indices (NDVI, SRVI, and NDWI). There were no differences in SSI and NSSI responses to specific ion concentration in the high salinity treatments. These results indicated that the SSI and NSSI are not sensitive to the specific ion concentration in irrigation water. However, the SSI and NSSI were higher for the sodium water than the choride water in the low salinity treatments. It is likely that this difference was caused by the fact that the high SAR water decreased infiltration and caused water stress.
9
Talone, Marco. "Contributrion to the improvement of the soil moisture and ocean salinity (SMOS) sea surface salinity retrieval algorithm". Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/48633.
Testo completoAbstract (sommario):
The European Space Agency's Soil Moisture and Ocean Salinity (SMOS)
satellite was launched on November, 2, 2009 from the Russian cosmodrome
of Plesetsk. Its objective is to globally and regularly collect measurements of
soil moistre and Sea Surface Salinity (SSS). To do that, a pioneering instru-
ment has been developed: the Microwave Imaging Radiometer by Aperture
Synthesis (MIRAS), the rst space-borne, 2-D interferometric radiometer
ever built; it operates at L-band, with a central frequency of 1.4135 GHz,
and consists of 69 antennas arranged in a Y shape array. MIRAS' output
are brightness temperature maps, from which SSS can be derived through
an iterative algorithm, and using auxiliary information. For each overpass
of the satellite an SSS map is produced, with an estimated accuracy of 1
psu (rmse). According to the Global Ocean Data Assimilation Experiment
(GODAE) the mission requirement is instead speci ed as 0.1 psu after av-
eraging in a 10-day and 2 2 spatio-temporal boxes.
In previuos works ((Sabia et al., 2010), or more extensively in Dr. Sabia's
Ph.D. thesis (Sabia, 2008)) the main error sources in retrieving SSS from
SMOS measurements were determined as:
1. Scene-dependent bias in the simulated measurements,
2. L-band forward modeling de nition,
3. Radiometric sensitivity and accuracy,
4. Constraints in the cost function, and
5. Spatio-temporal averaging.
This Ph.D. thesis, is an attempt of reducing part of the aforementioned
errors (the relative to the one-overpass SSS (1 - 4)) by a more sophisticated
data processing.
Firstly, quasi-realistic brightness temperatures have been simulated using
the SMOS End-to-end Performance Simulator (SEPS) in its full mode and
an ocean model, as provider for geophysical parameters. Using this data
set the External Brightness Temperature Calibration technique has been
tested to mitigate the scene-dependent bias, while the error introduced by
inaccuracies in the L-band forward models has been accounted for by the
application of the External Sea Surface Salinity Calibration.
Apart from simulated brightness temperatures, both External Brightness
Temperature Calibration and External Sea Surface Salinity Calibration have
been tested using real synthetic-aperture brightness temperatures, collected
by the Helsinki University of Technology HUT-2D radiometer during the
SMOS Calibration and Validation Rehearsal Campaign in August 2007 and
ten days of data acquired by the SMOS satellite between July 10 and 19,
2010.
Finally, a study of the cost function used to derive SSS has been performed:
the correlation between measurement mis ts has been estimated and the
e ect of including it in the processing have been assessed.
As an outcome of a 3-month internship at the Laboratoire LOCEAN in
Paris, France, a theoretical review of the e ect of the rain on the very top
SSS vertical pro le has been carried out and is presented as Appendix.
10
Wong, Vanessa, e u2514228@anu edu au. "The effects of salinity and sodicity on soil organic carbon stocks and fluxes". The Australian National University. Faculty of Science, 2007. http://thesis.anu.edu.au./public/adt-ANU20080428.223144.
Testo completoAbstract (sommario):
Soil is the worlds largest terrestrial carbon (C) sink, and is estimated to contain approximately 1600 Pg of carbon to a depth of one metre. The distribution of soil organic C (SOC) largely follows gradients similar to biomass accumulation, increasing with increasing precipitation and decreasing temperature. As a result, SOC levels are a function of inputs, dominated by plant litter contributions and rhizodeposition, and losses such as leaching, erosion and heterotrophic respiration. Therefore, changes in biomass inputs, or organic matter accumulation, will most likely also alter these levels in soils. Although the soil microbial biomass (SMB) only comprises 1-5% of soil organic matter (SOM), it is critical in organic matter decomposition and can provide an early indicator of SOM dynamics as a whole due to its faster turnover time, and hence, can be used to determine soil C dynamics under changing environmental conditions.¶
Approximately 932 million ha of land worldwide are degraded due to salinity and sodicity, usually coinciding with land available for agriculture, with salinity affecting 23% of arable land while saline-sodic soils affect a further 10%. Soils affected by salinity, that is, those soils high in soluble salts, are characterised by rising watertables and waterlogging of lower-lying areas in the landscape. Sodic soils are high in exchangeable sodium, and slake and disperse upon wetting to form massive hardsetting structures. Upon drying, sodic soils suffer from poor soil-water relations largely related to decreased permeability, low infiltration capacity and the formation of surface crusts. In these degraded areas, SOC levels are likely to be affected by declining vegetation health and hence, decreasing biomass inputs and concomitant lower levels of organic matter accumulation. Moreover, potential SOC losses can also be affected from dispersed aggregates due to sodicity and solubilisation of SOM due to salinity. However, few studies are available that unambiguously demonstrate the effect of increasing salinity and sodicity on C dynamics. This thesis describes a range of laboratory and field investigations on the effects of salinity and sodicity on SOC dynamics.¶
In this research, the effects of a range of salinity and sodicity levels on C dynamics were determined by subjecting a vegetated soil from Bevendale, New South Wales (NSW) to one of six treatments. A low, mid or high salinity solution (EC 0.5, 10 or 30 dS/m) combined with a low or high sodicity solution (SAR 1 or 30) in a factorial design was leached through a non-degraded soil in a controlled environment. Soil respiration and the SMB were measured over a 12-week experimental period. The greatest increases in SMB occurred in treatments of high-salinity high-sodicity, and high-salinity low-sodicity. This was attributed to solubilisation of SOM which provided additional substrate for decomposition for the microbial population. Thus,
as salinity and sodicity increase in the field, soil C is likely to be rapidly lost as a result of increased mineralisation.¶
Gypsum is the most commonly-used ameliorant in the rehabilitation of sodic and saline-sodic soils affected by adverse soil environmental conditions. When soils were sampled from two sodic profiles in salt-scalded areas at Bevendale and Young, SMB levels and soil respiration rates measured in the laboratory were found to be low in the sodic soil compared to normal non-degraded soils. When the sodic soils were treated with gypsum, there was no change in the SMB and respiration rates. The low levels of SMB and respiration rates were due to low SOC levels as a result of little or no C input into the soils of these highly degraded landscapes, as the high salinity and high sodicity levels have resulted in vegetation death. However, following the addition of organic material to the scalded soils, in the form of coarsely-ground kangaroo grass, SMB levels and respiration rates increased to levels greater than those found in the non-degraded soil. The addition of gypsum (with organic material) gave no additional increases in the SMB.¶
The level of SOC stocks in salt-scalded, vegetated and revegetated profiles was also determined, so that the amount of SOC lost due to salinisation and sodication, and the increase in SOC following revegetation relative to the amount of SOC in a vegetated profile could be ascertained. Results showed up to three times less SOC in salt-scalded profiles compared to vegetated profiles under native pasture, while revegetation of formerly scalded areas with introduced pasture displayed SOC levels comparable to those under native pasture to a depth of 30 cm. However, SOC stocks can be underestimated in saline and sodic landscapes by setting the lower boundary at 30 cm due to the presence of waterlogging, which commonly occurs at a depth greater than 30 cm in saline and sodic landscapes as a result of the presence of high or perched watertables. These results indicate that successful revegetation of scalded areas has the potential to accumulate SOC stocks similar to those found prior to degradation.¶
The experimental results from this project indicate that in salt-affected landscapes, initial increases in salinity and sodicity result in rapid C mineralisation. Biomass inputs also decrease due to declining vegetation health, followed by further losses as a result of leaching and erosion. The remaining native SOM is then mineralised, until very low SOC stocks remain. However, the C sequestration potential in these degraded areas is high, particularly if rehabilitation efforts are successful in reducing salinity and sodicity. Soil ecosystem functions can then be restored if organic material is available as C stock and for decomposition in the form of either added organic material or inputs from vegetation when these salt-affected landscapes are revegetated.
11
Huang, Longbin. "Interactions between sulphur dioxide and soil salinity in wheat plants". Thesis, Huang, Longbin (1993) Interactions between sulphur dioxide and soil salinity in wheat plants. PhD thesis, Murdoch University, 1993. https://researchrepository.murdoch.edu.au/id/eprint/51916/.
Testo completoAbstract (sommario):
Increasing sulphur dioxide (SO2) concentration in the atmosphere with expansions of electricity production and mineral processing in the world has led to numerous studies and understandings of adverse impacts of SO2 on growth and physiology of plants in Although there have been many studies on SO2 dose-response (physiology, growth, and (or) yield) relationships in plants, there is a lack of understanding of influences of environmental stress such as NaCl salinity, on plant responses to elevated SO2 concentrations in the air, which may occur in agricultural areas such as India, China and Australia with agricultural and natural ecosystems. low rainfall, or artificial irrigation and elevated SO2 levels in the air. Since stomatal conductance predominantly controls SO2 uptake and then its toxicity in leaf cells, salinity induced-stomatal closure could decrease the SO2 uptake and protect plants against SO2 toxicity. On the other hand, SO2 itself may induce changes in stomatal conductance, this may in turn, influence leaf transpiration, then salt (NaCl) uptake from the transpiration stream, and eventual salt toxicity in NaCl salinity-stressed plants, Therefore, simultaneous exposure to soil NaCl salinity and SO2 may modify each other's effects on the responses of physiology and growth in the plants. The studies in this thesis examined responses of growth and physiology in wheat plants exposed to SO2, NaCl salinity and their combination under near ambient conditions.
Wheat (Triticum aestivum cv. Wilgoyne (Ciano/Gallo)) plants were exposed to factorial treatments of SO2 and NaCl salinity in fumigation chambers with rain-exclusion tops under near-ambient conditions. In experiment 1, wheat plants were exposed to a factorial combination of three levels of salinity (with high Na/Ca ratio): control, 50 and 100 mM NaCl, and three levels of SO2: < 10 (ambient), 44 and 107 nl 1-1 for 4 hours per day for up to 110 days. In experiment 2, wheat plants were exposed to a factorial combination of two levels of salinity (with low Na/Ca ratio): control and 50 mM NaCl, and three levels of SO2: < 10 (ambient), 231, and 441 nl 1-1 for 4 hours per day for up to 51 days.
Low concentrations of SO2 (44 and 107 nl 1-1) stimulated vegetative growth in early growth phase, but had no effect later. Exposure to higher SO2 concentration (441 nl 1-1) significantly decreased plant growth. Low SO2 concentrations increased grain yield, but higher SO2 concentration (441 nl 1-1) decreased ear yield. Shoot to root ratios in plants were not changed by the low SO2 concentrations (44 and 107 nl 1-1), but increased by the relatively higher SO2 concentrations (231 and 441 nl 1-1). Increasing NaCl concentrations significantly reduced plant growth and grain yield. Severe NaCl salinity caused a substantial decrease in root growth, due to the effect of high Na+/Ca2+ ratio, resulting in an increase in Mild NaCl salinity initially decreased shoot growth, resulting in a decrease in shoot to root ratio, but later a shoot to root ratio. significant decrease in root growth developed, resulting in an increase in shoot to root ratio. The effects of SO2 fumigation and NaCl salinity on plant dry weights and shoot to root ratios were mostly additive, except that dry weight in plants subject to mild NaCl salinity was decreased less by 441 nl 1-1 SO2 fumigation than the nonsaline plants. Exposure to 231 nl 1-1 SO2 increased shoot to root ratio in plants with mild NaCl.
To understand physiological mechanisms behind the negative growth responses to SO2 fumigation, NaCl salinity and their combinations, stomatal conductance, sulphur and salt accumulation, photosynthesis, carbohydrate concentrations, and nitrogen metabolism parameters were examined in long-term fumigation experiments under near-ambient conditions.
In the long-term exposure to increased SO2 concentrations, the responses of plant growth and yield were negatively correlated with SO2 concentrations, but not with concentrations of sulphur in plant tissues. Plants exposed to low (107 nl 1-1) and relatively higher concentrations of SO2 (441 nl 1-1) had similar concentrations of sulphur in leaves. Reductions in growth and yield in plants exposed to higher concentrations of SO2 resulted from SO2 toxicity to physiological processes, such as nutritional and ionic balances, photosynthesis, and nitrogen metabolism. Exposure to 441 nl 1-1 SO2 significantly decreased stomatal conductance, net photosynthesis rate, and carbohydrate availability, which contributed an increase in shoot to root ratio. SO2 increased sulphate anion concentration which significantly disturbed ionic balance, causing increased K+ and decreased Na2 + , Ca2+ and CP concentrations and the nitrogen/sulphur balance in plant tissues. Although SO2 fumigation did not affect nitrogen uptake rate, it changed nitrogen distribution, nitrate reductase activity in leaves, soluble protein content and concentrations of total amino acids in plant tissues.
Salt toxicity and secondary physiological damages contributed to growth and yield reductions in plants subject to prolonged NaCl Increasing NaCl concentrations caused excessive salt (C1-, Na+) accumulation in plant tissues, and decreases in Although net photosynthesis rates in the youngest fully expanded leaves were little affected by NaCl salinity, long-term exposure to NaCl salinity decreased nonstructural carbohydrate concentrations in plant Cumulative salt injury may have caused a significant salinity stress. concentrations of K+ and sulphate anion. tissues. photosynthetic loss in old leaves and a decrease in total carbon gain in plants. Increasing NaCl salinity also significantly disturbed nitrogen metabolism in plants, by decreasing nitrogen uptake, altering nitrogen distribution, and increasing accumulation of total amino acids.
The nature of interactions between SO2 fumigation and NaCl salinity appeared to depend on their effects on the uptake and toxicity of SO2 and NaCl salt to physiological processes. Although severe NaCl salinity significantly decreased sulphur concentration in leaves of plants exposed to SO2, due to NaCl-induced increase in stomatal resistance, it decreased growth and yield in plants exposed to low SO2 concentrations and severe salinity. However, mild NaCl salinity that induced a slight increase in stomatal resistance, only slightly decreased leaf sulphur concentration in plants exposed to higher concentrations of SO2. Therefore mild NaCl salinity could not effectively protect plants against SO2 toxicity through reducing SO2 uptake in the long term, In contrast, exposure to 441 nl l-1 SO2 significantly decreased Cl' and Na+ concentrations, but increased K+ concentrations in leaves of plants subject to long-term mild salinity stress, which decreased salt toxicity to physiological processes.
Fumigation with SO2 concentrations of less than 441 nl 1-1, additively affected photosynthesis, carbohydrate production, and nitrogen metabolism parameters in plants subject to long-term NaCl salinity. Exposure to 441 nl 1-1 SO2 and mild NaCl salinity had antagonistic interactions on physiological responses, such as carbohydrate concentrations and nitrogen metabolism parameters. Plant tolerance to the long-term NaCl salinity was enhanced by 441 nl 1-1 SO2 fumigation by decreasing Na+ and CF concentration and increasing K+ concentration in leaves, and salt toxicity to physiological processes, resulting in antagonistic interactions on growth and yield. It is concluded that increasing NaCl salinity could not effectively protect plants against SO2 toxicity on physiology and growth by increasing leaf stomatal resistance, in the wheat plants exposed to a long-term simultaneous SO2 fumigation under ambient conditions. The two stresses are most likely to additively affect physiological responses, growth and yield in wheat plants in the long term. However, relatively higher SO2 fumigation appeared to protect the saline plants from salt toxicity to physiological processes and eventual growth, through decreasing stomatal conductance and salt concentrations in plant tissues. The effects of SO2 fumigation, NaCl salinity and their combination on the physiological responses to eventual growth in plants are discussed in the context of conceptual models.
12
Schuch, Ursula K., James Walworth, Tilak Mahato e Andrew Pond. "Accumulation of Soil Salinity in Landscapes Irrigated with Reclaimed Water". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/216640.
Testo completoAbstract (sommario):
The long-term use of reclaimed water for landscape maintenance and the effects on soil chemistry and soil structure were investigated. Irrigation with reclaimed versus potable water for five years or more affects chemical properties of soil. Soils irrigated with reclaimed versus potable water had higher EC. Monsoon precipitation had less of a leaching effect than anticipated and significantly reduced EC only on two out of 13 sites. Soils irrigated with reclaimed water had higher SAR values than those irrigated with potable water and can potentially develop infiltration problems in the future. Contour maps of the EC for three depths of one site as measured by soil samples and EC as predicted by EM38 measurements for pre- and post-monsoon sampling times were developed.
13
Al-Sibai, Mahmoud. "Movement of solutes in structured soils during intermittent leaching : a theoretical and laboratory study". Thesis, University of Newcastle Upon Tyne, 1996. http://hdl.handle.net/10443/509.
Testo completoAbstract (sommario):
Soil salinity is one of the major problems in and and semi-arid zones, affecting up to 50% of arable land in Syria. Salt-affected soils are usually desalinized by leaching the excess salts out of the soil profile. Some studies have shown that applying the leaching water intermittently instead of continuously may result in more efficient leaching. This thesis aims to investigate, theoretically and experimentally, the benefits and limitations of intermittent leaching and to develop mathematical models able to simulate solute transport through structured soils under such conditions. Laboratory leaching experiments were conducted on bi-continuum media, as an analogue of structured soils, created by packing porous aggregates (ceramic spheres or soil aggregates of uni- or multi- diameters) in glass columns. The columns were either leached continuously or intermittently and with different pore-water velocities. Intermittent leaching was undertaken either under saturated or drained conditions. Under "saturated conditions" the column remained saturated throughout the experiment, while under "drained conditions" the column was allowed to drain at the beginning of each rest period and remained like this until being saturated again for the next leaching period. The solute concentration in the leachate was monitored continuously (either using a flow-through conductivity cell, or by using ion-selective electrodes for Ký and Br' ) to produce breakthrough curves. These curves were used to investigate solute transport through such media and validate the developed models. The experiments showed that water savings of up to 22% under intermittent leaching from a soil aggregate column were possible under saturated conditions. Such saving increased with aggregate size, flow velocity and duration of rest period. Under drained conditions, for ceramic spheres, 12% more solute was leached with the same amount of water under intermittent leaching. Two models were developed, the SIL (Saturated Intermittent Leaching) and the DIL (Drained Intermittent Leaching) models, for saturated and drained conditions respectively. The SIL model simulated solute transport in structured soils under intermittent leaching. The governing equations during displacement period were the mobile-immobile convection-dispersione quations. During the rest period the flow is stopped, and the solute transfers only by diff-usion between immobile and mobile water regions. The DIL model simulated solute transport when the soil drained. Here, during the displacement period, the mobile water was drained. The model simulated this using the equations of the SIL model by assuming that air displaced the solution in a piston-type displacement. During the rest periods the solute difluses within the aggregates establishing a more uniform concentration in the immobile water across the aggregate. The models can be used with a wide range of column conditions and for both sorbed and non-sorbed solutes. Both models were verified against experimentarel sults.
14
Amer, Saud Abdulaziz 1953. "SPECTRAL REFLECTANCE MEASUREMENTS OF SALT-AFFECTED SOIL". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276542.
Testo completoAbstract (sommario):
Salt-affected soils have undermined the effectiveness of agricultural development of considerable areas of the world, especially in the arid and semi-arid regions. This research is set out for the direct measurement of salt-affected soil. Two experiments were conducted to study the influence of different salt types and concentrations on spectral reflectance of soil. In the first experiment, five different salts (Na₂SO₄, NaHCO₃, CaCO₃, CaCl₂ and NaCl) were mixed individually with Gila soil at 0.51, 1.51 and 3.0% by weight. The second experiment was conducted to examine the spectral response of sodium sulfate and sodium bicarbonate (individually and in combination) in Gila soil at 3.0 and 6.0% by weight. Reflectance measurements were made over all soil treatments under different moisture conditions. Upon drying (24-hour after wetting), different salt types and concentrations showed different spectral response. The chemical analysis of soil samples have indicated some important relationships which influenced, directly and indirectly, the spectral reflectance of soil surfaces.
15
Owojori, Olugbenga J. (Olugbenga John). "Influence of clay content and salinity on the bioavailability and toxicity of metals (copper and zinc) to soil organisms". Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1484.
Testo completoAbstract (sommario):
Thesis (PhD (Botany and Zoology))—University of Stellenbosch, 2009.ENGLISH ABSTRACT: Metal pollution is a problem of increasing global concern. It could arise from industrial activities, as well as pesticide use in agriculture, among other sources. For adequate protection of the soil ecosystem from metal toxicity, the bioavailability of metals must be properly evaluated. A plethora of soil factors affect the bioavailability of metals to soil organisms. These include pH, clay and organic matter contents, salinity among others. While much is known about the influence of some of these parameters, little is known on how clay content and salinity modify the bioavailability of metals to soil organisms. This study investigated the influence of clay content and salinity on partitioning, uptake and toxicity of two essential metals (Cu and Zn) to the earthworm Eisenia fetida in separate laboratory trials. Partitioning of the metals was evaluated with 0.01 M CaCl2, DTPA (di-ethylene-triamine-penta acetic acid), and nitric acid extractions. The metal content of worms was determined by acid digestion, while growth, cocoon production, and mortality were used as endpoints showing toxicity to metals and/or salinity. To test the validity of some of the laboratory results, a field study was undertaken, using the earthworm Aporrectodea caliginosa. Further, the study assessed the effect of salinity, using a battery of laboratory tests (acute, chronic and avoidance tests) with natural and/or artificial soils on four species of organisms (a collembolan Folsomia candida, a potworm Enchytraeus doerjesi and two earthworm species E. fetida and A. caliginosa), representing different feeding patterns and ecological roles in soil. Results showed that with increased clay content, there was increased availability of Cu in the substrate, and increased toxicity to E. fetida as shown by data for mortality and growth. The situation with Zn was less significant at sub-lethal concentrations but much so at lethal concentrations. DTPA and CaCl2 extracted metals revealed changes in partitioning of Cu and Zn with changes in clay content, but this trend was not always consistent. Both DTPA and CaCl2 revealed increased availability of Zn in substrates with increased salinity. Salinity had an additive to synergistic effect with Zn in toxicity to E. fetida. When combined with Cu, salinity also increased the availability of Cu as shown by CaCl2 extracted fraction, and had additive effect on toxicity of Cu to the earthworm. The field study did not succeed in in iv confirming the results of the laboratory study due to confounding role of flooding after heavy rainfall and subsequent leaching of salts and Cu. The results of the experiment on acute and chronic toxicity tests for NaCl on E. fetida showed LC50 of 5436 mg/kg NaCl and EC50 for growth and cocoon production of 4985 and 2020 mg/kg NaCl. These values showed that earthworms might be negatively affected in many soils containing fairly moderate concentrations of salts. Similarly, A. caliginosa could not survive in natural soil containing relatively low salt concentrations (EC = 1.62 dS/m) while reproduction was severely affected at lower EC value of 0.52 dS/m. F. candida and E. doerjesi could survive in the highest salinity soil (EC = 1.62 dS/m) used in this study but their reproduction was severely affected from 1.03 dS/m. Overall, it appears that of all the taxa used, earthworm species were the most sensitive to saline stress and could proof useful in determining ‘safe levels’ of salt in contaminated soils. The results of the avoidance test showed that A. caliginosa avoided both natural and artificial saline soil containing concentrations lower than those avoided by E. fetida. The conclusion is that the influence of clay content and salinity on the bioavailability of Cu and Zn depends largely on the metal in question, but generally speaking, bioavailability and toxicity of the metals were reduced with increased clay content while the opposite was true for salinity. If the species used in this study can be seen as fairly representative of a wide range of soil organisms, the conclusion is that salinisation of soil will be detrimental to most soil organisms at relatively low saline concentrations. Given the role of beneficial soil organisms in several soil processes which in turn contribute to soil fertility and sustainable use of land, it is recommended that any farming practices that may lead to an increase in salt content of agricultural soils should be discouraged.
AFRIKAANSE OPSOMMING: Metaalbesoedeling is ‘n probleem wat toenemende globale kommer veroorsaak. Dit kan ontstaan as gevolg van industriële aktiwiteite sowel as van plaagmiddelgebruik in die landbou en ander bronne.Ten einde die grondekostelsel genoegsaam te beskerm, moet die biobeskikbaarheid van metale ge-evalueer word. ‘n Verskeidenheid van grondfaktore be-invloed die biobeskikbaarheid van metale vir grondorganismes Hulle sluit onder andere in pH, klei, organiese inhoud en soutgehalte. Hoewel heelwat bekend is oor die rol van sommige van hierdie parameters, is min bekend oor hoe klei en soutgehalte die biobeskikbaarheid van metale vir grondorganismes kan modifieer. Hierdie studie het die invloed van kleiinhoud and soutgehalte op die verdeling/partisie, opname en toksisiteit van twee essensiële metale (Cu en Zn) vir die erdwurm Eisenia fetida in afsonderlike laboratoriumproewe ondersoek. Kompartementele verdeling van die metale is geevalueer deur middel van ekstraksie-metodes met 0.01 M CaCl2, DTPA (di-etileentriamien- penta asysnsuur), en salpertersuur ekstraksies. Die metaalinhoud van wurms is bepaal deur suurverterings en spektrofotometriese analises te doen terwyl groei, kokonproduksie en mortaliteit van organismes gebruik is as gevoeligheidseindpunte om toksisiteit van metale en soutgehalte aan te toon. Om die geldigheid van somige van die laboratoriumresultate te toets, is ‘n veldstudie ook onderneem met die erdwurm Aporrectodea caliginosa. Die effek van soutgehalte is verder ondersoek deur ‘n battery van laboratoriumtoetse met vier spesies (‘n kollembool Folsomia candida,’n potwurm Enchytraeus doerjesi en twee erdwurmspesies E. fetida en A. caliginosa), wat verskillende voedingspatrone verteenwoordig. Die resultate het getoon dat met toenmende klei-inhoud was daar ‘n toename in die beskikbaarheid van Cu vir opname vanuit die substraat, asook ‘n toename in toksisiteit vir E. fetida soos deur die gegewens vir mortaliteit en groei uitgewys. Die situasie met Zn was minder betekenisvol by subletale konsentrasies en selfs baie minder so by letale konsentrasies. DTPA en CaCl2 ge-ekstraheerde metale het veranderinge in die partisie/verdeling van Cu en Zn uitgewys met verandering in klei-inhoud, maar die tendens was nie altyd konstant nie. Beide DTPA en CaCl2 ekstraksie het toenemende beskikbaarheid van Zn in substrate uitgewys met toenemende soutinhoud. Soutinhoud het ‘n additiewe/toegevoegde tot sinergistiese vi toksisiteitseffek saam met Zn vir E. fetida. In kombinasie met Cu het soutgehalte ook die geskatte biobeskikbaarheid van Cu verhoog soos uitgewys deur die CaCl2, geekstraheerde fraksie, en het ‘n additiewe effek gehad op die toksisitiet van Cu vir die erdwurm. Die veldstudie kon nie die resultate van die laboratoriumstudie bevestig nie weens die belemmerende rol van vloede na swaar reënneerslae en daaropvolgende uitloging van soute en Cu. Die resultate van die eksperimentele ondersoek na die akute en chroniese effekte van NaCl op E. fetida het ‘n LC50 van 5436 mg/kg NaCl en EC50 vir groei en kokonproduksie van 4985 en 2020 mg/kg NaCl opgelewer. Hierdie waardes het aangetoon dat erdwurms moontlik negatief beinvloed kan word in baie gronde wat ‘n redelike gemiddelde konsentrasie van soute bevat. Soortgelyk kon A. caliginosa nie oorleef in natuurllike grond wat relatief lae soutkonsentrasies bevat het (EC=1.62 dS/m) nie terwyl voortplanting sterk ge-affekteer is by ‘n lae EC waarde van 0.52 dS/m. F. candida en E. doerjesi kon oorleef in die grond met die hoogste soutgehalte (EC= 1.62 dS/m) maar hulle voortplanting is ernstig geknou vanaf 1.03 dS/m. In geheel blyk dit dat van allle taksa wat gebruik is, erdwurms die sensitiefste was vir die stres wat deur soutgehalte veroorsaak is. Die kennis kan nuttig wees in die bepaling van “veilige vlakke” van sout in gekontamineerde gronde. Die resultate van die vermydingstoetse het getoon dat A. caliginosa beide natuurlike en kunsmatig versoute gronde vermy het by konsentrasies wat heelwat laer was as dié wat deur E. fetida vermy is Die gevolgtrekking is dat die invloed van klei en soutgehalte op die biobeskikbaarheid van Cu en Zn grootliks afhanklik is van die metale wat betrokke is en dat biobeskikbaarheid en toksisiteit normaalweg verminder het met verhoogde klei-inhoud, met die teenoorgestelde wat waar was in die geval van soutgehalte. Indien die spesies wat in die studie gebruik is beskou kan word as redelik verteenwoordigend van ‘n wye reeks van grondorganismes, is die gevolgtrekking dat versouting van gronde nadelig sal wees vir meeste grondorganismes, selfs by relatief lae soutkonsentrasies. In die lig van die rol wat nuttige grondorganismes speel in verskeie grondprosesse wat bydraend is tot grondvrugbaarheid en volhoubare gebruik van gronde, word dit aanbeveel dat enige boerderypraktyk wat mag lei tot verhoging van die soutinhoud van landbougronde ontmoedig moet word.
16
Ghorbani, Hadi. "Sludge application and salinity on the bioavailability of cadmium in soil". Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413487.
Testo completo
17
Ma, Qifu. "Soil salinity and water stress modify crop sensitivity to SO2 exposure". Thesis, Ma, Qifu (1993) Soil salinity and water stress modify crop sensitivity to SO2 exposure. PhD thesis, Murdoch University, 1993. https://researchrepository.murdoch.edu.au/id/eprint/42300/.
Testo completoAbstract (sommario):
Sulphur dioxide (SO2) is a pnmary gaseous pollutant which has toxic effects on the growth, yield and quality of both agricultural and natural plant species. Although plant responses to SO2 exposure have been extensively studied, much less is understood concerning the influences of other environmental stresses on the expression of effects of gaseous air pollutants. Evaluation of such interactions should be of an economic importance in agriculture and horticulture since plants growing in the field usually encounter air pollution and other stresses simultaneously. Soil water stress and salinity are the common environmental stresses and they have some physiological similarities. This thesis aims to investigate to what extent water stress and salinity modify or amplify the detrimental effects of SO2 on foliar injury, plant growth and yield, and some physiological and biochemical changes in potato (Solanum tuberosum L. cv. Russet Burbank) and soybean (Glycine max L. cv. Buchanan) crops under field conditions.
SO2 exposure induced growth reductions in well-watered potato plants but usually not in the water-stressed plants, indicating a protective function of soil moisture stress in the response of plants to SO2. This could be caused by a reduced SO2 uptake m water-stressed plants, as well-watered plants had much higher leaf sulphur concentrations than did the water-stressed plants at the same SO2 fumigation levels. SO2 also increased leaf sulphur concentrations in soybean, but simultaneous exposure to SO2 and salinity significantly decreased leaf sulphur concentrations when compared with exposure to SO2 alone. As a consequence, SO2-induced foliar injury was more severe in the well-watered or nonsaline plants than in the water-stressed or saline plants.
Exposure conditions can also be important in determining the response of a plant to stress interactions. Contrasts of sequential and simultaneous exposures to SO2 and salinity were made in this project so as to examine stress compensatory mechanisms and predisposition characteristics. It was found that low salinity pretreatment (27 mM NaCl) ameliorated the detrimental effects of SO2 on soybean growth probably by inducing stomatal closure. However, high salinity (48 mM NaCl) treated plants, which also showed high stomatal resistance, were severely injured by subsequent SO2 exposure especially at high SO2 concentrations (300 nl 1-1). It was likely that high salinity pretreatment decreased or even destroyed plant homeostasis due to direct injury of high ion concentrations. By comparison, plants pretreated with SO2 became vulnerable to salt injury and those pretreated with high SO2 were killed after 12 days of high salt stress. This was probably because SO2 altered the patterns of assimilate allocation favouring shoot growth at the expense of root growth and induced other metabolic changes. As a consequence, the resistance of polluted plants to salinity stress was reduced.
SO2 pollutant increased the shoot to root ratios by either reducing root growth or stimulating shoot growth, whereas soil moisture stress had the opposite effect. Exposure to 300 nl 1-1 SO2 under well-watered conditions induced an increase in the shoot to root (including tuber) ratios of potato plants early in the growing season. In contrast, water stress decreased the ratios in the control and 110 nl 1-1 SO2 treatments, but not at 300 nl I-1 SO2 indicating that high SO2 had disrupted this acclimatory response to soil moisture stress. SO2-induced increase in the shoot to root ratios was also observed in the soybean experiments. However, it appeared that soil salinity did not significantly affect the ratios.
High SO2 decreased the number and weight of root nodules, and suppressed nodule nitrogenase activity. Consequently, both shoot and root nitrogen concentrations were reduced. In combination with low salinity, however, the adverse effects of high SO2 on nodule number, specific nodule activity and plant nitrogen concentrations were ameliorated. Biomass was usually not very sensitive to the interactive effects of SO2 and salinity, probably because it is slower to respond to the stresses following physiological and biochemical processes. In the field, stress interactions may become even more complicated due to interactions with other environmental stresses.
In conclusion, moderate soil salinity and moisture stress can modify crop sensitivity to SO2 exposure mainly through stomatal mechanisms. Such interactions, together with the knowledge of interactions of gaseous au pollutants and other environmental stresses (e.g. light, humidity and temperature), are important when we attempt to establish dose or concentration-response relationships for the development of predictive models for the effects of air pollutants on crops or native plants. Environmental factors may readjust the dose thresholds of au pollutants, above which detrimental effect are likely and below which insignificant effects or growth stimulations occur. Therefore, air quality standards designed to protect vegetation may need to· consider variations in regional environmental conditions.
18
Al-Ismaily, Said Salim. "Nitrogen mineralization of manure-amended soil: Effects of salinity and moisture content". Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/290018.
Testo completoAbstract (sommario):
Application of manure has been used to increase the nitrogen status of many arid and semi-arid agricultural soils, however, organic nitrogen contained in animal manures must be mineralized prior to utilization by crops. Nitrogen mineralization is, like other biological processes, affected by soil water status. This can be due to the direct influence of soil moisture and/or salt interactions on the nitrogen dynamics. It is critical to understand the interactive effects of salt and water on nitrogen in soils amended with organic fertilizer. Such knowledge may be used for improving and quantifying nitrogen use efficiency. Objectives of this study were (i) to examine the relative and interactive influences of soil osmotic and matric water potentials on nitrogen transformations in manure-amended and non-manured soils, (ii) to determine the extent of nitrogen mineralization over a range of soil water potentials, and (iii) to study the effect of manure addition on nitrogen dynamics in an agricultural desert soil. Gila fine sandy loam soil was treated by addition of varying amounts of distilled water, NaCl, and dairy manure and incubated at depth of 20 cm in 0.025 mm thickness Ziploc® bags. Ammonium nitrogen, nitrate nitrogen, gravimetric soil moisture content, and total soil water potential were measured weekly for 16 weeks. Our study showed a decrease in the amount of inorganic N released from both the non-manured and manure-amended soils at total soil water potentials of approximately -55 bars or less. Maximal amounts of inorganic-N were released at potentials of -23 to -3.5 bars. There was an accumulation in the amounts of NH₄-N released at potentials of -55 bars or less, presumably because of a reduction in net nitrification. The manure caused nitrogen immobilization especially during the early part of our study. Immobilization also occurred in non-manured soil, but this generally lasted only a few weeks. Immobilization was prolonged in soils with lower water potentials. Net N mineralization in the manure-amended soils was higher than in the non-manured soils when soil moisture content was at field capacity.
19
Gillespie, Trudi. "Genetic variation in salt tolerance of four African Acacia species". Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327422.
Testo completo
20
Khandker, Md Humayun Kabir. "Crop growth and water-use from saline water tables". Thesis, University of Newcastle Upon Tyne, 1994. http://hdl.handle.net/10443/580.
Testo completoAbstract (sommario):
How much water can a crop abstract from below a saline water table and how does the salinity affect yield? These questions are important because shallow groundwater may represent a substantial resource in flat, low-lying areas, but may also represent a threat to sustainability where salinity is high. A series of experiments in a glasshouse aimed to elucidate irrigation management practice under salinity conditions and to develop a root uptake model under both osmotic and matric stresses. The extraction of soil water and groundwater by lettuce and perennial ryegrass crops were measured in three instrumented lysimeters. Water table depths were 0.6,0.9 and 1.2 rn below the soil surface. The lysimeters were initially saturated with saline water (electrical conductivity 4.5 dS m- 1 for lettuce, 9.4 dS m- I for the first crop of ryegrass and 0.4,7.5 & 15.0 dS m-1 for the second crop of ryegrass) and drained until an equilibrium soil water profile was attained. Water with the same electrical conductivity was then supplied by Marione siphons to maintain the constant water table. The water table contribution was recorded and water losses from the soil profile were estimated from daily readings of soil water potential using tensiometersa; nd gypsum blocks. Solute samples were extracted periodically for salinity measurement. The cropping period of lettuce was 90 days from sowing and the lst & 2nd cropping periods of ryegrass were 223 & 215 days respectively. The first ryegrass experiment showed that the water table depth (60,90 and 120 cm) did not have significant contribution (37,36 and 36 mm) on either total soil moisture use or groundwater contribution. Similar results were found for total soil moisture use for lettuce, though the groundwater contribution varied significantly. The second ryegrass experiment showed that salinity at the water table strongly influenced total soil moisture use, but the total groundwater contribution varied only slightly. The overall crop experiments show that the groundwater contribution was within the range of 25-30% of the total water use, except for the 15 dS m7l treatment where the contribution was greater than the soil moisture use. Groundwater contribution rate was higher when the plants were subjected to more osmotic and matric stresses. Yield component data show that increasing salinity leads to a reduction in total yield, but the drymatter proportion was higher. Higher salinities occurred in the upper 15 cm of the root zone, because of the greater soil moisture depletion. Below that depth the salinization rate was smaller, because of the greater groundwater contribution in the later part of the season. There is reasonable agreement between measured and estimated (based on convective transport theory) values soil salinity. Salinities increased in the root zone by about 3-fold of initial salinity for lettuce and around 4-fold for ryegrass in the top 5 cm depth, but below 15 cm depth it was less than 2 fold. Finally, a simplified model was developed to describe the interaction of root-zone salinity and water uptake, considering salinity and water stress as additive. The model shows that the higher the root-zone salinity stress, the higher the predicted water uptake while plant uptake considered -1.5 MPa. This variation is ranged from 4 to 17% for 0.4 to 9.4 dS m-1 and 30 % for 15 dS m-1. The model was developed in a climate with low atmospheric demand, but needs testing in a more severe environment.
21
Sameni, A.-M. "The effect of salinity and sodicity on the structure and hydraulic conductivity of soil". Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234545.
Testo completo
22
Aloy, i. Lleonart Merce. "Leaf ion concentrations and salt tolerance in barley". Thesis, Bangor University, 1994. https://research.bangor.ac.uk/portal/en/theses/leaf-ion-concentrations-and-salt-tolerance-in-barley(b9c4ca87-24dd-424d-b5f6-7c8f24c3a886).html.
Testo completoAbstract (sommario):
Breeding and selection for salt tolerance has been limited because of the large heterogeneity of natural saline soils and the lack of efficient criteria for measuring salt tolerance. Regulation of salt balances in leaves is an important aspect of salt tolerance. This work analyses the relationship between leaf ion concentrations and salt tolerance with the aim of using these traits as indicators of salt tolerance. This is done both in solution culture (hydroponics) and field trials (sprinkler irrigation with saline water). Varieties were found to differ in the amounts of ions accumulated in their leaves. However, these differences did not relate directly with their level of salt tolerance. The lack of correlation was partly due to difficulties in estimating salt tolerance in the field. Also, the Triple Line Sprinkler system (TLS) used in the field experiments posed several problems, the most important ones being related to direct ion absorption by the leaves. The high concentrations of CaC12 (in addition to NaCl) used in the irrigation water added a further complication. In hydroponic experiments, a minimum of 2 mol in-' Ce' was enough to prevent an indiscriminate entry of Na' and to ameliorate the growth inhibition of plants growing at 200 mol in-' NaCl. Higher Caý' concentrations (50 mol in-' CaCl2) reduced even more the concentrations of Na' in leaves without significantly affecting growth. At these high levels of CaCl2 any toxic effect was probably caused by high Clconcentrations.
23
Jayasekera, Samudra University of Ballarat. "An investigation into modification of the engineering properties of salt affected soils using electrokinetics". University of Ballarat, 2008. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/12805.
Testo completoAbstract (sommario):
Soil salinity (due to ingress of excess amounts of dissolved salts in soil pores) and soil sodicity (due to excess amounts of sodium ions attached to the clay surface) are significant forms of land degradation in many parts of the world in particular in arid and semi arid regions. In Australia, soil salinity has long been identified as the major form of land degradation and the greatest environmental threat. Saline soils cover almost 6% of Australia’s land mass and impose severe threats on agricultural productivity and built infrastructure with an estimated annual loss of $250 million. In recent years, ‘soil sodicity’ is recognised as a far more significant form of land degradation and a severe environmental problem both in terms of affected land area and impact on the environment than is salinity as a problem in Australia. One third of Australian land mass is occupied by sodic soils costing an estimated $2 billion each year in lost production alone, with further significant impacts on the economy due to extensive damage to infrastructure facilities and the environment. [...]Doctor of Philosophy
24
Molatakgosi, Goitsemodimo. "Impact of infield irrigation management by Botswana cabbage farmers on soil salinity". Thesis, Cranfield University, Cranfield University at Silsoe, 2005. http://hdl.handle.net/1826/1224.
Testo completoAbstract (sommario):
Some vegetable farmers in the semi- arid Botswana are struggling or closing down
their enterprises citing the cost of irrigation and salty water as the problem.
Irrigation with water from the salt-laden underground water is known to be the main
sources of salts for arid and semi-arid agricultural land. Crops grown in saline
environments show symptoms similar to those shown by drought-affected crops
hence more irrigation is needed therefore increasing the irrigation cost. Research
from other semi arid areas shows that water with high salinity levels can be used for
irrigation without increasing soil salinity to values beyond critical levels. A lot of
studies have been done which show that the impacts of saline irrigation water
depend on the irrigation management. This study therefore aims at recommending
infield irrigation management practices to be used by cabbage farmers in Botswana
without increase in soil salinity to levels that will affect crop yield.
A survey was conducted to identify the infield irrigation management practices
presently used by cabbage farmers in Botswana. Rootzone salinity trend due to the
identified infield irrigation management was simulated for 20 years using WaSim
simulation model. Recommendations on irrigation management practices were made
for those soil salinity trends that reached critical levels.
It was realised that there are no common infield irrigation management used by
farmers. The way farmers manage infield irrigation could not be identified with the
factors involved in irrigation scheduling. Infield irrigation management by the
farmers contribute to the soil salinity increase in their fields and some of the farmers are already using saline soils. Most farmers are not aware of the saline conditions they are farming on and those who know do not know about the soil salinity measures. The study recommends a need to educate farmers on irrigation under
saline environments and also a need for farmers to include soil salinity control in
their irrigation planning.
25
Khuori, Nabil. "A study of the potential of dry drainage for controlling soil salinity". Thesis, University of Newcastle upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239795.
Testo completo
26
Samak, Abdel-Lateif Abdel-Wahab [Verfasser]. "Soil moisture, crop yield and soil salinity relocation under partial rootzone drying irrigation / Abdel-Lateif Abdel-Wahab Samak". Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2012. http://d-nb.info/1024386198/34.
Testo completo
27
Gerhart, Vanda Jane. "Optimizing Native and Landscape Plant Establishment Under Marginal Soil and Water conditions in Southwestern Deserts". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1026%5F1%5Fm.pdf&type=application/pdf.
Testo completo
28
Jayasekera, Samudra. "An investigation into modification of the engineering properties of salt affected soils using electrokinetics". Thesis, University of Ballarat, 2008. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/34198.
Testo completoAbstract (sommario):
Soil salinity (due to ingress of excess amounts of dissolved salts in soil pores) and soil sodicity (due to excess amounts of sodium ions attached to the clay surface) are significant forms of land degradation in many parts of the world in particular in arid and semi arid regions. In Australia, soil salinity has long been identified as the major form of land degradation and the greatest environmental threat. Saline soils cover almost 6% of Australia’s land mass and impose severe threats on agricultural productivity and built infrastructure with an estimated annual loss of $250 million. In recent years, ‘soil sodicity’ is recognised as a far more significant form of land degradation and a severe environmental problem both in terms of affected land area and impact on the environment than is salinity as a problem in Australia. One third of Australian land mass is occupied by sodic soils costing an estimated $2 billion each year in lost production alone, with further significant impacts on the economy due to extensive damage to infrastructure facilities and the environment. [...]Doctor of Philosophy
29
Jayasekera, Samudra. "An investigation into modification of the engineering properties of salt affected soils using electrokinetics". University of Ballarat, 2008. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/15710.
Testo completoAbstract (sommario):
Soil salinity (due to ingress of excess amounts of dissolved salts in soil pores) and soil sodicity (due to excess amounts of sodium ions attached to the clay surface) are significant forms of land degradation in many parts of the world in particular in arid and semi arid regions. In Australia, soil salinity has long been identified as the major form of land degradation and the greatest environmental threat. Saline soils cover almost 6% of Australia’s land mass and impose severe threats on agricultural productivity and built infrastructure with an estimated annual loss of $250 million. In recent years, ‘soil sodicity’ is recognised as a far more significant form of land degradation and a severe environmental problem both in terms of affected land area and impact on the environment than is salinity as a problem in Australia. One third of Australian land mass is occupied by sodic soils costing an estimated $2 billion each year in lost production alone, with further significant impacts on the economy due to extensive damage to infrastructure facilities and the environment. [...]Doctor of Philosophy
30
Ali, Abdul-Mehdi Saleh. "Reactions of urea phosphate in calcareous and alkaline soils: Ammonia volatilization and effects on soil sodium and salinity". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184694.
Testo completoAbstract (sommario):
Nitrogen (N) loss in the form of volatilized ammonia (NH₃) is a considerable problem when ammonium (NH₄⁺) forming fertilizers are applied to calcareous or alkaline soils. Large areas of agricultural land, contain alkalinity and salinity problems, are potentially suitable for crop production with little alteration. This study was conducted to determine and compare the effectiveness of urea phosphate (UP) in reducing soil alkalinity and NH₃ loss. The volatilization of NH₃ from UP and urea (U) was studied on 3 selected soils (Hayhook SL, Laveen L and Latene L) using an aeration system. Urea phosphate and U were each applied at rates of 0, 50, 100 and 200 ppm-N either to the surface dry or in solution or mixed with the soil. The volatilized NH₃ was trapped in sulfuric acid, sampled periodically and analyzed for N using the semi microkjeldahl distillation apparatus. The effect of UP, Sulfur-Foam (SF), Phosphuric Solution (PHP) and a mixture of SF and UP (Mix) on leaching soil sodium (Na) and salinity was also studies on two soils (Pima L and Crot CL) in columns. Each of these amendments was applied at a rate of one and two equivalent amounts of the exchangeable Naₑₓ. The highest N loss in the form of NH₃ occurred when U was applied to Hayhook soil. However, UP applied to Hayhook soil (neutral to acidic, coarse textured and low CaCO₃ content) resulted in the lowest NH₃-N loss. Less NH₃-N loss was found from U application to Laveen and Latene soils (fine textured with higher CaCO₃ content) than with Hayhook soil. The general trend was higher N loss, in the form of volatilized NH₃, with surface application dry or in solution than when mixed with the soil. This trend showed an increase in the amount of volatilized NH₃ with increasing rate of N application. Urea phosphate was as effective as PHP or Mix (acid containing fertilizers) treatments in reducing soil salinity and alkalinity in Pima and Crot soils. No difference was found between rates of application (1 and 2 equivalent amount of Naₑₓ) except for soil pH. A similar trend in the decrease in soil salinity was found to that of the pH which was in the order PHP, UP, Mix, SF and control treatments. No significant difference was found between SF and control treatments in all parameters. No significant difference was found between treatments for exchangeable Ca. This was affected by the Ca compounds present in the soil. Generally, UP is a potential fertilizer for supplying N and phosphorus (P) as plant nutrients, reducing NH₃ volatilization, and can be used as a soil amendment to control soil salinity and alkalinity.
31
Omar, Mohamed Abdel-Hamed Mohamed. "Physiological investigations of the response of wheat (Triticum aestivum L.) to soil salinity". Thesis, University of Newcastle Upon Tyne, 1986. http://hdl.handle.net/10443/594.
Testo completoAbstract (sommario):
A series of greenhouse and control environment experiments were carried out to study the response of some wheat cultivars (Triticum aestivum L. ) to soil salinity. The rate and percentage of seed germination were reduced by increasing soil salinity. The cultivar Falchetto was more tolerant in terms of germination than the other cultivars under saline conditions. Increasing salinity consistently reduced the growth and dry matter production of all wheat cultivars used. The most sensitive growth character to salinity was leaf area and tiller number while net assimilation rate was least sensitive and sometimes not affected by salinity. The retardation of growth under salt stress in this study may result from reduced leaf area for photosynthesis, but the cause of reduced leaf area is not clear. In all cultivars tested, grain yield and its components were reduced by increasing soil salinity (0 - 0.6% salt) or irrigation with saline water (0 - 4000 ppm salt). The most sensitive yield characters to salinity were spike number and grain number per spike while spike length and spikelet number per spike were less sensitive as compared with the other components. Falchetto and Shakha 62 were less sensitive than the other cultivars used in this study. Leaf proline content increased while leaf chlorophyll content decreased with increasing soil salinity. Also, leaf and stem content of sodium, calcium and magnesium increased with increasing salinity levels both in vegetative parts and in grains. Increasing soil salinity increased ash and protein content of wheat grains but decreased moisture and total carbohydrate content. Application of nitrogen fertilizer under saline conditions enhanced grain yield and its components and to some extent countered the adverse effect of soil salinity up to 0.4%. While added nitrogen did not increase growth and dry weight of wheat plant significantly, crop growth rate increased significantly. On the other hand spraying wheat crop with trace elements did not affect the growth and grain yield and its components except 1000 kernel weight under saline conditions. The interaction effect between salinity and some environmental factors was significant on germination and growth. Under saline and non-saline conditions increasing temperature from 10 to 20°C increased germination capacity and depressed it between 20 and 30°C. Also, increased relative humidity from 47 to 92% increased germination capacity. For vegetative growth, generally, increasing temperature up to 20°C, relative humidity from 47 to 92%, and available soil water content from 20 to 100% increased vegetative growth and dry matter production of wheat plant under saline and non-saline conditions. The interaction effect between salinity and presoaking with plant growth regulators (CCC, GA3, IAA and Kinetin) and salt solutions (Nacl and Cacl2 ) on germination and growth of wheat accelerated germination under saline and non-saline conditions. For some characters presoaking with these plant growth regulators or salt reduced the deleterious effect of salinity and improved plant performance at these early stages of growth under saline conditions. Water and osmotic potentials, total and relative water content (RWC) and transpiration rate decreased and stomatal number per microscope field increased with increasing soil salinity, but turgor potential was essentially unchanged by increasing soil salinity indicating osmotic adjustment. Also, it is evident from the water relations, PEG and RH experiments that ion toxicity effect operated in addition to the osmotic one during early stages of growth
32
Folefoc, Asongbecap Daniel. "Geochemical study of soil salinity in a toposequence near Riebeeck West, South Africa". Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/10448.
Testo completoAbstract (sommario):
Bibliography: leaves 84-91.A geochemical investigation of salt distribution in soils of the semi-arid of Western Cape, South Africa, was carried out following a pilot study which revealed widespread soil salinity in the Berg River catchment. The present study looks at the distribution of the salts along a toposequence in a subcatchment of the Berg River underlain by Malmesbury Group shale. The objectives were: to investigate salt distribution in relation to landscape topography; to identify potentially harmful trace elements associated with the salinity; and to determine the processes responsible for salt distribution. Ten soil profiles were dug to a depth of 200 cm at points along a slope of angle 10.20 along and 367 m long. The profiles at the crest of the toposequence are underlain by silcrete and alluvium while Malmesbury shale parent material underlies the rest of the profiles. Contour drains disrupt the natural shape of the slope. The soil texture is loamy sand to clay loam at the crest and loamy to sandy-clay loam in the midslope. Mineralogy at the crest is quartz dominated and kaolinite occurs in the mid and lower slope.
33
Scudiero, Elia. "Multiscale Soil Salinity Assessment at the Southern Margin of the Venice Lagoon, Italy". Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3422637.
Testo completoAbstract (sommario):
Saltwater intrusion affects many coastlands around the world contaminating fresh-groundwater and decreasing soil quality. In order to manage saline soils one should understand the spatiotemporal dynamics of salinity in the soil profile and its spatial variability at field scale. In the last decades, soil and pore-water salinity have been assessed using geophysical techniques, most commonly with the use of apparent electrical conductivity (ECa) measurements. At point-scale, pore-water salinity can be estimated once its relationship with ECa, soil properties, and water content is understood. Moreover, most sensors for water content estimation normally provide biased readings in saline conditions and in soil with high clay and organic carbon contents. At field-scale proximal-sensing can be used to characterize large portions of land from a relatively small number of soil samples. Sometimes, characterizing salinity is however not sufficient to understand crop yield spatial variability, which can be also influenced by other soil properties. Understanding the influence of salinity and other soil properties on crop productivity can be useful in the identification of areas that can be managed site-specifically.
The general aim of this dissertation is to evaluate some sensor-based methodologies for monitoring and characterizing salinity and other related soil properties both at point- and field-scale. In particular, at point-scale the dissertation will deal with the issues regarding the use of capacitive-resistive technology for water content and pore-water salinity estimation. At field-scale some methodologies will be proposed in order to characterize the spatial variability of salinity and other soil properties influencing maize (Zea mais L.) yield using soil proximal-sensing. All the material presented in this manuscript regard the soils of an area affected by saltwater intrusion located at the southern edge of the Venice Lagoon (Italy).
The dissertation is structured in five chapters. The first one includes a review on commonly used methodologies for point- and field-scale salinity assessment. An overview on the environmental issues concerning the coastland at the southern margin of the Venice Lagoon is also presented. The second chapter deals with the calibration of a low-cost capacitance-resistance probe for simultaneous monitoring of soil water content and salinity. In the third chapter an ECa-directed soil sampling scheme optimization procedure is proposed. The forth chapter analyzes maize yield as a function of soil chemical and physical properties and investigates on the use of soil-proximal sensing correlated to soil spatial variability for site-specific management units. The final chapter presents the general conclusions of the work.L’intrusione salina interessa molte zone costiere del mondo con effetti negativi sulla qualità dell’acqua di falda e del suolo. Per gestire i problemi di salinità è necessario capirne le dinamiche temporali a livello di profilo di suolo e la variabilità spaziale a scala di campo. Tecniche geofisiche, in particolare l’utilizzo della conducibilità elettrica apparente (ECa), sono state utilizzate negli ultimi decenni per stimare la salinità del suolo e della soluzione circolante. A scala puntuale la bontà delle misure di salinità della soluzione circolante è legata alla giusta interpretazione del rapporto che la lega ad ECa, alle caratteristiche del suolo e al contenuto idrico. Inoltre, i sensori che misurano l’umidità del suolo spesso forniscono misure falsate in suoli salini e con alto contenuto di argilla e/o sostanza organica. A scala di campo il proximal-sensing può essere utile per caratterizzare vaste porzioni di territorio a partire da un numero relativamente ridotto di campioni di suolo. Spesso la caratterizzazione della salinità non è sufficiente per capire la variabilità spaziale delle rese colturali, che può essere influenzata da altre caratteristiche del suolo. Capendo come la salinità e altre proprietà del suolo influenzano la produttività agraria può essere utile per identificare delle aree in cui apportare interventi agronomici sito-specifici. L’obiettivo generale di questo lavoro è valutare delle metodologie per monitorare e caratterizzare la salinità del suolo ed altri parametri chimico-fisici del suolo ad essa legati, con l’ausilio di sensori, sia a scala puntuale che di campo. In particolare a scala puntuale si affrontano le problematiche relative all’utilizzo di sensoristica capacitivo-resistiva per stimare il contenuto volumetrico e la salinità della soluzione circolante. Mentre a scala di campo si propongono delle metodologie per caratterizzare la variabilità spaziale della salinità del suolo e di altre proprietà che influenzano la resa di Zea mais L. con l’utilizzo di tecniche di proximal-sensing del suolo. Questa tesi riguarda i suoli di un’area di studio interessata da intrusione salina, al margine meridionale della Laguna di Venezia. La tesi è strutturata in cinque capitoli. Il primo include una review sulla metodologia comunemente usata per caratterizzare la salinità del suolo con metodi geofisici sia a scala puntuale che di campo. È inoltre presentata una panoramica introduttiva sulle problematiche ambientali relative alla zona a sud della Laguna di Venezia. Il secondo capitolo si concentra sulla calibrazione di una sonda (low-cost) capacitivo-resistiva da utilizzare per stime in continuo di contenuto idrico volumetrico e salinità della soluzione circolante. Il terzo capitolo propone una metodologia per ottimizzare schemi di campionamento del suolo sulla base della variabilità spaziale di misure geofisiche. Il quarto capitolo analizza la variabilità spaziale della resa colturale in funzione delle proprietà chimico-fisiche del suolo e propone l’utilizzo di dati di proximal-sensing del suolo ad esse correlati per identificare delle aree di gestione omogenee. Infine, l’ultimo capitolo riporta le conclusioni generali e delle note conclusive sui lavori presentati nella tesi.
34
Hawks, Austin McCoy. "Salinity Inventory and Tolerance Screening in Utah Agriculture". DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/546.
Testo completoAbstract (sommario):
Soil salinity, a yield-limiting condition, has plagued crop production for centuries by reducing crop productivity. Research has introduced methods for successfully managing soil salinity. This research discusses the adaptation of established management methods to create new soil salinity management techniques. One adapted technique is an automated crop screening apparatus. A new design was created and successfully used in rapidly screening two strawberry cultivars to determine their tolerance to salinity. Screening crops and determining their tolerance to yield-limiting conditions are essential in managing soil salinity. Another salinity management tool used in this research was electromagnetic induction (EMI). EMI was used to complete a basin-scale inventory over an 18,000 ha study area in Cache County, Utah. The data obtained during the inventory were used to create EMI calibration models and a basin-scale map showing the spatial distribution of apparent soil electrical conductivity (ECa). These new methods for crop tolerance screenings and basin-scale salinity inventories will assist in successfully managing soil salinity and decrease its effect on the global food supply.
35
Bahizire, François B. "Effect of salinity on germination and seedling growth of canola (Brassica napus L.) /". Link to the online version, 2007. http://hdl.handle.net/10019.1/1939.
Testo completo
36
Al-Hazzouri, Abbas Ahmad 1949. "Effect of soil salinity and acidity on the germination of Quercus emoryi and Robinia neo-mexicana seeds". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/291761.
Testo completoAbstract (sommario):
The purpose of the study was to determine the effect of four salt concentrations and four acid levels of soil solution on the germination of Quercus emoryi and Robinia neo-mexicana seeds, and to study the effects of the cation concentration changes in solution (Na, Ca, Mg, K) and exchangeable cation concentration. The solution extracts and exchange phases of both soils, salt accumulation in the soil increased by increasing the salinity and acidity of the water applied. Exchangeable sodium was related directly to the SAR of the applied solutions. The soil responded differently to the salty water and acid water. Both soil treatments released Ca, Mg and K to the soil solution from the dissolution of the primary minerals and cation exchange reaction.
37
Diatta, Andre Amakobo. "Effects of Biochar Application on Soil Fertility and Pearl Millet (Pennisetum glaucum L.) Yield". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/80944.
Testo completoAbstract (sommario):
Biochar amendment to agricultural soils has been promoted for use in agricultural systems, both to mitigate global warming by increasing long-term soil carbon (C) sequestration and to enhance soil fertility and crop productivity. The objective of this study was to evaluate the effects of a single biochar application from peanut shell (Arachis hypogea L.) and mixed pine (Pinus spp.) wood to a Typic Hapludults in Blacksburg (VA, USA) and from peanut shell and eucalyptus (Eucalyptus camaldulensis) wood to a tropical, sandy, salt-affected soil in Ndoff (Fatick, Senegal) at 0, 10, and 20 Mg ha⁻¹ on soil chemical properties, inorganic nitrogen supply, and pearl millet production responses under field conditions for two growing seasons (2014 and 2015). Biochar application to temperate soils (Blacksburg) significantly increased total soil carbon, nitrogen, and plant available potassium in both years. In addition, pearl millet yields significant increased (53%) at the 20 Mg ha⁻¹ rate of peanut shell biochar in 2014 but did not persist in year 2. Beneficial effects largely appeared due to nutrient additions. Biochar treatment to tropical, sandy, salt-affected soils (Ndoff) had no effect on soil chemical properties. These results suggest that biochar application could improve soil fertility and crop productivity in temperate soils but had limited effects on tropical, sandy, salt-stressed soils in this study. The disparate results between these two field studies could be explained by differences in soil properties and climate, biomass feedstock, pyrolysis processes, and biochar handling, as well as experimental set-up.Master of Science
38
Abd-Elwahed, Mohammed Saifeldeen. "Assessment of Soil Salinity Problems in Agricultural Areas Through Spatial and Temporal Remote Sensing". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1380%5F1%5Fm.pdf&type=application/pdf.
Testo completo
39
Amakor, Xystus N. "Using Electromagnetic Induction Sensing to Understand the Dynamics and Interacting Factors Controlling Soil Salinity". DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1723.
Testo completoAbstract (sommario):
Soil salinization is of great concern in the irrigated arid and semi-arid western United States due to its threat to sustainable agricultural productivity and thus is closely monitored. A widely accepted and traditional standard method for estimating soil salinity is the electrical conductivity of the saturated paste extracts (ECe). However, this method underestimates salinity due to ion pair formation in high ionic strength solution. Numerous studies have recommended the use of an electromagnetic induction (EMI) sensing technique to monitor field-scale soil salinity due to rapidness and non-destructiveness of the sampling. However, because the EMI measurement (ECa) is related to a host of soil properties, calibrating ECa to salinity in a non-homogeneous setting is particularly challenging. The main objective of this study is to understand the dynamics and interacting factors controlling soil salinity using an EMI sensor. Specifically, a correction is made for the underestimation of soil salinity from saturated paste extracts, and a calibration model is developed that is capable of predicting salinity directly from ECa despite the non-homogeneity of potential perturbing factors. A comparison is made of salinity measurement methods based on soil saturated pastes with respect to specific soil management goals. Results show that ion pairing exists even in low ionic strength solution and by diluting the saturated paste extracts to conductivities ≤ 0.03 dS m -1 (ECed), ion pairing is minimized. An improved salinity estimate is obtained by computing total dissolved solids (TDS, in mM) from the ECed values, and then multiplying the TDS by the dilution factor. We also developed a calibration model using quantile regression, which makes no assumption about the distribution of the errors, and which is capable of predicting low range soil salinity (such as that in calcareous soils) from ECa depth-weighted measurements (ECH25ECe). A comparison of ECe, ECed, ECH25ECe, and direct measurement of EC in soil pastes (“ Bureau of Soils Cup ” method, ECcup) across six depths, three texture groups, and the combinations of EC method and depth or texture groups, supports the use of the ECH25ECe method to rapidly and reliably monitor salinity in calcareous soils of arid and semiarid regions.
40
Arif, Hamayun. "Water relations of salt stressed wheat". Thesis, Bangor University, 1990. https://research.bangor.ac.uk/portal/en/theses/water-relations-of-salt-stressed-wheat(b523794e-42f4-4165-bb35-11f07b7bbf28).html.
Testo completoAbstract (sommario):
The present study was conducted to investigate the water relations of individual plant cells and the biophysical parameters controlling plant growth in the context of salt stress. Growth and water relations were studied in growing as well as in mature zones of the first emerged leaf of wheat seedlings (cv. Flanders, a British variety) in the context of NaCl stress. Various levels of NaCl (0,25,50,75,100,125 and 150 mol m) -3 were used to salinize the media. I In the case of leaf elongation rate a two phase response was found i. e. an immediate decrease and then, a recovery in the elongation rate. Leaf elongation rate decreased within 1-2 minutes of the onset of stress and, later, a recovery started 1-2 h after the salt addition. The time taken for the recovery was proportional to the levels of external salinity. After 24 h the elongation rate was almost fully recovered for all the NaCl concentrations. A similar response was observed when equi-osmolar concentrations (with NaCl) of mannitol were added to the media. In control plants turgor pressure of the expanding cells was about 0.45 MPa while tissue osmotic pressure was equal to 1.1 MPa showing that the cell had a low water potential (-0.6 MPa). The transpiration tension was equivalent to 0.1 MPa. Turgor pressure in th e growing cells did not change after the salt addition (0- 150 mol m-3 NaCl), however, the tissue osmotic pressure continuously increased with time. Turgor pressure dropped when more -3 than 150 mol m NaCl were applied to the media i. e. 200 and 250 mol m. -3 This is presented as evidence that growing leaf cells - maintained their turgor pressure In response. to . the salt stress by taking up osmotically -active solutes present in the cell wall. The salt stress had not any effect on Instron tensiometric measurements of elastic and plastic extension of the cell wall. A different turgor pressure response was found in the mature cells. Turgor pressure was about 1.0 MPa, almost twice that in the growing cells, while tissue osmotic pressure was similar to that found in the growing cells i. e. 1.1 MPa. After the application of the stress the turgor pressure dropped within 15- 20 min of the application of all the concentrations of NaCl. The osmotic pressure of osmotically active solutes present in the cell wall, nwr was almost negligible i. e. 4 0.1 MPa, in mature cells and so could not contribute to turgor maiýtenance. The extent of decrease was proportional to the external stress of 25, 50 and 75 mol m-3 NaCl only. Turgor pressure recovery, due to osmotic adjustment, started after about 10-12 h of the stress initiation. Complete turgor recovery was achieved after 24-48 h of the onset of stress depending on the applied NaCl concentration. Tissue osmotic pressure increased continuously with time. An increase in the nw was inferred during the whole experimental period and after 6d of the stress application that appeared to correspond to the magnitude of external stress. The concentrations of major ions and sugars were determined to measure their contribution towards the osmotic adjustment. Under control conditions Na +, ci-, PO 4 3- ' so 4 2- , glucose, fructose and sucrose were present in small amounts, while, K+ and No 3- were the-major osmotica. Their concentrations were about 200. mol _m-3. After the stress a large increase in the concentrations of Na + and Cl was observed, the sucrose concentration increased to a small extent. However, other osmotica remained Uniform for whole of the experimental time. A small decrease was observed in k+ concentration in response to higher salt levels. volumetric elastic modulus, -c, of mature cells was remained unchanged by the salt stress. However, the apparent resistance of the root cortex to osmotically driven water flow increased with the increase in stress level. No conclusion could be drawn about the contribution of these parameters to the control of growth and to leaf water relations in the context of salt stress. The possible use of turgor pressure recovery in the mature cells was investigated for assessing the extent of salt tolerance of various Pakistani wheat varieties. These varieties were previously rated according to their performance in absolute grain yield in response to NaCl stress. No simple correlation was found.
41
Ripley, Dana Cameron. "Changes in Soil Salinity Levels with the Use of Recycled Water on Cool Season Vegetables". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1111.
Testo completoAbstract (sommario):
Agricultural production in Monterey County, California is a multi-billion dollar industry. Near the coast, seawater intrusion has threatened to degrade the groundwater quality due to over-pumping of the aquifer. The Monterey Regional Water Pollution Control Agency (MRWPCA), in partnership with the Monterey County Water Resources Agency, has provided recycled water since 1998 to over 12,000 acres of prime agricultural farmland in the northern Salinas Valley in an effort to reduce groundwater removal. The dominant soil types in the region are clay loam and clay soils, which are both susceptible to sodium (Na) accumulation and water infiltration problems. Recycled water blended with well water is used to irrigate cool season vegetables (i.e., artichokes, broccoli, Brussels sprouts, celery, cauliflower, and lettuce) and strawberries. A long-term study was implemented by MRWPCA to monitor salinity levels in commercial vegetable fields because of grower concerns that salts in the recycled water would have long term effects on soil quality. Accumulation of salts over time would make the soil less productive. Soil salinity levels were monitored at three Control and three Test Sites beginning in the spring of 2000. The Control Sites received well water, and the adjacent Test Sites received an approximate 2:1 blend of recycled and well water, respectively. Control and Test Sites were paired based on location to compare the same soil, crop, drainage systems, and farming practices. The soil was sampled three times per year from all sites: spring (before planting), mid-summer after harvest of the first crop, and late fall after the second crop harvest. Composites of four cores were collected at each site from the zero to 36-inch depth at 12-inch intervals. Each 12-inch interval soil sample was analyzed for pH, electrical conductivity (ECe), extractable cations (Na+, Ca2+, Mg2+, and K+) and extractable anions (Cl-, NO3-, and SO4-). After 10 years of monitoring, the data showed that using recycled water blended with well water at the Test Sites increased the ECe of the soil profile from 2.1 to 2.5 dS/m and increased the sodium adsorption ratio (SAR) from 3.0 to 3.9. The data also showed that using well water at the Control Sites increased the ECe of the soil profile from 1.4 to 2.6 dS/m and the change in SAR was negligible. The Test and Control Sites were significantly different for ECe and SAR, which was expected considering a higher salt content in the recycled water compared to the well water. The significant differences for ECe and SAR were associated with the significant differences in soil Na+ levels between the Test and Control Sites. The SAR and ECe of soil samples from all sites were in a range acceptable for vegetable production. The use of recycled water for irrigation of cool season vegetables and strawberries in the study area has not shown an indication of degraded soil productivity. Based on vegetable production and the slow increase of salts in the soil, recycled water can be used for long-term irrigation with proper management.
42
Barr, N. F. "Salinity control, water reform and structural adjustment : the Tragowel Plains Irrigation District /". Connect to thesis, 1999. http://eprints.unimelb.edu.au/archive/00000230/l.
Testo completo
43
Medeiros, Wiliana JÃlia Ferreira de. "Responses and adaptations of young plants of dwarf coconut - green to soil salinity and waterlogging". Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16901.
Testo completoAbstract (sommario):
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorThe coconut crop in Brazil stands out for its economic and social importance. The coconut cultivation has been in troduced in several regions of the country, however, the Northeast stands out with the largest plantations and production. Currently, a major problem in the agricultural sector, especially in semi-arid regions, has been the process of soil salinization. This problem is accentuated by the use of water with high salt concentration. Another factor existing in saline environments is excess water, especially, in clay soils and with poor drainage. The use of species toler ant to salinity has been a recommended strategy, to promote the rehabilitati on of degraded soils by excess salts. Thus, the objective of this work, was to evaluate the effects of the associations between soil salinity and waterlogging, at the responses and adaptations of young plants of coconut. The work was conducted, in agreenhouse, in the experimental area of the Meteorological Station, Campus Pici, the Federal University of CearÃ, in FortalezaâCearÃ, a randomized block design arranged in split plot scheme, with five repetitions, was used.The variables on which the data were collected over time, the experimental design was arranged in split split plots. The plots were formed by five cycles of waterlogging (0; 1; 2; 3 e 4), to 30, 60, 90 e 120 days, lasting four days each cycle, and the subplots were constituted by the five levels of soil salinity (1.70; 11.07; 16.44; 22.14 e 25.20 dS/m). Biometric, physiological a nd nutritional variables were eva luated in plants. In the soil, were evaluated fertility and the electrical conductivity (EC). The growth inhibition of the seedlings was caused more by soil salinity, than by waterlogging. The effects of waterlogging on the growth of plants decreases, with increasing salinity. Gas exchanges were influenced, mainly, by the soil salinity factor, and these responses were related to stomatal causes and not stomatal. The salinity factor resulted in accumulation of P and K in the soil, consequence of lower growth and lower extraction by plants. The reduction in growth and leaf gas exchange is associated with o smotic effects, and an increase in foliar levels of potentially toxic ions (Na+and Cl-). The results did not evidenced nutritional deficiency induction. The coconut plants presented potential to be utilized in revegetation programs, in areas affected by salts, up to the salt level of 11.07 dS/m.
A cocoicultura, no Brasil, se destaca por sua importÃncia econÃmica e social. O cultivo do coqueiro vem sendo introduzido em vÃrias regiÃes do paÃs, e a regiÃo Nordeste se destaca com as maiores plantaÃÃes e produÃÃes. Atualmente, um dos principais problemas no setor agrÃcola, sobretudo, em regiÃes semiÃridas, vem sendo o processo de salinizaÃÃo dos solos. O problema à acentuado mediante a utilizaÃÃo de Ãguas com alta concentraÃÃo de sais. Outro fator existente nos ambientes salinos à o excesso de Ãgua, notadamente, em solos argilosos e com drenagem deficiente. A utilizaÃÃo de espÃcies vegetais tolerantes à salinidade tem sido uma estratÃgia recomendada para promover a reabilitaÃÃo de solos degradados pelo excesso de sais. Assim, objetivou-se com este trabalho, avaliar os efeitos das associaÃÃes entre salinidade do solo e encharcamento, nas respostas e adaptaÃÃes de plantas jovens de coqueiro-anÃo-verde. O experimento foi conduzido, em ambiente protegido, na Ãrea experimental da EstaÃÃo AgrometeorolÃgica - Campus do Pici, da Universidade Federal do CearÃ, no municÃpio de Fortaleza â CearÃ, sob delineamento estatÃstico de blocos casualizados, arranjados em parcelas subdivididas com cinco repetiÃÃes. Nas variÃveis em que os dados foram coletados ao longo do tempo, o delineamento estatÃstico foi arranjado em parcelas subsubdivididas. As parcelas foram formadas por cinco ciclos de encharcamento (0; 1; 2; 3 e 4), aos 30, 60, 90 e 120 dias, com duraÃÃo de quatro dias cada ciclo, e as subparcelas foram constituÃdas por cinco nÃveis de salinidade do solo (1,70; 11,07; 16,44; 22,14 e 25,20 dS m-1). VariÃveis biomÃtricas, fisiolÃgicas e nutricionais foram avaliadas nas plantas. No solo, avaliaram-se a fertilidade e a condutividade elÃtrica (CE). A inibiÃÃo do crescimento das mudas foi ocasionada muito mais pela salinidade do solo, do que pelo encharcamento. Os efeitos do encharcamento do solo sobre o crescimento das mudas diminuiu, com aumento da salinidade. As trocas gasosas foram influenciadas, principalmente, pelo fator salinidade do solo, sendo que estas respostas foram relacionadas à causas estomÃticas e nÃo estomÃticas. O fator salinidade resultou em acÃmulo de P e K no solo, sendo consequÃncia do menor crescimento e da menor extraÃÃo pelas plantas. A reduÃÃo no crescimento e nas trocas gasosas foliares està associada aos efeitos osmÃticos, e ao aumento nos teores foliares de Ãons potencialmente tÃxicos (Na+ e Cl-). Os resultados nÃo evidenciaram induÃÃo de deficiÃncia nutricional. As plantas de coqueiro apresentaram potencial para serem utilizadas em programas de revegetaÃÃo, em Ãreas afetadas por sais, atà o nÃvel salino de 11,07 dS m-1.
44
Simó, Josa Iolanda. "The european framework for soil sustainability: mapping soil quality in model areas in Catalonia". Doctoral thesis, Universitat de Lleida, 2016. http://hdl.handle.net/10803/385616.
Testo completoAbstract (sommario):
Soil degradation is defined as a decrease in soil quality, which is caused by non sustainable soil
management. When the soil is losing its functionality is directly related with decreasing soil
quality.
This PhD proposes a scheme of intrinsic soil indicators for determining soil quality. This scheme
includes three different sets of soil quality indicators derived from basic soil use criteria. Such
criteria is based upon indicator availability, suitability and usefulness. These indicators are
grouped according to three different soil threats; declining organic matter, desertification and soil
salinity. These indicators were chosen under a European framework (COM (2002) 179 final) and
by natural processes. With respect to this framework, these indicators should be interpretable in
the context of soil quality, whilst also providing an auditable pathway through which soil
management decisions can be made.
The methods selected showed helpful results determining soil quality being well selected for the
use of soil indicators. EM measurements provide relevant information on within-field variability
of soil salinity. SOC distribution is important to be calculated in space and in depth. The
MEDALUS and RUSLE models can assess the extent, intensity and severity of desertification
processes in the target area.La degradació dels sòls es defineix com la disminució de la seva qualitat causada per un mal ús per part de l’espècie humana, o bé per causes generals. Així doncs, la pèrdua de funcionalitat del sòl està lligada a la disminució de la seva qualitat. En aquesta tesi s’ha estudiat el comportament d’indicadors de qualitat del sòl escollits sota un marc polític de la Unió Europea (COM(2002)). En concret, s’han estudiat indicadors relacionats amb tres amenaces/qualitat del sòl, contingut de matèria orgànica, grau de desertificació de les terres i estat de salinitat dels sòls, amb l’objectiu de validar la seva funcionalitat per qualificar el sòl. Els estudis s’han portat a terme en dues àrees ben diferenciades de Catalunya, al marge esquerra del Delta de l’Ebre i a una zona concreta del municipi de Canalda-Odén (Solsona) a la Catalunya central. Els mètodes seleccionats han mostrat donar bons resultats en la determinació de la qualitat del sòl, sent ben seleccionats com indicadors de qualitat del sòl. L’ús de l’electromagnètic sensor proporciona bona informació per a l’estudi de la variabilitat de la salinitat del sòl. La distribució carboni orgànic del sòl és important calcular-lo per veure com canvia tan en l'espai com en profunditat. Els models MEDALUS i RUSLE han mostrat avalar l'abast, la intensitat i la gravetat dels processos de desertificació a la zona d’estudi.
La degradación de los suelos se define como la disminución de su calidad del suelo causada por un mal uso por parte de la especie humana, o bien por causas generales. Así pues, la pérdida de la funcionalidad del suelo está ligada a la disminución de calidad de éste. En la presente tesis se ha estudiado el comportamiento de indicadores de calidad del suelo escogidos bajo un marco político de la Unión Europea (COM(2002)). En concreto, se han estudiado indicadores relacionados con tres amenazas del suelo, contenido de materia orgánica, grado de desertificación de las tierras y estado de salinidad de los suelos, con el objetivo de validar su funcionalidad para cualificar el suelo. Los estudios se han realizado en 2 áreas bien diferenciadas de Catalunya, en el margen izquierdo del Delta del Ebro y una zona concreta del municipio de Canalda-Odén (Solsona) en la Catalunya central. Los métodos seleccionados han mostrado dar buenos resultados en la determinación de la calidad del suelo, siendo bien seleccionados como indicadores de calidad del suelo. El uso del sensor electromagnético proporciona buena información para el estudio de la variabilidad de la salinidad del suelo. La distribución carbono orgánico del suelo es importante calcularlo para ver cómo cambia tanto en el espacio como en profundidad. Los modelos MEDALUS y RUSLE han mostrado avalar el alcance, la intensidad y la gravedad de los procesos de desertificación en la zona de estudio.
45
Wallace, Casey Ruth. "Riparian Graminoid Species Responses and Productivity in Compromised Environmental and Soil Conditions". Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31731.
Testo completoAbstract (sommario):
Riparian buffers have been created as a sustainable and effective way to combat the harmful effects of excess nitrogen and soil salinity in riparian settings. The goal of this research was to determine what species will I) germinate in saline environments and II) establish and produce sufficient biomass while being exposed to increased nitrogen. Incubation of eight native riparian graminoid species were evaluated for their ability to germinate in MgSO4-induced salinity. In a greenhouse study, seven riparian graminoid species were evaluated to quantify their ability to survive and take up nitrogen, mimicking buffer strips exposed to high inputs of runoff nitrogen. Slender wheatgrass and green needlegrass were able to germinate successfully when exposed to MgSO4 with EC levels up to 16 dS m-1 and 8 dS m-1, respectively. Of the graminoid species tested, smooth brome yielded sufficient biomass and nitrogen uptake percentages in a controlled setting.
46
Aluvilu, Anastasia N. "Responses of capsicum frutescenes cultivar serrano and capsicum annuum cultivar capistrano to meloidogyne incognita race 2,salinity and growth period". Thesis, University of Limpopo (Turfloop Campus), 2010. http://hdl.handle.net/10386/858.
Testo completo
47
Ado, Maman Nassirou. "Evaluation in situ et en conditions contrôlées de la phytodésalinisation des Vertisols irrigués. Cas d’étude du périmètre rizicole de Kollo (Niger) dans la vallée du fleuve Niger". Thesis, Rennes, Agrocampus Ouest, 2017. http://www.theses.fr/2017NSARD082/document.
Testo completoAbstract (sommario):
L’objectif général de ce travail est de comprendre et d’évaluer le rôle des cultures, à fort développement racinaire et susceptibles de se développer en milieu salin et saturé, sur le processus de phytodésalinisation des Vertisols. L’étude est réalisée sur le périmètre irrigué de Kollo (Niger) dans la vallée du fleuve Niger et couple deux expérimentations : i) la première in situ teste la capacité de Echinochloa stagnina à dessaler les Vertisols durant 15 mois en comparaison avec le riz (Oriza sativa) et le sol nu submergé et ii) la deuxième, au laboratoire sur des colonnes du sol, étudie l’effet de E. stagnina sur les propriétés hydro-structurales des Vertisols durant 11 mois et vise à analyser et modéliser le processus de la phytodésalinisation des VertisolsLes résultats montrent que la porosité du sol croît progressivement sur le sol cultivé avec E. stagnina. La macroporosité totale est plus élevée sur le sol cultivé avec E. stagnina (6 à 10 %) que sur le sol nu (2 à 4 %). La salinité des Vertisols décroît significativement avec le temps du développement des cultures. A la fin de l’expérimentation in situ, le stock des sels dans la couche 0-60 cm a baissé de 33 à 36 % sous E. stagnina et seulement de 3 % pour le riz et le sol nu submergé. Au laboratoire, le stock des sels initial a baissé de 65 à 87 % sous E. stagnina et de 34 à 45 % sur le sol nu submergé. Il est nécessaire de comprendre davantage l’interaction entre les différents processus (fissuration, salinité, géochimie) intervenants pendant la période d’inter-cultureThe general objective of this study was to understand and to evaluate the role of crops, characterized by heavy root development and susceptible to growth in saline and flooded conditions, on phytodesalinization process of Vertisols.The study was conducted in the irrigated perimeter of Kollo (Niger) in Niger River valley and coupled two experimental approaches: i) a field study to test the capacity of Echinochloa stagnina to reclaim Vertisols salinity during 15 months in comparison with rice (Oriza sativa) and ponded bare soil and ii) a laboratory experimentation on soil columns to study the effect of E. stagnina roots on hydro-structural properties of Vertisols during 11 months and aims to analyze and modelling phytodesalinization processes of VertisolsThe results showed that the soil porosity progressively increased under soil cultivated with E. stagnina. The soil macroporosity was higher on soil cultivated with E. stagnina (6-10%) than bare soil (2-4%). The soil salinity of Vertisols significantly decreased with time of crop development. At the end of field study, the initial salt stock of 0-60 cm layer decreased by 33 to 36% under the E. stagnina crop and only by 3% under rice crop and ponded bare soil. In laboratory study, initial salt stock decreased by 65 to 87% under soil cultivated with E. stagnina and by 34 to 45% under ponded bare soil. It is necessary to understand the interactions between the different processes (cracking, salinity, and geochemistry) involved during the intercropping season
48
Silva, Alexandre Reuber Almeida da. "Responses and adaptations of coconut plants "Green Dwarf" to interactions between water stress and soil salinity". Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14726.
Testo completoAbstract (sommario):
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoCoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
In this work morphological, physiological, biochemical and nutritional responses, to elucidate the possible adaptive strategies of young coconut plants, cultivating "Green Dwarf", involved with tolerance to the effects of stress isolated and combined soil salinity and water stress. In the experiment, conducted in a greenhouse, the greenhouse type, in Fortaleza, CearÃ, were evaluated under statistical design of randomized blocks in a split plot arrangement, the effects of different levels of water stress by imposing different percentages resets the potential evapotranspiration - ETpc (20; 40; 60; 80 and 100%), related to increasing levels of soil salinity (1.72, 6.25, 25.80 and 40.70 dS m-1) provided by soils derived from the Irrigated Perimeter Morada Nova - PIMN. The effects of treatments on plants were evaluated using the variables: plant height, leaf number, stem diameter, leaf area, biomass production (root, shoot and total), compared root dry biomass of aerial-1, to salinity tolerance indices, leaf gas exchange (stomatal conductance, transpiration, photosynthesis, instant and intrinsic efficiency of water use), quantum yield of chlorophyll fluorescence (Fv Fm-1) level for total chlorophyll (Spad index) , total content of chlorophyll (a + b) and carotenoids, leaf water potential, leaf and root levels of inorganic solutes (potassium ions, sodium and chloride) and organic (total soluble carbohydrates, N - aminossolÃveis and free proline) and nutritional state (foliar nutrients of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, manganese and zinc). The growth and biomass production of the plants are sharply reduced by the conditions of water stress and high soil salinity, apparently being more critical to fluid restriction culture. The degree of water stress can enhance the susceptibility to salinity. The physiological mechanisms are effectively limited when water stress and salinity act separately and / or together. The effects of water stress are more effective in the reduction of physiological parameters, to the detriment soil salinity. The magnitudes of physiological responses of plants to water supply and salinity depend on the intensity of stress. Adaptive physiological responses of plants are related mainly to stomatal regulation. In conditions of drought and soil salinity, the plants have linear reductions in the total levels of chlorophyll. Carotenoid levels respond to the combined effects of water availability and soil salinity and reflect the antagonism between them. The coconut has a number of physiological adjustments mechanisms that give the species a partial tolerance to drought stress and / or saline. Saline ions K+, Na+ and Cl- accumulate significantly in young coconut plants, to the detriment of organic solutes, both in the leaves and in the roots, evidencing an apparent root retention ions. Salinity did not change the concentration of organic solutes, however, show up increments in leaf and root levels of free proline in response to water stress. Water stress and soil salinity interact, affecting the nutritional status of plants, except for the nutrient P. Leaf contents of nutrients N, Ca, S, Fe, Mn and Zn grow positively with the increase of water availability and are reduced substantially with increasing salinity. The interaction of smaller water deficit levels with the highest saline levels maximizes the leaf contents of Mg and Cu and minimizes K. During the establishment of coconut seedlings, the need for macronutrients follows the descending order: N, K Ca, Mg, S and P and micronutrients: Fe, Mn, Zn and Cu. The plant nutrition proved to be adequate, except for the imbalances observed in nutrients K, Mg, S and Mn. The coconut seedlings show full capacity of the establishment in saline soils PIMN, corresponding to the level of electrical conductivity to 6.50 dS m-1, but only when the water supply remains adequate. For the higher salinity levels the plants survive, yet the size of the same is reduced by around 50%, even when fully irrigated.
Neste trabalho foram estudadas repostas morfolÃgicas, fisiolÃgicas, bioquÃmicas e nutricionais, visando elucidar as possÃveis estratÃgias adaptativas de plantas jovens de coqueiro, cultivar âAnÃo Verdeâ, envolvidas com sua tolerÃncia aos efeitos dos estresses isolados e/ou combinados, salinidade do solo e deficiÃncia hÃdrica. No experimento, conduzido em casa de vegetaÃÃo, do tipo telado, em Fortaleza, CearÃ, avaliaram-se, sob delineamento estatÃstico de blocos casualizados, no arranjo de parcelas subdivididas, os efeitos de diferentes nÃveis de deficiÃncia hÃdrica, mediante a imposiÃÃo de distintos percentuais de reposiÃÃes da evapotranspiraÃÃo potencial da cultura - ETpc (20; 40; 60; 80 e 100%), associados à crescentes nÃveis de salinidade do solo (1,72; 6,25; 25,80 e 40,70 dS m-1), proporcionados pelos solos oriundos do PerÃmetro Irrigado Morada Nova - PIMN. Os efeitos dos tratamentos sobre as plantas foram avaliados por meio das variÃveis: altura de plantas, nÃmero de folhas, diÃmetro do caule, Ãrea foliar, produÃÃo de biomassa (radicular, parte aÃrea e total), relaÃÃo biomassa seca raiz parte aÃrea-1, Ãndices de tolerÃncia à salinidade, trocas gasosas foliares (condutÃncia estomÃtica, transpiraÃÃo, fotossÃntese, eficiÃncia instantÃnea e intrÃnseca de uso da Ãgua), rendimento quÃntico da fluorescÃncia da clorofila a (Fv Fm-1), teores relativos de clorofila total (Ãndice Spad), teores totais de clorofilas (a+b) e de carotenÃides, potencial hÃdrico foliar, teores foliares e radiculares dos solutos inorgÃnicos (Ãons potÃssio, sÃdio e cloreto) e orgÃnicos (carboidratos solÃveis totais, N - aminossolÃveis e prolina livre) e estado nutricional (teores foliares dos nutrientes nitrogÃnio, fÃsforo, potÃssio, cÃlcio, magnÃsio, enxofre, ferro, cobre, manganÃs e zinco). O crescimento e a produÃÃo de biomassa das plantas sÃo acentuadamente reduzidos pelas condiÃÃes de restriÃÃo hÃdrica e de elevada salinidade do solo, sendo aparentemente mais crÃtica à cultura a restriÃÃo hÃdrica. O grau de estresse hÃdrico à capaz de acentuar a suscetibilidade à salinidade. Os mecanismos fisiolÃgicos sÃo efetivamente limitados quando a deficiÃncia hÃdrica e a salinidade atuam isoladamente e/ou em conjunto. Os efeitos do estresse hÃdrico se mostram mais efetivos nas reduÃÃes dos parÃmetros fisiolÃgicos, em detrimento à salinidade do solo. As magnitudes das respostas fisiolÃgicas das plantas ao suprimento hÃdrico e à salinidade dependem das intensidades do estresses. As respostas fisiolÃgicas adaptativas das plantas estÃo relacionadas, principalmente, à regulaÃÃo estomÃtica. Em condiÃÃes de dÃficit hÃdrico e de salinidade do solo, as plantas apresentam reduÃÃes lineares nos teores totais de clorofilas. Os teores de carotenÃides respondem aos efeitos combinados da disponibilidade hÃdrica e da salinidade do solo e refletem o antagonismo entre estes. O coqueiro apresenta uma sÃrie de mecanismos de ajustes fisiolÃgicos que conferem à espÃcie uma parcial tolerÃncia ao estresse hÃdrico e/ou salino. Os Ãons salinos K+, Na+ e Cl- acumulam-se significativamente em plantas jovens de coqueiro, em detrimento aos solutos orgÃnicos, tanto nas folhas quanto nas raÃzes, sendo evidenciada uma aparente retenÃÃo radicular de Ãons. A salinidade nÃo altera os teores dos solutos orgÃnicos, todavia, denotam-se incrementos nos teores foliares e radiculares de prolina livre em resposta à deficiÃncia hÃdrica. A deficiÃncia hÃdrica e a salinidade do solo interagem, afetando o estado nutricional das plantas, excetuando o nutriente P. Os teores foliares dos nutrientes N, Ca, S, Fe, Mn e Zn crescem positivamente com a ampliaÃÃo da disponibilidade hÃdrica e reduzem-se substancialmente com o aumento da salinidade. A interaÃÃo dos menores nÃveis de deficiÃncia hÃdrica com os maiores nÃveis salinos maximiza os teores foliares de Mg e Cu e minimiza os de K. Durante o estabelecimento das plantas jovens de coqueiro, a necessidade de macronutrientes obedece à ordem decrescente: N, K Ca, Mg, S e P e à de micronutrientes: Fe, Mn, Zn e Cu. A nutriÃÃo das plantas mostra-se adequada, excetuando-se, os desequilÃbrios observados nos nutrientes K, Mg, S e Mn. As plantas jovens de coqueiro mostram plena capacidade de estabelecimento nos solos salinizados do PIMN, atà o nÃvel de condutividade elÃtrica correspondente a 6,50 dS m-1, porÃm apenas quando o suprimento hÃdrico se mantÃm adequado. Para os nÃveis de salinidade mais elevados as plantas sobrevivem, contudo o porte das mesmas reduz-se em torno de 50%, mesmo quando plenamente irrigadas.
49
Thapa, Resham. "Spring Wheat (Triticum aestivum L.) Response to Nitrogen (N) Loss Management and Sulfate-Based Soil Salinity". Thesis, North Dakota State University, 2016. https://hdl.handle.net/10365/27961.
Testo completoAbstract (sommario):
The first study was conducted during 2014 growing season at Glyndon, MN to evaluate the effectiveness of nitrification inhibitor or both urease and nitrification i.e. double inhibitors on reducing N losses in a rainfed spring-wheat (Triticum aestivum L.) system. Our findings suggested that amending urea with double inhibitors might be an effective strategy to reduce all possible N losses without compromising crop yields from urea-fertilized soils.
The second study was conducted to understand the responses of spring-wheat to sulfate-based salinity stress under greenhouse and field conditions. Results from the greenhouse study indicated that the threshold soil ECe (EC using saturated-paste-extract method) affecting grain and straw yields were 8.2 and 2.9 dS m-1, respectively. However in fields, crop roots were subjected to heterogeneous salinity and the preferential root-growth in the least saline surface 0-60 cm soil layers resulted in greater salinity-tolerance to crops than that observed in a greenhouse study.Koch Agronomic Services, Inc.
North Dakota Wheat Council
50
Nava, Leon Jose Angel 1956. "CHLORIDE AND NITRATE DISTRIBUTION IN THE SOIL WITH FURROW AND BURIED DRIP IRRIGATION (SALINITY, SANDY LOAM)". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276671.
Testo completo