Literatura científica selecionada sobre o tema "Soil salinity"
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Artigos de revistas sobre o assunto "Soil salinity"
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SUHAIL, Faris Mohammed, e Imad Adnan MAHDI. "Test the efficiency of mycorrhizal fungi (Glomus fasciculatum) and magnetic water to reduce the effect of salinity on plant onion (Allium cepa L.)". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 70, n.º 2 (25 de novembro de 2013): 325–33. http://dx.doi.org/10.15835/buasvmcn-agr:9750.
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We carried out two factorial experiments in pots (capacity 4 kg) in order to increase the salt tolerance of one of our important plant - onion, using inoculation with mycorrhizal fungi (Glomus fasciculatum) and magnetized water under conditions of salinity stress. The first experiment aims the interaction between fungus inoculation and four levels of saline drainage water (0.66, 5.0, 7.5, 10.0 ds/m) and the second experiment aims the interaction between the inoculation factor and the water magnetic and two soils with different salinity (5.6, 13.4 ds/m). The results showed that the inoculation with the mycorrhizal fungi led to a significant increase in height, fresh weight and dry weight of onions to all levels of salinity compared with no addition of inoculation, while led to a significant reduction in electrical conductivity and the percentage of AM colonization of all levels of salts water. The treatment with inoculation and magnetized water when the salinity was 13.4 ds.m-1 recorded significant increase for plants height, fresh weight and dry weight (38.46%, 60.0%, 92.30%) respectively compared to the variant without inoculation, only with addition of water non-magnetized at the same soil salinity. The addition of mycorrhizal fungi (Glomus fasciculatum) and magnetized water impact significant in reducing the electric conductivity (Ec) in soil salinity (13.4 ds/m) while it affects significantly the percentage of AM colonization in both two soils.
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Dasberg, S., e A. Nadler. "Soil salinity measurements". Soil Use and Management 4, n.º 4 (dezembro de 1988): 127–33. http://dx.doi.org/10.1111/j.1475-2743.1988.tb00749.x.
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Kucherenko, M. "Lesoprigodnost soil salinity". Актуальные направления научных исследований XXI века: теория и практика 3, n.º 2 (1 de maio de 2015): 42–45. http://dx.doi.org/10.12737/11026.
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Jena, P. K., e V. Rajaramamohan Rao. "Influence of salinity, rice straw and water regime on nitrogen fixation in paddy soils". Journal of Agricultural Science 111, n.º 1 (agosto de 1988): 121–25. http://dx.doi.org/10.1017/s0021859600082903.
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SummaryIn a laboratory incubation study, the effect of natural and artificial soil salinity on the soil N2fixation, nitrogenase (C2H2reduction) and N2-fixing populations was evaluated in rice soils under two water regimes. N2fixation was less pronounced in two saline soils and in a normal non-saline soil amended with salt mixture (salinity level of 4 and 30 dS/m) than in a non-saline soil under flooded and nonflooded conditions. Flooded soils amended with rice straw showed higher N2-fixing activity than the non-flooded soils at all salinity levels used in the study. Leaching the saline soil improved N2fixation. An increase in the soil salinity led to a decrease in the populations of at least three groups of N2-fixing micro-organisms. The population density of anaerobic N2fixers and Azospirillum in a saline soil increased considerably after leaching or after addition of rice straw. Azotobacter populations were little affected by the salinity levels used in this study. Results indicate that soil amelioration for salinity with leaching and organic matter addition would improve the implicated microbial populations and N2fixation in salt-affected rice soils.
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Al-Busaidi, A. S., e P. Cookson. "Salinity–pH Relationships in Calcareous Soils". Journal of Agricultural and Marine Sciences [JAMS] 8, n.º 1 (1 de janeiro de 2003): 41. http://dx.doi.org/10.24200/jams.vol8iss1pp41-46.
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Soil pH is the most commonly requested analysis undertaken during farm advisory work. Determination of pH assists in understanding many reactions that occur in soil. Variations in pH between soils have been related to a number of other soil parameters. In this study thirty different soils were collected from agricultural areas to have a wide range of pH, salinity, and texture. The objective was to study the relationship between soil pH and salinity. A negative relationship was found between soil salinity and pH. The main factor contributing to this relationship was probably the presence of soluble Ca2+ ion in soil. Variations in soluble Ca2+ ion concentrations between soils were negatively related to soil pH and positively related to soil salinity. Other soil properties that may affect pH, including CEC, CaCO3, clay content, gypsum and sodium adsorption ratio (SAR), were also determined.
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Simmons, H. B. "SALINITY PROBLEMS". Coastal Engineering Proceedings 1, n.º 2 (1 de janeiro de 2000): 7. http://dx.doi.org/10.9753/icce.v2.7.
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The basic sources of salt-water pollution are the ocean, industry, and the soil. The ocean is responsible for the intrusion of salt water into rivers, canals, and lakes, and for infiltration of sea water into aquifiers which are tapped by wells. Industry causes salt-water pollution by discharging the brine of mines, oil wells, tanneries, and other industrial wastes into rivers and lakes. The soil is a source of salt-water pollution because of the run-off from chloride-bearing soils and the solution of soluble rocks. The most common and important source of salt-water pollution is the ocean, and is the only source considered in this paper.
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HM Alfarraji, SA Alsaedi, AS Fadhel e IB Abdulrazaq. "Role of composted organic material in reducing hazardous effect of salinity stress on biological nitrogen fixation and plant growth in salt affected soils of arid region". Open Access Research Journal of Science and Technology 5, n.º 2 (30 de julho de 2022): 001–8. http://dx.doi.org/10.53022/oarjst.2022.5.2.0047.
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Application of organic matter (OM) has shown positive effects on growth and yield of crop grown under soil salinity stress. The present study was conducted to estimate effectiveness of OM in enhancing Biological Nitrogen Fixation (BNF) in soil and in return improving growth and yield of cowpea. Therefore, role of (OM) in alleviating impact of salinity stress on (BNF) in soils of arid region was evaluated in medium textured soils of different content of salts content. Experiment was conducted in pots under greenhouse conditions. Salinity range studied was 3.5, 8.2 and 12.4 dSm-1 in J1, J2, and J3 soil respectively. Compost as OM was added at 15, 25 and 50 g Kg-1 soil. Cowpea local variety was used as a test crop. Total nitrogen in soils without the addition of organic matter after harvesting was the least at the highest salinity level and the highest was in the soil of the least salinity level. Number of root nodules reduced by 27.0% and 49.0% when soil salinity increased to 8.2 and 12.4 dSm-1, respectively, compared to that in soil of 3.5 dSm-1. Total N in Cowpea plant linearly increase with the increase of level of (OM) addition. Rate of Increase in total N was the highest at the lowest salinity level soil and was the least at the highest salinity level soil. Weight of root nodules decreased by 45% when soil salinity increased by 42%. Addition of OM at a rate of 25 g OM Kg-1 soil to J1 soil of (3.5 dSm-1) and soil J3 of 12.4 dSm-1 weight of root nodules increased by 47.0%. and 21.7%, respectively. Dry weight of Cowpea plant grown in the three soils received different levels of OM decreased with the increase of soil salinity irrespective of level of OM addition. Addition of OM at a rate of 15, 25, and 50 g kg-1 soil of 3.5 dSm-1 seed yield increased by 65%,130%, and 136% respectively. These results had confirmed the role of OM in alleviating salinity stress on BNF process in soil.
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Ergashovich, Kholliyev Askar, Norboyeva Umida Toshtemirovna, Jabborov Bakhtiyor Iskandarovich e Norboyeva Nargiza Toshtemirovna. "Soil Salinity And Sustainability Of Cotton Plant". American Journal of Agriculture and Biomedical Engineering 03, n.º 04 (22 de abril de 2021): 12–19. http://dx.doi.org/10.37547/tajabe/volume03issue04-03.
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The following article deals with the data obtained as a result of the effect of soil salinity on the physiological properties and tolerance levels of medium-fibre cotton varieties. Also, changes in physiological processes under the influence of different levels of salinity and differences in the adaptive properties of varieties have been noted. Salinity had a negative impact on all studied cotton varieties, while the radical decline in yield and its quality was observed in varieties with high levels of adaptability and hardiness.
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Mahajan, G. R., B. L. Manjunath, A. M. Latare, R. D'Souza, S. Vishwakarma e N. P. Singh. "Spatial and temporal variability in microbial activities of coastal acid saline soils of Goa, India". Solid Earth Discussions 7, n.º 4 (4 de novembro de 2015): 3087–115. http://dx.doi.org/10.5194/sed-7-3087-2015.
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Abstract. The aim of the present investigation was to study the spatio-temporal variability of the microbial activities in coastal saline soils (locally called Khazan) of Goa, India (west coast region). The coastal soil salinity is a major constraint for reduced crop yields and abandonment of farming in these areas. Three replicated global positioning based soil samples (0–0.20 m depth) from each of four salinity groups i.e. non-saline (EC=0.08±0.06 dS m−1), weakly saline (EC=2.04±0.06 dS m−1), moderately saline (EC=3.50±0.57 dS m−1) and strongly saline (EC=5.49±0.49 dS m−1) during three seasons–monsoon, post-monsoon and pre-monsoon were collected. Soil microbial activity in terms of soil microbial carbon (MBC), MBC as a fraction of soil organic carbon (SOC) (MBC/SOC), basal soil respiration (BSR), metabolic quotient (qCO2) and soil enzyme activities–dehydrogenase, phosphatase and urease was tested. In all the seasons, the soil cationic composition depended significantly (p<0.01) on salinity levels and the exchangeable sodium (Na) was the second most dominant among the tested cations. The MBC, MBC/SOC and BSR reduced significantly with increasing salinity, whereas qCO2 increased with increased salinity levels. In general, MBC, MBC/SOC and BSR and soil enzyme activities were observed as: salinity levels–strongly saline < moderately saline < weakly saline < non-saline and season–post–monsoon > monsoon > during pre-monsoon season. The mean MBC and MBC/SOC of non-saline soils were 1.61 and 2.28 times higher than that of strongly saline soils, whereas qCO2 of strongly saline soils was 2.4 times higher than that of non-saline soils. This indirectly indicates the salinity stress on the soil microorganisms. Irrespective of season, the soil enzyme activities decreased significantly (p<0.05) with increasing salinity levels. Suitable countermeasures needs to be taken up to alleviate the depressive salinity effect on the microbial and activity for the sustainable crop production in the coastal saline soils of Goa, India.
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Prior, LD, AM Grieve, PG Slavich e BR Cullis. "Sodium chloride and soil texture interactions in irrigated field grown sultana grapevines. III. Soil and root system effects". Australian Journal of Agricultural Research 43, n.º 5 (1992): 1085. http://dx.doi.org/10.1071/ar9921085.
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Five salinity treatments, ranging between 0.37 and 3.47 dS m-1, were applied through a trickle irrigation system to own-rooted sultana grapevines for six years. The changes in soil salinity levels and the relationship between soil salinity and yield were studied, and a simplified salt balance model was developed to calculate leaching fractions. Soil salinity was strongly influenced by soil texture as well as by salt treatment, because leaching fractions were lower in heavier soils; they averaged 23% in the lightest soils and 10% in the heaviest. Leaching fractions also increased with salt treatment, from 7% in the 0.37 dS m-1 treatment to 24% in the 3.47 dS m-1 treatment. This was probably because water use by salinized vines was lower. Yield was correlated with mean soil salinity, ECe, but the relationship was not as good as with plant salinity levels. The fitted model accounted for between 52 and 62% of the variance. It was concluded that soil salinity levels at the end of winter should be maintained below 1.0 dS m-1 in order to keep yield losses below 10%. For own-rooted sultana grapevines in Sunraysia, this requires a leaching fraction of about 8%. Rootzone depth and root density were lower in the heavier soils, and were decreased by salt treatment. The deleterious effects of salt treatment on clay dispersion and soil hydraulic conductivity were also greater in the heavier soils. Soil properties must therefore be considered when predicting the effects of saline water on crop productivity, especially in the long term.
Teses / dissertações sobre o assunto "Soil salinity"
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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.
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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.
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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.
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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.
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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.
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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.
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Ries, Mackenzie Lynn. "The Effect of Salinity on Soil Microbial Community Structure". Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31807.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
Livros sobre o assunto "Soil salinity"
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Eilers, R. G. Soil salinity Manitoba. [Winnipeg, Canada]: Canada-Manitoba Soil Inventory, Land Resource Research Centre, Research Branch, Agriculture Canada, 1990.
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Victoria. Office of the Auditor-General., ed. Salinity. Melbourne: L.V. North, Govt. Printer, 1993.
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Chhabra, Ranbir. Soil salinity and water quality. Brookfield, VT: A.A. Balkema, 1996.
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Taskforce, Western Australia Salinity. Salinity: A new balance. Western Australia: Salinity Taskforce, 2001.
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Eilers, R. G. Soil degradation risk indicator: Soil salinity risk component. Ottawa: Agriculture and Agri-Food Canada, 1996.
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Singh, Raj Vir, M. Tech., Ph. D., ed. Drainage and salinity control. Delhi: Himanshu Publications, 1991.
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Kapoor, A. S. Biodrainage: A biological option for controlling waterlogging and salinity. New Delhi: Tata McGraw-Hill Pub. Co., 2001.
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H, Frenkel, e Meiri A, eds. Soil salinity: Two decades of research in irrigated agriculture. New York, N.Y: Van Nostrand Reinhold, 1985.
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Shahid, Shabbir A., Mahmoud A. Abdelfattah e Faisal K. Taha, eds. Developments in Soil Salinity Assessment and Reclamation. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-5684-7.
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Singh, N. T. Irrigation and soil salinity in the Indian subcontinent: Past and present. Bethlehem: Lehigh University Press, 2005.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Soil salinity"
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Srivastava, Priyanka, Qiang-Sheng Wu e Bhoopander Giri. "Salinity: An Overview". In Soil Biology, 3–18. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18975-4_1.
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Hardie, Marcus, e Richard Doyle. "Measuring Soil Salinity". In Plant Salt Tolerance, 415–25. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-986-0_28.
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Gupta, Raj K., I. P. Abrol, Charles W. Finkl, M. B. Kirkham, Marta Camps Arbestain, Felipe Macías, Ward Chesworth et al. "Soil salinity and salinization". In Encyclopedia of Soil Science, 699–704. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-3995-9_552.
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Mukherjee, Swapna. "pH, Salinity and Sodicity". In Current Topics in Soil Science, 155–64. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92669-4_15.
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Okon, Okon Godwin. "Effect of Salinity on Physiological Processes in Plants". In Soil Biology, 237–62. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18975-4_10.
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Bado, Souleymane, Brian P. Forster, Abdelbagi M. A. Ghanim, Joanna Jankowicz-Cieslak, Günter Berthold e Liu Luxiang. "Protocol for measuring soil salinity". In Protocols for Pre-Field Screening of Mutants for Salt Tolerance in Rice, Wheat and Barley, 13–19. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-26590-2_3.
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Kasotia, Amrita, Ajit Varma e Devendra Choudhary Kumar. "Bacterial-Mediated Amelioration Processes to Plants Under Salt Stress: a Review". In Soil Salinity Management in Agriculture, 237–88. Waretown, NJ : Apple Academic Press, 2017.: Apple Academic Press, 2017. http://dx.doi.org/10.1201/9781315365992-11.
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Singh, Y. P. "Sustainable Reclamation and Management of Sodic Soils: Farmers’ Participatory Approaches". In Soil Salinity Management in Agriculture, 289–315. Waretown, NJ : Apple Academic Press, 2017.: Apple Academic Press, 2017. http://dx.doi.org/10.1201/9781315365992-12.
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Sreelatha, A. K., e K. S. Shylaraj. "Pokkali Rice Cultivation in India: a Technique for Multi-Stress Management". In Soil Salinity Management in Agriculture, 317–36. Waretown, NJ : Apple Academic Press, 2017.: Apple Academic Press, 2017. http://dx.doi.org/10.1201/9781315365992-13.
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Chaitanya, A. Krishna, Shrikant Badole, Arbind Kumar Gupta e Biplab Pal. "Prevention, Reclamation and Management of Acid and Acid Sulphate Soils". In Soil Salinity Management in Agriculture, 337–63. Waretown, NJ : Apple Academic Press, 2017.: Apple Academic Press, 2017. http://dx.doi.org/10.1201/9781315365992-14.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Soil salinity"
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Zhang, Zhimei, Yanguo Fan, Zhijun Jiao, Xin Wang e Qi Wu. "Baseline-Based Soil Salinity Index (BSSI): A New Soil Salinity Index for Monitoring Soil Salinization". In IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2022. http://dx.doi.org/10.1109/igarss46834.2022.9883453.
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Kishore, N. K., e Manish Bhagat. "Study of soil resistivity variation with salinity". In First International Conference on Industrial and Information Systems. IEEE, 2006. http://dx.doi.org/10.1109/iciis.2006.365624.
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Amir Pooya Sarraf, Farnood Vahdat, Ebrahim Pazira e Hosein Sedghi. "Estimating Reclamation Water Requirement and Predicting Final Soil Salinity for Soil Desalinization". In 9th International Drainage Symposium held jointly with CIGR and CSBE/SCGAB Proceedings, 13-16 June 2010, Québec City Convention Centre, Quebec City, Canada. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2010. http://dx.doi.org/10.13031/2013.32129.
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Teggi, S., S. Costanzini, F. Despini, P. Chiodi e F. Immordino. "SPOT5 imagery for soil salinity assessment in Iraq". In SPIE Remote Sensing, editado por Ulrich Michel, Daniel L. Civco, Manfred Ehlers, Karsten Schulz, Konstantinos G. Nikolakopoulos, Shahid Habib, David Messinger e Antonino Maltese. SPIE, 2012. http://dx.doi.org/10.1117/12.974498.
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Font, J., C. Gabarro, J. Ballabrera, A. Turiel, J. Martinez, M. Umbert, F. Perez et al. "SMOS CP34 soil moisture and ocean salinity maps". In 2012 12th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad). IEEE, 2012. http://dx.doi.org/10.1109/microrad.2012.6185236.
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Wu, Xuerui, Junming Xia, Shuanggen Jin, Weihua Bai e Zhounan Dong. "IS Soil Salinity Detectable by GNSS-R/IR?" In IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2019. http://dx.doi.org/10.1109/igarss.2019.8898902.
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Van Pelt, R. Scott, Sujith Ravi, Guoming M. Zhang e Paolo D’Odorico. "Salinity and Sodicity Effects on Soil Erodibility and Dust Emissions". In Soil Erosion Research Under a Changing Climate, January 8-13, 2023, Aguadilla, Puerto Rico, USA. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2023. http://dx.doi.org/10.13031/soil.2023067.
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Van Pelt, R. Scott, Sujith Ravi, Guoming M. Zhang e Paolo D’Odorico. "Salinity and Sodicity Effects on Soil Erodibility and Dust Emissions". In Soil Erosion Research Under a Changing Climate, January 8-13, 2023, Aguadilla, Puerto Rico, USA. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2023. http://dx.doi.org/10.13031/soil.23067.
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Szyplowska, Agnieszka, Justyna Szerement, Arkadiusz Lewandowski, Marcin Kafarski, Andrzej Wilczek e Wojciech Skierucha. "Impact of Soil Salinity on the Relation Between Soil Moisture and Dielectric Permittivity". In 2018 12th International Conference on Electromagnetic Wave Interaction with Water and Moist Substances (ISEMA). IEEE, 2018. http://dx.doi.org/10.1109/isema.2018.8442298.
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Lucas, A. A. T., S. J. S. Santos, A. O. Aguiar Netto, J. A. Santos, I. S. Lima e D. B. S. Farias. "SOIL SALINITY IN IRRIGATED PERIMETER JACARÉ-CURITIBA - SE, BRAZIL". In III Inovagri International Meeting. Fortaleza, Ceará, Brasil: INOVAGRI/INCT-EI, 2015. http://dx.doi.org/10.12702/iii.inovagri.2015-a281.
Texto completo da fonteRelatórios de organizações sobre o assunto "Soil salinity"
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Dalton, Frank N., Shmuel Dasberg, James D. Rhoades e Arie Nadler. Time Domain Reflectometry: Simultaneous-in-situ Measurement of Soil Water Content and Salinity. United States Department of Agriculture, outubro de 1985. http://dx.doi.org/10.32747/1985.7566699.bard.
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M., Devkota, Gupta R.K., Martius C., Lamers J.P.A., Sayre K.D. e Vlek P.L.G. Soil salinity management on raised beds with different furrow irrigation modes in salt-affected lands. Center for International Forestry Research (CIFOR), 2015. http://dx.doi.org/10.17528/cifor/005519.
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Miyamoto, Seiichi, e Rami Keren. Improving Efficiency of Reclamation of Sodium-Affected Soils. United States Department of Agriculture, dezembro de 2000. http://dx.doi.org/10.32747/2000.7570569.bard.
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Sodium affected soils, along with salt-affected soils, are distributed widely in irrigated areas of the arid and semi-arid region of the world. Some of these soils can and must be reclaimed to meet the increasing demand for food, and existing irrigated lands must be managed to reduce salinization and alkalization associated with deteriorating irrigation water quality. This project was conducted for examining ways to reduce the use of chemical amendments and large quantities of leaching water for reclaiming sodic soils or for preventing soil sodification, We hypothesized that sodicity of calcareous soils irrigated with moderately sodic irrigation water can be controlled by maximizing dissolution of soil CaCO3. The work performed in Israel has shown that dissolution of CaCO3 can be enhanced by elevating the CO2 partial pressure in soils, and by increasing pore water velocity. The concentration of Ca in pore water was at an order of 1.5 mmolc L-1 at a CO2 partial pressure of 5 kPa, which is sufficient to maintain SAR below 4 at salinity of irrigation water of 0.5 dS m-1 or less. Incorporation of crop residue at a flesh weight of 100 Mg ha-1 reduced the exchangeable Na percentage from 19 to 5%, while it remained 14% without crop residue application These findings indicate a possibility of preventing soil sodification with appropriate crop rotation and residue management without chemical amendments, provided that soils remain permeable. In the case of highly sodic soils, dissolution of CaCO3 alone is usually insufficient to maintain soil permeability during initial leaching. We examined the effect of salinity and sodicity on water infiltration, then developed a way to estimate the amendments required on the basis of water infiltration and drainage characteristics, rather than the traditional idea of reducing the exchangeable Na percentage to a pre-fixed value. Initial indications from soil column and lysimeter study are that the proposed method provides realistic estimates of amendment requirements. We further hypothesized that cultivation of salt-tolerant plants with water of elevated salinity can enhance reclamation of severely Na-affected soils primarily through improved water infiltration and increased dissolution of CaCO3 through respiration. An outdoor lysimeter experiment using two saline sodic Entisols sodded with saltgrass for two seasons did not necessarily support this hypothesis. While there was an evidence of increased removal of the exchangeable Na originally present in the soils, the final salinity and sodicity measured were lowest without sod, and highest when sodded. High transpiration rates, coupled with low permeability and/or inadequate leaching seemed to have offset the potential benefits of increased CaCO3 dissolution and subsequent removal of exchangeable Na. Although vegetative means of reclaiming sodic soils had been reported to be effective in sandy soils with sufficient permeability, additional study is needed for its use in saline sodic soils under the high evaporative demand. The use of cool season grass after initial salt leaching with CaCl2 should be explored. Results obtained from this project have several potential applications, which include the use of crop residues for maintaining sodium balance, the use of CaCl2 for initial leaching of poorly permeable clayey sodic soils, and appraisal of sodicity effects, and appropriate rates and types of amendments required for reclamation
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Dudley, Lynn M., Uri Shani e Moshe Shenker. Modeling Plant Response to Deficit Irrigation with Saline Water: Separating the Effects of Water and Salt Stress in the Root Uptake Function. United States Department of Agriculture, março de 2003. http://dx.doi.org/10.32747/2003.7586468.bard.
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Standard salinity management theory, derived from blending thermodynamic and semi- empirical considerations leads to an erroneous perception regarding compensative interaction among salinity stress factors. The current approach treats matric and osmotic components of soil water potential separately and then combines their effects to compute overall response. With deficit water a severe yield decrease is expected under high salinity, yet little or no reduction is predicted for excess irrigation, irrespective of salinity level. Similarly, considerations of competition between chloride and nitrate ions have lead to compensation hypothesis and to application of excess nitrate under saline conditions. The premise of compensative interaction of growth factors behind present practices (that an increase in water application alleviates salinity stress) may result in collateral environmental damage. Over-irrigation resulting in salinization and elevated ground water threatens productivity on a global scale. Other repercussions include excessive application of nitrate to compensate for salinity, unwillingness to practice deficit irrigation with saline water, and under-utilization of marginal water. The objectives for the project were as follows: 1) To develop a database for model parameterization and validation by studying yield and transpiration response to water availability, excessive salinity and salt composition. 2) To modify the root sink terms of an existing mechanism-based model(s) of water flow, transpiration, crop yield, salt transport, and salt chemistry. 3) To develop conceptual and quantitative models of ion uptake that considers the soil solution concentration and composition. 4) To develop a conceptual and quantitative models of effects of NaCl and boron accumulation on yield and transpiration. 5) To add a user interface to the water flow, transpiration, crop yield, salt transport, chemistry model to make it easy for others to use. We conducted experiments in field plots and lysimeters to study biomass production and transpiration of com (Zeamays cv. Jubilee), melon (Cucumismelo subsp. melo cv. Galia), tomato (Lycopersiconesculentum Mill. cv. 5656), onion (Alliumcepa L. cv. HA 944), and date palms (Phoenix Dactylifera L. cv. Medjool) under salinity combined with water or with nitrate (growth promoters) or with boron (growth inhibitor). All factors ranged from levels not limiting to plant function to severe inhibition. For cases of combined salinity with water stress, or excess boron, we observed neither additive nor compensative effects on plant yield and transpiration. In fact, yield and transpiration at each combination of the various factors were primarily controlled by one of them, the most limiting factor to plant activity. We proposed a crop production model of the form Yr = min{gi(xi), where Yr = Yi ym-1 is relative yield,Ym is the maximum yield obtained in each experiment, Xi is an environmental factor, gi is a piecewise-linear response function, Yi is yield of a particular treatment. We selected a piecewise-linear approach because it highlights the irrigation level where the response to one factor ceases and a second factor begins. The production functions generate response "envelopes" containing possible yields with diagonal lines represent response to Xi alone and the lines parallel to the X-axis represent response to salinity alone. A multiplicative model was also derived approximating the limiting behaviour for incorporation in a hydrochemical model. The multiplicative model was selected because the response function was required to be continuous. The hydrochemical model was a better predictor of field-measured water content and salt profiles than models based on an additive and compensative model of crop response to salinity and water stress.
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Warrick, Arthur W., Gideon Oron, Mary M. Poulton, Rony Wallach e Alex Furman. Multi-Dimensional Infiltration and Distribution of Water of Different Qualities and Solutes Related Through Artificial Neural Networks. United States Department of Agriculture, janeiro de 2009. http://dx.doi.org/10.32747/2009.7695865.bard.
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The project exploits the use of Artificial Neural Networks (ANN) to describe infiltration, water, and solute distribution in the soil during irrigation. It provides a method of simulating water and solute movement in the subsurface which, in principle, is different and has some advantages over the more common approach of numerical modeling of flow and transport equations. The five objectives were (i) Numerically develop a database for the prediction of water and solute distribution for irrigation; (ii) Develop predictive models using ANN; (iii) Develop an experimental (laboratory) database of water distribution with time; within a transparent flow cell by high resolution CCD video camera; (iv) Conduct field studies to provide basic data for developing and testing the ANN; and (v) Investigate the inclusion of water quality [salinity and organic matter (OM)] in an ANN model used for predicting infiltration and subsurface water distribution. A major accomplishment was the successful use of Moment Analysis (MA) to characterize “plumes of water” applied by various types of irrigation (including drip and gravity sources). The general idea is to describe the subsurface water patterns statistically in terms of only a few (often 3) parameters which can then be predicted by the ANN. It was shown that ellipses (in two dimensions) or ellipsoids (in three dimensions) can be depicted about the center of the plume. Any fraction of water added can be related to a ‘‘probability’’ curve relating the size of the ellipse (or ellipsoid) that contains that amount of water. The initial test of an ANN to predict the moments (and hence the water plume) was with numerically generated data for infiltration from surface and subsurface drip line and point sources in three contrasting soils. The underlying dataset consisted of 1,684,500 vectors (5 soils×5 discharge rates×3 initial conditions×1,123 nodes×20 print times) where each vector had eleven elements consisting of initial water content, hydraulic properties of the soil, flow rate, time and space coordinates. The output is an estimate of subsurface water distribution for essentially any soil property, initial condition or flow rate from a drip source. Following the formal development of the ANN, we have prepared a “user-friendly” version in a spreadsheet environment (in “Excel”). The input data are selected from appropriate values and the output is instantaneous resulting in a picture of the resulting water plume. The MA has also proven valuable, on its own merit, in the description of the flow in soil under laboratory conditions for both wettable and repellant soils. This includes non-Darcian flow examples and redistribution and well as infiltration. Field experiments were conducted in different agricultural fields and various water qualities in Israel. The obtained results will be the basis for the further ANN models development. Regions of high repellence were identified primarily under the canopy of various orchard crops, including citrus and persimmons. Also, increasing OM in the applied water lead to greater repellency. Major scientific implications are that the ANN offers an alternative to conventional flow and transport modeling and that MA is a powerful technique for describing the subsurface water distributions for normal (wettable) and repellant soil. Implications of the field measurements point to the special role of OM in affecting wettability, both from the irrigation water and from soil accumulation below canopies. Implications for agriculture are that a modified approach for drip system design should be adopted for open area crops and orchards, and taking into account the OM components both in the soil and in the applied waters.
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Freeman, Stanley, Russell Rodriguez, Adel Al-Abed, Roni Cohen, David Ezra e Regina Redman. Use of fungal endophytes to increase cucurbit plant performance by conferring abiotic and biotic stress tolerance. United States Department of Agriculture, janeiro de 2014. http://dx.doi.org/10.32747/2014.7613893.bard.
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Major threats to agricultural sustainability in the 21st century are drought, increasing temperatures, soil salinity and soilborne pathogens, all of which are being exacerbated by climate change and pesticide abolition and are burning issues related to agriculture in the Middle East. We have found that Class 2 fungal endophytes adapt native plants to environmental stresses (drought, heat and salt) in a habitat-specific manner, and that these endophytes can confer stress tolerance to genetically distant monocot and eudicot hosts. In the past, we generated a uv non-pathogenic endophytic mutant of Colletotrichum magna (path-1) that colonized cucurbits, induced drought tolerance and enhanced growth, and protected 85% - 100% against disease caused by certain pathogenic fungi. We propose: 1) utilizing path-1 and additional endophtyic microorganisms to be isolated from stress-tolerant local, wild cucurbit watermelon, Citrulluscolocynthis, growing in the Dead Sea and Arava desert areas, 2) generate abiotic and biotic tolerant melon crop plants, colonized by the isolated endophytes, to increase crop yields under extreme environmental conditions such as salinity, heat and drought stress, 3) manage soilborne fungal pathogens affecting curubit crop species growing in the desert areas. This is a unique and novel "systems" approach that has the potential to utilize natural plant adaptation for agricultural development. We envisage that endophyte-colonized melons will eventually be used to overcome damages caused by soilborne diseases and also for cultivation of this crop, under stress conditions, utilizing treated waste water, thus dealing with the limited resource of fresh water.
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Shani, Uri, Lynn Dudley, Alon Ben-Gal, Menachem Moshelion e Yajun Wu. Root Conductance, Root-soil Interface Water Potential, Water and Ion Channel Function, and Tissue Expression Profile as Affected by Environmental Conditions. United States Department of Agriculture, outubro de 2007. http://dx.doi.org/10.32747/2007.7592119.bard.
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Constraints on water resources and the environment necessitate more efficient use of water. The key to efficient management is an understanding of the physical and physiological processes occurring in the soil-root hydraulic continuum.While both soil and plant leaf water potentials are well understood, modeled and measured, the root-soil interface where actual uptake processes occur has not been sufficiently studied. The water potential at the root-soil interface (yᵣₒₒₜ), determined by environmental conditions and by soil and plant hydraulic properties, serves as a boundary value in soil and plant uptake equations. In this work, we propose to 1) refine and implement a method for measuring yᵣₒₒₜ; 2) measure yᵣₒₒₜ, water uptake and root hydraulic conductivity for wild type tomato and Arabidopsis under varied q, K⁺, Na⁺ and Cl⁻ levels in the root zone; 3) verify the role of MIPs and ion channels response to q, K⁺ and Na⁺ levels in Arabidopsis and tomato; 4) study the relationships between yᵣₒₒₜ and root hydraulic conductivity for various crops representing important botanical and agricultural species, under conditions of varying soil types, water contents and salinity; and 5) integrate the above to water uptake term(s) to be implemented in models. We have made significant progress toward establishing the efficacy of the emittensiometer and on the molecular biology studies. We have added an additional method for measuring ψᵣₒₒₜ. High-frequency water application through the water source while the plant emerges and becomes established encourages roots to develop towards and into the water source itself. The yᵣₒₒₜ and yₛₒᵢₗ values reflected wetting and drying processes in the rhizosphere and in the bulk soil. Thus, yᵣₒₒₜ can be manipulated by changing irrigation level and frequency. An important and surprising finding resulting from the current research is the obtained yᵣₒₒₜ value. The yᵣₒₒₜ measured using the three different methods: emittensiometer, micro-tensiometer and MRI imaging in both sunflower, tomato and corn plants fell in the same range and were higher by one to three orders of magnitude from the values of -600 to -15,000 cm suggested in the literature. We have added additional information on the regulation of aquaporins and transporters at the transcript and protein levels, particularly under stress. Our preliminary results show that overexpression of one aquaporin gene in tomato dramatically increases its transpiration level (unpublished results). Based on this information, we started screening mutants for other aquaporin genes. During the feasibility testing year, we identified homozygous mutants for eight aquaporin genes, including six mutants for five of the PIP2 genes. Including the homozygous mutants directly available at the ABRC seed stock center, we now have mutants for 11 of the 19 aquaporin genes of interest. Currently, we are screening mutants for other aquaporin genes and ion transporter genes. Understanding plant water uptake under stress is essential for the further advancement of molecular plant stress tolerance work as well as for efficient use of water in agriculture. Virtually all of Israel’s agriculture and about 40% of US agriculture is made possible by irrigation. Both countries face increasing risk of water shortages as urban requirements grow. Both countries will have to find methods of protecting the soil resource while conserving water resources—goals that appear to be in direct conflict. The climate-plant-soil-water system is nonlinear with many feedback mechanisms. Conceptual plant uptake and growth models and mechanism-based computer-simulation models will be valuable tools in developing irrigation regimes and methods that maximize the efficiency of agricultural water. This proposal will contribute to the development of these models by providing critical information on water extraction by the plant that will result in improved predictions of both water requirements and crop yields. Plant water use and plant response to environmental conditions cannot possibly be understood by using the tools and language of a single scientific discipline. This proposal links the disciplines of soil physics and soil physical chemistry with plant physiology and molecular biology in order to correctly treat and understand the soil-plant interface in terms of integrated comprehension. Results from the project will contribute to a mechanistic understanding of the SPAC and will inspire continued multidisciplinary research.
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Crowley, David E., Dror Minz e Yitzhak Hadar. Shaping Plant Beneficial Rhizosphere Communities. United States Department of Agriculture, julho de 2013. http://dx.doi.org/10.32747/2013.7594387.bard.
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PGPR bacteria include taxonomically diverse bacterial species that function for improving plant mineral nutrition, stress tolerance, and disease suppression. A number of PGPR are being developed and commercialized as soil and seed inoculants, but to date, their interactions with resident bacterial populations are still poorly understood, and-almost nothing is known about the effects of soil management practices on their population size and activities. To this end, the original objectives of this research project were: 1) To examine microbial community interactions with plant-growth-promoting rhizobacteria (PGPR) and their plant hosts. 2) To explore the factors that affect PGPR population size and activity on plant root surfaces. In our original proposal, we initially prqposed the use oflow-resolution methods mainly involving the use of PCR-DGGE and PLFA profiles of community structure. However, early in the project we recognized that the methods for studying soil microbial communities were undergoing an exponential leap forward to much more high resolution methods using high-throughput sequencing. The application of these methods for studies on rhizosphere ecology thus became a central theme in these research project. Other related research by the US team focused on identifying PGPR bacterial strains and examining their effective population si~es that are required to enhance plant growth and on developing a simulation model that examines the process of root colonization. As summarized in the following report, we characterized the rhizosphere microbiome of four host plant species to determine the impact of the host (host signature effect) on resident versus active communities. Results of our studies showed a distinct plant host specific signature among wheat, maize, tomato and cucumber, based on the following three parameters: (I) each plant promoted the activity of a unique suite of soil bacterial populations; (2) significant variations were observed in the number and the degree of dominance of active populations; and (3)the level of contribution of active (rRNA-based) populations to the resident (DNA-based) community profiles. In the rhizoplane of all four plants a significant reduction of diversity was observed, relative to the bulk soil. Moreover, an increase in DNA-RNA correspondence indicated higher representation of active bacterial populations in the residing rhizoplane community. This research demonstrates that the host plant determines the bacterial community composition in its immediate vicinity, especially with respect to the active populations. Based on the studies from the US team, we suggest that the effective population size PGPR should be maintained at approximately 105 cells per gram of rhizosphere soil in the zone of elongation to obtain plant growth promotion effects, but emphasize that it is critical to also consider differences in the activity based on DNA-RNA correspondence. The results ofthis research provide fundamental new insight into the composition ofthe bacterial communities associated with plant roots, and the factors that affect their abundance and activity on root surfaces. Virtually all PGPR are multifunctional and may be expected to have diverse levels of activity with respect to production of plant growth hormones (regulation of root growth and architecture), suppression of stress ethylene (increased tolerance to drought and salinity), production of siderophores and antibiotics (disease suppression), and solubilization of phosphorus. The application of transcriptome methods pioneered in our research will ultimately lead to better understanding of how management practices such as use of compost and soil inoculants can be used to improve plant yields, stress tolerance, and disease resistance. As we look to the future, the use of metagenomic techniques combined with quantitative methods including microarrays, and quantitative peR methods that target specific genes should allow us to better classify, monitor, and manage the plant rhizosphere to improve crop yields in agricultural ecosystems. In addition, expression of several genes in rhizospheres of both cucumber and whet roots were identified, including mostly housekeeping genes. Denitrification, chemotaxis and motility genes were preferentially expressed in wheat while in cucumber roots bacterial genes involved in catalase, a large set of polysaccharide degradation and assimilatory sulfate reduction genes were preferentially expressed.
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Cohen, Roni, Kevin Crosby, Menahem Edelstein, John Jifon, Beny Aloni, Nurit Katzir, Haim Nerson e Daniel Leskovar. Grafting as a strategy for disease and stress management in muskmelon production. United States Department of Agriculture, janeiro de 2004. http://dx.doi.org/10.32747/2004.7613874.bard.
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The overall objective of this research was to elucidate the horticultural, pathological, physiological and molecular factors impacting melon varieties (scion) grafted onto M. cannonballus resistant melon and squash rootstocks. Specific objectives were- to compare the performance of resistant melon germplasm (grafted and non-grafted) when exposed to M. cannoballus in the Lower Rio Grande valley and the Wintergarden, Texas, and in the Arava valley, Israel; to address inter-species relationships between a Monosporascus resistant melon rootstock and susceptible melon scions in terms of fruit-set, fruit quality and yield; to study the factors which determine the compatibility between the rootstock and the scion in melon; to compare the responses of graft unions of differing compatibilities under disease stress, high temperatures, deficit irrigation, and salinity stress; and to investigate the effect of rootstock on stress related gene expression in the scion. Some revisions were- to include watermelon in the Texas investigations since it is much more economically important to the state, and also to evaluate additional vine decline pathogens Didymella bryoniae and Macrophomina phaseolina. Current strategies for managing vine decline rely heavily on soil fumigation with methyl bromide, but restrictions on its use have increased the need for alternative management strategies. Grafting of commercial melon varieties onto resistant rootstocks with vigorous root systems is an alternative to methyl bromide for Monosporascus root rot/vine decline (MRR/VD) management in melon production. Extensive selection and breeding has already produced potential melon rootstock lines with vigorous root systems and disease resistance. Melons can also be grafted onto Cucurbita spp., providing nonspecific but efficient protection from a wide range of soil-borne diseases and against some abiotic stresses, but compatibility between the scion and the rootstock can be problematic. During the first year experiments to evaluate resistance to the vine decline pathogens Monosporascus cannonballus, Didymella bryoniae, and Macrophomina phaseolina in melon and squash rootstocks proved the efficacy of these grafted plants in improving yield and quality. Sugars and fruit size were better in grafted versus non-grafted plants in both Texas and Israel. Two melons (1207 and 124104) and one pumpkin, Tetsukabuto, were identified as the best candidate rootstocks in Texas field trials, while in Israel, the pumpkin rootstock RS59 performed best. Additionally, three hybrid melon rootstocks demonstrated excellent resistance to both M. cannonballus and D. bryoniae in inoculated tests, suggesting that further screening for fruit quality and yield should be conducted. Experiments with ABA in Uvalde demonstrated a significant increase in drought stress tolerance and concurrent reduction in transplant shock due to reduced transpiration for ‘Caravelle’ plants. In Israel, auxin was implicated in reducing root development and contributing to increased hydrogen peroxide, which may explain incompatibility reactions with some squash rootstocks. However, trellised plants responded favorably to auxin (NAA) application at the time of fruit development. Gene expression analyses in Israel identified several cDNAs which may code for phloem related proteins, cyclins or other factors which impact the graft compatibility. Manipulation of these genes by transformation or traditional breeding may lead to improved rootstock cultivars. Commercial applications of the new melon rootstocks as well as the ABA and TIBA growth regulators have potential to improve the success of grafted melons in both Israel and Texas. The disease resistance, fruit quality and yield data generated by the field trials will help producers in both locations to decide what rootstock/scion combinations will be best.