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1
Ashraf, Muhammad. "Dynamics of soil water under non-isothermal conditions." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336299.
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Bastviken, Paulina. "Soil water solution DOC dynamics during winter in boreal hillslopes." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229128.
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When plants and animals die they are decomposed into microscopic particles of organic carbon. In the ground, these carbon particles are dissolved in the soil water and eventually transported to the streamchannel with the flow of the groundwater. Today the quantities of dissolved organic carbon (DOC) have been observed to increase in many lakes and streams around the world, which constitute a threat against the water quality and ecologic environment of these surface waters. The amount of organic carbon that is dissolved and transported in the soil water is mainly controlled by processes related to temperature and hydrology, two factors which vary seasonally. Because of difficulties to sample soil water at temperatures below 0°C studies of DOC transport between soil and water during the winter season are limited. This study therefore conducted a winter sampling of soil water, with the focus on DOC. Samples were collected in March 2014 at sites along three hillslopes, orthogonal to two streams, in a typical Swedish boreal forest northwest of Umeå. The soil water was extracted with the help of suction lysimeters installed at different depths in the soil, and heating equipmentpowered by batteries. The collected samples were analyzed for DOC concentration and absorbance after which the results were grouped together with results from previous sampling campaigns, conducted in the summer and autumn of 2013. Parallel to this, data representing a longer time series (2009 to 2012) at another hillslope was processed. During the summer and autumn an increase in DOC concentration was observed. The increase was assumed to be caused by high production and effective degradation of organic matter in the soil during this warm period. Generally, a decrease in the DOC concentration then followed during the winter season. One possible reason for this decrease could be that the bacterial degradation in the soil continued, during the winter, and transformed the dissolved carbon into CO2 and CH4. Another possibility is that the DOC was flushed into the streams by autumn rain events. The study also found differences concerning the DOC concentration and character in the soil water, as well as the seasonal variation of these parameters, with soil depth and distance from the stream along the hillslope profile. These differences could be correlated to the organic content of the soil, from which the soil water had been extracted.
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Baigys, Giedrius. "Soil water regime and nitrate leaching dynamics applying no-tillage." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20090217_111111-32108.
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The impact of different agricultural systems used in agriculture on the leaching of nutrients and nitrates first of all depends on many factors that are not noticed and sometimes even underestimated by farmers trying to reach larger yields and better economic results. This article analysis the issue of changes in water regime and nitrate nitrogen leaching under the change of agricultural systems; such issue has not been investigated in Lithuania before. This research is especially relevant under the conditions of the Middle Lithuanian Lowland, where annual crops (cereals and sugar beet) area mainly cultivated, the ground is aerated in-tensely thus increasing the mineralization of organic substances and a lot of fertilizers are used. The change of conventional tillage for reduced tillage resulted in the decrease of the resources of surface soil water by 4,91-5,85 % and after changing it into no-tillage water resources decreased by 23,4 %. Reduced tillage and late ploughing are appropriate environmental means reducing nitrate nitrogen leaching from soil.<br>Įvairių žemdirbystės sistemų naudojamų žemės ūkyje poveikis maisto medžiagų ir labiausiai nitratų išsiplovimui priklauso nuo daugelio veiksnių, kurių žemdirbiai siekdami didesnių derlių ir geresnių ekonominių rezultatų nepastebi, o kartais ir reikiamai neįvertina. Šiame darbe, nagrinėjamas šalyje netirtas vandens režimo ir nitratų azoto išplovimo pasikeitimų, keičiantis žemdirbystės sistemoms, klausimas. Šie tyrimai ypač aktualūs Lietuvos Vidurio lygumos sąlygomis, kur daugiausia auginama vienmečių augalų (javų ir cukrinių runkelių), kasmet žemė intensyviai aeruojama, taip didinant organinių medžiagų mineralizaciją, naudojama daug trąšų. Pakeitus tradicinį žemės dirbimą į sumažintą žemės dirbimą paviršinio dirvožemio sluoksnio vandens atsargos sumažėjo 4,91-5,85 %, o pakeitus į neariminį žemės dirbimą vandens atsargos sumažėjo 23,4 %. Sumažintas žemės dirbimas bei vėlyvas arimas yra tinkamos aplinkosauginės priemonės, mažinančios nitratų azoto išplovimą iš dirvožemio.
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Karavokyris, Ioannis. "Modelling the dynamics of water in field soil-plant systems." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46385.
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Chen, Liping. "Soil Characteristics Estimation and Its Application in Water Balance Dynamics." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9789/.
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This thesis is a contribution to the work of the Texas Environmental Observatory (TEO), which provides environmental information from the Greenbelt Corridor (GBC) of the Elm Fork of the Trinity River. The motivation of this research is to analyze the short-term water dynamic of soil in response to the substantial rainfall events that occurred in North Texas in 2007. Data collected during that year by a TEO soil and weather station located at the GBC includes precipitation, and soil moisture levels at various depths. In addition to these field measurements there is soil texture data obtained from lab experiments. By comparing existing water dynamic models, water balance equations were selected for the study as they reflect the water movement of the soil without complicated interrelation between parameters. Estimations of water flow between soil layers, infiltration rate, runoff, evapotranspiration, water potential, hydraulic conductivity, and field capacity are all obtained by direct and indirect methods. The response of the soil at field scale to rainfall event is interpreted in form of flow and change of soil moisture at each layer. Additionally, the analysis demonstrates that the accuracy of soil characteristic measurement is the main factor that effect physical description. Suggestions for model improvement are proposed. With the implementation of similar measurements over a watershed area, this study would help the understanding of basin-scale rainfall-runoff modeling.
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Chen, Liping Acevedo Miguel Felipe. "Soil characteristics estimation and its application in water balance dynamics." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9789.
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Shahadha, Saadi Sattar. "Measured Soil Hydraulic Properties as RZWQM2 Input to Simulate Soil Water Dynamics and Crop Evapotranspiration." UKnowledge, 2018. https://uknowledge.uky.edu/pss_etds/110.
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Agricultural system models integrate many different processes that cannot all be measured in field experiments and help quantify soil water dynamics, crop evapotranspiration, and crop growth with high temporal resolution. Understanding soil water dynamics and crop evapotranspiration is essential to improve agricultural management of field crops. For example, the interaction between nitrogen application rate and water dynamics is not sufficiently understood. In most cases, model simulations deviate from field measurements, especially when model input parameters are indirectly and unspecifically derived. The extent to which measured soil hydraulic property inputs decrease the discrepancy between measured and simulated soil water status is not well understood. Consequently, this study: (i) investigated thr use of measured soil hydraulic properties as Root Zone Water Quality Model (RZWQM2) inputs compared to indirectly derived inputs; (ii) explored the capability of calibrating measured soil hydraulic property input parameters for one crop and using them for other crops without further calibration; (iii) studied the effect of the nitrogen application rate on the behavior of soil water dynamics and crop evapotranspiration using RZWQM2 under different rainfall amounts. To evaluate the model in different field management conditions, a field experiment with soybean, corn, wheat, and fallow soil was conducted from 2015 – 2017 to collect field data to calibrate and validate the RZWQM2 model. The model presented a satisfactory response to using measured soil hydraulic property inputs and a satisfactory capability to quantify the effect of nitrogen rates on daily crop evapotranspiration, soil water dynamics, and crop growth. With sufficient measurements of soil hydraulic parameters, it was possible to build a RZWQM2 model that produced reasonable results even without calibration.
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Sherriff, Sophie C. "Soil erosion and suspended sediment dynamics in intensive agricultural catchments." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/e4d08cd3-dc85-4e0e-96e2-f76430ee27e3.
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Excessive delivery of fine sediment from agricultural river catchments to aquatic ecosystems can degrade chemical water quality and ecological habitats. Management of accelerated soil losses and the transmission of sediment-associated agricultural pollutants, such as phosphorus, is required to mitigate the drive towards sustainable intensification to increase global food security. Quantifying soil erosion and the pathways and fate of fine-grained sediment is presently under-researched worldwide, and particularly in Ireland. This thesis established a sediment monitoring network upon an existing catchment study programme (Agricultural Catchments Programme) in five instrumented catchments (~10 km2) across Ireland. The research used novel, high quality measurement and analysis techniques to quantify sediment export, determine controls on soil erosion and sediment transport, and identify sediment contributions from multiple sources in different agricultural systems over time to evaluate approaches to fine sediment management. Results showed suspended sediment measurement using a novel ex situ methodology was valid in two of the study catchments against in situ and direct depth-integrated cross-section methodologies. Suspended sediment yields in the five intensive agricultural catchments were relatively low compared to European catchments in the same climatic zone, attributed to regionally-specific land use patterns and land management practices expressed in terms of ‘landscape complexity’ (irregular, small field sizes partitioned by abundant hedgerows and high drainage ditch densities) resulting in low field-to-channel connectivity. Variations in suspended sediment yield between catchments were explained primarily by soil permeability and ground cover, whereby arable land use on poorly-drained soils were associated with the largest sediment yields. Storm-event sediment export and sediment fingerprinting data demonstrated that sediment connectivity fluctuations resulted from rainfall seasonality, which in turn regulated the contrasting spatial and temporal extent of surface hydrological pathways. Increased transport occurred when and where sediment sources were available as a result of hillslope land use (low groundcover) or channel characteristics. Field topsoils were most vulnerable when low groundcover coincided with surface hydrological pathways; frequently on poorly-drained soils and following extreme rainfall events on well-drained soils as storage decreased. Although well-drained soils currently demonstrate low water erosion risk, past sugar beet crops exposed freshly drilled soils during periods of greater rainfall risk and soil removal during crop harvesting. Sediment loss from grassland catchments dominated by poorly-drained soils and extensive land drainage (sub-surface and surface) primarily derived from channel banks due to the delivery of high velocity flows from up-catchment drained hillslopes. Catchment specific soil erosion and sediment loss mitigation measures are imperative to cost-effectively preserve or improve soil and freshwater ecosystem quality worldwide.
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Makris, Konstantinos Christos. "Soil and colloidal phosphorous dynamics in three KY soils bioavailability, transport and water quality implications /." Lexington, Ky. : [University of Kentucky Libraries], 2002. http://lib.uky.edu/ETD/ukypssc2003t00069/KCMakris%5FMS%5FThesis.pdf.
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Thesis (M.S.)--University of Kentucky, 2002.<br>Title from document title page. Document formatted into pages; contains xiii, 163 p. :ill. Includes abstract. Includes bibliographical references (p. 152-162).
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Makris, Konstantinos Christos. "SOIL AND COLLOIDAL PHOSPHORUS DYNAMICS IN THREE KY SOILS: BIOAVAILABILITY, TRANSPORT AND WATER QUALITY IMPLICATIONS." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/408.
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Particulate P constitutes a significant portion of the total P found in surface runoff water. Water dispersed P-containing particles can travel long distances via surface runoff and reach water bodies causing decrease in water quality. The main objective of the study was to evaluate the potential facilitation of P transport by the water dispersed soil colloids (WDC) using three KY soils with a long-term record of poultry manure, and fertilizer P applications. Sequential fractionation for both whole soils and colloidal samples revealed that the WDC had a greater total and labile P content than the soil as a whole. Also, application of manure and fertilizer P seemed to decrease colloidal organic P fractions and increase the inorganic P fractions over the period of a growing season (May to September). Laboratory settling kinetics experiments were set up for the clay-colloidal fractions of the soils. It was shown that particulate P fractions paralleled WDC settling kinetics whereas dissolved P fractions remained in solution even after 36 hours. Field taken intact soil cores were leached with colloidal suspensions to test the effect of WDC on the vertical P movement. Results illustrated the preferential flow of particulate P though the macropores. When water was applied to the manure amended soil, dissolved P levels increased significantly over the control. WDC additions lowered dissolved P levels to the manure-amended columns, by sorbing to the WDC particles, but still greater than the dissolved P levels of the columns that had not been applied with manure.
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Dlamini, Musa V. "Short-Term Water Use Dynamics in Drainage Lysimeters." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/5877.
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Turfgrass water use (seasonal turfET) and crop coefficients were determined and a mathematical soil-water balance model for non-weighing drainage lysimeters, which simulates the occurrence (timing and amount) of drainage, was developed. Pairs of non-weighing drainage lysimeters were used to determine crop coefficients for turfgrass in four locations in the state of Utah: Logan Golf and Country Club, Murray Golf Course, Brigham Young University (Spanish Fork) Experiment Farm, and Sunbrook Golf Course (St. George).
Daily weather data including air temperature, relative humidity, average wind travel, total solar radiation, precipitation, and average soil temperature were collected with an electronic weather station at each site. Daily precipitation was measured in three sites throughout the season: Murray, Spanish Fork, and Sunbrook. At Logan Golf and Country Club, precipitation was measured to November 10,2002.
Water use (averages of two lysimeters) during the growing season varied from 684 to 732 mm for three years (2000- 2002) for the mid-April through late-October observation period at Logan Golf Course; 699 mm for May through October at Murray; 469 mm at Spanish Fork; and 896 mm for late-February through early November at Sunbrook, for 2002 growing season. Calculated seasonal Etr using the 82 Kimberly Penman equation with a 1 00-miles-per-day wind travel limit varied from 1166 to 1229 mm at Logan Golf and Country Club, 1067 mm at Murray, 839 mm at Spanish Fork, and 1574 mm at Sunbrook. Seasonal Etr calculated using the PM ASCE std Etr equation was greater than the 82 Kimberly Peru11an . Seasonal Eto calculated using the FAO#56 Eto equation was less than both the 82 Kimberly Penman and the PM ASCE std Etr equations.
Calculated crop coefficients (as a ratio of measured crop water use and calculated potential evapotranspiration) based on alfalfa reference evapotranspiration with the 1982 Kimberly-Penman equation averaged 0.58 for the three years at Logan. Seasonal averages varied from 0.57 to 0.60. Seasonal crop coefficients (2002) were 0.57 for Logan, Spanish Fork, and Sunbrook, and 0.65 for Murray. Short-period crop coefficients also varied within a given season. Short-term crop coefficients derived from a time of wetting and drainage experiment averaged 0.55 at Logan, 0.56 at Murray, 0.60 at Spanish Fork, and 0.56 at Sunbrook.
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Jaumann, Stefan [Verfasser], and Kurt [Akademischer Betreuer] Roth. "Estimation of Soil Water Dynamics Based on Hydrogeophysical Measurements / Stefan Jaumann ; Betreuer: Kurt Roth." Heidelberg : Universitätsbibliothek Heidelberg, 2018. http://d-nb.info/1177385953/34.
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White, II David Allen. "Vegetation Controls on the Dynamics and Quality of Soil Organic Carbon in an Arid, Hyperthermic Ecosystem." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193315.
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Arid lands comprise vast regions of terrestrial land, highlighting the importance of understanding their role in the global carbon cycle. The objective of this study was to determine the effect of Prosopis velutina (mesquite), Larrea tridentata (creosote) and a combination of Bouteloua barbata, Bouteloua aristidoides, Aristida adscensionis, and some Cynodon dactylon (mixed grass) vegetation types on soil organic carbon (SOC) dynamics and quality in an arid, hyperthermic ecosystem of southern Arizona. This was accomplished by quantifying vegetation type control over: (i) local scale SOC stocks; (ii) soil aggregate stability; (iii) SOC turnover and microbial community composition; (iv) the distribution of SOC in physically defined fractions; and (v) the thermal nature and composition of SOC. The results from this study demonstrated significant variation in SOC dynamics and quality between vegetation with potential feedbacks to SOC sequestration of atmospheric CO₂.
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Leuther, Frederic [Verfasser], Hans-Jörg Gutachter] Vogel, and Jörg [Gutachter] [Bachmann. "Impact of treated wastewater irrigation on soil structure and soil water dynamics / Frederic Leuther ; Gutachter: Hans-Jörg Vogel, Jörg Bachmann." Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2019. http://nbn-resolving.de/urn:nbn:de:gbv:3:4-1981185920-140560.
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Leuther, Frederic [Verfasser], Hans-Jörg [Gutachter] Vogel, and Jörg [Gutachter] Bachmann. "Impact of treated wastewater irrigation on soil structure and soil water dynamics / Frederic Leuther ; Gutachter: Hans-Jörg Vogel, Jörg Bachmann." Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2019. http://d-nb.info/1210727757/34.
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Zakharova, Anna. "Soil organic matter dynamics: influence of soil disturbance on labile pools." Thesis, University of Canterbury. School of Biological Sciences, 2014. http://hdl.handle.net/10092/9944.
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Soils are the largest pool of carbon (C) in terrestrial ecosystems and store 1500 Gt of C in their soil organic matter (SOM). SOM is a dynamic, complex and heterogeneous mixture, which influences soil quality through a wide range of soil properties. Labile SOM comprises a small fraction of total SOM (approximately 5%), but due to its rapid turnover has been suggested to be most vulnerable to loss following soil disturbance. This research was undertaken to examine the consequences of soil disturbance on labile SOM, its availability and protection in soils using the isotopic analysis of soil-respired CO₂ (δ¹³CO₂).
A range of soils were incubated in both the short- (minutes) and long-term (months) to assess changes in labile SOM. Shifts in soil-respired δ¹³CO₂ over the course of soil incubations were found to reflect changes in labile substrate utilisation. There was a rapid depletion of δ¹³CO₂ (from a starting range between -22.5 and -23.9‰, to between -25.8 and -27.5‰) immediately after soil sampling. These initial changes in δ¹³CO₂ indicated an increased availability of labile SOM following the disturbance of coring the soil and starting the incubations. Subsequently δ¹³CO₂ reverted back to the initial, relatively enriched starting values, but this took several months and was due to labile SOM pools becoming exhausted.
A subsequent study was undertaken to test if soil-respired δ¹³CO₂ values are a direct function of the amount of labile SOM and soil physical conditions. A range of pasture soils were incubated in the short-term (300 minutes), and changes in soil-respired δ¹³CO₂ were measured along with physical and chemical soil properties. Equilibrium soil-respired δ¹³CO₂, observed after the initial rapid depletion and stabilisation, was a function of the amount of labile SOM (measured as hot water extractable C, HWEC), total soil C and soil protection capacity (measured as specific soil surface area, SSA). An independent experimental approach to assess the effect of SSA, where labile SOM was immobilised onto allophane – a clay mineral with large, active surface area – indicated limited availability of labile SOM through more enriched δ¹³CO₂ (in a range between -20.5 and -20.6 ‰) and a significant (up to three times) reduction in HWEC.
In the third study, isotopic measurements were coupled with CO₂ evolution rates to directly test whether equilibrium soil-respired δ¹³CO₂ can reflect labile SOM vulnerability to loss. Soils were sampled from an experimental tillage trial with different management treatments (chemical fallow, arable cropping and permanent pasture) with a range of C inputs and soil disturbance regimes. Soils were incubated in the short- (300 minutes) and long-term (600 days) and changes in δ¹³CO₂ and respiration rates measured. Physical and chemical fractionation methods were used to quantify the amount of labile SOM. Pasture soils were characterised by higher labile SOM estimates (HWEC; sand-sized C; labile C respired during long-term incubations) than the other soils. Long-term absence of plant inputs in fallow soils resulted in a significant depletion of labile SOM (close to 50% based on sand-sized C and HWEC estimates) compared with pasture soils. The values of δ¹³CO₂ became more depleted in 13C from fallow to pasture soils (from -26.3 ‰ to -28.1 ‰) and, when standardised (against the isotopic composition of the solid soil material), Δ¹³CO₂ values also showed a decrease from fallow to pasture soils (from -0.3 ‰ to -1.1 ‰). Moreover, these patterns in isotopic measures were in strong agreement with the amount of labile SOM and its availability across the soils, and were best explained by the isotopic values of the labile HWEC fraction.
Collectively, these results confirm that labile SOM availability and utilisation change immediately after soil disturbance. Moreover, isotopic analysis of soil-respired CO₂ is a powerful technique, which enables us to probe mechanisms and examine the consequences of soil disturbance on labile SOM by reflecting its availability and the degree of SOM protection.
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Balasubrahmanyam, Sunil K. "Environmental dynamics of Benomyl and Thiabendazole." Thesis, Virginia Tech, 1986. http://hdl.handle.net/10919/50496.
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The comprehensive environmental dynamics of the heterocyclic Benzimidazole fungicides, Benomyl and Thiabendazole was investigated. This included examining their fate and distribution in the terrestrial and aquatic phases of a laboratory microcosm comprised of silty clay loam soil and plants. The soil component constituted a major relocation site, with approximately 45 and 75% of initial Benomyl (recovered as MBC) and Thiabendazole concentrations being recovered from the soil component of the microcosm, respectively, while 53 and 27% translocated into corn plants. The adsorption mechanism/s of these fungicides onto soil components were investigated using silty clay loam, silty loam and sandy soils as well as Ca-bentonite. These studies indicated that both fungicides were adsorbed to the highest degree on silty clay loam, followed by silty loam and sandy soils. Their adsorption on Ca-bentonite was found to be a function of the pH of the suspension, suggesting that in the presence of increasing ll *activity on the clay surfaces, Benomyl and Thiabendazole become protonated to form positively charged molecules. These may then react with the clay surfaces forming Fungicide-clay complexes. The effect of different CaCl, concentrations on the adsorption process demonstrated that an increase in the salt concentration, at a constant pH resulted in a decrease in the amounts of adsorbed fungicide. The transport of the fungicides (adsorbed onto soil particles) as a consequence of scdiment runoff into aquatic systems was also estimated. Results of the simulation of overland sediment runoff from sections of the Chowan river basin into the Meherrin river following a rainstorm, indicate that significant quantities of Benomyl and Thiabendazole could be transported into aquatic systems. Adsorption studies also indicated that the adsorption process is reversible. Thus, any significant increases in the pH of receiving bodies of water could result in the release of Benomyl and Thiabendazole from sediment causing a contamination of the aquatic system.<br>Master of Science
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Uddin, S. M. Mijan. "Understanding soil water repellency under native vegetation in Australia: An empirical and molecular dynamics approach." Thesis, Uddin, S. M. Mijan (2017) Understanding soil water repellency under native vegetation in Australia: An empirical and molecular dynamics approach. PhD thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/40269/.
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Soil water repellency (SWR) is a major land management issue across southern Australia and inhibits the infiltration of water into soil with effects on the germination of crops and pastures and run-off in agricultural and forested land. SWR is a natural phenomenon and generally occurs in the surface layers of sandy soils where hydrophobic materials mostly of plant origin occur as particulate organic matter and as waxy coatings on soil particles. Although its incidence and severity have been anecdotally related to the previous native vegetation little is known about the specific organic compounds that may derive from this vegetation. Previous studies have concentrated on characterizing the contribution of soil organic matter, and this and the fact that soils are complex mixtures of a broad range of organic components may have obscured the contribution of a small concentration of compounds from the native species to SWR. Moreover, the precise distribution of these compounds (e.g., as coatings or in interstices between soil particles) and their contribution to SWR has not been quantified.
Although analysis of soil solvent extracts can identify the relative amounts of individual compounds, it is often difficult to determine the relative importance of all components in inducing SWR. It is even harder to determine synergistic effects from combinations of components. Experimental studies provide a broad understanding of the bulk effects of hydrophobic molecular coatings but do not provide a molecular level understanding of the coating structure or of its kinetic and/or thermodynamic stability. The molecular arrangement of those organic compounds on the soil particles have been shown to have implications for both the incidence and dynamics of SWR. Thus the present study employed a range of approches to understand SWR in native vegetation: i) quantifying the contribution of canopy derived exudates from native tree species to SWR, ii) discerning the contribution of organic matter in different pools (e.g., on particle surfaces, as interstitial matter) to SWR and iii) examining the physical interaction of the organic molecules (without and with water) with soil mineral surfaces.
Canopy derived exudates were captured using an improvised technique, and organic compounds were extracted using nonpolar and polar solvents. In order to discern the contribution of different carbon pools to SWR, soils were separated into mineral and interstitial matter. Soils were extracted using a sonication technique. Individual and combinations of compounds were loaded onto acid washed sand (AWS) using a rotary evaporator. This experimental loading and measurement was complemented by fully atomistic molecular dynamics simulations with Materials Studio v 7.0 to understand the physical interaction of the molecules with mineral surfaces.
A range of different organic compounds that are widely reported in the incidence of SWR were detected in the canopy derived exudates and soil extracts. They were mostly long-chain alkanes, fatty acids, phytols, phytanols, amides, aldehydes, ketones, terpenoids, steroids, and some complex ring containing structures. Though there was similarity in the composition of both the nonpolar and polar compounds of exudates of Banksia menziesii, Eucalyptus marginata, Xanthorrhoea preissii and Allocasuarina fraseriana, the concentration level of the chemical species was found to be significantly different. The concentrations were found to differ over the sampling period. For example, docosanoic acid was found to be dominant in the summer for B. menziesii and X. preissii. while in E. marginata and A. fraseriana it was evident in the winter.
Moreover, the concentration level of the chemical species derived from the soil extracts were also found to be significantly different between the species of A. fraseriana, E. marginata, E. wandoo and B. menziesii. Notably, the main difference between A. fraseriana and the other three species (E. marginata, E. wandoo and B. menziesii) was the presence of long chain fatty acids and fatty alcohols. The concentration of the compounds was even different in different soil components (e.g., minerals and interstitial matter) of the soil matrix. For example, the concentration level of the individual compound derived from the bulk soil was similar to the total concentration level of the compound derived from both the coarse mineral materials and interstitial matters.
The molecular level arrangement of various hydrophobic molecules with mineral surfaces also varied. For example, amphiphilic molecules at surface density of 2.3 molecs/nm2 were found in a tilted arrangement on kaolinite while on quartz surfaces they formed layered arrangements. However, silica did not favor a certain order of arrangement of the molecules due to its amorphous surface. The surface characteristics and polarity (abundance of OH groups) of the substrate (kaolinite > silica) were found to significantly modify the organo-mineral interactions. Different biogenic volatile organic compounds (BVOCs) or terpenoids commonly observed in vegetation smoke or forest fire, were not found to induce SWR. Moreover, the long chain amphiphilic molecules exhibited a balance between molecule-molecule and molecule-surface interactions on the quartz surface that supported surface adhesion, which in turn led to the formation of a hydrophobic layer. Furthermore, soil moisture or the addition of water molecules was found to significantly modify the conformation of molecules at the organo-mineral interfaces. For example, the polar kaolinite and silica surfaces were found to easily wet-up and reorganization of amphiphilic molecules on the surfaces took place following aquation. The stronger interaction between water and organic molecules can thus be inversely correlated to organo-mineral interaction on soil particles.
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Shepherd, Greg William. "A comparative agroecosystems analysis of soil water and root dynamics under six different vegetative cover types." [Ames, Iowa : Iowa State University], 2006.
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Poltoradnev, Maksim [Verfasser], and Thilo [Akademischer Betreuer] Streck. "Measuring and modelling of soil water dynamics in two German landscapes / Maksim Poltoradnev ; Betreuer: Thilo Streck." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2018. http://d-nb.info/1160301867/34.
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Livesley, Stephen. "The distribution and dynamics of roots and soil nitrogen and water in tree row agroforestry systems." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285967.
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WEHR, RACHEL NICOLE. "LONG-TERM PRECIPITATION TRENDS OF TWO UNIQUELY WATER-LIMITED ECOSYSTEMS: IMPLICATIONS FOR FUTURE SOIL MOISTURE DYNAMICS." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/614199.
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Roughly 40% of the Earth’s land surface is classified as arid or semiarid. These areas are expected to see changes in the frequency and magnitude of precipitation, which could have major implications for soil water resources, vegetation, water supply, and biome evolution. This study analyzed long-term precipitation trends in two water-limited ecosystems with bimodal precipitation regimes: a desert shrubland at the Santa Rita Experimental Range (SRER-SRC) and a mixed conifer system at the Santa Catalina Mountain Critical Zone Observatory (SCM-CZO). Specifically, we analyzed frequency and timing of precipitation in summer and non-summer seasons and compared seasonal precipitation patterns to soil moisture dynamics. Our study shows declining precipitation over the past few decades at both locations, with significant decreases in non-summer precipitation driving decreases in annual precipitation. We show that shallow soil moisture responds to storms of all sizes, and the deep layer responds to large storms or a series of small storms at both sites. Shallow soil moisture is especially vulnerable at SRER-SRC as a result of exponential water loss following a large storm. We expect that declining precipitation will have major implications for soil water resources and the healthy functioning of water-limited ecosystems.
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This work is being further developed for future publication in the Water Resources Research journal in close collaboration with Shirley Papuga (University of Arizona) and Aloah Pope (University of Arizona).
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van, Quang Pham. "Soil formation and soil moisture dynamics in agriculture fields in the Mekong Delta, Vietnam conceptual and numerical models." Licentiate thesis, KTH, Land and Water Resources Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10508.
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<p>Previous studies of agricultural conditions in the Mekong Delta (MD) have identified soil compaction as an obstacle to sustainable production. A conceptual model for soil formation was presented to demonstrate the link between soil hydrology and plant response. Detailed studies of soil moisture dynamics in agricultural fields were conducted using a dynamic process-orientated model. Pressure head and water flow were simulated for three selected sites during a year for which empirical data were available. Daily meteorological data were used as dynamic input and measured pressure head was used to estimate parameter values that satisfied various acceptance criteria. The Generalised Likelihood Uncertainty Estimation (GLUE) approach was applied for calibration procedures with 10,000 runs, each run using random values within the chosen range of parameter values. To evaluate model performance and uncertainty estimation, re-sampling was carried out using coefficient of determination (R2) and mean error (ME) as the criteria. Correlations between parameters and R2 (and ME) and among parameters were also considered to analyse the relationship of the selected parameter set in response to increases/decreases in the acceptable simulations. The method was successful for two of the three sites, with many accepted simulations. For these sites, the uncertainty was reduced and it was possible to quantify the importance of the different parameters.</p><p> </p>
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da, Silva Cerozi Brunno, and Silva Cerozi Brunno da. "Phosphorus Dynamics, Mass Balance and Mineralization in Aquaponics Systems." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/620832.
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This study involves tracing inputs, partitioning, and outputs of phosphorus (P) through an aquaponics system. A mathematical model was developed to describe the dynamics of phosphorus in an aquaponics nutrient solution, and to maximize P use efficiency and minimize P waste. We assessed the influence of pH on the availability and speciation of phosphorus in an aquaponics nutrient solution. By using Visual MINTEQ, a freeware chemical equilibrium model for the calculation of element speciation, solubility equilibria, and sorption for natural waters, it was discovered that high pH values favor the formation of calcium phosphate complexes, decreasing the concentration of free phosphorus in aquaponics nutrient solutions. In addition, the mineralization of organic phosphorus in aquaponics systems was evaluated using treatments with phytase supplementation to fish diets, and incorporation of a microbial inoculant in the aquaponics nutrient solution. Overall, dietary phytase and microorganisms promoted phosphorus mineralization and enhanced phosphorus utilization in aquaponics systems. In the end, we conclude that aquaponics systems can keep the same growth performance and quality of vegetable crops grown in conventional systems when the availability and dynamics of phosphorus are well managed.
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Leighton-Boyce, G. "Spatio-temporal dynamics and hydrogeomorphic implications of soil water repellency within Eucalyptus forests in north-central Portugal." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637874.
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This thesis investigates spatio-temporal variations in soil water repellency and their hydrogeomorphic effects within eucalyptus plantations in north-central Portugal. Rainfall simulation with and without wetting agents were used to quantify the effects of repellency on overland flow, slopewash, splash detachment and wetting patterns at the small-plot scale on long-unburnt and recently burnt terrain. Monitoring over 16-months (>9000 paired repellency and soil moisture measurements) was carried out at four different sites at meso-(2 m) and micro-scales (10 cm) to establish spatio-temporal repellency patterns. Repellency increased overland flow generation 16-fold on unburnt terrain at the small-plot scale. Responses on burnt terrain were similarly enhanced with a mean overland flow coefficient of 70% being recorded. Where present, eucalyptus litter layer greatly reduced overland flow and erosions by providing considerable moisture storage and protection. Repellency extent varied seasonally, being widespread following prolonged dry periods and minimal following prolonged wet periods. At its maximum, it was spatially contiguous under 10-year-old eucalyptus stands, but discontinuous under younger stands (d5 years). Discontinuously repellent terrain included wettable soil columns dispersed over the slope area. Regardless of season or extent of repellency, where repellency was recorded it was mainly of extreme severity (³36% Ethanol). Repellency begins to break down following >50 mm but d140 mm rainfall and may become re-established (from minimal extent to contiguous surface repellency) after d22 days of generally dry weather. Where soils were continuously repellent following long dry periods, these soils were wettable at moisture contents ³275 vol. and repellent at d145 vol. Between these thresholds soils could be wettable or repellent. Implications of the spatio-temporal repellency patterns found for slope and catchment hydrogeomorphic responses are explored.
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Walecka-Hutchison, Claudia Walworth James L. "Nitrogen dynamics in diesel biodegradation effects of water potential, soil C:N ratios, and nitrogen cycling on biodegradation efficacy /." FIND on the Web, 2005.
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Thesis (Ph. D. - Soil, Water, and Environmental Science)--University of Arizona.<br>Appendix A - Hydrocarbon biodegradation rates and water potential in nitrogen augmented desert soils, by Claudia Walecka-Hutchison and James L. Walworth ; Appendix B - Assessment of C:N ratios and water potential for nitrogen optimization in diesel bioremediation, by Claudia Walecka-Hutchison and James L. Walworth ; Appendix C - Evaluating the effects of gross nitrogen mineralization, immobilization and nitrification on nitrogen fertilizer availability during diesel biodegradation, by Claudia Walecka-Hutchison and James L. Walworth. Includes bibliographical references (leaves 71-82) and appendices.
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Pinto, Victor Meriguetti. "Simulation of water and nitrogen dynamics in a Cerrado soil under coffee cultivation using SWAP and ANIMO models." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/64/64134/tde-02022016-105753/.
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Agriculture when only focused on production leads to an unsustainable use of inputs with negative consequences to the environment and human health. One consequence of the excessive use of fertilizers is the pollution of surface and underground water resources in agricultural eco-systems and their boundaries. The Brazilian Cerrado has been suffering the transformations of the intensive agriculture during the last decades. Due to the poor fertility of soils, in general very sandy and of low pH, the use of agricultural inputs is intensified and the nutrient downward transport by leaching becomes a serious problem in different regions. Information about the current use practices of fertilizer use in the Cerrado environment must be gathered for a healthy transition of this biome. Models based on physical and chemical processes are useful tools to simulate water and nutrient dynamics in agricultural systems, including the related losses due to adopted managements. They have the potential to evaluate different scenarios to predict outcomings of such practices. Among the available models for such processes, SWAP (Soil, Water, Atmosphere and Plant model) has been used under several agronomic conditions to describe hydrologic processes, and ANIMO (Nitrogen in Agriculture model) to simulate N cycling in agricultural systems. Our study presents an application of SWAP to adult perennial coffee crops along one productive cycle, with focus on deep drainage losses and irrigation management in a representative Brazilian Cerrado management system. The SWAP/ANIMO combination was used in this study to simulate N absorption by coffee plants and N leaching in the form NO3-N, as a result of an intensive fertilizer management practice. The ANIMO program was calibrated in relation to one N treatment, of 400 kg ha-1 year-1, and was evaluated with independent data of NO3-N in soil solution of another treatment of 800 kg ha-1 year-1. The yearly water balance (WB) obtained from SWAP was similar to that obtained through a sequential climatologic WB of Thornthwaite and Matter. However, the monthly deep drainage values obtained by SWAP as compared to the WB values presented differences with a determination coefficient of 0.77 in a linearization of the results. Irrigation scenarios with intervals of 3(IF3), 5(IF5), 10 (IF10) e 15 (IF15) days between water applications were simulated by SWAP and compared with the irrigation management practiced in the farm where the experiment was carried out. These simulations showed for longer intervals (IF15) drainage losses were smaller, water productivity higher, as well as relative productivity. Measurements of N absorption by plants obtained experimentally were similar to ANIMO simulations. Sensitivity analyses of the model showed that leaching and soil solution concentration of NO3-N are sensitive to soil pH and temperature of the decomposition processes. We conclude that the combination of SWAP with ANIMO was efficient for the description of the N cycle in a Cerrado soil-plant-atmosphere system<br>A agricultura focada apenas na produção leva ao uso insustentável de recursos resultando em consequências negativas para o meio ambiente e a saúde humana. Uma consequência do uso excessivo de fertilizantes é a contaminação dos recursos hídricos subterrâneos e superficiais em ecossistemas agrícolas e nos seus arredores. Devido o solo da região do Cerrado ser pobre em nutrientes, predominantemente arenoso e com alta acidez, o uso de insumos agrícolas é intensificado e o transporte químico de nutrientes via lixiviação é um problema para a agricultura intensiva nas diferentes regiões. Informações sobre as atuais práticas de uso de fertilizantes e seus efeitos no ambiente de Cerrado precisam ser coletadas para reduzir os impactos da agricultura nesse ecossistema. Modelos baseados em processos físicos e químicos são ferramentas úteis para simular a dinâmica da água e nutrientes no meio agrícola e as perdas associadas aos manejos adotados, com potencial para avaliar diferentes cenários de previsão dos resultados dessas práticas. Entre os modelos baseados em processos, o SWAP (modelo Solo, Água, Atmosfera e Planta) tem sido utilizado com sucesso em várias condições agronômicas para descrever processos hídricos, e o ANIMO (modelo de nitrogênio na agricultura) para simular o ciclo do nitrogênio em sistemas agrícolas. Nosso estudo apresenta uma aplicação do SWAP para culturas de café perenes maduras ao longo de um ciclo produtivo, com foco nas perdas por drenagem e no manejo da irrigação em um sistema típico do Cerrado Brasileiro. A combinação dos modelos SWAP/ANIMO foi utilizada nesse estudo para simular a absorção de N pelas plantas de café e a lixiviação do nitrogênio na forma de nitrato (NO3-N) resultante de uma prática de manejo de fertilizantes intensiva. O ANIMO foi calibrado para o cenário correspondente à aplicação de 400 kg ha-1 ano-1 de fertilizante mineral, e foi avaliado com dados independentes de NO3-N na solução do solo medidos em parcelas de outro tratamento que receberam 800 kg ha-1 ano-1. O balanço hídrico anual obtido pelo SWAP foi semelhante ao obtido pelo balanço sequencial climatológico, de Thornthwaite e Matter. No entanto, os valores mensais de drenagem profunda obtidos pelo SWAP e comparados com os resultados do balanço climatológico apresentaram diferenças, com um coeficiente de determinação de 0,77 na linearização dos resultados. Cenários de irrigação com intervalos de 3 (IF3), 5 (IF5), 10 (IF10) e 15 (IF15) dias entre aplicações de água foram simulados utilizando o SWAP e comparados com a prática de manejo da fazenda onde o estudo experimental foi realizado. As simulações dos cenários com o SWAP mostraram que as irrigações com intervalos mais longos (IF15) apresentam menores quantidades de perdas por drenagem, maior produtividade da água e produtividade relativa da cultura. As medidas de absorção de N pelas plantas obtidas experimentalmente foram similares às estimativas do modelo ANIMO. As analises de sensibilidade do modelo mostraram que as previsões da lixiviação e concentração de NO3-N na solução do solo são sensíveis às variáveis pH do solo e temperatura de referência dos processos de decomposição. Conclui-se que a combinação dos modelos unidimensionais baseados em processos SWAP/ANIMO foi eficaz na descrição do ciclo do N avaliado no sistema solo-planta do Cerrado
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Walecka-Hutchison, Claudia. "Nitrogen dynamics in diesel biodegradation : effects of water potential, soil C:N ratios, and nitrogen cycling on biodegradation efficacy." Diss., The University of Arizona, 2005. http://hdl.handle.net/10150/191274.
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Respirometric experiments were performed to evaluate the role of nitrogen in aerobic diesel biodegradation. Specific objectives included 1) evaluating the effects of water potential induced by various nitrogen amendments on diesel biodegradation rates in arid region soils, 2) comparing concurrent effects of C:N ratios and soil water potential on diesel degradation rates, and 3), measuring gross rates of nitrogen cycling processes in diesel-contaminated soil to determine duration of fertilizer bioavailability. In all studies, increasing nitrogen fertilization resulted in a decrease in total water potential and correlated with an increase in lag phase and overall reduction in microbial respiration. Highest respiration and estimated diesel degradation was observed in the 250 mg N/kg soil treatments regardless of diesel concentration, nitrogen source, or soil used, suggesting an inhibitory osmotic effect from higher rates of nitrogen application. The depression of water potential resulting in a 50% reduction in respiration was much greater than that observed in humid region soil, suggesting higher salt tolerance by microbial populations of arid region soils. Due to the dependence on contaminant concentrations, use of C:N ratios was problematic in optimizing nitrogen augmentation, leading to over-fertilization in highly contaminated soils. Optimal C:N levels among those tested were 17:1, 34:1, and 68:1 for 5,000, 10,000 and 20,000 mg/kg diesel treatments respectively. Determining nitrogen augmentation on the basis of soil pore water nitrogen (mg N/kg soil H₂0) is independent of hydrocarbon concentration but takes into account soil moisture content. In the soil studied, optimal nitrogen fertilization was observed at an average soil pore water nitrogen level of 1950 mg N/kg H₂0 at all levels of diesel contamination. Based on the nitrogen transformation rates estimated, the duration of fertilizer contribution to the inorganic nitrogen pool at 5,000 mg/kg diesel was estimated at 0.9, 1.9, and 3.2 years in the 250, 500, and 1000 mg/kg nitrogen treatments respectively. The estimation was conservative as ammonium fixation, gross nitrogen immobilization, and nitrification were assumed as losses of fertilizer with only gross mineralization of native organic nitrogen contributing to the most active portion of the nitrogen pool.
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Bonita, John Anthony. "The Effects of Vibration on the Penetration Resistance and Pore Water Pressure in Sands." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29417.
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The current approach for using cone penetration test data to estimate soil behavior during seismic loading involves the comparison of the seismic stresses imparted into a soil mass during an earthquake to the penetration resistance measured during an in-situ test. The approach involves an indirect empirical correlation of soil density and other soil related parameters to the behavior of the soil during the loading and does not involve a direct measurement of the dynamic behavior of the soil in-situ. The objective of this research was to develop an approach for evaluating the in-situ behavior of soil during dynamic loading directly through the use of a vibrating piezocone penetrometer.
Cone penetration tests were performed in a large calibration chamber in saturated sand samples prepared at different densities and stress levels. A total of 118 tests were performed as part of the study. The piezocone penetrometer used in the investigation was subjected to a vibratory load during the penetration test. The vibratory units used in the investigations were mounted on top of a 1m section of drill rod that was attached at the lower end to the cone penetrometer. Pneumatic impact, rotary turbine, and counter rotating mass vibrators were used in the investigation. The vibration properties generated by the vibratory unit and imparted into the soil were measured during the penetration test by a series of load cells and accelerometers mounted below the vibrator and above the cone penetrometer, respectively. The tip resistance, sleeve friction and pore water pressure were also measured during the test by load cells and transducers in the cone itself.
The vibration and cone data were compiled and compared to evaluate the effect of the vibration on the penetration resistance and pore water pressure in the soil mass. The results of the testing revealed that the influence of the vibration on the penetration resistance value decreased as the density and the mean effective stress in the soil increased, mainly because the pore water pressure was not significantly elevated throughout the entire zone of influence of the cone penetometer at the elevated stress and density conditions. An analysis of the soil response during the testing resulted in the generation of a family of curves that relates the soil response during the vibratory and static penetration to the vertical effective stress and density of the soil. The data used to generate the curves seem to agree with the proposed values estimated through the empirical relationship. An evaluation of the effects of the frequency of vibration was also performed as part of the study. The largest reduction in penetration resistance occurred when the input vibration approximated the natural frequency of the soil deposit, suggesting that resonance conditions existed between the input motion and the soil. An energy-based approach was developed to compare the energy imparted into the soil by the vibrator to the energy capacity of the soil. The input energy introduced into the soil mass prior to the reduction in penetration resistance agrees well with the energy capacity of the soil, especially in tests at the low effective stress level where a high excess pore water pressure was observed.<br>Ph. D.
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Ferreira, Nicole Costa Resende. "Effects of climate change on corn: numerical simulation of soil water dynamics in a corn crop in Illinois (USA)." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-16032018-123509/.
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Given the importance of climate conditions in the agricultural environment, more specifically in the transport of water in the soil, there is a need to understand the effects of climate change on the water dynamics in the soil. This influence of climate conditions in the agricultural environment seems to be important in evapotranspiration, water availability for plants and roots, and for other processes. Many theoretical models have been developed to characterize the physical processes involved in water and transport. Climate prediction models such as the suite of models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) make it possible generate climate data that can be used to characterize physical and biological processes. This research focuses on two main aspects: 1) the effects of climate change on the occurrence of extreme events that may affect agricultural processes in the region of Urbana-Champaign, in Illinois (USA) and 2) the effects of climate change on the dynamic of soil water in a corn crop (two fields, ANW and ASW) in the studied area. To explore the impacts of climate change on the occurrence of extreme events, the errors of some climate models from CMIP5 were evaluated and the models were subsequently used to develop indices to represent the occurrence of extreme events. These indices were calculated from observed data, and historical and future simulations, considering pessimistic and optimistic scenarios of climate change. The model that best represents the climate in the region was used to provide input data for Hydrus simulation of the soil water dynamics in two fields with different drainage system layout. These simulations with the Hydrus model were made for current conditions and for near term, midcentury, and end of century time periods (2011-2040, 2041-2070, 2071-2100, respectively). The results indicate that the variation of precipitation in the future may result in increased in one (RX1DAY) and five days (RX5DAY) maximum precipitation, and in the number of consecutive dry days (CDD) and consecutive wet days (CWD). Changes in temperature will be reflected as an increase of the indices of maximum and minimum values of temperatures and summer days (TNn, TNx, TXn, TXx and SU); and decreasing of the index of icing and frost days (ID, FD). This increasing of temperatures will represent a risk for agriculture, due to increased evapotranspiration, which will increase crop water demand and can create a hydric stress. Results of Hydrus simulations of surface flux, cumulative surface flux, runoff, cumulative runoff, soil water storage and cumulative infiltration, with input data from the IPSL model, are presented. These variables are critical in a corn crop, and are dependent on climate variables, soil conditions, parameters of the study region, drainage system, crop characteristics, inter alia. The ANW field had lower values of surface flux and cumulative surface flux comparing to the ASW field. This results is indicative that the risk associated with the ASW drainage system layout is higher than that of the ANW drainage system layout, related to the wider spacing between drains and the difficulty in removing water at the required rate. In general, the maximum and average values of surface flux and cumulative surface flux, will increase over time. In addition, it is noticeable that all Hydrus simulation indicates increasing maximum surface runoff and cumulative surface runoff over time. Percentile changes in average runoff and cumulative runoff are dependent on the period simulated. Increases range from 5.61 to 24.4% in the short term (2011-2040), 16.45 to 39.32% in the medium term (2041-2070) and 3.32 to 19.98% in the long term (2071-2100) compared to historical simulation. The maximum values of infiltration tend to be higher in all simulations when compared to the reference period in both fields. Changes in cumulative infiltration are indicative that infiltration will increase in the future. With respect to the correlation between runoff and extreme events, all simulations showed that the correlation between runoff and extreme precipitation events (RX1DAY ranges between 0.76 and 0.78, and RX5DAY ranges between 0.5 and 0.66), are higher than the correlation between runoff and precipitation (ranges between 0.31 and 0.43). This approach can improve the understanding of climate changes impacts on sustainable groundwater management based on adaptive management. Information gained in this work can be used to design monitoring systems to manage a sustainable groundwater in future climate regimes and create mitigation measures to prevent any risk for food security. An implication of the study is that the impact of climate change on water resources is a function of the projection scenario. The study was limited by the use of daily time step, necessitated by the large data sets.<br>Dada a importância das condições climáticas no ambiente agrícola, mais especificamente no transporte de água, é necessário compreender o efeito da mudança climática dinâmica da água no solo. Muitos modelos teóricos foram desenvolvidos para caracterizar os processos físicos envolvidos no transporte da água. Os modelos de previsão climática, como o conjunto de modelos do CMIP5, permitem gerar dados climáticos que podem ser usados para caracterizar processos físicos e biológicos. Esta pesquisa foca em dois aspectos principais: 1) efeito das mudanças climáticas na ocorrência de eventos extremos que podem afetar os processos agrícolas na região e 2) efeitos das mudanças climáticas na dinâmica da água no solo sob uma cultura de milho (dois campos experimentais, ANW e ASW) em uma região de Illinois (EUA). Os resultados encontrados indicam que a variação da precipitação no futuro pode causar o aumento de RX1DAY, RX5DAY, CDD e CWD. Considerando os eventos extremos de temperatura, percebemos que o aumento da temperatura média, máxima e mínima será refletido no aumento dos indices TNn, TNx, TXn, TXx e SU; e na diminuição dos indices ID e FD. Este aumento de temperaturas representará um risco para a agricultura considerando a evapotranspiração, que aumentará a necessidade de água das plantas e poderá criar um estresse hídrico. Os resultados apresentam as simulações do modelo IPSL aplicado no modelo Hydrus para simular, fluxo superficial, fluxo superficial acumulado, escoamento superficial, escoamento superficial acumulado, armazenamento de água do solo e infiltração acumulada. Essas variáveis são importantes na produção de milho e são função das variáveis climáticas, condições do solo e também alguns parâmetros da região de estudo, como o sistema de drenagem, as características da cultura e outros. O campo ANW apresentou valores mais baixos de fluxo superficial em comparação ao campo ASW. Isso indica que o risco associado ao sistema de drenagem ASW é maior que o ANW, que está relacionado ao maior espaçamento entre os drenos e a dificuldade em drenar a quantidade necessária de água. A tendência do fluxo superficial e do fluxo cumulativo de superfície, em geral, é de aumento em cenários de mudanças climáticas (em valores máximos e médios). Também é notável que toda a simulação indica o aumento do escoamento superficial em termos de valores máximos. O percentil de mudanças nos valores médios de escoamento mostra que a projeção climática tende a aumentar o escoamento superficial em diferentes cenários de simulação. Esta faixa crescente é de 5,61 a 24,4% em curto prazo (2011-2040), 16,45 a 39,32% em médio prazo (2041-2070) e 3,32 a 19,98% em longo prazo (2071-2100) em relação à simulação histórica (1976-2005). Os valores máximos de infiltração tendem a ser maiores em todas as simulações quando comparados ao período de referência (em ambos os campos). Além disso, mudanças na infiltração acumulada indicam que a infiltração média tende a aumentar no futuro. Considerando a correlação entre o escoamento superficial e os eventos de extremos climáticos, todas as simulações indicaram que a correlação entre o escoamento e os eventos extremos de precipitação RX1DAY (varia entre 0,76 e 0,78) e RX5DAY (varia entre 0,5 e 0,66), sendo estas maiores do que a correlação entre o escoamento superficial e a precipitação (intervalos entre 0,31 e 0,43). Conclui-se, portanto, que a ocorrência de eventos de extremos climáticos está mais associada as variáveis estudadas do que a condição climática em si, tendo impactos diretos na agricultura. O estudo mostra diferentes indicações do impacto das mudanças climáticas no recurso hídrico usando diferentes projeções. Uma dificuldade da pesquisa é sobre a grande quantidade de dados ea necessidade de tempo de passagem diário para a integração de variáveis. Esta abordagem pode melhorar a compreensão dos impactos das mudanças climáticas na gestão sustentável das águas subterrâneas com base no gerenciamento adaptativo. As informações obtidas neste trabalho podem ser usadas para projetar sistemas de monitoramento para gerenciar águas subterrâneas de maneira sustentável em regimes climáticos futuros e criar medidas de mitigação para garantir a segurança alimentar.
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Hasnat, Abul, University of Western Sydney, of Science Technology and Environment College, and School of Environment and Agriculture. "Soil-water use and irrigation scheduling under fruit tree-turf alley cropping system in Hawkesbury Area." THESIS_CSTE_EAG_Hasnat_A.xml, 2003. http://handle.uws.edu.au:8081/1959.7/614.
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Efficient use of irrigation and nutrients are becoming increasingly important in commercial orchards in the Hawkesbury area. Proper irrigation scheduling practices can help in the better use of irrigation water and reduce environmental impacts. Field experiments were conducted during February 1999 to June 2000 to understand soil-water use, and to evaluate farmer’s irrigation practice under an alley cropping system consisting of turf and stone fruits. The study was carried out at Atlas Farm, 3.5 km from the University of Western Sydney, Hawkesbury campus. The experimental site is a floodplain of the Hawkesbury River. The river flows within 1 km of the farm boundaries. The study was conducted under the farmer’s existing irrigation water and nutrient management practices. The main aims of the thesis were to study the movement and redistribution of soil-water and soil-moisture dynamics in the turf and stone fruit alley cropping system and to understand deep percolation losses and nitrogen leaching using the water balance approach. The study indicated that drainage occurred mainly after heavy rainfall and when there was rainfall for a few consecutive days. Thus irrigation application should be delayed if there is a likelihood of rain in a few consecutive days to prevent loss of water due to deep drainage. Furthermore, the study showed irrigation scheduling was essential to reduce nitrate leaching in the field; that irrigation depths should be varied according to the stage of crop growth, and the proper timing of irrigation application could help reduce deep percolation and runoff losses.<br>Master of Science (Hons) (Agriculture)
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DAYANTHI, WANNIARACHCHI KANKANAMGE CHANDRANI NEETHA. "ANALYSIS OF NITROGEN DYNAMICS IN SOIL COLUMNS TO EVALUATE NITRATE POLLUTION DUE TO RECLAIMED WASTEWATER IRRIGATION." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/49139.
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学位授与大学：京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2851号 ; 請求記号: 新制/工/1419 ; 整理番号: 25536<br>Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(工学)<br>甲第13380号<br>工博第2851号<br>新制||工||1419(附属図書館)<br>25536<br>UT51-2007-Q781<br>京都大学大学院工学研究科都市環境工学専攻<br>(主査)教授 田中 宏明, 教授 藤井 滋穂, 教授 清水 芳久<br>学位規則第4条第1項該当
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Benard, Pascal [Verfasser], and Andrea [Akademischer Betreuer] Carminati. "Microhydrological niches in soils : how mucilage and EPS alter soil hydraulic properties and water dynamics / Pascal Benard ; Betreuer: Andrea Carminati." Bayreuth : Universität Bayreuth, 2020. http://d-nb.info/1209196573/34.
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Marryanna, Lion. "Effects of spatio-temporal distribution of soil moisture on a lowland dipterocarp forest at Pasoh Forest Reserve in Peninsular Malaysia." Kyoto University, 2018. http://hdl.handle.net/2433/232153.
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Villalobos-Vega, Randol. "Water Table and Nutrient Dynamics in Neotropical Savannas and Wetland Ecosystems." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/389.
Full textAbstract:
The Tropical savannas of central Brazil (cerrado) and the Everglades wetland (Florida) ecosystems are ideal systems to study landscape spatial mosaics and their interactions. Both ecosystems show a variety of plant physiognomies distributed within small spatial scales and elevation gradients. Such variety of plant physiognomies provide an opportunity to investigate the roles of climate, topography, nutrient availability and water table dynamics as determinants of plant physiognomic distributions, and their role in shaping regional systems. South Florida Wetlands and the tropical savannas of central Brazil are examples of hydrologically-controlled ecosystems. In hydrologically-controlled ecosystems water sources, the availability of nutrients, and the patterns of water movement play important roles in determining vegetation structure and function. The main objective of this study was to understand ecosystem level processes that shape different physiognomies in two hydrologically-controlled ecosystems. I conducted field work at the IBGE ecological reserve, a field experimental station located in Brasilia, Brazil. I also worked at the Everglades National Park in an area located near the south entrance of the Park in Homestead, Florida. I carried out three interconnected studies investigating water and nutrient dynamics: (1) In a Brazilian savanna I manipulated levels of litter input and measured changes to soil properties, organic matter decomposition and tree growth. I found that changes in litter input affect soil physicochemical properties and soil biochemical processes. I also found that litter dynamics influence tree growth through their effects on soil physicochemical properties. (2) I also studied the effect of water table depth and its temporal variation on spatial patterns of vegetation distribution in the cerrado landscape. I monitored diurnal and seasonal changes in water table depth along two tree-density and topographic gradients. In addition, I measured woody species composition, growth rates of four tree species, litter production, soil nutrients, and nutrient resorption efficiency along those two gradients. I found that water table depth has an important role in determining the spatial distribution of cerrado physiognomies; it also affects tree growth, species composition and nutrient resorption efficiency. (3) In the Everglades I studied patterns of underground water uptake by two vegetation types. I monitored seasonal and diurnal changes in water table depth in a Hammock forest, in a stand dominated by the invasive woody species Schinus terebinthifolius, as well as the water level in an adjacent lake. I estimated stand level transpiration using two different approaches: with sap flow measurements and diurnal oscillations in water table levels. Then, I calculated the total quantity of groundwater withdrawn by evapotranspiration for the wet and dry seasons in the Hammocks and in the exotic invaded site and then compared the results. I found that water uptake by Everglades trees is well coupled to diurnal changes in water table depth and that the amount of water withdrawn from the groundwater was larger during the wet season than during the dry season. Finally, I detected hydrological feedbacks between different vegetation types and nearby bodies of water. Results of this study contributes to the current knowledge of ecosystem level processes in tropical and subtropical ecosystems where water circulation and water availability play a dominant role in shaping vegetation structure and function.
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Neilson, Julia Worsley. "Bacterial Diversity of the Atacama Desert, Chile: The Challenges of Characterizing the Community Dynamics of Extreme Oligotrophic Ecosystems." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242364.
Full textAbstract:
This dissertation examines the bacterial diversity of hyperarid and arid regions of the Atacama Desert, Chile, as a first step towards understanding the global biogeochemical significance of arid-land microbial communities. The specific objectives were to characterize bacterial diversity and infer the possible metabolic potential of these bacterial communities, and to evaluate the influence of moisture exposure on community structure. In addition, the strengths and limitations of available tools for probing microbial diversity and activity in terrestrial ecosystems were characterized for their application to extreme oligotrophic communities. Preliminary PCR-DGGE analysis of a west-east elevational transect from the Pacific Ocean near Antofagasta to the western slopes of the central Andes indicated that bacterial communities along this transect belonged to two distinct community types: 1) hyperarid (700 - 2000 m) and 2) arid (2500 - 4500 m) communities that included both vegetated and unvegetated regions. Subsequent diversity analysis of these two regions revealed novel but distinct communities in both regions. A greater diversity was observed in the unvegetated arid regions than in the unvegetated hyperarid areas. The unvegetated arid sites were characterized by a bacterial community harboring a combination of radiotolerant and halotolerant heterotrophs as wells as diverse phylotypes closely related to chemolithoautotrophs. These rare phylotypes may be uniquely adapted to arid ecosystems. Molecular tools evaluated for community diversity analysis included PCR-DGGE, Sanger-clone and 454-pyrosequencing analysis of 16S rRNA gene libraries, and the use of reverse transcriptase quantitative PCR (RT-qPCR) for quantifying the impact of environmental variables on the metabolic activity of a specific organism. These techniques were evaluated using the ecosystems of the Atacama Desert as well as model ecosystems designed to address specific questions. Molecular tools are invaluable to the study of microbial ecology because they facilitate the study of fastidious organisms that are difficult or impossible to culture, but the analysis presented in this dissertation demonstrates that each of these methods has limitations and biases which must be acknowledged to avoid inaccurate conclusions from skewed results. The most complete picture of the taxonomic and functional profile of a microbial community is obtained by employing a combination of molecular techniques.
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Blume, Theresa, Erwin Zehe, and Axel Bronstert. "Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes." Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4492/.
Full textAbstract:
Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes,
especially in data scarce or previously ungauged catchments.
The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes) than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture
response allows for visualization of flow processes in the unsaturated
zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale) and binary indicator maps (for the long-term and hillslope
scale). Annual dynamics of soil moisture and decimeterscale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a datascarce
catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation
for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to self-reinforcing flow paths.
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Harrison-Kirk, T. "The effects of drying and rewetting cycles on carbon and nitrogen dynamics in soils of differing textures and organic matter contents." Lincoln University, 2008. http://hdl.handle.net/10182/656.
Full textAbstract:
Many researchers have reported differences in soil C and N dynamics between soils of different textures and/or soil organic matter contents. However, it has proven difficult to determine the exact relationships and mechanisms between C and N dynamics and soil texture/SOM. There are few studies that consider how these soil physical and chemical conditions influence the effects of drying and rewetting on the mineralisation of C and N and the microbial transformations that follow. The objectives of this study were: 1) To determine the effects of repeated drying and rewetting cycles on C and N dynamics in soils of differing textural class and organic matter levels. 2) To use C & N mineralised at constant moisture contents to calculate mineralisation during dry/wet cycles for comparison with actual mineralisation. Two soil types with contrasting textures were chosen and 6 paddocks on each soil type were selected to produce an OM gradient for each soil. Three moisture treatments were chosen to simulate moist (field capacity at -0.01 MPa), moderately dry (120% of wilting point at -1.5 MPa) and very dry (80% of wilting point at - 1.5 MPa) field conditions. The dry moisture treatments were then combined with a rewet treatment where they were either rewet or maintained dry (+ or – rewet), resulting in a total of five dry/rewet treatments. Soils were packed into funnel tops to a BD of 1.1 g/cm³ and sealed in glass jars fitted with septa to allow gas sampling. Drying was achieved using silica gel which allowed continued gas measurement during drying periods. Gas samples were collected throughout the experiment and analysed for CO₂ by IRGA and N₂O by GC. At the start and end of the study, soils were analysed for Min N, MBC, MBN, HWC, DOC, POM, total C and total N. The correlation between calculated and actual C mineralisation data indicates that the intercept is not consistent with the origin and that the slope is not consistent with the 1:1 line. While those paddocks with high %C had high cumulative C mineralisation, there didn’t appear to be any strong relationship between soil texture or OM content and the difference between actual and calculated C mineralisation. A plot of calculated C mineralisation rates against the actual C mineralisation rates shows that much of the error in the calculated cumulative data arises from an underestimation of the mineralisation flush when the dry soil is rewetted, especially during the first dry-rewet cycle, and an over estimation of the rate at which respiration decreases as the soil dries. In order to use C mineralisation data from soils held at constant moisture contents to accurately predict C mineralisation in soils exposed to dry-rewet cycles, knowledge of the stress history for the soil would be required e.g. size, duration and frequency of rainfall events, dry rates etc. The N₂O-N emission data is inherently more variable than the C mineralisation data. The fine-textured soils tend to have much higher N₂O-N emissions than the coarser soils, probably due to the creation of anoxic sites upon rewetting in the fine-textured soils. The data indicates that prediction of N₂O-N emissions in soils exposed to dry-rewet cycles using emission data from soils held at constant moisture contents would be very inaccurate, primarily due to the inherent variability of N₂O-N emissions in soils.
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Dang, Duy-Minh. "Dynamics of nitrogen and carbon cycling associated with greenhouse gas emissions in the salt-affected soils." Phd thesis, Canberra, ACT : The Australian National University, 2018. http://hdl.handle.net/1885/148885.
Full textAbstract:
Salinity is one of the most severe environmental
factors limiting the productivity of aquaculture and agriculture.
The worldwide area of salt-affected soils is predicted to become
even more widespread in the future due to climate change and
sea-level rise. However, the soil nitrogen and carbon dynamics
associated with soil-induced gas emissions under salinity are not
well understood. The main objective of this study was to
investigate changes of soil carbon and nitrogen cycling
associated with greenhouse gas emissions, plant growth and
fertilizer recovery under effects of different salinity levels.
This study addressed research issues with the following main
objectives. The main aim of the study reported in Chapter 2 was
to analyse greenhouse gas production from different soils with
different times of lid closure and to assess the effects of
different activation time on gas emissions from soils. The
results showed that the 20-min sampling interval at the closure
time of maximum 80 minutes had good results with less variance
either for soil types or monitored gases. Lengthening activation
times for the incubation study may affect emission rates due to
differences in soil properties. The study in Chapter 3 examined
the effects of salinity and additional sources of nitrogen and
carbon on soil nitrogen and carbon cycling in an acid sulphate
soil (ASS) and an alluvial soil. The findings of this study
demonstrated that salinity significantly decreased N2O emissions
from the acid sulphate soil but did not affect emissions from the
alluvial soil. The addition of glucose and nitrate enhanced N2O
production in both salt-affected soils. This investigation
indicated that salinity altered the carbon and nitrogen cycles in
the acid sulphate soil; it recommends that future fertiliser and
crop management will need to account for the changed nutrient
cycling caused by saline water intrusion and climate change. The
objective of the study reported in Chapter 4 was to identify a
relationship between induced-soil gas emissions and the abundance
of denitrification genes in a salt-affected soil. Increased
salinity caused a decrease in both flux and cumulation of the
N2O-N production and soil respiration from the incubated soil.
The study result also showed that elevated salinity increased the
denitrifying genes in the incubated acid sulphate soil. Abundance
of the nir genes was usually high between the first and second
week of incubation, while number of copies of the nosZ gene were
significantly low at those times. Another study presented in
Chapter 5 investigated changes in soil properties, the dynamics
of N and its effects on rice growth and yield under different
salinity levels by using a 15N label fertilizer technique.
Flooding soils for two weeks by saline water greatly decreased
rice yield and yield components in the acid sulphate soil. High
salinity significantly lowered the recovery of fertilizer N by
rice plants, especially in the acid sulphate soil where the crop
did not produce any grain. The loss of fertilizer nitrogen was
highly controlled by the interaction effect of soil types and
salinity. Findings from the thesis substantially and originally
contribute to the literature on salt-affected soils and will
assist in developing new managemental interventions and
strategies for soils where increased salinity is a real
possibility in the future.
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Shrestha, Paliza. "Water Quality Performance And Greenhouse Gas Flux Dynamics From Compost-Amended Bioretention Systems & Potential Trade-Offs Between Phytoremediation And Water Quality Stemming From Compost Amendments." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/851.
Full textAbstract:
Stormwater runoff from existing impervious surfaces needs to be managed to protect downstream waterbodies from hydrologic and water quality impacts associated with development. As urban expansion continues at a rapid pace, increasing impervious cover, and climate change yields more frequent extreme precipitation events, increasing the need for improved stormwater management. Although green infrastructure such as bioretention has been implemented in urban areas for stormwater quality improvements and volume reductions, these systems are seldom monitored to validate their performance. Herein, we evaluate flow attenuation, stormwater quality performance, and nutrient cycling from eight roadside bioretention cells in their third and fourth years of implementation in Burlington, Vermont. Bioretention cells received varying treatments: (1) vegetation with high-diversity (7 species) and low-diversity plant mixes (2 species); (2) proprietary SorbtiveMediaTM (SM) containing iron and aluminum oxide granules to enhance sorption capacity for phosphorus; and (3) enhanced rainfall and runoff (RR) to certain cells (including one with SM treatment) at three levels (15%, 20%, 60% more than their control counterparts), mimicking anticipated precipitation increases from climate change.
Bioretention water quality parameters monitored include total suspended solids (TSS), nitrate/nitrite-nitrogen (NOx), ortho-phosphorus (Ortho-P), total nitrogen (TN) and total phosphorus (TP), which were compared among bioretention cells’ inflows and outflows across 121 storms. Simultaneous measurements of flow rates and volumes allowed for evaluation of the cells’ hydraulic performances and estimation of pollutant load and event mean concentration (EMC) removal. We also monitored soil CO2 and N2O fluxes, as they represent a potential nutrient loss pathway from the bioretention cells. We determined C and N stocks in the soil media and vegetation, which are critical design elements of any bioretention, to determine the overall C and N balances in these systems.
Significant average reductions in effluent stormwater volumes and peak flows were reported, with 31% of the storms events completely captured. Influent TSS loads and EMCs were well retained by all cells irrespective of treatments, storm characteristics, or seasonality. Nutrient removal was treatment-dependent, where the SM treatments consistently removed P loads and EMCs, and sometimes N as well. The vegetation and RR treatments mostly exported nutrients to the effluent. We attribute observed nutrient exports to the presence of excess compost in the soil filter media. Rainfall depth and peak inflow rate undermined bioretention performance, likely by increasing pollutant mobilization through the filter media. While the bioretention cells were a source of CO2, they varied between being a sink and source of N2O. CO2 fluxes were orders of magnitude higher than N2O fluxes. However, soil C and N, and plant C and N in biomass was seen to largely offset respiratory CO2-C and biochemical N2O-N losses from bioretention soil. The use of compost in bioretention soil media should be reduced or eliminated. If necessary, compost with low P content and high C: N ratio should be considered to minimize nutrients losses via leaching or gas fluxes.
In order to understand trade-offs stemming from compost amendments, we conducted a laboratory pot study utilizing switchgrass and various organic soil amendments (e.g., different compost types and coir fiber) to a sandy loam soil contaminated with heavy metals and studied potential nutrient leaching and pollutant uptake. Addition of organic amendments significantly reduced metal bioavailability, and improved switchgrass growth and metal uptake potential. While no differences in soil or plant metal uptake were observed among the amendments, significant differences in nutrient leaching were observed.
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Kusumo, Bambang Hari. "Development of field techniques to predict soil carbon, soil nitrogen and root density from soil spectral reflectance : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North, New Zealand." Massey University, 2009. http://hdl.handle.net/10179/1015.
Full textAbstract:
The objectives of this research were to develop and evaluate a field method for in situ measurement of soil properties using visible near-infrared reflectance spectroscopy (Vis-NIRS). A probe with an independent light source for acquiring soil reflectance spectra from soil cores was developed around an existing portable field spectrometer (ASD FieldSpecPro, Boulder, CO, USA; 350-2500 nm). Initial experiments tested the ability of the acquired spectra to predict plant root density, an important property in soil carbon dynamics. Reflectance spectra were acquired from soil containing ryegrass roots (Lolium multiflorum) grown in Allophanic and Fluvial Recent soils in a glasshouse pot trial. Differences in root density were created by differential nitrogen and phosphorus fertilization. Partial least squares regression (PLSR) was used to calibrate spectral data (pre-processed by smoothing and transforming spectra to the first derivative) against laboratory-measured root density data (wet-sieve technique). The calibration model successfully predicted root densities (r2 = 0.85, RPD = 2.63, RMSECV = 0.47 mg cm-3) observed in the pots to a moderate level of accuracy. This soil reflectance probe was then tested using a soil coring system to acquire reflectance spectra from two soils under pasture (0-60 mm soil depths) that had contrasting root densities. The PLSR calibration models for predicting root density were more accurate when soil samples from the two soils were separated rather than grouped. A more accurate prediction was found in Allophanic soils (r2 = 0.83, RPD = 2.44, RMSECV = 1.96 mg g-1) than in Fluvial Recent soils (r2 = 0.75, RPD = 1.98, RMSECV = 5.11 mg g-1). The Vis-NIRS technique was then modified slightly to work on a soil corer that could be used to measure root contents from deeper soil profiles (15- 600 mm depth) in arable land (90-day-old maize crop grown in Fluvial Recent soils). PLSR calibration models were constructed to predict the full range of maize root densities (r2 = 0.83, RPD = 2.42, RMSECV = 1.21 mg cm-3) and also soil carbon (C) and nitrogen (N) concentrations that had been determined in the laboratory (LECO FP- 2000 CNS Analyser; Leco Corp., St Joseph, MI, USA). Further studies concentrated on improving the Vis-NIRS technique for prediction of total C and N concentrations in differing soil types within different soil orders in the field. The soil coring method used in the maize studies was evaluated in permanent and recent pastoral soils (Pumice, Allophanic and Tephric Recent in the Taupo-Rotorua Volcanic Zone, North Island) with a wide range of soil organic matter contents resulting from different times (1-5 years) since conversion from forest soils. Without any sample preparation, other than the soil surface left after coring, it was possible to predict soil C and N concentrations with moderate success (C prediction r2 = 0.75, RMSEP = 1.23%, RPD = 1.97; N prediction r2 = 0.80, RMSEP = 0.10%, RPD = 2.15) using a technique of acquiring soil reflectance spectra from the horizontal cross-section of a soil core (H method). The soil probe was then modified to acquire spectra from the curved vertical wall of a soil core (V method), allowing the spectrometer’s field of view to increase to record the reflectance features of the whole soil sample taken for laboratory analysis. Improved predictions of soil C and N concentrations were achieved with the V method of spectral acquisition (C prediction r2 = 0.97, RMSECV = 0.21%, RPD = 5.80; N prediction r2 = 0.96, RMSECV = 0.02%, RPD = 5.17) compared to the H method (C prediction r2 = 0.95, RMSECV = 0.27%, RPD = 4.45; N prediction r2 = 0.94, RMSECV = 0.03%, RPD = 4.25). The V method was tested for temporal robustness by assessing its ability to predict soil C and N concentrations of Fluvial Recent soils under permanent pasture in different seasons. When principal component analysis (PCA) was used to ensure that the spectral dimensions (which were responsive to water content) of the data set used for developing the PLSR calibration model embraced those of the “unknown” soil samples, it was possible to predict soil C and N concentrations in “unknown” samples of widely different water contents (in May and November), with a high level of accuracy (C prediction r2 = 0.97, RMSEP = 0.36%, RPD = 3.43; N prediction r2 = 0.95, RMSEP = 0.03%, RPD = 3.44). This study indicates that Vis-NIRS has considerable potential for rapid in situ assessment of soil C, N and root density. The results demonstrate that field root densities in pastoral and arable soil can be predicted independently from total soil C, which will allow researchers to predict C sequestration from root production. The recommended “V” technique can be used to assess spatial and temporal variability of soil carbon and nitrogen within soil profiles and across the landscape. It can also be used to assess the rate of C sequestration and organic matter synthesis via root density prediction. It reduces the time, labour and cost of conventional soil analysis and root density measurement.
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Stark, Christine H. "Effects of long- and short-term crop management on soil biological properties and nitrogen dynamics." Lincoln University, 2005. http://hdl.handle.net/10182/30.
Full textAbstract:
To date, there has been little research into the role of microbial community structure in the functioning of the soil ecosystem and on the links between microbial biomass size, microbial activity and key soil processes that drive nutrient availability. The maintenance of structural and functional diversity of the soil microbial community is essential to ensure the sustainability of agricultural production systems. Soils of the same type with similar fertility that had been under long-term organic and conventional crop management in Canterbury, New Zealand, were selected to investigate relationships between microbial community composition, function and potential environmental impacts. The effects of different fertilisation strategies on soil biology and nitrogen (N) dynamics were investigated under field (farm site comparison), semi-controlled (lysimeter study) and controlled (incubation experiments) conditions by determining soil microbial biomass carbon (C) and N, enzyme activities (dehydrogenase, arginine deaminase, fluorescein diacetate hydrolysis), microbial community structure (denaturing gradient gel electrophoresis following PCR amplification of 16S and 18S rDNA fragments using selected primer sets) and N dynamics (mineralisation and leaching). The farm site comparison revealed distinct differences between the soils in microbial community structure, microbial biomass C (conventional>organic) and arginine deaminase activity (organic>conventional). In the lysimeter study, the soils were subjected to the same crop rotation (barley (Hordeum vulgare L.), maize (Zea mais L.), rape (Brassica napus L. ssp. oleifera (Moench)) plus a lupin green manure (Lupinus angustifolius L.) and two fertiliser regimes (following common organic and conventional practice). Soil biological properties, microbial community structure and mineral N leaching losses were determined over 2½ years. Differences in mineral leaching losses were not significant between treatments (total organic management: 24.2 kg N ha⁻¹; conventional management: 28.6 kg N ha⁻¹). Crop rotation and plant type had a larger influence on the microbial biomass, activity and community structure than fertilisation. Initial differences between soils decreased over time for most biological soil properties, while they persisted for the enzyme activities (e.g. dehydrogenase activity: 4.0 and 2.9 µg g⁻¹ h⁻¹ for organic and conventional management history, respectively). A lack of consistent positive links between enzyme activities and microbial biomass size indicated that similarly sized and structured microbial communities can express varying rates of activity. In two successive incubation experiments, the soils were amended with different rates of a lupin green manure (4 or 8t dry matter ha⁻¹), and different forms of N at 100 kg ha⁻¹ (urea and lupin) and incubated for 3 months. Samples were taken periodically, and in addition to soil biological properties and community structure, gross N mineralisation was determined. The form of N had a strong effect on microbial soil properties. Organic amendment resulted in a 2 to 5-fold increase in microbial biomass and enzyme activities, while microbial community structure was influenced by the addition or lack of C or N substrate. Correlation analyses suggested treatment-related differences in nutrient availability, microbial structural diversity (species richness or evenness) and physiological properties of the microbial community. The findings of this thesis showed that using green manures and crop rotations improved soil biology in both production systems, that no relationships existed between microbial structure, enzyme activities and N mineralisation, and that enzyme activities and microbial community structure are more closely associated with inherent soil and environmental factors, which makes them less useful as early indicators of changes in soil quality.
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Anderson, Axel Edward. "Patterns of water table dynamics and runoff generation in a watershed with preferential flow networks." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/504.
Full textAbstract:
Our understanding of subsurface flow depends on assumptions of how event characteristics and spatial scale affect the relationships between subsurface water velocity, discharge, water table dynamics, and runoff response. In this thesis, three chapters explore some of these patterns for a hillslope and small watershed in coastal British Columbia. In the first chapter, tracers were applied under natural and steady state conditions to determine the relationship between lateral tracer velocities and various hillslope and event characteristics; such as hillslope subsurface flow, rainfall intensity, water table level, hillslope length, and antecedent condition. The results showed that preferential flow made up a large percentage of the subsurface flow from the gauged hillslope. Flow velocities as measured by tracers were affected by slope length and boundary conditions. The flow velocity was most closely related to the rainfall intensity, and changes in flow velocity were large compared to the changes in the water table. In the second chapter, the preferential flow features that transmitted water during steady state were investigated by staining the soil with a food dye solution and excavating the soil. These data were used to explore the link between the topographical factors (slope and contributing area), the network of preferential features and soil properties. The contributing area appeared to be an indicator of the size of the preferential features and their connectivity. In the final manuscript chapter, water table level and stream discharge measurements were used to determine if areas within a watershed with runoff dominated by preferential flow could be grouped based on the observable physical information such as slope, contributing area, distance to stream, and vegetation. Preferential flow made the water table responses dynamic and thus, distinct zones could not be identified. Models of the water table – runoff were not able to predict the water table response for other sites with similar physical characteristics. Even though there was high variability in the results, the patterns and relationships revealed in this thesis conform to existing conceptual models of hillslope subsurface preferential flow. These patterns and relationships may be useful in developing or validating numerical models.
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Valentín-Vargas, Alexis. "Analysis of the Phylogenetic and Functional Dynamics of Microbial Communities in Metalliferous, Acid-Generating Mine Tailings Subject to a Phytostabilization Treatment." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/307007.
Full textAbstract:
Extensive research conducted over the last decade has demonstrated the great potential of phytostabilization for the reclamation of abandoned mine tailing piles. The right combination of plant species and soil amendments can facilitate the growth of a permanent vegetative cover on the tailings that will help minimize the mobilization of metal-bearing particles by means of wind dispersion and water erosion. Despite previous research efforts, the diversity and potential role of microbial populations inhabiting the root zone of the plants on the stabilization of the metal(loid) contaminants remains mostly unresolved. The study presented in this dissertation represents one of the first comprehensive efforts aimed to understand the ecology and dynamics of microbial communities colonizing both bulk and rhizosphere tailings during phytostabilization as an initial step towards elucidating the role of microbes in the stabilization of metal(loid) contaminants during the remediation treatment. This study was divided into two main projects: (1) the first aimed to monitor the temporal variations in functional and taxonomic diversity of prokaryotic populations in acid-generating metalliferous mine tailings during phytostabilization to determine how they respond to and/or influence changes in environmental parameters and to identify key patterns in their composition that may serve as bioindicators of soil health and the success of the remediation treatment; and (2) the second aimed to expand our understanding of the dynamics of root-associated bacterial, fungal and archaeal communities during mine tailing phytostabilization and how the dynamic behavior of the communities correspond to the growth of plants, the addition of soil amendments, and fluctuations in environmental conditions. The results presented here demonstrate that different microbial groups respond differently to changes in environmental conditions during phytostabilization, suggesting that by monitoring the behavior of specific microbial groups in the systems (as bioindicators) we may be able to assess the effectiveness of the remediation treatment. Furthermore, the results from the taxonomic and functional analysis of the microbial communities served as the basis for the development of a model that explains the ecology and distribution of dominant microbial groups in the tailings that may significantly contribute to the oxidation of iron-sulfides, the production of acid mine drainage, and to facilitate plant establishment and survival during phytostabilization.
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Sabesan, Aarthy. "Geo-spatial assessment of the impact of land cover dynamics and distribution of land resources on soil and water quality in the Santa Fe River watershed." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007460.
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Otoo, James Nii Aboh. "Suspended Sediment Transport Dynamics and Sediment Yields in Relation to Watershed Characteristics, Upper Green River Basin, Kentucky." TopSCHOLAR®, 2010. http://digitalcommons.wku.edu/theses/158.
Full textAbstract:
Sediment delivery is a major problem in the Green River, Kentucky, home of 71 of the state’s 103 known mussel species and 151 fish species. The river also provides water for many of its surrounding counties. This research focuses on how suspended sediment loads, grain size, and sediment concentration during runoff events are related to watershed characteristics.
The research characterized suspended sediment loads, grain size, and sediment concentration during runoff events and how they were related to watershed characteristics such as hydro-climatic regime, watershed size, geology and soils, topography and landuse conditions and land cover conditions. The study focused on Brush Creek and Pitman Creek watersheds in the Upper Green River Basin. This research can help in the planning and development of effective environmental strategies by screening out mitigation measures that would not be effective for implementation to minimize sediment load and suspended sediment concentration in the Green River, thereby improving the water quality of the river. Water quality was monitored using data sondes positioned at selected sites in the two watersheds. Water samples were collected during turbidity thresholds of 100 NTU and analyzed for suspended sediment concentrations. Regression models between ‘discharge and stage’ and also between ‘average turbidity and suspended sediment concentration’ were formulated and load estimates were made and compared.
Four sets of samples were collected, two at Brush Creek on 11 April (Brush Creek’s event 1) and 3 May (Brush Creek’s event 2) and the other two at Pitman Creek on the 12 February (Pitman Creek’s event 1) and 3 March (Pitman Creek’s event 2) all in the year 2008. The suspended sediment samples collected for all four events were well graded but had relatively more silt than clay and sand. This could be due to the fact that more time and energy was needed to break the bonds in clay minerals or particles and also to the fact that more energy was also needed to transport sand compared to silt. Brush Creek watershed’s particles had smaller grain sizes than Pitman Creek watershed’s particles. All four events showed clockwise hysteresis indicating that most of the sediments from both watersheds during the events were derived from the bed and banks of the channel or area adjacent to the channel.
The 11 April event (Brush Creek’s event 1) produced an estimated load of 1.1 x 105 kg and a sediment yield of 5.3 x 102 kg/km2. The 3 May event (Brush Creek’s event 2) produced an estimated load of 3.8 x 104 kg and a sediment yield of 1.8 x 102 kg/km2. Brush Creek watershed’s estimated load for the period compared was 4.9 x 105 kg and a sediment yield of 2.3 x 103 kg/km2 (53 kg/km2/day).
The 12 February event (Pitman Creek’s event 1) produced an estimated load of 2.9 x 105 kg and a sediment yield of 8.4 x 102 kg/km2. The 3 March event (Pitman Creek’s event 2) produced an estimated load of 5.7 x 105 kg and a sediment yield of 1.6 x 103 kg/km2. Pitman Creek watershed’s estimated load for the period compared was 1.1 x 106 kg and a sediment yield of 3.1 x 103 kg/km2 (71 kg/km2/day).
Pitman Creek watershed’s higher number of stream network per unit area, its high elevation and relief, its high percentage of erodible soil per unit area, its lesser area of protection of erodible soil by its vegetation compared to Brush Creek watershed’s are responsible for its higher sediment load and yield.
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Medeiros, João Carlos. "Funções de pedotransferência em estudos do funcionamento hídrico do solo da região sudeste do estado do Pará." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-26032012-105416/.
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O entendimento dos processos hídricos do solo, tais como infiltração, drenagem, e disponibilidade de água para as plantas, necessita do conhecimento da relação entre o conteúdo de água no solo e o potencial matricial, representado pela curva de retenção de água no solo (CRA). No entanto, a determinação da CRA demanda tempo e possui um custo relativo alto. Uma alternativa é sua determinação através de modelos que estimam a CRA a partir de alguns atributos de fácil determinação, chamados funções de pedotransferência (FPT). A finalidade desse trabalho foi quantificar os efeitos da mudança do uso do solo sobre os atributos físicos e hídricos no Sudeste do Estado do Pará. Utilizou-se o banco de dados do Projeto Serviços ecossistêmicos e sustentabilidade das paisagens agrosilvipastoris da Amazônia Oriental, para obter dados de textura (areia, silte e argila), densidade do solo (Ds), carbono orgânico (CO), pH, capacidade de troca de cátions (CTC) e, as vezes, as CRA. Primeiramente, foram avaliadas 16 FPT existentes na literatura; 8 FPT paramétricas, que estimam os parâmetros empíricos do modelo de van Genuchten e 8 FPT pontuais, que estimam a umidade em potenciais específicos de água no solo. Posteriormente, buscando maior capacidade preditiva das FPT, através da técnica de regressão múltipla, desenvolveu-se uma FPT utilizando os atributos do solo mensurados no projeto. As melhores FPT foram utilizadas para estimar os parâmetros do modelo de van Genuchten nos sítios onde não havia CRA medida. Através desta extrapolação, avaliou-se o efeito da mudança de uso do solo sobre a distribuição dos tamanhos de poros, utilizando-se análise de componentes principais (ACP). Dentre as FPT testadas, as que apresentaram melhor resultado foram as FPT propostas por Tomasella et al. (2000), no entanto, a avaliação de desempenho realizada mostrou resultados não satisfatórios. Por outro lado, os resultados apresentados pela FPT desenvolvida neste trabalho alcançaram boa capacidade preditiva dos parâmetros empíricos do modelo de van Genuchten (1980). A ACP possibilitou identificar uma grande variabilidade entre os atributos medidos e estimados dos solos. Devido a esta variabilidade, não foram detectadas diferenças marcantes nos atributos dos solos em função do uso. Para isso, faz-se necessário estudos complementares, aumentando a escala e/ou classes de solo.<br>The understanding of soil water attributes, such as infiltration, drainage, solute movement and water availability for plants, needs the knowledge of the relationship between water content and soil matric potential, represented by the soil water retention curve (SWRC). However, the determination of the SWRC demands considerable time and has a relatively high cost. An alternative is to model its determination using pedotransfer functions (PTF) that calculate the SWRC parameters using easily obtainable soil attributes. The aim of this study was to use PTF to quantify the effects of changing land use on soil hydro-physical attributes at three locations in southern Pará. The database obtained in the project \"Ecosystem services and sustainable agroforestry landscapes in Eastern Amazonia\" was used in order to obtain soil texture data (sand, silt and clay), bulk density (Bd), organic carbon (OC), pH, cation exchange capacity (CEC) and the SWRC. First, 16 PTF found in the literature were evaluated (8 estimating the empirical parameters of the van Genuchten (1980) model and 8 to estimate soil moisture at specific matric potentials). Later, aiming at a greater predictive ability, a PTF was developed using the technique of multiple regression and the soil attributes determined in the project. The best PTF were used to estimate the model parameters of van Genuchten (1980) at the locations where there was no SWRC data. These results were used to determine the changes in pore distribution due to land use using principal component analysis (PCA). These changes were also associated with changes in content of OC and Bd using multivariate analysis. Of the FPT found in the literature the one that showed the best performance was the FPT developed by Tomasella et al. (2000), however, the evaluation performed showed poor results when the data was extrapolated to the locations where no SWRC were determined. The results presented by the FPT developed in this work showed a better efficiency in determining the SWRC in the locations that did not have this information. The PCA analysis performed on this data identified a large variability among the measured and estimated soil attributes. Because of this variability, there were no marked differences in soil attributes depending on land use. For this, more detailed studies are necessary at a increasing scale and/or at the soil class level.
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Bossa, Yaovi Aymar [Verfasser]. "Multi-scale modeling of sediment and nutrient flow dynamics in the Oueme catchment (Benin) : towards an assessment of global change effects on soil degradation and water quality / Yaovi Aymar Bossa." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1044082437/34.
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Bertram, Janet. "Effects of cow urine and its constituents on soil microbial populations and nitrous oxide emissions." Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1334.
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New Zealand’s 5.3 million strong dairy herd returns approximately 106 million litres of urine to pasture soils daily. The urea in that urine is rapidly hydrolysed to ammonium (NH₄⁺), which is then nitrified, with denitrification of nitrate (NO₃⁻) ensuing. Nitrous oxide (N₂O), a potent greenhouse gas (GHG), is produced via nitrification and denitrification, which are enzyme-catalysed processes mediated by soil microbes. Thus microbes are linked intrinsically to urine patch chemistry. However, few previous studies have investigated microbial dynamics in urine patches. Therefore the objective of these four experiments was to investigate the effects on soil microbial communities of cow urine deposition. Methods used included phospholipid fatty acid (PLFA) analyses of microbial community structure and microbial stress, dehydrogenase activity (DHA) assays measuring microbial activity, and headspace gas sampling of N₂O, ammonia (NH₃) and carbon dioxide (CO₂) fluxes. Experiment 1, a laboratory study, examined the influence of soil moisture and urinary salt content on the microbial community. Both urine application and high soil moisture increased microbial stress, as evidenced by significant changes in PLFA trans/cis and iso/anteiso ratios. Total PLFAs and DHA showed a short-term (< 1 week) stimulatory effect on microbes after urine application. Mean cumulative N₂O-N fluxes were 2.75% and 0.05% of the nitrogen (N) applied, from the wet (70% WFPS) and dry (35% WFPS) soils, respectively. Experiment 2, a field trial, investigated nutrient dynamics and microbial stress with plants present. Concentrations of the micronutrients, copper, iron and molybdenum, increased up to 20-fold after urine application, while soil phosphorus (P) concentrations decreased from 0.87 mg kg ⁻¹ to 0.48 mg kg⁻¹. Plant P was also lower in urine patches, but total PLFAs were higher, suggesting that microbes had utilised the available nutrients. Microbial stress again resulted from urine application but, in contrast to experiment 1, the fungal biomass recovered after its initial inhibition. Studies published during the course of this thesis reported that hippuric acid (HA) and its hydrolysis product benzoic acid (BA) significantly reduced N₂O-N emissions from synthetic cow urine, thus experiment 3 investigated this effect using real cow urine. Cumulative N₂O-N fluxes were 16.8, 5.9 and 4.7% of N applied for urine (U) alone, U+HA and U+BA, respectively. Since NH₃-N volatilisation remained unchanged, net gaseous N emissions were reduced. Trends in total PLFAs and microbial stress were comparable to experiment 1 results. Experiment 4 studied HA effects at different temperatures and found no inhibition of N₂O-N fluxes from HA-amended urine. However, mean cumulative N₂O-N fluxes were reduced from 7.6% of N applied at 15–20°C to 0.2% at 5–10°C. Total cumulative N emissions (N₂O-N + NH₃-N) were highest at 20°C (17.5% of N applied) and lowest at 10°C (9.8% of N applied). Microbial activity, measured as potential DHA, increased with increasing temperature. This work has clearly shown that the stimulation and inhibition of the soil microbial community by urine application are closely linked to soil chemistry and have significant impacts not only on soil nutrient dynamics but also on N₂O-N emissions and their possible mitigation.
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Campos, ângelo Antônio. "Simulação numérica do movimento de água e solutos em solos não saturados." Universidade Federal do Espírito Santo, 2007. http://repositorio.ufes.br/handle/10/6583.
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Previous issue date: 2007-03-30<br>The interest in studying problems of underground drainage and solutos transport not in soils saturated it has been increasing significantly in the last years, mainly because of the growing concern with the quality of the soil and of the
environment in general. Applied fertilizers in agricultural lands move below the zone radicular of the plants and they can contaminate underground water tables and aqüíferos. One of the most significant challenges of the current agriculture is the
increase of the competitiveness associated to the preservation of the environment, allowing maintainable benefits in the agricultural explorations. The impact of
pollutants in the quality of the underground water has been research object and of public health, especially in areas where she is to main source of drinking water. The mathematical models appear as useful tool in the prediction of as and when she should proceed the irrigation and the behavior of the solutos in solo.Devido to the complexity involved in these physical phenomena, it is used now beside the experimental work, the numeric simulation as forecast tool. The numeric simulation of the problem of infiltration of water and solutos in soil not saturated it is of great
importance, because the growth of the agricultural production demands transformations with technological innovations that allow the improvement of the productivity of the cultures. To simulate the transport transiente of fertilizers, defensive, herbicidas and pollutant in an agricultural soil not saturated it is necessary the solution of two equations you not differentiate lineal. One of them is the equation of Richards, that governs the movement of water in the soil and, after your solution for a certain time, the results obtained for humidity, they are used for the solution of the other equation that treats of the transport of a certain soluto in matter. This work had for objective, to solve the proposed model of infiltration of water and soluto in the soil for the method of finite volumes, being used programming FORTRAN 90, to treat
the case of the non linearidade of the movement of the water and a certain soluto not in soils saturated. Among the analyzed solutos, we used samples of abrasive mud
coming of the sawmills and politrizes of the companies of marbles and granites of the municipal district of Cachoeiro of Itapemirim, where several rehearsals and analyses were accomplished, to feed the program and to evaluate the material in subject it is a pollutant in potential of the soil. The proposed method was shown appropriate to solve problems of infiltration of water and solutos transport not in soils saturated.<br>O interesse em estudar problemas de escoamento subterrâneo e transporte de solutos em solos não saturados tem aumentado significativamente nos últimos anos, principalmente por causa da preocupação crescente com a qualidade do solo e do meio ambiente em geral. Fertilizantes aplicados em terras agrícolas movem-se abaixo da zona radicular das plantas e podem contaminar lençóis de
água subterrâneos e aqüíferos. Um dos desafios mais significativos da agricultura atual é o aumento da competitividade associada à preservação do meio ambiente,
permitindo benefícios sustentáveis nas explorações agrícolas. O impacto de contaminantes na qualidade da água subterrânea tem sido objeto de pesquisa e de saúde pública, especialmente em regiões onde ela é a principal fonte de água
potável. Os modelos matemáticos surgem como ferramenta útil na predição de quanto e quando se deve proceder a irrigação e o comportamento dos solutos no solo.Devido à complexidade envolvida nestes fenômenos físicos, utiliza-se
atualmente ao lado do trabalho experimental, a simulação numérica como ferramenta de previsão. A simulação numérica do problema de infiltração de água e solutos em solo não saturado é de grande importância, pois o crescimento da
produção agrícola exige transformações com inovações tecnológicas que permitam a melhoria da produtividade das culturas. Para simular o transporte transiente de
fertilizantes, defensivos, herbicidas e poluentes num solo agrícola não saturado é necessária a solução de duas equações diferenciais não lineares. Uma delas é a
equação de Richards, que governa o movimento de água no solo e, após a sua solução para um determinado tempo, os resultados obtidos para umidade, são empregados para a solução da outra equação que trata do transporte de um
determinado soluto em particular. Este trabalho teve por objetivo, resolver o modelo proposto de infiltração de água e soluto no solo pelo método de volumes finitos, utilizando-se programação FORTRAN 90, para tratar o caso da não inearidade da movimentação da água e um determinado soluto em solos não saturados. Dentre os solutos analisados, utilizamos amostras de lama abrasiva provenientes das serrarias e politrizes das empresas de mármores e granitos do município de Cachoeiro de Itapemirim, onde foram realizados vários ensaios e análises, para alimentar o x programa e avaliar se o material em questão é um contaminante em potencial do solo. O método proposto mostrou-se adequado para resolver problemas de infiltração de água e transporte de solutos em solos não saturados.