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1
Watson, J., and M. Sheedy. "Crop Water Use Estimates." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/210312.
Повний текст джерелаАнотація:
Irrigation scheduling, by keeping track of irrigation applications, soil storage and crop water use, has been computerized by a number of different individuals. A key component of the computerized methods is the estimation of a reference crop evapotranspiration rate. Complaints about one such method, AZSCHED, led the authors to compare the reference crop evapotranspiration values calculated by AZSCHED with those calculated by a second procedure available used by AZMET. Results of the comparison indicated that no significant difference existed between methods, for either a traditionally "long season", or a contemporary "short season" growing period. AZSCHED did estimate crop water use to be about 5% - 8% more than AZMET, an amount that is not of importance considering the irrigation inefficiencies created by field non-uniformities. Experience by the authors indicates that inappropriate selection of irrigation efficiencies and/or soil water holding capacity may be the main cause of user complaints.
2
Subedi-Chalise, Kopila. "Impacts of Crop Residue and Cover Crops on Soil Hydrological Properties, Soil Water Storage and Water Use Efficiency of Soybean Crop." Thesis, South Dakota State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10265200.
Повний текст джерелаАнотація:
Cover crops and crop residue play a multifunctional role in improving soil hydrological properties, soil water storage and water use efficiency (WUE). This study was conducted to better understand the role of crop residue and cover crop on soil properties and soil water dynamics. The study was conducted at the USDA-ARS North Central Agricultural Research Laboratory, located in Brookings, South Dakota. Two residue removal treatments that include low residue removal (LRR) and high residue removal (HRR) were established in 2000 with randomized complete block design under no-till corn (Zea mays L.) and soybean (Glycine max L.) rotation. In 2005, cover crop treatments which include cover crops (CC) and no cover crops (NCC) were integrated into the overall design. Soil samples were collected in 2014, 2015 and 2016. Data from this study showed that LRR treatment resulted in lower bulk density (BD) by 7 and 9% compared to HRR in 2015 and 2016, respectively, for 0-5 cm depth. Similarly, LRR treatment significantly reduced soil penetration resistance (SPR) by 25% in 0-5 cm depth compared with HRR treatment. In addition to this, LRR treatment significantly increased soil organic carbon (SOC) concentrations and total nitrogen (TN) by 22 and 17%, respectively, in 0-5 cm. Similarly, CC treatment resulted in lower BD and SPR by 7% and 23%, respectively, in 0-5 cm depth in 2015 compared with NCC treatment. The LRR significantly increased soil water infiltration by 66 and 22% compared to HRR in 2014 and 2015, respectively. Similarly, the CC treatment significantly increased infiltration by 82 and 22% compared to the NCC in 2014 and 2015, respectively. The significant impact of a crop residue was observed on soil water retention (SWR) in 2014 and 2015 for the 0-5 cm depth. The LRR and CC treatments increased the soil volumetric moisture content (VMC) and soil water storage (SWS) on the surface 0-5 cm depth. However, the trend was not always significant during the growing season. The CC treatment significantly impacted the soybean yield by 14% and WUE by 13% compared with NCC treatment. Some interaction of residue by cover crops was observed on BD, SPR, VMC, and SWS, which showed that the use of cover crops with LRR can be beneficial in improving the soil properties.
3
Khandker, Md Humayun Kabir. "Crop growth and water-use from saline water tables." Thesis, University of Newcastle Upon Tyne, 1994. http://hdl.handle.net/10443/580.
Повний текст джерелаАнотація:
How much water can a crop abstract from below a saline water table and how does the salinity affect yield? These questions are important because shallow groundwater may represent a substantial resource in flat, low-lying areas, but may also represent a threat to sustainability where salinity is high. A series of experiments in a glasshouse aimed to elucidate irrigation management practice under salinity conditions and to develop a root uptake model under both osmotic and matric stresses. The extraction of soil water and groundwater by lettuce and perennial ryegrass crops were measured in three instrumented lysimeters. Water table depths were 0.6,0.9 and 1.2 rn below the soil surface. The lysimeters were initially saturated with saline water (electrical conductivity 4.5 dS m- 1 for lettuce, 9.4 dS m- I for the first crop of ryegrass and 0.4,7.5 & 15.0 dS m-1 for the second crop of ryegrass) and drained until an equilibrium soil water profile was attained. Water with the same electrical conductivity was then supplied by Marione siphons to maintain the constant water table. The water table contribution was recorded and water losses from the soil profile were estimated from daily readings of soil water potential using tensiometersa; nd gypsum blocks. Solute samples were extracted periodically for salinity measurement. The cropping period of lettuce was 90 days from sowing and the lst & 2nd cropping periods of ryegrass were 223 & 215 days respectively. The first ryegrass experiment showed that the water table depth (60,90 and 120 cm) did not have significant contribution (37,36 and 36 mm) on either total soil moisture use or groundwater contribution. Similar results were found for total soil moisture use for lettuce, though the groundwater contribution varied significantly. The second ryegrass experiment showed that salinity at the water table strongly influenced total soil moisture use, but the total groundwater contribution varied only slightly. The overall crop experiments show that the groundwater contribution was within the range of 25-30% of the total water use, except for the 15 dS m7l treatment where the contribution was greater than the soil moisture use. Groundwater contribution rate was higher when the plants were subjected to more osmotic and matric stresses. Yield component data show that increasing salinity leads to a reduction in total yield, but the drymatter proportion was higher. Higher salinities occurred in the upper 15 cm of the root zone, because of the greater soil moisture depletion. Below that depth the salinization rate was smaller, because of the greater groundwater contribution in the later part of the season. There is reasonable agreement between measured and estimated (based on convective transport theory) values soil salinity. Salinities increased in the root zone by about 3-fold of initial salinity for lettuce and around 4-fold for ryegrass in the top 5 cm depth, but below 15 cm depth it was less than 2 fold. Finally, a simplified model was developed to describe the interaction of root-zone salinity and water uptake, considering salinity and water stress as additive. The model shows that the higher the root-zone salinity stress, the higher the predicted water uptake while plant uptake considered -1.5 MPa. This variation is ranged from 4 to 17% for 0.4 to 9.4 dS m-1 and 30 % for 15 dS m-1. The model was developed in a climate with low atmospheric demand, but needs testing in a more severe environment.
4
Hassan, Ahmad. "The contribution by the water table to crop water use." Thesis, University of Newcastle Upon Tyne, 1990. http://hdl.handle.net/10443/142.
Повний текст джерелаАнотація:
The contribution by the water table to crop water use was evaluated in the absence of surface water application from lysimetric studies in a glassliouse during 1988, 1989 and 1990. The water table contribution was measured for beans, barley and lettuce in the presence of constant water tables 60, 90 and 120 cm deep. The water table contributed to about 27.0, 16.4 and 11.4% of evapotranspiration of barley with water tables 60, 90 and 120 cm deep, respectively. The contribution in lettuce was found to be 34.7, 13.5 and 6.0% for the 60, 90 and 120 cm water tables, respectively. The water table could not contribute to the evapotranspiration of beans because the initial soil moisture suction profile was not in equilibrium, and there was always a zero-flux plane above the water table. Capillary upward flux from the water table was also measured using Darcy's equation and by direct measurement. For this, unsaturated hydraulic conductivity was determined in the laboratory from diffusivity over a wide range of moisture content. Conductivity values were also evaluated in situ using Darcy's equation. In situ and laboratory conductivity values were well fitted by Gardner's (1958) conductivity function but not by that of Rijtema (1965). Root water uptake was evaluated using the extraction-term approach. A very small proportion of roots near the water table was absorbing water from the capillary fringe iii the case of a deep-rooted crop (barley) for all water table depths. Lettuce, a shal1ow-rootd crop, was absorbing water from the water table although roots were confined to the top 5 cm depth for all water table depths. A simulation model (CAPROW) was developed to account for capillary rise from constant water tables. The model can also predict soil moisture content, root water uptake and inflow to roots provided soil physical parameters and relevent data are known. Parameters needed to run the model were determined from the bean experiment with the water table at 60 cm depth. CAPROW was used to simulate results for water tables at 90 and 120 cm under three different crops. Model predictions of soil moisture contents at harvest agreed well with the measured values. The predicted cumulative upward flux in barley and lettuce under two different water table treatments agreed closely with the measured values. The contribution by the water table to water use by barley was found to be 16.4 and 11.4% for 90 and 120 cm water table depths, respectively. Corresponding simulated values were 15.5 and 10.4%. For lettuce, measured contributions from the water table to evapotranspiration were 13.5 and 6.0%. Corresponding simulated values were 15.7 and 6.7%.
5
Dalton, James A. "Contribution of upward soil water flux to crop water requirements." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/344938/.
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6
Sedibe, Moosa Mahmood. "Optimising water use efficiency for crop production." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53541.
Повний текст джерелаАнотація:
Thesis (MScAgric)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: Poor water management and poor water use efficiency (WUE) have been identified as one of the major problems experienced by vegetable growers in most of the developing countries, including South Africa. This poor management and poor utilization of water have led to a drastic decline in the quality and quantity of available water. In South Africa agriculture uses about 50% of available water. Increasing water demand for domestic, industrial and mining uses, may decrease agriculture's share to less than the current 50%, henceforth, better utilization of this resource is imperative. Selection of a good irrigation system can limit water loss considerably. Some irrigation systems have a potential to save more water than others do. Since irrigation systems affect the WUE of crops, care should be taken when selecting an irrigation system under conditions of limited water quantity. Ebb-and- Flood watering systems have been introduced for effective sub-irrigation and nutrient delivery within closed systems. Such a system was adapted in South Africa, to develop a vegetable production unit for use by families in rural communities, while saving substantial amounts of water. A need to further improve the WUE of this system was subsequently identified. Two studies were conducted at the experimental farm of the University of Stellenbosch (Department of Agronomy). The first trial was conducted under controlled conditions in a glasshouse, and the second under open field conditions. In the first trial, Beta vulgaris (Swiss chard) and Amaranthus spp. ('Imbuya') were grown in two root media; gravel and pumice. In addition, an 'Ebb-and-Flood' and a 'Constant level' system were used with nutrient solutions at two electrical (EC) conductivity levels 1.80 and 3.60 mS cm-I. The results of this (2x2x2x2) factorial experiment indicated that a combination of the 'Ebb-and-Flood' system with gravel as a root medium produced the best results at a low EC, when 'imbuya' was used. A high total WUE was found with 'imbuya', (7.35 g L-I) at EC 1.80 mS cmicompared to a relatively low WUE of 5. 90 g L-I when the 3.60 mS cm-I nutrient solution was used. In the second trial, 'Imbuya's' foliage dry mass, leaf area and WUE was evaluated under field conditions at the Stellenbosch University experimental farm, during the summer of2002. The experimental farm (33°55'S, 18°52'E) is situated in the cooler coastal wine grape-producing region of South Africa with a relatively high annual winter rainfall. This trial was conducted on an alluvial soil, with clay content of 25% and a pH of 5.9 (KC!). A closed 'Ebb-and-Flood' system was compared with two open field irrigation systems ('Drip' and 'Flood') using nutrient solutions at two electrical conductivity levels (1.80 and 3.60 mS cm-i) in all three cases. Foliage dry mass, leaf area as well as WUE was best with 'Drip' irrigation, when a nutrient solution with an electrical conductivity of 3.60 mS cm-i was used. In spite of the fact that additional ground water was available for the soil grown 'Drip' and 'Flood' treatments, the 'Ebb-and-Flood' system outperformed the 'Flood' treatment, especially when the nutrient solution with an EC of 3.6 mS cm-i was used. Insufficient root aeration in the flooded soil could have been a contributing factor. The fact that the 'Ebb-and-Flood' and 'Drip' systems gave the best results when the high EC solution was used to fertigate the plants, may indicate that the plants could have hardened due to the mild EC stress, better preparing them to adapt to the extreme heat that was experienced in the field.
AFRIKAANSE OPSOMMING: Swak: bestuur van water en 'n swak: water-gebruik-doeltreffendheid (WOD) is as een van die belangrikste probleme geïdentifiseer wat deur groente produsente in die meeste ontwikkelende lande, insluitend Suid-Afrika, ervaar word. Hierdie swak bestuur en benutting van water het daartoe bygedra dat 'n drastiese afname in die kwaliteit asook in die kwantiteit van beskikbare water ervaar word. In Suid-Afrika gebruik die landbou-sektor ongeveer 50% van die beskikbare water. Toenemende water behoeftes vir huisgebruik, industrieë en die mynbou mag hierdie 50% aandeel van die landbou sektor laat krimp. Beter benutting van hierdie skaars hulpbron is dus noodsaaklik. Die keuse van goeie besproeiingsisteme mag waterverliese merkbaar beperk aangesien sekere sisteme se water-besparingspotensiaal beter as ander is. Aangesien besproeiingstelsels die WOD van gewasse beïnvloed, is spesiale sorg nodig waar 'n besproeiingstelsel onder hierdie toestande van beperkte waterbronne gekies moet word. 'Ebb-en-Vloed' sisteme kan aangewend word om water en voedingselemente van onder in 'n wortelmedium te laat opstoot en in 'n geslote sisteem te laat terugdreineer. So 'n sisteem is in Suid-Afrika ontwikkel waarmee groente vir families in landelike gebiede geproduseer kan word terwyl water bespaar word. 'n Behoefte om die WOD van hierdie produksiesisteem verder te verbeter is egter geïdentifiseer. Twee ondersoeke is by die Universiteit van Stellenbosch se proefplaas (Departement Agronomie) gedoen. Die eerste proef is onder beheerde omgewingstoestande in 'n glashuis uitgevoer en die tweede onder veld toestande. In die eerste proef is Beta vulgaris (Snybeet) en Amaranthus spp. ('Imbuya') in twee tipes wortelmedia; gruis en puimsteen verbou. 'n 'Ebb-en-Vloed' asoook 'n 'Konstante vlak' besproeiingsisteem is gebruik terwyl voedingsoplossings ook by twee peile van elektriese geleiding (EC) teen 1.80 en 3.60 mS cm-I toegedien is. Die resultate van hierdie (2x2x2x2) fakroriaal eksperiment het aangetoon dat 'n kombinasie van die 'Ebb-en-Vloed' sisteem met gruis as 'n wortelmedium die beste resultate teen 'n lae EC lewer waar 'imbuya' gebruik is. Die WOD met 'imbuya' was hoog (7.35 g L-1) by 'n EC van 1.80 mS cm-I, vergeleke met 'n relatief lae WOD van 5. 90 g L-1 waar die 3.60 mS cm-I voedingsoplossing gebruik is. In die tweede proef is 'Imbuya' se droë blaarmassa, blaar oppervlakte en WOD onder veldtoestande op die Universiteit van Stellenbsoch se proefplaas in die somer van 2002 ge-evalueer. Die proefplaas (33°55'S, 18°52'E) is in die koeler kusstreke van die wyndruif produksiegebied in die winterreëngebied van Suid-Afrika geleë. Hierdie proef is op alluviale grond met 25% klei en 'n pH van 5.9 (KCi) uitgevoer. 'n Geslote 'Ebb-en-Vloed' sisteem is met twee veld-besproeiingsisteme vergelyk ('Drup' en 'Vloed') terwyl voedingsoplossings teen twee peile van elektriese geleiding (1.80 en 3.60 mS cm-I) in al drie gevalle gebruik is. Blaar droëmassa, blaaroppervlakte asook die WGD was die beste met 'Drup' besproeiing waar die EC van die voedingsoplossing 3.60 mS cm-I was. Ten spyte van die feit dat ekstra grondwater vir die 'Drup' and 'Vloed' behandelings beskikbaar was, het die 'Ebben- Vloed' stelsel beter as die 'Vloed' behandeling gedoen veral waar die voedingsoplossing se EC 3.6 mS cm-I was. Swak wortelbelugting was waarskynlik die rede waarom vloedbesproeiing swak produksie gelewer het. Die feit dat die 'Drup' en die 'Ebb-en-Vloed' behandelings in die veldproef die beste gedoen het waar die EC hoog was, mag moontlik met die gehardheid van die plante verband hou wat aan ekstreem warm en dor toestande blootgestel was.
7
Ping, Zhang. "The partitioning of water loss between crop transpiration and soil evaporation in potato crops." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303926.
Повний текст джерела
8
Hector, D. J. "Capture of soil water by crop root systems." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378493.
Повний текст джерела
9
Kazemi, Hossein V. "Estimating crop water requirements in south-central Kansas." Thesis, Kansas State University, 1985. http://hdl.handle.net/2097/9859.
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10
Perez, Jose 1950. "WATER AND NITROGEN EFFECTS ON THE CROP WATER STRESS INDEX OF COTTON." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275339.
Повний текст джерела
11
Arnet, Kevin Broc. "Cover crops in no-tillage crop rotations in eastern and western Kansas." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4086.
Повний текст джерела
12
Lena, Bruno Patias. "Crop evapotranspiration and crop coefficient of jatropha from first to fourth year." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-06012017-111443/.
Повний текст джерелаАнотація:
The determination of crop coefficient (Kc) with adequate methodology is important to quantify regional water requirement. Jatropha (Jatropha curcas L.) Kc is still unknown and this information will be essential to provide reliable irrigation parameters, as well as for crop zoning. The objective of this study was to determine jatropha actual crop evapotranspiration (ETc) and Kc from 1st to 4th growing year, and correlate Kc with leaf area index (LAI) and cumulative thermal unit (CTU). The experiment was performed from March 2012 to August 2015 at \"Luiz de Queiroz\" College of Agriculture (ESALQ)/University of São Paulo (USP), at Piracicaba city, SP, Brazil. The experiment was divided into center pivot, drip, and rainfed treatments. Two large weighing lysimeters (12 m2 each lysimeter) per treatment were used to determine jatropha ETc (one plant per lysimeter). Reference evapotranspiration (ET0) was determined by Penman-Monteith method from a weather station data situated close to the treatments. Daily Kc was determined for the two irrigated treatments by the ration between ETc and ET0 (Kc=ETc/ET0). LAI was determined using the LAI-2200 plant canopy analyzer, which was previously calibrated for jatropha canopy type. In all growing years, LAI was almost zero at the beginning of vegetative stage, increasing until a maximum during productive stage, and decreasing to zero in the leaf senescence stage. Annual ETc trend during the three growing was very similar, which was explained by the different growing periods and the LAI variation. In the 1st year Kc was 0.47 for both treatments. In the 2nd, 3rd, and 4th years Kc ranged from 0.15 to 1.38 for center pivot treatment and from 0.15 to 1.25 for drip treatment. Kc average in 2nd, 3rd, and 4th years during vegetative and productive growing periods was 0.77, 0.93, and 0.82 for center pivot treatment, respectively, and 0.69, 0.79, and 0.74 for drip treatment, respectively. The relationship between Kc and LAI for the center pivot treatment was adjusted to a logarithmical equation with coefficient of determination (R2) and root mean square error (RMSE) of 0.7643 and 0.334, respectively. For the drip treatment R2 was 0.8443 and 0.2079, respectively. In all three years analyzed, Kc related to CTU by a 3rd degree polynomial equation for both treatments.A determinação de coeficiente de cultivo (Kc) com metodologia adequada é essencial para quantificar o consumo hídrico de cultivos em diferentes regiões. Valores de Kc do pinhão-manso (Jatropha curcas L.) ainda não foram determinados e essa informação é muito importante para auxiliar o manejo de irrigação de maneira adequada. O objetivo desse estudo foi determinar a evapotranspiração (ETc) e Kc do 1º ao 4º ano de cultivo do pinhão-manso, e correlacionar Kc com o índice de área foliar (IAF) e a soma da unidade térmica (SUT). O experimento foi realizado de março de 2012 à agosto de 2015 na Escola Superior de Agricultura \"Luiz de Queiroz\" (ESALQ)/Universidade de São Paulo (USP), na cidade de Piracicaba, SP, Brasil. O experimento foi divido nos tratamentos irrigados por pivô central, gotejamento e sem irrigação. Foram utilizados dois lisímetros de pesagem (12 m2 de superfície em cada lisímetro) por tratamento para realizar a determinação de ETc (uma planta por lisímetros). A evapotranspiração de referência (ET0) foi determinado pelo método de Penman-Monteith a partir de dados meteorológicos coletados na estação meteorológica localizada ao lado do experimento. Valores diários de Kc foram determinados nos tratamentos irrigados pela razão entre ETc e ET0 (Kc=ETc/ET0). IAF foi determinado utilizando o equipamento LAI-2200 Plant Canopy Analyzer, que foi previamente calibrado para adequar as características do dossel do pinhão-manso. Em todos os anos avaliados, o IAF foi quase zero durante o início do período vegetativo, aumentando os valores conforme a planta começou a se desenvolver até atingir valores máximos durante o período produtivo, decrescendo os valores até zero no estádio de desenvolvimento de senescência foliar. A variação anual de ETc no 2º, 3º e 4º ano foi muito similar, explicado pelos diferentes períodos de desenvolvimento da cultura e a variação de IAF no ano. No 1º ano, Kc foi 0,47 para os dois tratamentos irrigados. No 2º, 3º e 4º ano, Kc variou de 0,15 a 1,38 no tratamento irrigado por pivô central e de 0,15 a 1,15 no tratamento irrigado por gotejamento. A média dos valores de Kc no 2º, 3º e 4º ano durante os períodos vegetativos e produtivos foi de 0,77, 0,93 e 0,82 no tratamento irrigado por pivô central, respectivamente, e 0,69, 0,79 e 0,74 no tratamento irrigado por gotejamento, respectivamente. A relação entre Kc e IAF mostrou, para o tratamento irrigado por pivô central, um ajuste logaritmo com coeficiente de determinação (R2) e somatória do erro médio ao quadrado (SEMQ) de 0,7643 e 0,334, respectivamente, e 0,8443 e 0,2079 para o tratamento irrigado por gotejamento, respectivamente. Nos três anos analisados, Kc correlacionado com SUT mostrou o melhor ajuste à equação polinomial de 2ª ordem para os dois tratamentos.
13
Cusimano, Jeremy, Jean E. McLain, Susanna Eden, and Channah M. Rock. "Agricultural Use of Recycled Water for Crop Production in Arizona." College of Agriculture, University of Arizona (Tucson, AZ), 2015. http://hdl.handle.net/10150/561235.
Повний текст джерелаАнотація:
7 pp.Agriculture is by far the largest water-demanding sector in Arizona, accounting for 70% of water demand (ADWR, 2009). Arizona’s agriculture industry is extremely diversified, producing many crops that can legally be irrigated with recycled water, including cotton, alfalfa, wheat, citrus, and vegetables. Throughout the State, farming communities are taking advantage of increasing supplies of recycled water.
14
Mutiso, Samuel Kituku. "Water resources and crop production in Machakos District, Kenya." Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262188.
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15
Kern, James D. "Water Quality Impacts of Cover Crop/Manure Management Systems." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/40385.
Повний текст джерелаАнотація:
Crop production, soil system, water quality, and economic impacts of four corn silage production systems were compared through a field study including 16 plots (4 replications of each treatment). Systems included a rye cover crop and application of liquid dairy manure in the spring and fall.
The four management systems were: 1) traditional, 2) double-crop, 3) roll-down, and 4) undercut. In the fourth system, manure was applied below the soil surface during the undercutting process. In all other systems, manure was surface-applied. In the third system, the rye crop was flattened with a heavy roller after manure application.
Simulated rainfall was applied within 48 h of manure application. Measured constituent concentrations in runoff were compared with water quality criteria. Costs and returns of all systems were compared. The undercut system reduced loadings of all nutrients, but increased total suspended solids (TSS) concentration as compared with all other systems. The mean volume of runoff from the undercut system was less than half that from any other system, which influenced all constituent loadings. Mean TSS concentration in runoff from the undercut system was over three times the mean of any other system. The roll-down system had no significant effect on water quality as compared to the traditional system. The undercut system was reasonably effective in keeping phosphate phosphorus levels below the criterion set for bathing water. None of the systems generally exceeded nitrate nitrogen concentration criteria.
However, total phosphorus, orthophosphate, fecal coliform and e. coli criteria for drinking, bathing, shellfish harvest, and aesthetics were regularly exceeded by all of the systems. There were no differences among the treatments in effects on bacterial concentrations. The double-crop system produced significantly higher net returns than all other systems only if the value of the rye crop was $92.31/Mg or more. There were no significant differences in net returns of the traditional, roll-down, or undercut systems.Ph. D.
16
Abel, David Scott. "Cover crop effects on soil moisture and water quality." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34650.
Повний текст джерелаАнотація:
Master of ScienceDepartment of Agronomy
Nathan O. Nelson
Eutrophication of freshwater lakes and streams is linked to phosphorus (P) fertilizer loss from agriculture. Cover crops could help mitigate P loss but producers are concerned that they may use too much water. This study was conducted to better understand the effects cover crops have on soil moisture and P loss. Volumetric water content (θ) was measured at the Kansas Cover Crop Water Use research area at 10 depths throughout a 2.74 m soil profile in 5 cover crop treatments and compared to θ measured from a chemical fallow control. Total profile soil moisture in sorghum sudangrass (1.02 m) and forage soybean (1.03 m) did not significantly differ from chemical fallow (1.05 m) at the time of spring planting. However, water deficits were observed in double-crop soybean (1.01 m), crimson clover (0.99 m), and tillage radish (0.99 m). At the Kansas Agricultural Watersheds, runoff was collected and analyzed for total suspended solids, total P, and DRP from 6 cover crop/fertilizer management treatments over two years. In the first water year the cover crop reduced runoff, sediment, and total P loss by 16, 56, and 52% respectively. There was a significant cover by fertilizer interaction for DRP loss. When P fertilizer was broadcasted in the fall with a cover crop, DRP loss was reduced by 60% but was unaffected in the other two P fertilizer treatments. Results were different in the second water year. The cover crop reduced sediment loss (71% reduction), as was seen in year one, but neither the cover crop nor the fertilizer management had a significant effect on runoff volume or total P loss overall. Contrary to the 2014-2015 results, cover crop increased DRP load by 48% in 2015-2016. DRP load was 2 times greater in the fall broadcast treatment than it was in the spring injected treatment but there was not a significant fertilizer by cover crop interaction. In order to determine the long term effects of cover crops and P fertilizer management P loss parameters should be tracked for several more years.
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Barnes, Frank. "Estimating Crop Water Requirements in Arizona and New Mexico." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/203501.
Повний текст джерелаАнотація:
Relevant methods for estimating reference crop evaporation and crop evaporation for selected, pertinent crops growing in the semiarid environments of Arizona and New Mexico are investigated. Daily evaporation estimates over the period 2000-2010 are calculated using standard meteorological data from 35 weather stations. Compared to the FAO-56 Penman-Monteith reference evapotranspiration estimate, the Hargreaves and Priestley-Taylor equations overestimate by 5-15% while the temperature-based Blaney-Criddle method currently used in New Mexico underestimates by 8-13%, on average, the discrepancy being most severe in highly advective regions. Crop evaporation estimates are compared to the one-step Matt-Shuttleworth approach. The Blaney-Criddle method systematically underestimates crop evaporation by 7-30%, while underestimation using the climatically adjusted FAO-56 crop coefficient approach is 1-8% for short crops but ~20% for tall pecan and citrus orchards grown at atmospherically arid locations. Crop surface resistances derived using the Matt-Shuttleworth approach at Fabian Garcia in southern New Mexico compare favorably to literature values.
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Ottman, Michael. "Crop Coefficients for Estimating Small Grain Water Use, 2002." College of Agriculture, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/203652.
Повний текст джерелаАнотація:
Crop coefficients are used to estimate water use from reference evapotranspiration values provided by weather stations. Two varieties of barley and durum were planted at the Maricopa Agricultural Center in late November and early January. Water use was estimated from neutron probe readings and crop coefficients were calculated by dividing water use by reference evapotranspiration. The crop coefficients calculated in this study peaked close to 1.2, similar to published values, except for the short season barley cultivar Barcott which had much lower values than the other cultivars.
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Ottman, Michael. "Crop Coefficients for Estimating Small Grain Water Use, 2003." College of Agriculture, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/203653.
Повний текст джерелаАнотація:
Crop coefficients are used to estimate water use from reference evapotranspiration values provided by weather stations. Two varieties of barley and durum were planted at the Maricopa Agricultural Center in late November and early January. Water use was estimated from neutron probe readings and crop coefficients were calculated by dividing water use by reference evapotranspiration. The crop coefficients calculated in this study peaked at 1.0 or less in contrast to published values which generally peak around 1.2. The crop coefficients were lower at the later planting, and there appear to be differences between barley and durum and among barley varieties.
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Ottman, Michael. "Crop Coefficients for Estimating Small Grain Water Use, 2004." College of Agriculture, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/203654.
Повний текст джерелаАнотація:
Crop coefficients are used to estimate water use from reference evapotranspiration values provided by weather stations. Four varieties of barley and durum were planted at the Maricopa Agricultural Center early December and early January and one durum variety was planted at the Yuma Valley Agricultural Center in late December and mid-February. Water use was estimated from neutron probe readings and crop coefficients were calculated by dividing water use by reference evapotranspiration. The crop coefficients calculated in this study peaked from 1.0 to 1.3, and the peak averaged about 1.16. Some differences were detected among planting dates and varieties, but it has yet to be determined if these differences are of practical significance.
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Risley, John C., and C. Brent Cluff. "Crop Consumptive Use Simulation Using a Water Harvesting Model." Water Resources Research Center. The University of Arizona, 2013. http://hdl.handle.net/10150/306487.
Повний текст джерелаАнотація:
A Compartmented Reservoir Operation Program, CROP84, is a computer program developed, by C. B. Cluff (1977), as a tool for optimizing the design dimensions of water harvesting agriculture systems. This model is used in conjunction with a rainfall /runoff model called RAMOD. The objective of the research was to compare the actual and the simulated values of seasonal irrigation and consumptive use of four crops: wheat, sorghum, cotton, and grapes. After repeated simulations structural improvements were made in the soil moisture accounting routine of CROP84. These improvements were in the equations that calculated the rate of root growth, the soil moisture depletion fraction and actual evapotranspiration. In the final simulation, the percentage difference for crop consumptive use calculated from the actual data and the simulation was +2.6 % for sorghum, -2.4 % for grapes, +2.0 % for wheat, and -8.8 % for cotton.
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Aldakheel, Yousef Yacoub. "Remote sensing of crop water stress : measurements and modelling." Thesis, University of Salford, 1998. http://usir.salford.ac.uk/43021/.
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Martin, Edward C., Donald C. Slack, and E. J. Pegelow. "Water Use in Vegetables - Cauliflower." College of Agriculture, University of Arizona (Tucson, AZ), 2014. http://hdl.handle.net/10150/333141.
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Martin, Edward C., Donald C. Slack, and E. J. Pegelow. "Water Use in Vegetables - Carrots." College of Agriculture, University of Arizona (Tucson, AZ), 2014. http://hdl.handle.net/10150/333162.
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Manamathela, Sibongile Amelia. "The water footprint of selected crops within the Olifants/Doorn Catchment, South Africa." University of the Western Cape, 2014. http://hdl.handle.net/11394/4751.
Повний текст джерелаАнотація:
>Magister Scientiae - MScRapidly increasing global population is adding more pressure to the agricultural sector to produce more food to meet growing demands. However the sector is already faced with a challenge to reduce freshwater utilisation as this sector is currently using approximately 70% of global water freshwater resources. In South Africa, the agriculture sector utilizes approximately 62% of freshwater resources and contributes directly about5% to the Gross Domestic Product. South Africa is a water scarce country receiving less than 500mm/year of precipitation in most parts of the country, and consequently approximately 90% of the crops are grown under irrigation. Studies have evaluated irrigation practices and crop water use in the country. However information is lacking on the full impact of South African horticultural products on freshwater resources. The water footprint concept can be used to indicate the total and source (blue/green) of water used to produce the crops. Information about water footprint (WF) can be used for identifying opportunities to reduce the water consumption associated with production of vegetables and fruits at the field to farm- gate levels, including the more effective use of rainfall (green water) as opposed to water abstracted from rivers and groundwater (Blue water). It can also be used to understand water related risks associated with the production of crops and facilitate water allocation and management at catchment/water management scale. While the potential value of water footprint information is well recognized there is still inadequate knowledge on how best to determine the water footprints of various crops within a local context. The aim of this study was to determine the water footprint and the crop water productivity of navel oranges, pink lady apples and potatoes produced with the Olifant/Doorn water management area in South Africa.The water footprint of the navel oranges, pink lady apples and potatoes assessed following the water footprint network method was 125 litres/ kg, 108 litres/kg and 65 litres/ kg respectively. The study concluded that water footprint studies should be carried out on the whole catchment instead of one farm in order to assess the sustainability of the process.
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Copeland, Stephen Mark 1955. "Soil water potential as related to the Crop Water Stress Index of irrigated cotton." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276940.
Повний текст джерелаАнотація:
The application of the crop water stress index (CWSI) method to irrigation scheduling is enhanced by knowledge of the relationship between CWSI and soil water potential (SWP) and how this relationship is affected by soil texture. A study using the same cultivar of cotton on three different soils was conducted in southern Arizona over a single growing season. Detailed data were collected of CWSI and soil moisture content for several treatments that scheduled irrigations at threshold CWSI values. CWSI was correlated with soil water potential values calculated from pressure plate determined moisture release curves. Spatial variability of soil characteristics necessitated use of average rather than plot specific moisture release curves. Analysis showed a linear CWSI-SWP relationship that varied greatly with soil depth and study site. The study concluded that soil profile average SWP alone does not normalize the CWSI between sites with different soil textures.
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Enger, Matthew. "IMPACTS OF CONCENTRATED FLOW PATHS ON CROP YIELDS AND WATER QUALITY IN SOUTHERN ILLINOIS ROW CROP AGRICULTURE." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2380.
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Sediment and nutrient loss from agricultural landscapes contributes to water quality impairment and has the potential to impact crop yield. Best management practices (BMPs) such as riparian buffers have been designed to combat these issues; however, concentrated flow paths (CFPs) reduce their effectiveness and are often overlooked in agricultural fields. Conventional management of CFPs is to fill and grade them, however this provides only a short term solution leading to their reformation and increased sediment loss. The objectives of this project were: i) to determine if the filling of CFPs influence crop growth (yield and biomass), ii) determine a distance at which crop growth is no longer influenced by CFPs, iii) assess the impact that topography and CFPs have on crop growth, iv) analyze water quality in surface runoff leaving crop fields via CFPs, and v) develop an economic analysis for CFP’s influence on crop returns. Six small agricultural catchments, CFPs, and topographic positions (i.e., depositional, backslope, and shoulder) were delineated using ArcGIS and LiDAR data. In each catchment, six 4 m2 plots were established along CFPs where crop biomass and crop yield were measured. Additionally, six plots with no influence from CFPs were established as reference plots. Surface water quality was assessed by taking edge-of-field grab samples at the CFP outlet during significant rain events (i.e., precipitation exceeding 2.5 cm). Water samples were analyzed for total suspended solids (TSS), total phosphorus (TP), dissolved reactive phosphorus (DRP), ammonium-nitrogen (NH4+-N), and nitrate-N (NO3- -N). Through this study it was shown that CFPs served as a conduit for transporting nutrient and sediment laden runoff to receiving waters, that increasing/decreasing distance from CFPs had an impact on crop yields, and that there was no crop yield advantage from the filling of CFPs vs. leaving them unfilled. Median values for NO3-N (1.85 mg L-1) and TSS (140 mg L-1) in the Fill catchments were higher than the No-Fill catchments (0.77 mg L-1 and 35.5 mg L-1, respectively), while DRP and TP concentrations were higher in the No-Fill catchments (1.31 mg L-1 and 2.37 mg L-1, respectively) compared to the Fill catchments (0.91 mg L-1 and 1.83 mg L-1, respectively) over the growing season. Crop biomass and yield results between the depositional and backslope positions were similar regardless of treatment, but were lower than the reference plots and shoulder position. Results from the economic analysis on the cost of farming in/near CFPs indicated that the economic return was greatly dependent on precipitation. CFPs are generally concave positions on the landscapes and have been eroded to a clayey subsoil, both resulting in greater water accumulation and retention than elsewhere in the field. During wetter years, an economic loss was incurred nearest to the CFP and during drier years, sites nearest to CFPs saw positive returns. Farmers and land managers may consider implementing stabilization measures, such as grassed waterways, in CFPs since crop yields are typically lower in wetter years, there’s increased cost to maintain these areas, and accelerated sediment loss can exacerbate the crop yield losses and impact on water quality.
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Nambuthiri, Susmitha Surendran. "Soil water and crop growth processes in a farmer's field." Lexington, Ky. : [University of Kentucky Libraries], 2010. http://hdl.handle.net/10225/1140.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Kentucky, 2010.Title from document title page (viewed on May 12, 2010). Document formatted into pages; contains: xii, 310 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 298-309).
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McGinley, Susan. "New Barley Variety:"Low- Input" Crop Uses Less Water, Fertilizer." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2007. http://hdl.handle.net/10150/622139.
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Moberly, Joseph. "Crop water production functions for grain sorghum and winter wheat." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32560.
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Master of ScienceAgronomy
Robert Aiken
Xiaomao Lin
Productivity of water-limited cropping systems can be reduced by untimely distribution of water as well as cold and heat stress. The research objective was to develop relationships among weather parameters, water use, and grain productivity to produce production functions to forecast grain yields of grain sorghum and winter wheat in water-limited cropping systems. Algorithms, defined by the Kansas Water Budget (KSWB) model, solve the soil water budget with a daily time step and were implemented using the Matlab computer language. The relationship of grain yield to crop water use, reported in several crop sequence studies conducted in Bushland, TX; Colby, KS and Tribune, KS were compared against KSWB model results using contemporary weather data. The predictive accuracy of the KSWB model was also evaluated in relation to experimental results. Field studies showed that winter wheat had stable grain yields over a wide range of crop water use, while sorghum had a wider range of yields over a smaller distribution of crop water use. The relationship of winter wheat yield to crop water use, simulated by KSWB, was comparable to relationships developed for four of five experimental results, except for one study conducted in Bushland that indicated less crop water productivity. In contrast, for grain sorghum, experimental yield response to an increment of water use was less than that calculated by KSWB for three of five cases; for one study at Colby and Tribune, simulated and experimental yield response to water use were similar. Simulated yield thresholds were consistent with observed yield thresholds for both wheat and sorghum in all but one case, that of wheat in the Bushland study previously mentioned. Factors in addition to crop water use, such as weeds, pests, or disease, may have contributed to these differences. The KSWB model provides a useful analytic framework for distinguishing water supply constraints to grain productivity.
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Newby, Adam F. "Increasing Water Application Efficiency in Greenhouse Crop Production UsingGravimetric Data." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366376123.
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Jalali-Farahani, Hamid Reza 1960. "Crop water stress parameters for turfgrass and their environmental dependability." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/191950.
Повний текст джерелаАнотація:
The concept of crop water stress index (CWSI) was explored using empirical and theoretical models to evaluate bermudagrass water status. The empirical methods were simplifications of the crop energy balance equation. Measured field data were employed to develop the empirical CWSI parameters. Field data were collected from turf plots under three levels of irrigation for the 1986 growing season in Tucson, Arizona. The simplest empirical model of Idso gave the highest variance in estimates of CWSI for all treatments with the estimates being highly influenced by net radiation. An improved empirical model was developed when net radiation was included in the statistical analysis of the canopy temperature minus air temperature limits. In general, the most accurate estimates of CWSI were obtained by using the energy balance equation with constant values of potential canopy and aerodynamic resistances. Various methods were used to evaluate these resistances. Further research is needed to test the perfomance of the theoretically-derived CWSI and to develop more general methods of evaluating the resistances.
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Silvertooth, J. C., S. W. Stedman, and J. Tollefson. "Interaction of Pima Cotton Defoliation and Crop Water Stress Index." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/208291.
Повний текст джерелаАнотація:
A single field experiment was conducted in 1989 to evaluate the relationship of crop water status on Pima cotton defoliation by use of a crop water stress index (CWSI) as estimated by infrared thermometry. The entire study area was given the last irrigation uniformly on 24 August, and 20 row plots were outlined for the arrangement of three treatments in a randomized complete block design with three replications. Treatments consisted of making defoliant chemical application at three different targeted CWSI levels (0.40, 0.60, and 0.85). All defoliant treatments consisted of Dropp plus Accelerate (0.4 lb. and 1.5 pt. of material/acre, respectively) applied with a ground rig applicator. Results indicated no distinct advantage in terms of percent defoliation as a function of lower CWSI levels at which defoliants were applied. The defoliations made at 0.40 CWSI did result in more regrowth after 14 and 21 days. It appears from this test that Pima plants will defoliate satisfactorily with proper chemical treatments up to CWSI levels of 0.80. Further desiccation of the crop results in very erratic CWSI readings, resulting in difficulties in applying this technique to defoliation management. It does appear, though, that Pima cotton defoliation can be accomplished when CWSI readings are between 0.5 and 0.8 without substantial regrowth problems, providing precipitation or irrigation events do not occur.
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Sciarresi, Cintia Soledad. "OPTIMIZING COVER CROP ROTATIONS FOR WATER, NITROGEN AND WEED MANAGEMENT." UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/122.
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Winter cover crops grown in rotation with grain crops can be an efficient integrated pest management tool (IPM). However, cover crop biomass production and thus successful provisioning of ecosystem services depend on a timely planting and cover crop establishment after harvest of a cash crop in the fall. One potential management adaptation is the use of short-season soybeans to advance cover crop planting date in the fall. Cover crops planted earlier in the fall may provide a greater percentage of ground cover early in the season because of higher biomass accumulation that may improve weed suppression. However, adapting to short-season soybeans could have a yield penalty compared to full-season soybeans. In addition, it is unclear if further increasing cover crop growing season and biomass production under environmental conditions in Kentucky could limit nitrogen and water availability for the next cash crop. This thesis combines the use of field trials and a crop simulation model to address the research questions posed.
In Chapter 1, field trials evaluating yield and harvest date of soybean maturity group (MG) cultivars from 0 to 4 in 13 site-years across KY, NE, and OH, were used to calibrate and evaluate the DSSAT crop modeling software (v 4.7). The subsequent modeling analysis showed that planting shorter soybean maturity groups (MG) would advance date of harvest maturity (R8) by 6.6 to 11 days per unit decrease in MG for May planting or by 1 to 7.3 days for July planting. The earliest MG cultivar that maximized yield ranged from MG 0 to 3 depending on the location, allowing a winter-killed cover crop to accumulate between 257 to 270 growing degree days (GDD) before the first freeze occurrence when soybean was planted in May, and between 280 to 296 GDD when soybean was planted in July. Winter-hardy cover crops could accumulate 701 to 802 GDD following soybean planted in May and 329 to 416 GDD after soybean planted in July.
In Chapter 2, a two-year field trial was conducted at Lexington, KY to evaluate the effect of a soybean – cover crop rotation with soybean cultivars MG 1, 2, 3 or 4 on cover crop biomass and canopy cover, and on weed biomass in the fall and the following spring. Results showed that having cover crops was an efficient management strategy to reduce weed biomass in the fall and spring compared to no cover treatment. Planting cover crops earlier in the fall after a short-season soybean increased cover crop biomass production and percentage of ground cover in the fall, but not the following spring. Planting cover crop earlier after a short-season soybean did not improve weed suppression in the fall or spring compared to a fallow control with full-season soybean. Having a fall herbicide application improved weed control when there was a high pressure of winter annual weeds. By the spring, delaying cover crop termination increased cover crop biomass but also did weed biomass.
In Chapter 3, a soybean – cover crop – corn rotation was simulated to evaluate the effect of different soybean MG and cover crop termination, as well as year to year variability on water and nitrogen availability for the next corn crop in Lexington, KY. Simulations showed that when cover crops were terminated early, they did not reduced soil available water at corn planting. However, introducing a non-legume cover crop reduced total inorganic nitrogen content in the soil profile by 21 to 34 kg ha-1 implying 15 to 30 kg ha-1 less in corn nitrogen uptake. Cover crop management that was able to maintain similar available water values than fallow treatment while minimizing nitrogen uptake differences was cover crops planted after soybean MG 4 with an early termination. However, the best management strategies that will maximize ecosystem services from cover crops as well as cash crop productivity may need to be tailored to each environment, soil type, irrigation management, and must consider year-to-year variability.
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Yeap, Simon Guo Hong. "Implications of soil water repellence for crop growth and nutrition." Thesis, Yeap, Simon Guo Hong (2020) Implications of soil water repellence for crop growth and nutrition. PhD thesis, Murdoch University, 2020. https://researchrepository.murdoch.edu.au/id/eprint/59040/.
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In water-limited environments, dryland crop and pasture production on water-repellent sandy soils is often constrained by reduced water infiltration, accentuated overland flow and soil erosion, unstable wetting patterns, and the development of preferential flow paths in the soil profile, which consequently cause considerable spatial heterogeneity in soil water content, increased prevalence of isolated dry zones, and decreased overall soil water retention. The same processes are also likely to affect soil nutrient bioavailability and plant nutrient uptake. Indeed, while problems with crop nutrition on water-repellent sandy soils have been reported by many Australian growers, the role of soil water repellence in crop nutrition has not been studied to date and the mechanisms remain unclear. While various methods exist to manage soil water repellence for improving crop and pasture production (e.g., deep soil cultivation, clay spreading, wetting agent application, stimulation of wax-degrading microorganisms, furrow/on-row sowing and water harvesting, and no-tillage and stubble retention), the outcomes for crop nutrition post-amelioration are not well understood.
Several field and glasshouse experiments were, therefore, conducted to assess the implications of soil water repellence and its management on crop growth and nutrition on several sandy soil types from the southwest region of Western Australia. Preliminary field results showed that soil water repellence, if left unmanaged, could adversely affect wheat plant density, shoot dry matter production, K nutrition, and grain yield on a Grey Bleached-Ferric Kandosol (deep grey sandy duplex soil) at Meckering with a moderate water repellence value of up to 1.6 M using the molarity of ethanol droplet (MED) test, supporting the hypothesis that soil water repellence can adversely affect crop growth, nutrition, and grain production. However, it was also revealed at another site, with a Ferric Chromosol (sandy loam yellow duplex soil) at Kojonup, that increased soil water repellence could also increase canola plant density, shoot dry matter production, Cu nutrition, and seed yield when sown with 1 L/ha of banded wetting agent, despite prolonged severe water repellence (MED of 3.4 M) throughout the growing season. Although the underlying mechanisms could not be established from this preliminary study, it was concluded that soil water repellence may have both adverse and beneficial implications, but specific effects on nutrient availability in the root zone and crop nutrition were not defined.
Additional field studies were conducted to assess the effect of soil management practices (spading, one-way plough, subsoil clay spreading, and blanket applications of wetting agent) to alleviate soil water repellence on crop growth and nutrition. While all treatments except for one-way ploughing alleviated soil water repellence, only spading significantly improved wheat emergence, shoot dry matter, K nutrition, and grain yield on a Grey Tenosol (pale deep sandy soil) at Badgingarra. By contrast, at Moora, one-way plough treatments improved canola shoot dry matter and nutrition (Ca, S, B, Cu, and Zn contents) but did not mitigate severe water-repellence on a Ferric Chromosol (sandy ironstone gravel duplex soil), and had no effect on plant density or seed yield. However, the improvements due to soil cultivation can be attributed to the alleviation of soil compaction, given that the alleviation of soil water repellence by blanket-applied wetting agent (50 L/ha) and subsoil clay spreading treatments (250 t/ha; 50 % clay; 159 mg K/kg) had negligible effect on crop growth, nutrition, and grain production. Alleviation of soil water repellence was, therefore, not important for crop production at the Badgingarra and Moora study sites, presumably due to the presence of other soil constraints.
To avoid the confounding effects from multiple limiting factors evident in the field studies, a series of controlled glasshouse experiments were conducted to examine the effects of topsoil water repellence, topsoil thickness, fertiliser placement, variable low water supply, plant density, and/or surface topography on soil water content, soil nutrient availability, and early wheat growth and nutrition in 27 L containers. All glasshouse experiments demonstrated that severely water-repellent topsoil with a wettable furrow, which ensured uniform seedling emergence, significantly increased wheat seedling development, tiller number, shoot dry matter production, and nutrition (especially N, P, and K) during the early vegetative stage in wheat (40-51 DAS), under low but regular water supply (3.4-5.4 mm every two days). The growth stimulation was attributed to in situ water harvesting caused by preferential flow in the wettable furrow which increased the soil wetting and root depth relative to the completely wettable topsoil treatments that exhibited an even but shallow wetting depth. The even but shallow wetting patterns in completely wettable treatments consequently led to an overall decrease in plant-available water and plant water use efficiency, resulting in poor wheat growth and nutrition, especially under a limited water supply. These findings underscore the high efficacy of in situ water harvesting for improving early wheat growth and nutrition on water-repellent soils relative to completely wettable soils, thus demonstrating a beneficial role of soil water repellence in crop growth and nutrition. Adopting in situ water harvesting principles (i.e., furrow sowing, banding wetting agent in the furrow, and using winged knife-points and/or press-wheels) can, therefore, be an effective strategy for managing crop growth and nutrition on water-repellent sandy soils by maximising the use efficiency of limited soil water supply during the crop establishment period.
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Munyaradzi, Sipho Musevenzo Ward Andrew D. "Predicting soil water deficits and crop yields for Seneca County 1988 /." Connect to resource, 1991. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1145449951.
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Doria, Rufa. "Impact of climate change on crop water requirements in Eastern Canada." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104583.
Повний текст джерелаАнотація:
Crop production is highly dependent upon weather; therefore, future climate change could adversely affect the burgeoning global population. The primary objective of this study was to predict the consequences of climate change on agriculture. Since current climate projections use general circulation models (GCMs) on a global scale, a statistical downscaling model (SDSM) was used to downscale these outputs into a local scale, essential for reliable crop model simulations.By linking predicted changes in local climate to soil properties and crop characteristics through field and laboratory studies, thresholds of soil moisture content for efficient irrigation scheduling were defined, and an irrigation requirements model (IRM) was developed. Using the IRM, irrigation was triggered when soil moisture was 18 or 24 mm for peaches grown in clay and sandy soils, respectively, and was also triggered at 56 mm for grapes grown in clay soils. It was noteworthy that the IRM reduced irrigation needs by 20 to 25% without affecting yield of peaches (50 to 60 kg/tree). Regarding predicted increases in temperatures and variability in precipitation, the SDSM-HadCM3 A2 scenario forecast the greatest increases, namely ~3.5 and ~2.5°C in average monthly maximum and minimum temperatures, respectively, during the growing season, compared to a 1961-1990 base period. Moreover, precipitation events were also predicted to be more frequent (8 to 30%) and intense (10 to 50%) during crop growing months.With these future climate change scenarios, irrigated peach yield could increase 5 to 20%, since actual tree transpiration reached 0.8 kg/h (compared to a maximum of 0.4 kg/h without irrigation). Furthermore, with irrigation, fruit firmness, the best indicator of ripening and predictor of peach storage potential, is expected to improve by 20% over the current value of 340 kPa.The most novel aspect of this study was development of the IRM, and its prediction of optimal irrigation needed to sustain or increase crop yield and quality, and concurrently conserve water.La production agricole est très dépendante du climat; par conséquent, les futurs changements climatiques globaux pourraient avoir des effets adverses sur la population mondiale en plein essor. L'objectif principal de cette étude était de prédire les conséquences du changement climatique sur l'agriculture. Puisque les projections climatiques actuelles utilisent des modèles de circulation générale à une échelle globale, un modèle statistique de réduction (MSR) a été utilisé pour réduire ces données à l'échelle locale, ce qui est essentiel pour des simulations de production agricole.En reliant les changements du climat locaux prédits (modélisation) aux propriétés du sol et les caractéristiques des cultures (études sur le terrain et en laboratoire), les seuils du contenu en humidité du sol pour la planification d'un horaire d'irrigation efficace ont été définis, et un modèle de besoin en irrigation (MBI) a été développé. En utilisant ce modèle, l'irrigation était déclenchée lorsque l'humidité du sol était de 24 ou 18 mm pour les pêchers croissant en sols sablonneux ou argileux, respectivement, et a été déclenchée à 56 mm pour les vignes croissant en sol argileux. Il était remarquable que le MBI a réduit le besoin en irrigation de 20 to 25% sans affecter le rendement en pêches (50 to 60 kg/arbre).Concernant les augmentations de températures et les variabilités de précipitations prédites, le scénario SDMS-HadCM3 A2 prédit les plus fortes hausses, environ 3.5 et 2.5oC en moyenne pour les températures mensuelles maximum et minimum, respectivement, pendant la saison de croissance (comparé à une période de base 1961-1990). De plus, des précipitations plus fréquentes (8 to 30%) et plus intenses (10 to 50% durant les mois de croissance ont aussi été prédites.Avec ces scénarios de changements climatiques futurs, le rendement en pêches irriguées pourrait augmenter de 5 to 20%, puisque la transpiration des arbres a atteint 0.8 kg/h (comparé à un maximum de 0.4 kg/h sans irrigation). De plus, avec l'irrigation, la fermeté des fruits, le meilleur indicateur du mûrissement et prédicateur du potentiel d'entreposage des pêches, devrait s'améliorer de 20% (valeur actuelle, 340 kPa).L'aspect le plus novateur de cette étude a été le développement du modèle MBI, qui a prédit l'irrigation optimale requise pour maintenir ou augmenter le rendement et la qualité des cultures tout en conservant l'eau.
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Nyamudeza, Phibion. "Water and fertility management for crop production in semi-arid Zimbabwe." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243687.
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Flint, C. E. "Chemical regulation of crop growth and water use in winter cereals." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334018.
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Munyaradzi, Sipho Musevenzo. "Predicting soil water deficits and crop yields for Seneca County 1988." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1145449951.
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Zeywar, Nadim Shukry. "Water use and crop coefficient determination for irrigated cotton in Arizona." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185887.
Повний текст джерелаАнотація:
Crop coefficients (K(c)) are a useful means of predicting how much water is needed for irrigating a crop. The crop water stress index (CWSI), on the other hand, is a means of knowing when to irrigate. Two field experiments were conducted during the summers of 1990 and 1991 at Maricopa Agricultural Center and Marana Agricultural Center, respectively, to evaluate water use (evapotranspiration, ET) of different cotton varieties, to develop crop coefficients for cotton grown in the state of Arizona, and to evaluate empirical and theoretical crop water stress indices under field conditions. For the 1990 experiment, ET from the cotton variety DPL 77 was obtained using soil water balance (SWB) and steady state heat balance (SSHB) techniques. For the 1991 experiment, ET from two cotton varieties (DPL 20 and Pima S-6) was estimated using the Bowen ratio energy balance (BREB) method and the steady state heat balance method. Reference evapotranspiration (ETᵣ) was obtained from weather stations located close to the experimental plots. Average daily ET from the SSHB measurements ranged from 8.24 to 15.13 mm and from 10.34 to 12.12 mm for the 1990 and 1991 experiments, respectively. Total ET from the SWB was approximately 19% less than the total ET estimated by the SSHB. Total ET from individual plants was well correlated with average stem area over the evaluation periods. Daily ET from the two cotton varieties (DPL20 and Pima S-6) was approximately similar when irrigation conditions were the same, but differed later by as much as 48.4% as irrigation continued for the variety Pima S-6 only. Daily ET from the BREB measurements and ETᵣ were used to develop a crop coefficient curve for cotton grown at Marana, Arizona, which had a maximum smoothed value of 1.21. A critical value of CWSI equal to 0.3 was obtained by observing the pattern of the CWSI values over well-watered and drier conditions, and from previous research. Using the developed crop coefficient curve and the CWSI should provide a useful means of scheduling irrigation for cotton grown under climatic conditions similar to those at Marana, Arizona.
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Rude, Peter Heinz 1961. "Water management and crop selection for intensive gardens in arid regions." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/192004.
Повний текст джерелаАнотація:
Agricultural development projects in arid regions are hampered by lack of knowledge surrounding the efficient use of water and an understanding of the indigenous people. A method, using computer models, is presented for analyzing water management and selecting a crop mix for intensive gardens in arid regions. The crop mix is constrained by land and water availability and the nutritional requirements of a family. Model results indicate that an intensive garden grown during the entire year in Tucson, Arizona (annual precipitation of 285 mm), would require approximately 140 cm of water per unit area of land with an irrigation application efficiency of 73%. Results are based on irrigating the entire garden using the water requirement of the crop which has the highest demand for water since the previous irrigation. A table showing the nutritional content of five crops per unit of water applied during the growing season is presented.
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Garrot, Donald J. Jr, Delmar D. Fangmeier, and Stephen H. Husman. "Scheduling Irrigations on Cotton Based on the Crop Water Stress Index." College of Agriculture, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/204489.
Повний текст джерелаАнотація:
The Crop Water Stress Index (CWSI) was used to schedule irrigations on drip irrigated cotton research plots in Tucson and on eight acre furrow irrigated fields at the Marana and Maricopa Agricultural Centers. Scheduling irrigations when plots reached 0.30 CWSI units resulted in highest yields with 1403 lbs/acre cotton lint using 33.8 inches of water. The Marana and Maricopa fields yielded 1322 lb/acre on 28 inches and 1767 lb/acre on 58 inches of water, respectively.
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Ma, Qifu. "Soil salinity and water stress modify crop sensitivity to SO2 exposure." Thesis, Ma, Qifu (1993) Soil salinity and water stress modify crop sensitivity to SO2 exposure. PhD thesis, Murdoch University, 1993. https://researchrepository.murdoch.edu.au/id/eprint/42300/.
Повний текст джерелаАнотація:
Sulphur dioxide (SO2) is a pnmary gaseous pollutant which has toxic effects on the growth, yield and quality of both agricultural and natural plant species. Although plant responses to SO2 exposure have been extensively studied, much less is understood concerning the influences of other environmental stresses on the expression of effects of gaseous air pollutants. Evaluation of such interactions should be of an economic importance in agriculture and horticulture since plants growing in the field usually encounter air pollution and other stresses simultaneously. Soil water stress and salinity are the common environmental stresses and they have some physiological similarities. This thesis aims to investigate to what extent water stress and salinity modify or amplify the detrimental effects of SO2 on foliar injury, plant growth and yield, and some physiological and biochemical changes in potato (Solanum tuberosum L. cv. Russet Burbank) and soybean (Glycine max L. cv. Buchanan) crops under field conditions.
SO2 exposure induced growth reductions in well-watered potato plants but usually not in the water-stressed plants, indicating a protective function of soil moisture stress in the response of plants to SO2. This could be caused by a reduced SO2 uptake m water-stressed plants, as well-watered plants had much higher leaf sulphur concentrations than did the water-stressed plants at the same SO2 fumigation levels. SO2 also increased leaf sulphur concentrations in soybean, but simultaneous exposure to SO2 and salinity significantly decreased leaf sulphur concentrations when compared with exposure to SO2 alone. As a consequence, SO2-induced foliar injury was more severe in the well-watered or nonsaline plants than in the water-stressed or saline plants.
Exposure conditions can also be important in determining the response of a plant to stress interactions. Contrasts of sequential and simultaneous exposures to SO2 and salinity were made in this project so as to examine stress compensatory mechanisms and predisposition characteristics. It was found that low salinity pretreatment (27 mM NaCl) ameliorated the detrimental effects of SO2 on soybean growth probably by inducing stomatal closure. However, high salinity (48 mM NaCl) treated plants, which also showed high stomatal resistance, were severely injured by subsequent SO2 exposure especially at high SO2 concentrations (300 nl 1-1). It was likely that high salinity pretreatment decreased or even destroyed plant homeostasis due to direct injury of high ion concentrations. By comparison, plants pretreated with SO2 became vulnerable to salt injury and those pretreated with high SO2 were killed after 12 days of high salt stress. This was probably because SO2 altered the patterns of assimilate allocation favouring shoot growth at the expense of root growth and induced other metabolic changes. As a consequence, the resistance of polluted plants to salinity stress was reduced.
SO2 pollutant increased the shoot to root ratios by either reducing root growth or stimulating shoot growth, whereas soil moisture stress had the opposite effect. Exposure to 300 nl 1-1 SO2 under well-watered conditions induced an increase in the shoot to root (including tuber) ratios of potato plants early in the growing season. In contrast, water stress decreased the ratios in the control and 110 nl 1-1 SO2 treatments, but not at 300 nl I-1 SO2 indicating that high SO2 had disrupted this acclimatory response to soil moisture stress. SO2-induced increase in the shoot to root ratios was also observed in the soybean experiments. However, it appeared that soil salinity did not significantly affect the ratios.
High SO2 decreased the number and weight of root nodules, and suppressed nodule nitrogenase activity. Consequently, both shoot and root nitrogen concentrations were reduced. In combination with low salinity, however, the adverse effects of high SO2 on nodule number, specific nodule activity and plant nitrogen concentrations were ameliorated. Biomass was usually not very sensitive to the interactive effects of SO2 and salinity, probably because it is slower to respond to the stresses following physiological and biochemical processes. In the field, stress interactions may become even more complicated due to interactions with other environmental stresses.
In conclusion, moderate soil salinity and moisture stress can modify crop sensitivity to SO2 exposure mainly through stomatal mechanisms. Such interactions, together with the knowledge of interactions of gaseous au pollutants and other environmental stresses (e.g. light, humidity and temperature), are important when we attempt to establish dose or concentration-response relationships for the development of predictive models for the effects of air pollutants on crops or native plants. Environmental factors may readjust the dose thresholds of au pollutants, above which detrimental effect are likely and below which insignificant effects or growth stimulations occur. Therefore, air quality standards designed to protect vegetation may need to· consider variations in regional environmental conditions.
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Khan, M. F. "Rooting patterns, water use and productivity in wheat, rye and triticale." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234680.
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Martin, Edward C., Donald C. Slack, and E. J. Pegelow. "Water Use in Vegetables - Dry Bulb Onions." College of Agriculture, University of Arizona (Tucson, AZ), 2014. http://hdl.handle.net/10150/333152.
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Fangmeier, D. D., S. H. Husman, and D. J. Jr Garrot. "Irrigation Scheduling Based on the Crop Water Stress Index and Precision Water Application for High Cotton Yield." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/219764.
Повний текст джерелаАнотація:
The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.A modified, low- pressure linear move irrigation system was used to irrigate cotton at the Marana Agricultural Center, University of Arizona in 1985. Irrigations were scheduled using the Crop Water Stress Index (CWSI) for timing and a neutron probe to determine soil moisture deficits. Irrigations were applied when the CWSI reached 0.1 resulting in minimal seasonal water stress. Yields ranged from 3.14 bales /acre to 2.73 bales/acre from 2 acre plots. Total applied water ranged from 31.3 inches to 32.3. Total seasonal rainfall was 2.90 inches.
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Mallah, Abdul Nabi. "Effects of water stress and salinity on contrasting wheat genotypes." Thesis, Bangor University, 1991. https://research.bangor.ac.uk/portal/en/theses/effects-of-water-stress-and-salinity-on-contrasting-wheat-genotypes(d16c3b0e-d0a0-44e3-ada1-79fce0bd31ce).html.
Повний текст джерелаАнотація:
A series of experiments was carried out in the Department of Agriculture, University College of North Wales, Bangor, during October 1987 to September 1989. The purpose of these was to study the effects of water stress and salinity stress at different stages on long (Norman), medium (Fenman) and short duration (Wembley) wheat varieties in different environments. Effects of water stress were tested in large pots in different types of soil. Effects of salinity were tested by growing plants in solution culture. In both experiments water stress and salinity stress were imposed at three major stages, tillering to stem extension (TL-SE), stem extension to booting (SE-BG) and booting to maturity (BG-MT). These were tested in each variety in comparison with a control of each variety. Growth measurements, leaf number and area, stem area, shoot number, plant height, nitrogen %, nitrogen uptake, dry weight per plant were determined at the end of each stage. Soluble carbohydrates were determined at anthesis. This was done to find out how much these growth measurements were decreased during each stress period. Yield and yield components were determined at harvest. In these experiments the long duration variety took a long time in growth during TL-SE, in comparison to mid winter and spring wheat varieties. The long duration variety gave a higher plant, more straw dry weight production and more leaf number than the short duration variety. The long duration variety also gave a higher yield than the medium and short duration varieties, due to larger ears, more spikelets vi per ear, more grain number per ear and more grain number per spikelet. All varieties experienced higher temperatures and longer days during SE-BG and BG-MT in both experiments. The lengths of these stages therefore showed smaller variation between varieties. In water stress experiments the mixed peat-soil used in Experiment 2 dried out quicker than the normal field soil used in Experiment 1. The upper portion of the soil was dried before the lower portion of the soil during the stress period. With water stress at SE-BG and BG-MT the soil dried out quicker in both years. Gypsum blocks were used to give readings of water stress. with water stress at BG-MT the soil was completely dried out after the third week, in all varieties, due to higher plant height, higher temperature and more evaporation. Because of this water stress at BG-MT resulted in a short duration for ripening. In both water stress Experiments 1 and 2, in all varieties all water stress treatments decreased the growth measurements, decreased yield and yield components. In Norman water stress at TL-SE had a long stress period due to slow growth processes during cold winter. However, this stage had a similar effect on yield in Norman, Fenman and Wembley. In both water stress experiments in all varieties, water stress at SE-BG caused the largest reductions in growth measurements, because at this stage the plant had the greatest leaf area and temperature was higher, although the period of stress was only a few weeks. However, water stress at BG-MT caused the greatest decreases in yield. This stage showed the greatest vii decreases in yield and yield components, due to small grain size, fewer fertile spikelets, small size of ear, earlier leaf senescence, short duration for ripening, higher temperature, lack of soluble carbohydrate for grain f~lling from stem and pollination problems at anthesis time. In both salinity Experiments 1 and 2, all varieties had a larger green leaf area, more tillers and all varieties were much stronger after stem extension than in the water stress experiments due to the solution culture teChnique. Norman was more strong than the other varieties because of its long period grown in solution culture. Salinity at TL-SE was more damaging than other stages in all varieties. Salinity at TL-SE decreased the growth measurements, such as leaf area, stem area, plant height, dry weight per plant. Because of the growth measurement reduction, grain weight per plant, grain number per plant, grain number per ear, grain number per fertile spikelet and fertile spikelet per ear were decreased by salinity at this stage. Salinity at SE-BG and BG-MT also decreased growth measurements, decreased grain yield and yield components. Salinity at BG-MT decreased grain yield and yield components more than salinity at SE-BG. In Experiment 2 in all varieties with salinity at BG-MT plants were harvested a few days before other stages and the control. Norman was more sensitive with salinity at TL-SE than the other varieties because of its long period grown under salt stress. Norman was much stronger with salinity at SE-BG. Norman gave lower yield, yield components at BG-MT than other varieties at this stage.
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Gueneau, Arthur. "Crop water stress under climate change uncertainty : global policy and regional risk." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78495.
Повний текст джерелаАнотація:
Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 113-121).
Fourty percent of all crops grown in the world today are grown using irrigation, and shifting precipitation patterns due to climate change are viewed as a major threat to food security. This thesis examines, in the framework of the MIT Integrated Global System Model, the potential impacts of climate change on crop water stress and the risk implications for policy makers due to underlying uncertainty in climate models. This thesis presents the Community Land Model - Agriculture module (CLM-AG) that models crop growth and water stress. It is a global generic crop model built in the framework of the Community Land Model and was evaluated for maize, cotton and spring wheat. A full climate model, the IGSM-CAM, was first used to force CLM-AG and show the regional disparity of the response to climate change. Some areas like the Midwest or Equatorial Africa benefit from the higher precipitations associated to climate change while others like Europe or Southern Africa see the irrigation need for crops increase. The effect of a mitigation policy appeared contrasted, as water-stress for some areas (including Europe and Africa) is increased if greenhouse gases emissions are limited while for other areas (Central Asia, United States) it is reduced. A second analysis was carried in Central Zambia using uncertainty ensembles. The ensembles demonstrate the notable extent of the uncertainty stemming from different climate sensitivities and different regional patterns in climate models. Crops are impacted differently but a consistent result is that climate mitigation policies reduce uncertainty in crop water stress, making it easier to plan for any anticipated future climate change.
by Arthur Gueneau.
S.M.in Technology and Policy
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Alyemeny, Mohammed N. "Water use of the alfalfa crop under desert conditions in Saudi Arabia." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/11973.
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