Water use by alfalfa,maize, and barley as influenced by available soil water |
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| Authors: | AS Abdul-Jabbar TW Sammis DG Lugg CE Kallsen D Smeal |
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| Institution: | 1. Department of Crop and Soil Sciences, New Mexico State University, Box 3268, Las Cruces, NM 88003 U.S.A.;2. Agricultural Engineering Department, New Mexico State University, Box 3268, Las Cruces, NM 88003 U.S.A.;3. San Juan Branch Station, Farmington, NM U.S.A.;4. Plains Branch Station, Clovis, NM U.S.A. |
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| Abstract: | The availability of soil water is one of the most important determinants of crop production. Field studies were conducted to examine the relationships between relative evapotranspiration () and available water (W) for alfalfa, maize, and barley. Line source sprinkler irrigation systems were used to provide the variations in soil moisture. Actual evapotranspiration (E) was determined using the water balance method. Maximum evapotranspiration (Emax) was the highest E observed among all irrigation levels. Potential evapotranspiration (E0) was estimated using Penman's equation to characterize the evaporative demand.The results show that the relationships between and W were different for the three crops. For alfalfa, the relationship was dependent on the physical properties of the soil and on E0. In a clay loam soil, the decline in E from Emax commenced at a higher value of W than in a sandy loam soil. Furthermore, the rate of decline in E from Emax was dependent on E0 and was greater as E0 increased. In the sandy loam soil, the relationship between and W was not dependent on E0. For maize and barley in clay loam soils, as a function of W was linear, and was not dependent on E0. This study was compared to results reported in the literature, and it was hypothesized that differences were related mainly to the way variation in soil moisture was introduced over the measurement period. |
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