Yield and Water Use Efficiency of Grain Sorghum in a Limited Irrigation-Dryland Farming System1
- B. A. Stewart,
- J. T. Musick and
- D. A. Dusek2
A Limited Irrigation-Dryland (LID) farming system for the conjunctive use of rainfall and limited irrigation of graded furrows was developed and field tested. The unique feature of the LID system is that it actually adjusts, during the crop growing season, the amount of land irrigated since more land can be irrigated during above-average rainfall years with a limited amount of irrigation water than during below-average years. The design used a limited water supply to irrigate a larger area than could be conventionally irrigated. A graded furrow field, 600 m long on a 0.3 to 0.4% slope was divided into three water management sections. The upper half of the field was managed as “fully irrigated.” The next one-fourth was managed as a “tailwater runoff” section that utilized furrow runoff from the fully irrigated section. The lower one-fourth was managed as a “dryland” section capable of utilizing runoff from either rainfall or irrigation on the wetter sections. The system was field tested for 3 years with grain sorghum (Sorghum bicolor (L.) Moench) on a Pullman clay loam (fine, mixed, thermic family of Torretic Paleustolls). Seasonal rainfall values were 224 mm in 1979, 103 mm in 1980, and 424 mm in 1981 as compared to the average of about 250 mm. The LID system was successful in increasing the utilization efficiency of irrigation water. Irrigation water added to a field can be transpired, evaporated, percolated, lost as runoff, or left stored in the soil after harvest. The LID system tended to reduce all losses other than transpiration. When 125 mm or 185 mm of irrigation water were added with the LID system, the evapotranspiration by grain sorghum was increased by an almost equal amount. This increased grain yield an average of 154 kg/ha for each 10 mm added irrigation, compared to 92 kg/ha for each 10 mm under conventional irrigation practices.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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