Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 5, 2000
Publication Date: N/A
Technical Abstract: Knowledge of yield and soil water use relationships is fundamental for managing irrigation water supplies. Our objectives were to determine for grain sorghum [Sorghum bicolor (L.) Moench] and corn (Zea mays L.): 1) the soil water content at harvest that had resulted in grain yield decline compared with the full irrigation treatment, and 2) whether this yield response to water stress was similar for both crops. The crops were grow in lysimeters containing monolithic cores of either clay loam, silt loam, or sandy loam. Volumetric soil water content was determined using a neutron probe calibrated to each soil type. Both corn and sorghum grain yields had declined when about 25 to 30% of plant available water remained in the soil profile at harvest as compared with that for the full irrigation crop. The grain yield of corn grown in the clay loam dropped abruptly to 60% of the full irrigation treatment yield over a narrow range of mean soil water content (about 3%) compared with grain sorghum, which declined only to about 80%. In both the sandy loam and silt loam, corn and sorghum grain yields gradually dropped to about 80% of fully irrigated yields over a 10% change in soil water content.