Grain Sorghum Yield Response to Water Availability

Yield effects of irrigation on sorghum and corn were compared, but this report is merely focused on the sorghum phase of the crop rotation. Mean yield for irrigated sorghum was 168 bu/a, whereas dryland yield was 145 bu/a. The latter represents a yield improvement of 24 bu/a, an increase of approximately 2 bu/a per unit (in.) of water applied (considering a total of 11 in. of water applied in the irrigation block). The irrigated sorghum used a mean of 7.8 in. more water than the dryland, which suggests that the dryland sorghum consumed 3.4 in. more water from the soil profile than the irrigated sorghum (this value assumes no water losses due to runoff or deep percolation and is calculated from total precipitation and irrigation as well as changes in profile water status). Water use efficiency, or WUE, was calculated as the ratio of yield to water use. A trend for superior WUE of 6.5 bu/in. was documented under dryland conditions, compared with 5.6 bu/in. for irrigated sorghum