Supplemental irrigation for grain sorghum production in the US Eastern Coastal Plain

Authors: Stone, Kenneth - Ken; Sigua, Gilbert; Bauer, Philip

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2018
Publication Date: 4/20/2018
Citation: Stone, K.C., Sigua, G.C., Bauer, P.J. 2018. Supplemental irrigation for grain sorghum production in the US Eastern Coastal Plain. Applied Engineering in Agriculture. 34(2):395-402. https://doi.org/10.13031/aea.12615.
DOI: https://doi.org/10.13031/aea.12615

Interpretive Summary: The US eastern Coastal Plain produces a large amount of poultry and livestock. Much of the grain used to feed these animals is imported. Recently, to reduce the amount of imported grains, there was an emphasis on increasing regional grain production with grain sorghum having an important role. Grain sorghum is an important grain crop throughout the world and is generally considered drought tolerant which may match the regions soils that generally have low water holding capacities and highly variable rainfall can frequently expose crops to water stress. In the research, we initiated an experiment to determine the effect of supplemental irrigation on grain yield in the region on two varieties fertilized at three levels of nitrogen. During our 3-year study, seasonal rainfall was adequate to produce acceptable grain sorghum yields. Supplemental irrigation was applied to maintain adequate soil moisture and the irrigation depths applied were 51, 38, and 13 mm in 2012, 2013, and 2014, respectively. We found no significant difference in grain yield for the two varieties or for the three nitrogen application rates. The lack of response to nitrogen applications may have been related to adequate supplies in the soil from previous crops. This study results suggest that there would be little benefit to supplemental irrigation for sorghum production in the US eastern Coastal Plain.

Technical Abstract: Grain sorghum is an important grain crop throughout the world and is generally considered drought tolerant. Recently, in the US eastern Coastal Plain region, there was an emphasis on increasing regional grain production with grain sorghum having an important role. The region soils have low water holding capacities and highly variable rainfall can frequently expose crops to water stress. In the research, we initiated an experiment to determine the effect of supplemental irrigation on grain yield in the region on two varieties fertilized at 3 levels of nitrogen. During our 3-year study, seasonal rainfall was adequate to produce acceptable grain sorghum yields. Seasonal rainfall ranged from 421 mm in 2012 to 365 and 357 mm in 2013 and 2014, respectively. These rainfall amounts were greater than the seasonal calculated crop evapotranspiration requirement, but rainfall distribution was not adequate to maintain acceptable soil water potentials throughout the growing season. Supplemental irrigation was 51, 38, and 13 mm in 2012, 2013, and 2014, respectively, to maintain soil water potential above -30 kPa. These irrigation amounts did not increase grain sorghum yields. Additionally, we found no significant difference in grain yield for the two varieties or for increasing nitrogen applications. This lack of response to nitrogen applications may have been related to adequate supplies in the soil from previous crops. Results from this study suggest that there would be little benefit to supplemental irrigation for sorghum production in the US eastern Coastal Plain.