Impact of irrigation applications at soil moisture deficits on plant development and yield of indeterminate and determinate soybean varieties

As the Mississippi River Alluvial Aquifer declines, it is the duty of soybean producers to become more efficient irrigators. Research was established in 2012 and 2013 in the Mississippi Delta to evaluate plant development and yield of an indeterminate soybean variety with irrigation initiated at the R1 producer standard and compared to initiation timings at the R2, R4, and R5 growth stages once a 2" deficit was reached according to the FAO-56 Penman-Monteith model. Research was also conducted to evaluate seeding rates in irrigated and non-irrigated systems in Starkville and Stoneville, MS in 2013 and 2014. These data indicate that delaying irrigation initiation beyond R1 did not adversely affect yield, and in some instances even provided a small yield increase. Irrigation did show consistent yield benefit regardless of initiation timing over a non-irrigated system. No optimum seeding rate in terms of yield or net return was observed across site years.