Corn Yield Response To Managed Drainage And Polymer-Coated Urea Fertilizer In a Poorly-drained, Claypan Soil.

With poorly-drained claypan soils in the Midwestern U.S., it is common to have wet soil conditions in the spring and dry soil conditions in the summer. Management practices that can improve or mitigate the effects of excessive wet and dry soil conditions are essential to obtain maximum corn (Zea mays L.) yield potential. The objectives of the four-year study was to determine if subsurface drainage [free drainage (FD) or managed drainage (MD)] with polymer-coated urea (PCU) can increase corn yield compared to application of non-coated urea (NCU) without drainage (ND) in a claypan soil. Corn grain yields were low over the four-year study due to extreme wet conditions in 2010 that delayed planting and mild to extremely summer drought conditions in 2011-2013. Averaged over 2010-2013, corn grain yields ranged from 4.76 to 5.75 Mg ha^-1. Averaged over 2010-2013, the presence of drainage (FD or MD) increased corn yield (15-21%) compared to ND when NCU was applied. In absence of drainage, PCU increased corn grain yields 20% compared to NCU, which indicated that PCU mitigated the high N loss potential in a wet soil environment. Managed drainage averaged a 4% increase in corn yield compared to FD. Corn yield increases with drainage compared to ND were limited over the four years of this research; however, greater corn yield benefits from drainage of claypan soils might occur in years with greater overall yield potential.