Long‐term yield response of corn, wheat, and double‐crop soybean to tillage and N placement
2022
Sweeney, Daniel W. | Ruiz Diaz, Dorivar A. | Pedreira, Bruno C. | Havlin, John L.
On claypan soils of the eastern Great Plains, yield of no‐till crops often lags yield of crops grown with tillage, especially cereals requiring sound N management. The objective of this 14‐yr study was to determine the yield response of corn (Zea mays L.), winter wheat (Triticum aestivum L.), and double‐crop soybean [Glycine max (L.) Merr.] in a 2‐yr rotation to tillage system and N fertilizer placement. Tillage, N placement, or their interaction affected corn yield in all seven‐corn crop‐years. Corn yields averaged about 25% lower with no‐till than with conventional or reduced tillage and were never greater with no‐till in any year. Nitrogen fertilization increased corn yield by increasing kernels per ear; however, corn yield increase to subsurface band (knife) N applications compared with surface (broadcast or dribble) applications was only about 10%. In the lower‐yielding no‐till system, corn yield increase to knifed N fertilization was greater than in tilled systems and may partially ameliorate the no‐till yield decline. Average wheat yield was unaffected by tillage. Adding N more than doubled wheat yield, but differences in wheat yield between preplant N placements methods were small. Average double‐crop soybean yield was unaffected by tillage with few, inconsistent differences by year. Compared with no‐till, tillage tended to increase soil P and K, but soil organic matter was just redistributed with no net increase with no‐till. Thus, tillage and N placement treatments may affect corn but have lesser effects on wheat and double‐crop soybean and soil properties in this rotation.
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