Twenty Years of Grain Sorghum and Soybean Yield Response to Tillage and N Fertilization of a Claypan Soil

• Published in: Crop, forage & turfgrass management forage & turfgrass management, 2017-12, Vol.3 (1), p.1-7
• Main Author: Sweeney, Daniel W.
• Format: Article
• Language: English
• ISSN: 2374-3832; 2374-3832
• DOI: 10.2134/cftm2016.10.0070

Core Ideas Long‐term sorghum and soybean response to tillage and N on claypan soil is limited. Long‐term sorghum yields are often substantially less with no‐till on a claypan soil. Subsurface N may result in greater sorghum yield than with surface applications. Anhydrous NH3 applications to sorghum may partially ameliorate the no‐till yield penalty. Long‐term soybean yields are little affected by tillage on a claypan soil. Crops grown without tillage on claypan soils in the eastern Great Plains often yield less than with tillage, especially cereals that require careful management regarding N fertilization. The objective of this 20‐year study was to determine the response of grain sorghum [Sorghum bicolor (L.) Moench] and soybean [Glycine max (L.) Merr.] in rotation to tillage and N fertilization on a claypan soil in southeastern Kansas. Sorghum was affected by tillage, N fertilization, or their interaction, except in the first year. Sorghum yields averaged 22% lower, and were never greater, with no‐till than with conventional or reduced tillage. Nitrogen fertilization increased sorghum yield, largely because of the greater number of kernels per head. Yields with application of anhydrous NH3 averaged 12% more than with surface‐applied N sources. Yield in half of the crop years was affected by tillage × N fertilizer interactions, and the long‐term interaction suggests that in the lower‐yielding no‐till system, the response to anhydrous NH3 may be greater than in tilled systems. Soybean yield was little affected by tillage, the residual effect from N treatments, or their interaction. In 1986, conventional tillage resulted in greater yield than with no‐till, but the reverse was true in 2002, and there was no difference in yield among tillage systems in the other 8 years. Thus, the potential yield penalty for growing grain sorghum in a no‐till system may be partially ameliorated by subsurface anhydrous NH3 fertilization; however, tillage selection or N treatment residual may have little effect on long‐term soybean production on this claypan soil.