Corn Grain Yield and Nitrogen Utilization in Relation to Subsoiling and Nitrogen Rate on Paleudults
Wagger, M. G. | Vepraskas, M. J. | Vepraskas, M. J. | Denton, H. P.
Subsoiling is used to loosen root-restricting layers and increase rooting depth and water availability; however, little information is available regarding how to adjust the recommended fertilizer N rate. This study evaluated corn (Zea mays L.) grain yield response to subsoiling and N rate in 12 Typic and Arenic Paleudults from 1985 through 1987. Corn earleaf and grain N concentrations were also measured. Chisel plowing and subsoiling were factorially combined with either 0, 80, 120, 160, and 200 kg N ha⁻¹ or 80, 120, and 160 kg N ha⁻¹. The relative yield increase (RYI) due to subsoiling ranged from -2 to 145% during the 3-yr period due to variations in soil physical properties and rainfall distribution during the growing seasons. Regression equations for corn yield response to fertilizer N, based on pooled data sets with a RYI < or > 15% each year, were characterized as having the same slope but only different intercepts for each site and/or tillage system. Earleaf and grain N concentrations tended to he lower with subsoiling while grain N uptake was higher at five sites with relatively high RYIs. Apparent recovery of fertilizer N was similar between tillage systems, averaging 36% for subsoiled and 33% for nonsubsoiled treatments. Results from this study indicated that to obtain optimum corn yields the recommended N rate should be the same for chisel plowed and subsoiled tillage systems for soils with root-restrictive E horizons.
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