Corn Grain Yield and Nitrogen Utilization in Relation to Subsoiling and Nitrogen Rate on Paleudults

Abstract

AbstractSubsoiling 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 be 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.