Yield Response of Intensively Managed Corn and Soybean to Potassium Fertilizer Rate and Placement


07 Apr 2008

2007 Annual Interpretive Summary

Yield Response of Intensively Managed Corn and Soybean to Potassium Fertilizer Rate and Placement, 2007

The goal of this project was to examine the variation in corn and soybean yield response to varied input intensity applied across a field landscape. The objectives were to identify parts of the landscape that are most responsive to increased input levels, and to determine the particular constraints to crop growth at these locations during various stages of crop development. Seven strips of high-input treatments...comparing normal and high rates of K across normal and deep placement, and normal and high inputs of N, P, and plant density...were applied in the fall of 2001 along the full length of a large field in preparation for corn and soybeans. The treatments were repeated in 2003 and 2004 under a corn-soybean rotation. Starting in the fall of 2004, tillage and fertility treatments were applied only to corn, with soybeans relying on residual fertility.

In 2007, a new corn hybrid (Northrup King N45-A6) produced a top yield of 200 bu/A. As in previous years, intensive management produced yields about 10% higher than those obtained with normal management. Intensively managed corn also had 5% greater crude protein concentration in the grain, and 18% greater N concentration in the stover. Stalk nitrate was higher in treatments receiving high rates of both N and K. In contrast to the 2006 season in which treatments did not differ, residual soil nitrate levels in 2007 were 57% higher following intensive compared to normal management. Soybeans yielded 6% higher following intensively managed corn.

The project has provided 6 years of valuable data documenting the potential economic and environmental viability of intensive crop management. The project at this site was terminated with the 2007 season, and resources are being directed to a new project on ecological intensification of corn cropping systems. ON-24F