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

Intensive management aims to narrow the gap between potential and current yields of corn and soybeans. The goal of this project is to examine the variation across a field landscape in corn and soybean yield response to input intensity. The objectives are to identify parts of the landscape 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 potassium (K) across normal and deep placement, and normal and high inputs (nitrogen, phosphorus, and plant density)—were applied in the fall of 2001 across the full length of a large field, in preparation for corn and soybeans. The treatments were repeated in the fall of 2002, rotating the corn and soybeans.

Over the past 2 years, intensive management has boosted crop biomass more than yields. High inputs have boosted yields by about 4% each year. Potassium reduced corn lodging at high input levels in 2003. Responses to high rates of K have been stronger in upper slope positions than in middle and lower slope positions. The project is continuing in 2004. ON-24F