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


10 Mar 2003

2002 Annual Interpretive Summary

Spatial/temporal Yield Response of Intensively Managed Corn and Soybean to Variations in Potassium Fertilizer Rate and Placement, 2002

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 will be 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 [N], phosphorus [P], and plant density) were applied in the fall of 2001 across the full length of a large field, in preparation for corn and soybeans. Within each of these strips, three zones were selected for each crop and monitored intensively during the 2002 growing season. Despite a midsummer storm that induced lodging, the most intensive treatment produced the highest corn yield (160 bu/A), 4% higher than with normal input levels. Response to high rates of K was stronger with deep placement of P and K. In upper slope positions, soybean biomass increased 14% in response to high inputs, and 11% in response to high rates of K. The project is continuing in 2003. ON-24F