Building a Maximum Yield Cropping System for Corn, Wheat and Double-cropped Soybeans


23 Mar 2006

2005 Annual Interpretive Summary

Building a Maximum Yield Cropping System for Corn, Wheat, and Doublecropped Soybeans, 2005

The goal of this study is to develop a management program that increases crop yield, input efficiency, and profit potential in a predominantly no-till cropping system. This cropping system consists of four crops in 3 years: no-till soybeans in corn stubble, followed by minimum-till wheat doublecropped with no-till soybeans, and then no-till corn.

The rotation clearly improved corn and soybean yields compared to continuous cropping. Starting in 2000, nitrogen (N) use efficiency has appeared to improve when ammonium sulfate (AS) was blended into the N source, either urea or ammonium nitrate (AN).

In 2003, in no-till and strip-till corn with AS supplying one-third of the N, corn yield increased by 30 bu/A, particularly with split application, compared to broadcast urea. In 2004, doublecrop soybeans responded to N applied to the preceding winter wheat crop. Soybean yields were 4 to 5 bu/A higher where 120 lb N/A had been applied to the wheat, regardless of whether the N had been supplied as urea or a urea-AS blend. The same N sources applied directly to single-crop soybeans produced no yield response at all. In 2004, N applied to winter wheat increased yields by 26% in no-till and by 53% in a tilled soil, with an advantage of 3% to 6% from including AS in the blend. Agrotain applied to urea boosted wheat yields by 5% compared to urea alone. Blends of fertilizers containing AS tended to produce higher wheat yields than either urea or AN on their own. In contrast, a 2004 trial evaluating dry and liquid N sources for corn found little benefit to including AS in the blend, but showed some promise for several inhibitors and efficiency enhancers.

In 2005, various N sources were broadcast-applied to corn at the 4-leaf stage. AN produced the highest corn yield. Each pound of added N boosted yield by a bushel. Urea produced yields only 62% as high, but blending in AS or urease inhibitor boosted yields by 30 to 50%. Liquid urea-ammonium-nitrate produced yields about 45% higher than those with urea, but little benefit was observed from blending in either AS or urease inhibitor. MD-06F