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2006 Annual Report: Effect of Red Clover and Sweet Clover Following Wheat on the Following Year's Corn Yield


Winter wheat creates an opportunity to use the time from wheat harvest to next year's cropping season for an additional crop. The use of red clover or sweet clover can provide nitrogen to a subsequent corn crop. With costly nitrogen prices and high wheat prices, growers are looking at over-seeding legumes in winter wheat and using legumes for nitrogen and in some cases for forage. Another advantage is clover fills in and provides competition against weeds during late summer.

Methods and Materials

Winter wheat was planted in fall of 2004 and over-seeded with red clover and sweet clover in February of 2005. Legumes were controlled with herbicides in the spring of 2006 and planted to corn. Ammonium nitrate was applied at 0, 60 and 120 lb/acre rates on the west site and on the east side at 0, 60, 120 and 180 lbs/acre. Legumes were clipped shortly after wheat harvest to reduce weed competition.

Planting Date: April 18, 2006
Herbicides: Burndown: 2,4-D + Glyphosate + Dual + Atrazine + Callisto; Post: Accent + Clarity
Hybrid: Pioneer 34A16
Insecticides: Lorsban Banded 8oz/1000ft
Population: 32,400 seeds/acre
Row Width: 30-inch


Red clover can withstand shading better than sweet clover. Better stands of red clover resulted from over-seeding compared to sweet clover. The following chart shows the combined corn yields across all nitrogen rate treatments on a gumbo soil located on the Graves-Chapple West Side - Heitman Farm.

Graves-Chapple West Side-Heitman Farms

The following chart shows combined corn yields with different nitrogen rates following legumes. This data is from the Graves-Chapple site on the east side of interstate. This site has a silt loam soil and corn following sweet clover performed better at this site than corn following red clover. The low soil pH on the west side may have affected the response of corn yields to the sweet clover.

nitrogen rates