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Optimizing Seeding Rates for Winter Cereal Grains and Frost-Seeded Red Clover Intercrops

Blaser, B.C., Gibson, L.R., Singer, J.W., Jannink, J.L.
Agronomy journal 2006 v.98 no.4 pp. 1041-1049
Trifolium pratense, forage legumes, forage crops, Triticum aestivum, winter wheat, Triticosecale, triticale, intercropping, plant density, cropping systems, green manures, profitability, grain yield, dry matter accumulation, field experimentation, Iowa
Growing winter cereal grain/forage legume intercrops can provide multiple benefits to cropping systems in the North Central USA. Intercropping red clover (Trifolium pratense L.) with winter cereal grains can provide forage and a green manure crop. Seeding rate recommendations for sole crops may not optimize intercrop system productivity if interactions exist. This study was conducted during the 2002-2003 and 2003-2004 growing seasons to determine optimum cereal grain and red clover forage seeding rates for maximum returns using partial budget analyses. In March, red clover was frost-seeded at 0, 300, 600, 900, 1200, and 1500 seeds m-2 into winter wheat (Triticum aestivum L.) and triticale (X Triticosecale Wittmack) seeded at 100, 200, 300, and 400 seeds m-2 the previous October. Triticale and wheat maximized returns at seeding rates of 300 and 400 seeds m-2. No cereal grain by red clover seeding rate interactions were detected for red clover dry matter production (DM). Red clover plant densities after cereal grain harvest were 10 to 22% of the original seeding rates. Red clover DM production and return was maximized at 3.49 Mg ha-1 with 900 seeds m-2 in 2003 and 6.67 Mg ha-1 with 1200 seeds m-2 in 2004. Winter cereal/red clover intercrops in the North Central USA can maximize return using a cereal grain seeding rate between 300 and 400 seeds m-2 and red clover seeding rates between 900 and 1200 seeds m-2.