COVER CROPPING SYSTEMS FOR THE CENTRAL CORN-BELT

Corn (Zea mays L.) predominates in the central USA but grain sorghum [Sorghum bicolor (L.) Moench] may be preferable for cover crop systems. Effects of tillage (no-till and disk), cover crops, grain crop, planting date, and N fertilizer rate were investigated to compare grain sorghum and corn in cover crop systems. This 2-yr field study was conducted at Fisher, IL, on an Ashkum silty clay loam (fine, mixed, mesic Typic Haplaquolls); Toledo, IL, on a Cisne silt loam (fine, montmorillonitic, mesic Mollic Albaqualf); and Albion, IL, on a Belknap silt loam (coarse silty, mixed, mesic Aeric Fluventic Haplaquepts). Grain yield was not affected by tillage. Delayed planting of the grain crop inc cover crop biomass and N content at the expense of corn (128 vs. 106 bu/acre) and grain sorghum (94 vs. 89 bu/acre) yield. Grain yield following rye (Secale cereale L.) was less than when following hairy vetch (Vicia villosa Roth) or fallow. Optimal N rate was higher and yield was higher following hairy vetch (133 lb N/acre and 124 bu/acre) than following fallow (153 lb/N acre and 121 bu/acre) or rye (152 lb N/acre and 100 bu/acre), but cover crop establishment cost exceeded the benefit. Grain sorghum required less N than corn (108 vs. 180 lb N/acre), but the associated optimum yield (98 vs. 132 bu/acre) resulted in an economic advantage for corn. Thus, grain-sorghum-and-cover-crop systems are not attractive alternatives to corn-cover-crop or conventional-corn systems in the central Corn Belt.