EFFECT OF RYE (SECALE-CEREALE) MULCH ON WEED-CONTROL AND SOIL-MOISTURE IN SOYBEAN (GLYCINE MAX)

A four-year experiment was conducted near Urbana, IL to evaluate the effect of a rye cover crop on weed control, soybean yield and soil moisture. Soybeans were planted into either a rye mulch or com stubble (with and without spring tillage). Giant foxtail, velvetleaf, smooth pigweed and common lambsquarters control in the rye mulch plots was generally greater than 90% and better than the com residue treatments five weeks after planting. Weed control was generally better, except for lambsquarters, in the com residue without spring tillage plots compared to the spring-tilled plots. Herbicides improved weed control in the com residue plots but not in the no-till rye treatment, due to the excellent control by the rye mulch. Soil water content was lowest during June under the late-killed (killed at planting) rye during dry periods due to water depletion caused by the growing rye. During wet periods the rye mulch resulted in a wetter soil profile compared to the com residue treatments. Soybean yields were reduced in late-killed rye compared to early-killed rye (killed 2 wk prior to planting) due to soybean stand reductions in the late killed rye. Yields in early-killed rye and spring-tilled treatments were similar to or better than soybeans planted in com residue without spring tillage.