Monday, November 13, 2006

Effects of Cropping Systems on Winter Wheat and Double-crop Soybean Yield.

Kenneth Kelley, KSU-SE Ag. Research Center, "PO Box 316, N. 32nd & Pefley", Parsons, KS 67357, United States of America

In the eastern Great Plains, winter wheat is often rotated with other crops, such as soybean, corn, and grain sorghum, to diversify cropping systems.  Soybeans typically are planted as a double-crop after wheat harvest, giving 3 crops in 2 years.  This long-term research study investigates the combined effects of both crop rotation and tillage on yields of winter wheat and double-crop soybean in a 2-yr crop rotation in southeastern Kansas.  Over a 10-yr period, previous crop (corn, grain sorghum, and soybean) has had a smaller effect on wheat yield, compared with previous fertilizer research trials, mainly because nitrogen (N) and phosphorus (P) fertilizer was knifed below crop residues before planting to eliminate possible N losses from immobilization and to increase efficiency of applied P.  Wheat yields have been highest following soybean, intermediate following corn, and lowest following grain sorghum.  But, double-crop soybean yields were greatest when corn and grain sorghum preceded wheat and least when soybean preceded wheat.  Tillage (no-till vs disk) has had very little affect on wheat and double-crop soybean yields.  Results show the importance of evaluating all crop yields within a particular cropping system rather than just one segment of the rotation.