Strip Intercropping of Grain Sorghum/Soybean in Irrigated and Rainfed Environments

Abstract

A strip-intercropping system of grain sorghum [Sorghum bicolor (L.) Moench]/soybean [Glycine max (L.) Merr.] has potential to reduce soil erosion compared with a 2-yr rotation of large monoculture fields of these two crops. Our objective was to evaluate productivity and returns in a grain sorghum/soybean strip-intercropping system under irrigated and rainfed environments in eastern Nebraska. Crops were grown in alternating 20-ft. strips in a north-south orientation on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic typic Argiudoll). A full-season grain sorghum hybrid was grown with soybean cultivars of different maturity groups. Combine-harvested yields of the two border rows of grain sorghum and soybean were compared with the middle four rows of each crop to determine border effects. Under irrigation, grain sorghum yields in the outside two rows increased in 4 of 5 yr, a maximum of 21 bu/acre in 1986 and 1989, and 5-yr average of 9 bu/acre. Under rainfed conditions, grain sorghum border row yields were less consistent, averaging 2.5 bu/acre higher. Soybean yield reduction in border rows was variable, averaging 5 bu/acre for rainfed and 3 bu/acre for irrigated conditions. Soybean cultivar and planting system had limited effect on either sorghum or soybean yields. This system may be a useful alternative cropping pattern to reduce long-term soil erosion, a valuable result for society.