Evaluation of corn-soybean inter-cropping systems in southwestern Japan

Abstract

To assess the effects of inter-cropping corn and soybean under southwestern Japan’s climatic conditions, 5 different treatments were compared, namely: CW (mono-cropped corn - weeded); CTW (corn + soybean cv. Tachinagaha - weeded); CT (corn + soybean cv. Tachinagaha - unweeded); CSW (corn + soybean cv. Suzukaren - weeded); and CS (corn + soybean cv. Suzukaren - unweeded). Parameters measured were height, yield, nutrient composition of corn and soybean and the numbers of Japanese beetles (Popillia japonica). Plant height of mono-cropped corn was significantly (P0.05), while CTW treatment produced higher FMY and DMY for soybean (P0.05), while crude protein (CP) concentration in whole corn plants in CTW exceeded (P<0.05) those for mono-cropped corn and CSW treatments. These results indicated that soybean can be successfully inter-cropped with corn in southwestern Japan. Soybean plants may be infested with Japanese beetles. It is advisable to control weeds in the stands to reduce the level of beetle infestation and to minimize competition for the planted crops.