Changes in the Technology of Soybean Production

Introduction

In Serbia, corn is a common crop-preceding soybean. High soybean yield can be provided by growing soybean after corn, as well as other preceding crops. However, when the herbicides used for combating weeds in corn are not applied correctly, and in the years with a small amount of precipitations during the fall and winter, corn-soybean rotation does not give good results. In Serbia, soybean use to separate our field system: corn-wheat. If soybean would be planted after corn, and followed by winter wheat, a great contribution would be made to the improvement of agricultural production as a whole. Winter wheat could be sown early, due to earlier maturing of soybean compared to corn. Corn would be used less as preceding crop to wheat, so late hybrids with higher yielding than the early hybrids could be sown on those surfaces (Nenadić, 1995). The same author recommends corn-soybean-wheat rotation. In Minnesota, an increase in yield by 11% was measured in soybean cultivation in crop rotation (corn-soybean) compared to monoculture (Hicks & Peterson, 1981). Soybean in rotation with corn had significantly higher yields than when grown in monoculture (Dabney et al.,1988). The same conclusion in favor of corn-soybean rotation was also reached by Meese et al. (1991). Amounts of fertilizer applied to corn fertilizing depend on a number of factors, primarily on the amount of planned yield and the supply of nutrients in the soil. Depending on the planned yield (6-10 t ha^-1), the need for nitrogen varies between 160 and 300 kg ha^-1. The preceding crops favorable for soybean are winter wheat and other small grains. However, according to the three-year period research conducted by the same authors, there were no statistically significant differences in soybean yield when grown after corn and after wheat (Molnar et al., 1983).