Abstract
In Japan, approximately 80% of soybean is cultivated in upland converted paddy fields. A major problem in soybean production in such fields is the damage due to inadequate water content of soil which depresses the growth and yield of soybean. Recently, a water table control system, called the Farm-Oriented Enhancement for Aquatic System (FOEAS), was developed, and it is important to understand the combined effect of FOEAS and non-tillage cultivation on the growth and yield of soybean plants in farming scale fields. The objective of this study was to clarify the effects of three different cultivation methods (non-tillage narrow cultivation (NN), conventional rotary tillage narrow cultivation (CN), and conventional rotary tillage cultivation (CC)) on soybean growth, yield, and work efficiency in fields with FOEAS. In NN, the yield and nitrogen fixation of soybeans in FOEAS fields were increased by 25% and 24%, respectively, than those in the control field. In NN with FOEAS, due to increased emergence, shoot dry weight at maturity, ripened pod number, seed number, and hundred-seed-weight, the yield was increased by 12% and 69%, compared with that in CN and CC, respectively. The combined yield of NN was increased by 15% and 40%, compared with that in CN and CC, respectively. The combination of NN and FOEAS has some advantages, which include rapid seeding after rainfall, rapid sowing speed, low lodge-index at harvesting period, low weed biomass at harvesting period, and to skip intertillage-ridging. As a result, the seed yield in NN was greater than in either CN or CC, which suggests that the combination of FOEAS and non-tillage cultivation contributes to stable soybean production in Kanto District.
