Abstract
The ridge-making narrow row culture was conducted in Niigata Prefecture using soybean cultivar “Tachinagaha” which has strong lodging resistance. We investigated the growth and yield of soybeans, and the degree of weed emergence. In the narrow row culture, the main stem length at maturity was relatively long as compared with that in ridge-making culture (conventional culture), but lodging was slight. The yield was almost the same as that in the conventional culture and 100 seeds weight was heavier. Relative photosynthetically active radiation under the soybean canopy in narrow row culture was 10％ or less, and the weed growth was suppressed from about 50 days after planting. This indicated that soybeans covered the row space at an early stage. By spraying herbicide one month after planting, the weed emergence could be controlled below the level in conventional culture with inter-tillage and ridging. Thus, it is considered that sufficient weed control can be achieved in ridge-making narrow row culture (of “Tachinagaha”) by spraying herbicide once from 10 to 30 days after planting when the weeds begin to emerge. As a result, labor for weeding can be saved compared with the conventional culture. This cultivation may promote stable production of soybean with high quality especially in large-scale soybean fields.
