Abstract
In the Hokuriku district of Japan, there are many regions with gley soil that have inadequate drainage, leading to waterlogged conditions and significant plant damage. We grew soybean in ridge-cultivation systems for 3 years in fields with good and poor drainage. Yield was lower in the latter than in the former. The main factor for this outcome may be that soil moisture in the plow layer was higher in the poorly drained field. Plants grown in such a field have less nitrogen uptake, a smaller post-flowering leaf area index, reduced post-flowering root activity, reduced increase in dry weight of the top and root, fewer pre-flowering branch nodes per plant, and less flower buds and ripening pods per plant.
