Abstract
The effects of the groundwater table level controlled by the Farm-Oriented Enhancing Aquatic System (FOEAS) in an upland field converted from a paddy field on the soil water content, soil oxygen concentration, and growth of autumn-sowing cabbage were evaluated. We created two plots with groundwater tables maintained at -30 cm (HIGH) and -60 cm (LOW) from the soil surface. Although the LOW plot showed higher soil moisture suction than the HIGH plot, there was only a mild increase up to about 40 kPa. The groundwater tables in both plots fluctuated owing to rainfall. Increases in the soil water content and groundwater table by rainfall followed by a decrease in the oxygen concentration of soil gas as well as the air ratio were noted. In the HIGH plot, the oxygen concentration often dropped to 0% during the latter growth stage. In winter, plants in the HIGH plot had a slightly larger vertically projected area than those in the LOW plot, probably due to maintaining a high water content, but showed growth suppression later, resulting in a smaller head weight (about 60% of plants in the LOW plot). The results indicate that a constantly high groundwater table controlled by FOEAS would likely increase the incidence of excess-moisture injury and reduce the yield of cabbage.
