Characteristics of Daily Changes in Soil Moisture and Pore Water EC during the Growing Period of Chinese-yam Cropped on Andosol Upland Field

Abstract

In the Kamikita district of Aomori prefecture, Andosols with good physical properties is widely distributed, and it is known as a major production area for root vegetables, such as Chinese-yam and burdock. In this study, we explored the soil physical and chemical properties in a planting trench formed using a trencher before the cultivation of Chinese-yam, with the goal of properly managing drainage in the Andosol upland field in Chinese-yam cropping. In addition, during the growing season of the Chinese-yam, seasonal changes of soil hardness distribution, variation per day of soil moisture and electrical conductivity at each depth were monitored, and the quality survey was conducted after observing the tuber of Chinese-yam at the harvest season. At depths of 10, 30 and 60 cm at the harvesting season (early-November), saturated hydraulic conductivity decreased and the dry density increased approximately 1.2 times compared with the middle of May. Moreover, saturated hydraulic conductivity decreased with increasing depth, while dry density increased. In addition, soil hardness at depths deeper than 30 cm increased over time. From the above, it was clarified that the physical properties of the planting trench changed significantly after a growing season of approximately half a year. Moisture saturation at depths of 30, 60, and 100 cm tends to increase, was suggested that soil water tends to accumulate at depths shallower than 95 cm. From the results of the soil moisture observations using FMS and quality survey of Chinese-yam during harvesting season, rots and deformation of the tuber in Chinese-yam were not observed even if exposed to excessive moisture for approximately three days during the thickening growth.