Response characteristics and tomographic monitoring of the electric capacitance after irrigation in the soil-plant (ginkgo tree) continuum in a laboratory

摘要

The temporal and spatial variations of electrical capacitance of the soil-plant continuum in a laboratory were investigated. Based on a potted ginkgo tree with six irrigations, the electrical capacitance of the soil, trunk, and soil-trunk electrode pairs was measured, corresponding soil water content was computed, and spatial imaging was conducted. The soil electrical capacitance increases to a local maximum value immediately after irrigation, and then decreases gradually with time. During the late period of each drying procedure, there is a decussation area of high water content at the middle part of the circular region in the spatial imaging, which indicates root distribution in soil to some degree. Upon irrigation under a dry soil condition, the trunk electrical capacitance gradually increases for a period, and then begins to fluctuate with time; whereas, under a wet soil condition, it always fluctuates with time. Under a stable condition of overall change, the trunk electrical capacitance changes saltatorially and daily periodically. The temporal variation of the soil-trunk electrical capacitance exhibits both the character of soil and trunk.