Effective water harvesting using capillary barrier of unsaturated soils

A simple soil layer system which is composed of a fine soil layer underlain by a coarse soil layer provides the characteristics of capillary barrier. Water infiltrated into soil accumulates just above an interface between soil layers due to a physical difference in unsaturated hydraulic properties of soils. As their roots can easily utilize the water stored in the upper soil layer, plants grow effectively even under water saving irrigation. An effect of water stored in the upper soil layer on the plant growth was investigated in the sand soil field. Experiment plots of capillary barrier soil were constructed. Green vegetables were planted, and soil moisture contents were measured in the soils during 35days after seeding. It is found that the infiltration water effectively accumulated in the upper soil layer by the capillary barrier of soils, and the water stored significantly affected the plant growth.