抄録
In many arid and/or semi-arid regions where water is scarce, it is critical to reduce deep percolation below root zones. One of the approaches to achieve such goal is to introduce an artificial capillary barrier (CB), which usually consists of a layer of gravels. CBs occur at an interface of two soil layers with contrast hydraulic properties. Although it has been known to improve root zones by suppressing capillary rise of saline water and by inhibiting deep percolation of irrigated water, the optimum design of CB has not been fully established for cultivation. The main objectives of this study were to investigate 1) the effect of the CB design on suppressing the capillary rise, and 2) the effect of installing such CB layer on cultivating leaf vegetable under reduced irrigation condition. In this study, column experiments and cultivation experiments were conducted by introducing CBs as a means to improve water retention ability of the root zones. Komatsuna (Brassica rapa var. perviridis), one of the common leafy vegetables, was cultivated in containers with different soil layers in a phytotron located in a campus of Tokyo University of Agriculture and Technology. From our experiment, it was found that artificial CBs can be used to manage irrigation rates. Further investigations and experiments are needed to fully evaluate the effect of CBs.
