砂丘地土壌の水分の保留を高める一方法について

To be improved the water economy of sand-dune soil, it was investigated to determine the effect to the preservation of surface soil moisture by laying out in the subsoil thin layer of various substances -four sois of different texture, gravel and finely cutted straw.
(1 Water was added on the column of sand-dune soil in the glass tube, and per iodical changes of soil moisture in each strata were measured. When the thin layer is consist of gravel or finely cutted straw that possess the large pore, the greater part of capillary water were reserved in the sand stratun on the thin layer for along time. Capillar rise was stagnated at the aboven-mentioned layers.
2) Generally speaking, when wet sandy soil come in contact with dry clayey soil, capillary water moved largely from the former to the latter. In opposition, when wet cleyey soil come in contact with dry sandy soil, capillary water moved slightly from the former to the latter. It rmay be reasonable that capillasy water is apt to be discontinous in the sandy soil relatively.
3) The movement of gravitational waler is affected by the perrmeability of the stratum that show most slowly percolation. In the sand-dune soil, The more clayey soil texture of thin layer is, the more peameability of total soil layer decrease severely.