Studies on the Shape of Porous Pipe under Exposed Condition

Experimental studies on sub-irrigation method (VII)

Abstract

This study was carried out to decide the optimum type of porous pipe which was used for the sub-irrigation method by use of the negative pressure difference under exposed condition. Experiments were conducted using torus porous pipes, cylindrical porous pipes, and pod porous pipes and also by using Masa soil, Kuroboku soil, and Fudai field surface soil. In the experiments, the amount of water being suppled and the infiltration distance in the horizontal direction were measured for each type of pipe.
The results obtained are as follows.
1) Water supply and infiltration distance were clarified and seen as being dependent on the shape of the porous pipe.
2) Water supply and infiltration distance of the torus porous pipe was the largest of all porous pipes. Especially, torus porous pipe was judged to be suitable to sandy soil like Masa soil.
3) Pod porous pipe was judged to be the most unsuitable of all porous pipes because water supply was the least and yet the infiltration distance in the horizontal direction was the smallest.