Soil Moisture Management and Evaluation of Water-Saving Irrigation on Farms

Abstract

It is important for water economics, especially for efficient watersaving, to plan for suitable management of irrigation systems on farms.
In this study on water saving, the following subjects were investigated, evaluated and discussed.
(1) Irrigation scheduling for effective control of moisture flux:
The phenomenon of the upward/downward moisture flux between the rootzone and the moisture storage zone was investigated as an effective phenomenon for water saving irrigation.
Three methods of irrigation scheduling were comparatively evaluated.From the practical viewpoint, “fixed amount irrigation at variable intervals”was found to be the best of the three, on the basis of the results of theevaluation made of each type of scheduling.
(2) Drip irrigation for water saving:
Recently this system has been popular and has brought economical andeffective irrigation, because it is a system of partial irrigation. According tothe results of experiments carried out in sugar cane fields, the yield was keptat the same level as that in ordinary irrigation, while the amount of irrigatedwater was half of the amount in the usual system.
(3) Planting ratio:
The results of investigation on the planting ratio in the irrigation projecthave clearly shown that about 90% of crop planting is done in the springsummer season and aboilt 30% in the autumn-winter season. This factor cannot be neglected in irrigation planning for farms.