Behavior of Soil Water in Irrigation-Afected Crop Field

Abstract

By measuring pressure heads through an auto-recording tensiometer, behavior of soil water was observed in a crop field, which was affected by irrigation for surrounded paddy fields, in the Dejima area of Ibaraki Prefecture. Major observations are as follows:
(1) Behavior of soil water in a crop field near padd y fields is very affected by fluctuation of water table, rainfall, and evaporation.
(2) During the irrigation period, flux of soil water is generally downward in surface zone and upward in and above capillary zone and convergent zero flux plane is formed in and after rainfall. On the other hand, downward flux is generally dominant during the non-irrigation period.
(3) The auto-recording tensiometer is a very effective tool to trace the soil water in the unsaturated zone.