THE AREAL DISTRIBUTION OF SOIL-MOISTURE UNDER SPRINKLER IRRIGATION

The areal distributions of soil water content under varying uniformiti es of sprinkler water application were observed on two different soil types, to quantify the relationship between the subsurface distributio n of soil moisture and water application on the ground surface. Field experimental results showed evidence of the importance of redistributi on of the unevenly applied surface water. The water within the soil is more uniformly distributed than that applied through a sprinkler irri gation system. The extent of water redistribution within the soil prof ile depends mainly on the uniformity of initial soil water content and the total applied water. The distribution of water in the soil under a wide range of water application uniformities can be represented by a normal distribution function. The analyses for the influence of the n umber of samples on observation accuracy of soil moisture uniformity i ndicated that the number should not be less than nine.