Spatial Variability of Irrigation Water Percolation Rates and Its Relation to Rice Productivity

Aimrun Aimrun

doi:10.3844/ajassp.2010.51.55

Abstract

Problem statement: Study on spatial variability of vertical saturated hydraulic conductivity or percolation loss was conducted within a plot of an area of 1.2 ha paddy plot to find out the relationship between percolation rate and rice productivity. A paddy soil condition that permits percolation rate of 10-20 mm irrigation water day-1 was recommended in order to get high yield of rice. This value is very high when compared to typical values from 1-4 mm day-1 for the Malaysian engineers practiced in paddy fields. Approach: This study presented results of a study that relate the distribution of percolation rates with respect to rice yield productivity. Soil samples at 36 sampling points were collected. DGPS was used to locate the sampling points and then rice yields of the same point were collected. The relationship was determined by statistical correlation factor. Kriging method was used to map the distribution of percolation and yield. Results: The results of the study showed that percolation loss was very low and varied even within a small area. Spatial variability maps show that the area of high percolation rates is the same area that produced high yield. Even though high yields can be obtained from the areas of high percolation rate, it may not be the optimum rate. Conclusion: Higher yield within the area of high percolation may be due to less toxic since it is easily be drained out.

Highlights

Understanding the distribution of vertical movement of water or deep percolation loss within an irrigated area is important in precision farming of rice in view of improving efficiency of the irrigation water supply
The hardpan layer was harder to penetrate and no roots are found in the subsoil layer with grey, brown or dark brown colored soils (Aimrun et al, 2002)
The site is located on a flat coastal plain in the Northwest Selangor Agricultural Development Project (Projek Barat Laut Selangor, PBLS), Malaysia

Summary

Introduction

Understanding the distribution of vertical movement of water or deep percolation loss within an irrigated area is important in precision farming of rice in view of improving efficiency of the irrigation water supply. The information will allow the irrigation engineer or manager to manage the irrigation water more precisely, timely and cost effectively. The first layer (topsoil) up to 10 cm from the surface presents many coarse roots and the soil is black. The second layer (hardpan), usually between 10 and 30 cm from the surface, presents few tiny roots, black or dark brown with yellow mottles and drier than the first layer. The hardpan layer was harder to penetrate and no roots are found in the subsoil layer with grey, brown or dark brown colored soils (Aimrun et al, 2002)

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Results