Functional Performance of Parallel Drain Subsurface System in Waterlogged Paddy Field

Waterlogging induced salinity is a common problem in many command areas of irrigation projects. Subsurface drainage improves the productivity of poorly drained soils by decreasing the water table, providing greater soil aeration, improving root zone soil salinity and enhancing the crop yield. A pilot study has been conducted to explore the functional performance of the parallel drain subsurface system in waterlogged paddy field by considering the lateral drain spacing and drain depth are the factors influences the soil properties. This experiment was carried out in farmers’ field at Sembari village, Lalgudi, Tamil Nadu, India in waterlogged paddy field during October 2020 to February 2021. Treatments of this study consisted the combination of three lateral drains spacing of 7.5 m, 10.0 m and 12.5 m and two drain depths of 60 cm and 80 cm and a control plot. This study investigated the changes in soil properties, depth to water table, drainage coefficient and crop behaviors after installation of the system. Reduction in Soil pH, removal of slats in drain water, lowering the depth to water table and higher drainage coefficient recorded for narrow lateral drain spacing and deeper drain depth treatment has improved the root zone environment for crop growth. Paddy has been established very well in terms of plant height and number of tillers per plant in S1D2 (7.5 m drain spacing and 80 cm drain depth) treatment which was also reflected in grain yield and straw yield over undrained paddy field yield. Based on the results, it is recommended to install parallel drain subsurface system at 7.5 m drain spacing and 80 cm drain depth in the study area.