Effect of Subsurface Drainage on Rice Cultivation and Soil Salinity in the Nile Delta

Abstract

Water plays a prominent role in rice production. The continuous presence of water on rice fields also generates water percolation and groundwater recharge, which are often beneficial for other water uses. The experiment was conducted during summer 2002 in two locations, one with subsurface drainage and the other without subsurface drainage. This field experiment evaluated the suitability of irrigation water level for two new and short rice crop varieties under different subsurface drainage conditions. Results indicated that the water losses due to percolation might be quite high in irrigated rice cultivation in Egypt. The reduction of amounts of applied water was more pronounced in experimental fields without subsurface drainage status as compared with subsurface drainage status. The mean values of applied water increased with increasing irrigation water level under both drainage conditions. With regard to the water use efficiency (WUE), treatments without subsurface drainage status achieved higher values. Regarding to irrigation water levels, controlled water level at zero cm achieved the highest values of WUE for both drainage conditions with and without subsurface drainage. The data clearly showed that treatments without subsurface drainage status gave higher grain yield. Rice grain yield increased in the two selected varieties with increasing controlled water depth. The subsurface drainage status improved soil salinity characteristics by reducing SAR_{1: 5}, EC_{1: 5}, and total anions and cations in all the analyzed soil layers. Rice cropping and water management with deeper ponding depth led to improved soil salinity characteristics.