Grain Yield, Water Productivity, and Soil Nitrogen Dynamics in Drip Irrigated Rice under Varying Nitrogen Rates

Abstract

Water and nitrogen (N) saving rice (Oryza sativa L.) technology is required to meet the future food demand with decreasing resource availability. This emphasizes the importance of micro irrigation systems in field crops. Given the context, the present study was performed to evaluate the effect of subsurface drip irrigation on rice grain yield, water and N use efficiency and soil N dynamics. A field experiment was conducted for rice cultivation (cultivar Naveen) under subsurface drip irrigation (DIR) with two lateral spacings (S40 and S60) and four N fertilizer levels (0, 50, 75, and 100% of recommended dose) and puddle-transplanted rice (PTR) at N100 during dry season of 2012 to 2013 and 2013 to 2014. The results of the study revealed significant increase in grain yield with increase in N fertilizer level from N0 to N50 or N75 in DIR. At N75, the DIR resulted in 73% recovery of applied N and 32% saving of water while attaining similar grain yield (5043 kg ha–1 in S40N75 and 4851 kg ha–1 in S60N75) as of PTR-N100. The N dynamics revealed higher NH4 +–N and NO3 −–N contents in 0- to 18-cm layer in DIR compared with PTR. Both drip lateral spacings did not show any significant differences in grain yield, water and N use efficiency. Hence, the subsurface drip irrigation with 60 cm lateral spacing and 25 to 50% lower N application could increase the water and N use efficiency of rice with similar grain yield as of PTR.