Crop and water productivity of bed transplanted rice as influenced by various levels of nitrogen and irrigation in northwest India

Food security security and water resources in Indian Punjab are under threat and there is a need to produce more rice with less water. Therefore, an experiment was conducted at Ludhiana, during summers of 2009 and 2010 to evaluate water saving techniques in rice cultivation. The experimental site had loamy sand soils and the seasonal reference ET was 765 and 680 mm while rainfall was 818 and 652 mm during 2009 and 2010, respectively. The experiment (split-plot), involved methods of planting (fresh bed and puddled flat) and nitrogen levels (75% of recommended N, recommended N 120 kg ha(-1) and 125% of recommended N) in the main plots, and irrigation schedules (1 day, 2 days, 3 days after water disappearance and at soil suction of 150 20 cm) in the sub plots, with three replications. The transplanting of rice seedlings on sides of freshly constructed beds resulted in 15% irrigation water saving and 13.5% higher mean irrigation water productivity (IWP) with non-significant reduction in grain yield as compared to conventional (flat) transplanting. Grain yield and IWP increased significantly only up to a N level of 120 kg ha(-1) and further increase in N levels failed to produce significantly higher results. The highest grain yield was obtained with application of irrigation after 1 day of water disappearance and it was statistically at par with irrigation after 2 days of water disappearance and with soil suction based irrigation schedule. The IWP increased with the increase in interval between two successive irrigations. The interaction between methods of planting and irrigation schedules was found to be significant. The maximum grain yield was obtained in puddled flat irrigated after 1 day of water disappearance, which was statistically at par with all other treatment combinations except with beds irrigated after 3 days of water disappearance. The interaction was also found to be significant in case of IWP. The maximum IWP was observed in BI3. Thus, higher crop and water productivity in rice can be obtained by transplanting rice on the slopes of freshly constructed beds along with application of 120 kg N ha(-1) and irrigation application after 2 days of water disappearance or at soil suction of 150 +/- 20 cm. (C) 2011 Elsevier B.V. All rights reserved.