Effect of Water and Nitrogen Management on Water Productivity and Nitrogen Use Efficiency of Wheat in a Semi-arid Environment

A field experiment was carried out during 2009-11 on a sandy loam soil of IARI, New Delhi on wheat with four levels of irrigation (rainfed, irrigations to replenish 30, 60 and 100% moisture deficit from field capacity) as main plot factors and four levels of nitrogen (0, 30, 60 and 120 kg N/ha) as subplot factors in a split plot design. The soil moisture storage in the profile showed inverse relation with the nitrogen levels whereas direct relationship with the irrigation levels. The water use vs. wheat yield relation showed that 58 % variation in grain yield of wheat could be explained by water use. The grain yield showed increasing trend with increase in irrigation and nitrogen levels. The water productivity (WP) and economic water productivity (EWP) increased with increase in irrigation level up to 60 % SMD and thereafter it decreased. However, both WP and EWP showed increasing trend with increase in nitrogen levels. The agronomic nitrogen use efficiency (ANUE) and partial factor productivity of nitrogen (PFPN) increased with increase in irrigation levels, but with increase in nitrogen levels both ANUE and PFPN decreased. There was significant positive interaction between irrigation and nitrogen levels with respect to grain yield, water productivity and nitrogen use efficiency of wheat. Thus from this study, it may be concluded that wheat may be grown with irrigation to replenish 60% SMD to field capacity and at 120 kg N/ha to achieve higher water productivity and nitrogen use efficiency without any significant reduction in crop yield S. Pradhan et al 728 and thus resulting in saving of irrigation water in sandy loam soils of semiarid region of North India.