Yield, nitrogen-use efficiency, and distribution of nitrate-nitrogen in the soil profile as influenced by irrigation and fertilizer nitrogen levels under zero-till wheat in the eastern Indo-Gangetic plains of India
Samaresh Sahoo, Prabir Mukhopadhyay, Abhas Kumar Sinha, P. M. Bhattacharya, S. Rakesh, Rajkishore Kumar, Rajeev Padbhushan, Bijay Sıngh, Brajendra Parmar, Anand Kumar Vishwakarma, Amarendra Kumar, Brahamdeo Kumar Yadav, Shanti Bhushan, Atul Kumar, Megha Kaviraj, Upendra Kumar
Abstract
Due to the introduction of zero-till wheat in the Indo-Gangetic plains (IGP) in India, irrigation and fertilizer nitrogen (N) management needs to be modified from that followed under conventionally tilled fields. A field experiment was conducted to study the effect of irrigation and N levels on yield and N uptake by zero-till wheat, fertilizer N-use efficiency, and distribution of nitrate-N (NO 3 -N) in a soil profile under zero-till conditions in an acidic alluvial soil of the eastern IGP. The experiment was laid out in a split-plot design with four levels of irrigation as main plots (I 0 -no irrigation, rain-fed, I 1 -122 mm in one irrigation at 21 days after sowing (DAS), I 2 -263 mm in two irrigations at 21 and 42 DAS, and I 3 -386 mm in three irrigations at 21, 42, and 84 DAS) and 4 N levels [0 (N 0 ), 60 (N 1 ), 120 (N 2 ), and 150 (N 3 ) kg N ha −1 ] as subplots. Grain and straw yields were significantly higher at the irrigation level-I 2 and 120 kg N ha −1 -N 2 over the control (I 0 and N 0 ) and were at par with the highest applied levels of irrigation and N (I 3 and N 3 ). The nitrogen uptake by wheat followed a trend similar to yield for irrigation levels; however, it increased significantly up to 150 kg N ha −1 . After the harvest of wheat crop, more NO 3 -N was observed in the 60–90 cm subsurface soil layer than in the surface 0–15 cm and/or 15–30 cm and 30–60 cm subsurface soil layers. The highest NO 3 -N concentration was recorded in the treatment I 2 N 2 . Accumulation of NO 3 -N in the soil increased up to irrigation levels I 2 and with increasing doses of fertilizer N application. Combined applications of irrigation and N had a positive and significant influence on agronomic efficiency (AE) and apparent N recovery (ANR) but had no significant effect on physiological efficiency (PE). This study suggests that an appropriate combination of irrigation and N levels in zero-till wheat can lead to not only high-yield levels and N-use efficiency but also adequately control NO 3 -N leaching under acidic alluvial soils in the eastern IGP.