A study on evaluation of conservation agriculture and nitrogen management practices in wheat (Triticum aestivum L.) under maize ((Zea mays L.)-wheat cropping system was undertaken at the ICAR-Indian Agricultural Research Institute, New Delhi. Experiments were conducted in split-plot design with six main-plot treatments of tillage and crop establishment techniques, viz. conventional tillage-flat (CT-F), zero tillage-flat (ZT-F), CT-bed (CT-B), ZT-B, ZT-F with residue (ZT-F+R) and ZT-B with residue (ZT-B+R), while sub-plot treatments consisted of four nitrogen (N) levels, viz. 0, 60, 120 and 180 kg/ha. The results revealed that the minimum energy requirement for the production of wheat crop was estimated with ZT-B system which saved on an average 19.1 % input energy over the CT practices. Residue applied treatments (ZT-F+R/ZT-B+R) resulted the maximum gross output energy, but also significantly reduced the net output energy and energy-use efficiency (EUE) due to high energy involved in crop residues. The net output energy was recorded the maximum under ZT-F, whereas, the maximum EUE was estimated under ZT-B which was significantly higher than CT (27.8-31.4 %) and residue applied treatments. The highest irrigation water-use efficiency (IWUE) was recorded under ZT-B+R (26.0 % higher) and also saved 16.7 % irrigation water over the CT-based systems. Different indices of nitrogen-use efficiency (NUE) were observed statistically similar under different tillage and crop establishment techniques. However, in general, ZT-F resulted the maximum values of most of the indices of NUE. The energy indicators, IWUE and NUE were differed significantly due to N levels. The input and output energy and IWUE were increased significantly with each successive increase in levels of N from 0 to 120 kg N/ha, while reverse trends were observed with EUE and NUE, which were decreased significantly from 0 to 180 kg N/ha. Thus, considering the saving of inputs viz., energy-use and irrigation water, the study recommends that ZT-based system is an energy efficient and could be adopted with surface retention of crop residues to improve the water and nitrogen-use efficiencies in wheat.

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