Effect of residue management techniques on yield and nitrogen use efficiencies in a maize–wheat cropping system under reduced nitrogen inputs

Wheat and maize are the dominant cereal crops in Pakistan, but their productivity is often constrained by inefficient nitrogen use and poor residue management practices. Excessive reliance on synthetic fertilizers has led to soil degradation and low nitrogen use efficiency, highlighting the need for more sustainable nutrient management strategies. Therefore, this research was conducted to evaluate the effects of different crop residue management techniques combined with reduced nitrogen rates on crop productivity, soil fertility, and nitrogen efficiency in the wheat–maize cropping system at the Agronomy Research Farm, University of Agriculture Peshawar, during 2021–2023. A randomized complete block split-plot design was adopted with crop residue management as the main plot factor [comprising five treatments (control, 50% residue incorporated, 50% residue as mulch, 100% residue incorporated, and 100% residue as mulch] and nitrogen rates as the subplot factor [N1= control, N2 = 25% less than the recommended (90 kg ha−1 for wheat and 112.5 kg ha−1 for maize), and the recommended rate (N3 = 120 kg ha−1 for wheat and 150 kg ha−1 for maize)]. In wheat, the highest biological yield (9762 kg ha−1) was observed with N3, while N2 gave the highest grain yield (3947 kg ha−1). In maize, N3 produced the highest biological yield (13014 kg ha−1), and grain yield was statistically similar between N2 (3829 kg ha−1) and N3 (3889 kg ha−1). In wheat, N2 increased nitrogen content by 9.3% over N1, while in maize, N2 and N3 raised it by 15.0% and 13.0%, respectively. Nitrogen uptake in wheat was highest and statistically similar at N2 (101.1 kg ha−1) and N3 (98.7 kg ha−1); in maize, it was similar at N3 (98.4 kg ha−1) and N2 (93.3 kg ha−1). The highest biological yields were obtained with 100% residue incorporation in both wheat (9354 kg ha−1) and maize (12491 kg ha−1), statistically similar to 100% mulch. Grain yield was also highest with 100% residue incorporation in wheat and maize (3747 kg ha−1 and 3731 kg ha−1). Maximum nitrogen content and uptake were seen under 100% residue incorporation in both crops. Wheat showed the highest Nitrogen Use Efficiency (NUE) with N2 and 100% residue incorporated, while Agronomic Efficiency (AE) and Apparent Recovery Efficiency (ARE) peaked under N2 and N3. In maize, NUE, AE, and ARE also improved with N2 and 100% residue incorporation. It was settled that integrating 25% less nitrogen than recommended with 100% residue incorporation sustained higher yields, nitrogen content, and efficiency. This practice promotes sustainability by reducing nitrogen losses and lowering input costs.