Crop residues integration with nitrogen rates reduces yield-scaled nitrous oxide emissions and improves maize yield and soil quality

Maize production requires a large amount of nitrogen (N). However, a greater part of the N used gets lost to the environment as reactive forms including nitrous oxide (N 2 O). N 2 O emissions and associated soil-related factors were measured in a maize (Zea mays L.) field in the 5 th crop after initiation of the experiment in an annual maize-rice sequence. The treatments comprised two levels of crop residues (no residue, NR vs. 30 cm residue, CR) with four levels of N fertilizers (control; farmers' practice, FP; national recommended dose, RD, and 125% of RD, 1.25 RD). Mean and cumulative N 2 O emissions increased with N rate coupled with either residue level. The CR coupled with 1.25 RD had 10% higher N 2 O emissions than the same rate as NR. In contrast, yield-scaled N 2 O emissions were equal in 1.25 RD coupled with either residue level. However, higher N 2 O emissions in CR than in NR can be offset by the corresponding improvement in soil elemental quality, e.g. soil organic carbon, total N, P, K and S. The N 2 O emission factor, ranged from 0.99 to 1.34, and was higher in CR coupled with 1.25 RD than in any other combination suggesting that optimization of N rate is one of the best options to reduce N 2 O emissions. Maize grain yield was higher in RD and 1.25 RD than in the farmers' practice where the former two were similar to each other. Step-wise multiple regression showed that N application rate, soil organic carbon, total N and pH are the dominant factors controlling N 2 O emissions. Our results suggest that maize production can benefit from residue retention with the current N rate (RD) for better yield, soil quality and N 2 O mitigation. 1. Optimum fertilizer rate coupled with crop residue reduces N2O emissions.2. N2O emission factors in maize are comparable with the IPCC default value.3. Yield-scaled N2O emissions were similar in fields with and without crop residues.4. Maize yield was higher in crop residue coupled with recommended N rate.5. Recommended N with crop residue incorporation increased soil elemental quality.