Short-term effects of maize straw return with nitrogen fertilization on ammonia and nitrous oxide emissions in Northeast China

Abstract

The annual degradation of biological soil health within Northeast China (NC), specifically in the context of spring maize (Zea mays L.) cultivation, has been a growing concern. Improving straw management is a potential strategy to ameliorate this ongoing deterioration. This study aimed to determine the responses of soil gaseous nitrogen (N) losses to deep-plowed maize straw into the surface soil layer. The field experiment was conducted from 2019 to 2021 with six treatments: no straw (S₀N₀), half straw (7.5 ​t ​ha⁻¹, S_0.5N₀), and full straw return (15 ​t ​ha⁻¹, S₁N₀) without N fertilizer; no straw (S₀N₂₀₀), half straw (S_0.5N₂₀₀), and full straw return (S₁N₂₀₀) with 200 ​kg ​N ha⁻¹. The results indicated that the cumulative ammonia (NH₃) volatilization increased by 74.6% and 120.0% in S_0.5N₂₀₀ and S₁N₂₀₀ compared with S₀N₂₀₀, respectively. The cumulative nitrous oxide (N₂O) emissions were lower in S_0.5 and S₁ than in S₀ by 48.8% and 45.3%, respectively. The soil NO₃⁻-N content in the 0−80 ​cm layer was reduced by 48.5% and 56.5% in S_0.5 and S₁, respectively, compared with S₀. However, the agronomic efficiency of N (AE_N) decreased by 5.4% and 17.6% in S_0.5 and S₁, respectively, compared with S₀ in 2021. Overall, the deep incorporation of maize straw into farmland in NC primarily increased the NH₃ emission in the short term. However, it was beneficial for reducing the N₂O emission and avoiding N leaching into deeper soil layers. An increase in N fertilization would better meet the demand for maize growth, thus enhancing the yield. In the future, controlling the NH₃ emission to improve N use efficiency can further unleash the potential of the straw return to increase soil N reservoirs, enhance ecological benefits, and maintain food security.