秸秆还田与氮肥施用对稻田温室气体排放的影响

秸秆还田与氮肥施用是农田生态系统中碳氮元素的两大主要补给途径,其在调控稻田甲烷(CH₄)和氧化亚氮(N₂O)排放以及水稻产量方面具有重要作用。以往的研究主要关注秸秆还田或氮肥施用单因素对稻田温室气体排放的影响,而双因素互作对甲烷和氧化亚氮排放的影响尚未明确。同时,在秸秆还田条件下如何进行合理的氮肥施用鲜有深入研究。本研究基于3个氮肥处理(0、180、360 kg N/hm²)和3个秸秆还田处理(0、2.25、3.75 t/hm²)进行多年水稻田间定位试验,研究结果表明:CH₄季节累积排放随秸秆还田量增加而增加,与施氮量无显著正相关关系;N₂O季节累积排放随施氮量增加而增加,与秸秆还田量无显著正相关关系;秸秆还田对于产量的影响具有不确定性,两年均在秸秆不还田+不施氮处理(S0N0)出现最低产量,2021与2022年最低产量分别为5740.64和4903.75 kg/hm²。2021与2022年最高产量分别在秸秆不还田+高氮(S0N2)和高量秸秆还田+高氮(S2N2)出现,分别为10938.48和10384.83 kg/hm²。同时,本研究发现在低量秸秆还田条件下,在碳足迹(CF, Carbon Footprint)方面,施氮量为251 kg N/hm²时碳足迹达到最低点,为1.01 kg C/kg;而在生态经济净收益(NEEB, Net Ecosystem Economic Benefits)方面,施氮量为294 kg N/hm²时生态经济净收益达到最高点,为11778.15 元/hm²。为协同生态经济净收益与碳排放,在低量秸秆还田(S1)下,配合251-294 kg N/hm²的施氮量为最优施肥方案。研究结果为指导稻田温室气体减排、实现稻田碳中和以及农田管理提供了理论支撑,为实现水稻的高产稳产与低碳生产科学依据。

Effects of straw returning and nitrogen fertilizer application on greenhouse gas emissions in rice paddy fields and research on fertilizer recommendation

The incorporation of straw residues into fields and the application of nitrogen fertilizers represent two primary avenues for the supplementation of carbon and nitrogen elements in agricultural ecosystems. These practices play crucial roles in regulating greenhouse gas emissions, specifically methane (CH₄) and nitrous oxide (N₂O), as well as influencing rice crop yields. Previous research has predominantly focused on examining the individual im4 and N₂O emissions remain insufficiently elucidated. Simultaneously, there exists a dearth of in-depth investigations into the judicious application of nitrogen fertilizers under condition of straw incorporation. This study, based on multi-year in-field experiments in rice paddies, implemented three nitrogen fertilizer treatments (0, 180, and 360 kg N/hm²) and three straw incorporation treatments (0, 2.25, and3.75 t/hm²). Results revealed a positive correlation between the increased levels of straw incorporation and elevated seasonal cumulative CH₄ emissions, with no statistically significant positive correlation observed with nitrogen fertilizer levels. Conversely, the seasonal cumulative N₂O emissions demonstrated an increase commensurate with elevated nitrogen application levels, lacking a statistically significant positive correlation with straw incorporation levels. The impact of returning straw to the field on yield was uncertain, with the lowest yield observed in S0N0 treatment over two years. The lowest yields in 2021 and 2022 were 5740.64 and 4903.75 kg/hm², respectively. The highest production in 2021 and 2022 occurred in the treatments of S0N2 and S2N2, with 10938.48 and 10384.83 kg/hm², respectively. In the case of low straw incorporation, the carbon footprint (CF) of 251 kg N/hm² corresponded to the lowest carbon footprint, 1.01 kg C/kg; In terms of net ecosystem economic benefits (NEEB), the highest ecological and economic benefit was corresponding to the nitrogen application rate of 294 kg N/hm², which was 11778.15 CNY/hm². To optimize the ecological economic benefits and reduce carbon emissions under condition of low straw incorporation, the study recommended nitrogen application rate ranging from 251-294 kg N/hm² as the optimal fertilization scheme. The research results provide theoretical foundations for guiding mitigation strategies related to greenhouse gas emission in rice paddy fields, achieving carbon neutrality in paddy fields and farmland management, and informing agronomic practices for attaining high and stable rice yields with low-carbon production.