不同施肥措施对黑土区玉米氮效率及碳排放的影响

张杰; 金梁; 李艳; 赵士诚; 徐新朋; 魏丹; 张丽娟; 仇少君; 何萍; 周卫

doi:10.11674/zwyf.2021409

不同施肥措施对黑土区玉米氮效率及碳排放的影响

Effects of nutrient management techniques on nitrogen fertilizer efficiency and carbon emission of maize in a Mollisol

摘要

摘要:
目的以东北黑土区玉米生产体系为研究对象，探究不同施肥措施对玉米籽粒产量、氮肥利用效率及碳排放的影响，以实现该地区粮食平稳增产的同时降低农业生产碳排放。
方法在黑龙江典型黑土区进行了两年玉米田间试验，试验设5个处理：不施氮肥(CK)；推荐施肥处理(RF)；推荐施肥+有机氮替代20%化肥氮(MRF)；推荐施肥+秸秆还田(SRF)和农民传统施肥(TF)。通过调查玉米全生育期农资投入，结合生命周期评价法，系统分析不同处理下玉米籽粒产量、氮肥农学效率、氮肥偏生产力及碳排放的主要影响因子。
结果与TF处理相比，RF、MRF和SRF处理的玉米产量分别平均提高了1.3%、6.2%、7.6%，氮肥农学效率分别显著提高了31.3%、82.6%、50.3% (P < 0.05)，氮肥偏生产力分别显著提高了29.0%、69.0%、37.0% (P<0.05)；各处理籽粒产量、氮肥农学效率及氮肥偏生产力在不同年际间均无显著变化。玉米整个生长周期内，RF、MRF、SRF及TF处理的碳排放量较CK处理分别显著提高了37.6%、24.0%、38.5%、63.6% (P<0.05)，两年试验各施氮处理碳排放量均以MRF处理最低。玉米整个生产周期中碳排放的主要贡献因子是氮肥投入量及氮损失(N₂O+NH₃+NO₃^–)，贡献率超过70%；其次为农药与柴油投入，贡献率分别约为10.2%、13.6%；磷、钾肥占比最低，贡献率总和不足3%。与TF处理相比，RF、MRF及SRF处理的碳排放量分别显著降低了16.0%、24.7%、16.4%，MRF处理的碳排放量又较RF与SRF处理分别显著降低了9.9%、10.4% (P<0.05)。
结论在东北黑土区玉米生产中，氮肥用量及损失量贡献了70%的总碳排放。降低氮磷肥用量、提高钾肥用量可以保证玉米产量稳定。相较推荐施肥和秸秆还田处理，有机态氮代替20%化肥氮处理可以在稳产的同时，更有效地提高氮肥利用效率、减少氮素损失，因而其综合的碳排放最低，有利于实现农业可持续发展。

Abstract:
Objectives The yield, nitrogen (N) fertilizer use efficiency and carbon emission in maize production system were studied under different fertilizer management practices, in order to reduce the cumulative carbon emissions and increase fertilizer use efficiency in northeast China.
Methods A field maize experiment was conducted in a typical black soil type in Heilongjiang Province for two years under the recommended fertilizer rate application (RF), recommended N rate+ organic N replacing 20% chemical nitrogen fertilizer (MRF), recommended fertilizer rate + straw returned (SRF), farmers’ fertilizer rate (TF), and no nitrogen fertilizer (CK). Based on life-cycle assessment method, the grain yield, N agronomy efficiency, N partial productivity, and carbon footprint were evaluated.
Results Compared with TF, RF treatment, MRF and SRF treatments increased (P<0.05) maize yield by 1.3%, 6.2% and 7.6%; agronomic efficiency of N fertilizer by 31.3%, 82.6% and 50.3%; and nitrogen partial productivity by 29.0%, 69.0% and 37.0%, respectively. Compared with CK treatment over the two-year experimental period, the RF, MRF, SRF and TF treatments significantly increased carbon emission by 37.6%, 24.0%, 38.5%, 63.6%(P<0.05), respectively, and MRF treatment had the lowest carbon emission among the N fertilizer treatments each year. N fertilizer input and nitrogen loss (N₂O+NH₃+NO₃^–) were the main contributory factors, contributing more than 70% of the total carbon footprint during the maize life cycle, followed by pesticide and fuel consumption, which contributed 10.2% and 13.6%, respectively. Phosphorus and potassium fertilizer accounted for the lowest percentage of C emission, with contribution rate of less than 3%. Compared with TF treatment, the carbon footprint of RF, MRF and SRF treatments were significantly reduced by 16.0%, 24.7% and 16.4% (P<0.05), respectively, and the carbon footprint in MRF treatment was decreased by 9.9% and 10.4% in comparison with RF and SRF treatments, respectively.
Conclusions In black soil region of northeast China, 70% carbon footprint was contributed by N fertilizer and N loss, while phosphorous and potassium fertilizers accounted for less than 3%. Decreasing N and P input with an increase in K input will not affect maize yield, while replacing 20% of chemical N with organic fertilizer will not only increase maize yield, but also improve N-use efficiency and reduce N loss more effectively than recommended fertilization and straw returning, thus organic N replacing 20% chemical nitrogen fertilizer produce a significantly lower carbon footprint, and is beneficial to achieve sustainable development in agriculture.

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