新疆“宽早优”模式下施氮量对棉田碳足迹的影响

Effect of Nitrogen Application Rate on Carbon Footprint of Cotton Field under"Kuanzaoyou"Mode in Xinjiang

【目的】研究新疆“宽早优”模式下施氮量对棉田碳足迹的影响。【方法】采用生命周期评价法(LCA),设置不同施氮水平(0、120、240、360 kg/hm^(2)),分析施氮量对棉田碳足迹、碳足迹构成及产量的影响。【结果】当氮肥施用量(360 kg/hm^(2))减少33.3%(240 kg/hm^(2))和66.7%(120 kg/hm^(2))时,碳足迹分别下降了8.4%和17.6%。在N360处理下籽棉产量为8035.4 kg/hm^(2),在N240处理下籽棉产量为7797.2 kg/hm^(2),且N240、N360处理棉花籽棉产量差异不显著。灌溉用电、农膜及化肥引起温室气体排放对碳足迹贡献最大,分别占47.4%、25.2%和24.3%。随着施氮量的增加,棉田N2O排放总量随之增加,N360分别比CK、N120和N240显著高221.9%、123.1%和33.1%。【结论】随着施氮量的减少,棉花单位面积碳足迹也随之减少,在不影响产量的情况下,降低氮肥用量可以减少“宽早优”棉田碳足迹,在新疆地区实现以较少的碳足迹来获得较高的产量。

【Objective】Optimizing nitrogen input in cotton field is an effective strategy to reduce greenhouse gas emissions and improve crop yields.【Method】In this experiment,life cycle assessment(LCA)was used to study the effects of different nitrogen levels(0,120,240,360 kg/hm^(2))on the carbon footprint,carbon footprint composition and yield of cotton fields.【Results】As the amount of nitrogen applied decreases,the carbon footprint per unit area of cotton also decreases.When the amount of nitrogen fertilizer(360 kg/hm^(2))decreases by 33.3%(240 kg/hm^(2))and 66.7%(120 kg/hm^(2)),the carbon footprint dropped by 8.4%and 17.6%respectively.In terms of yield,with the increase of nitrogen application,cotton yield gradually increased.The seed cotton yield under N360 treatment was 8,035.4 kg/hm^(2),and that under N240 treatment was 7,797.2 kg/hm^(2),and there was no significant difference in the seed cotton yield between N240 and N360 treatment.In the production process of the"Kuanzaoyou"cotton planting model,the greenhouse gas emissions caused by irrigation electricity,agricultural filmand nitrogen fertilizer contribute the most to the carbon footprint,accounting for 47.4%,25.2%and 24.3%.With the increase of nitrogen application,the total emissions of N2O in cotton fields will increase,N360 was 221.9%,123.1%and 33.1%higher than CK,N120 and N240,respectively.【Conclusion】Without affecting the yield,reducing the amount of nitrogen fertilizer can reduce the carbon footprint of cotton fields in northern Xinjiang,thereby achieving higher yields with a smaller carbon footprint in the arid regions of Northwest China.