东北三省玉米生产资源投入和环境效应的时空特征

Temporal and Spatial Characteristics of Resources Input and Environmental Effects for Maize Production in the Three Provinces of Northeast China

【目的】玉米的总产量在我国三大主粮作物中最高,位居世界第二位。东北三省玉米种植面积占全国的39%,而资源投入相对较低。本研究旨在明确东北三省玉米生产资源投入和环境效应的时空特征。【方法】基于生命周期评价(life cycle assessment)方法,采用适用于东北三省玉米生产的活性氮损失模型,定量化评价东北三省2007—2016年玉米生产系统的资源投入(肥料、农药和柴油等)及其相关的活性氮损失和温室气体排放等环境风险。【结果】东北三省玉米生产资源投入在时空尺度上均存在较大差异。吉林省玉米生产的平均总施肥量为400 kg·hm^(-2),单产为7065 kg·hm^(-2),平均单位面积温室气体(GHG)排放量为2965 kg CO_(2)eq·hm^(-2),均为三省最高,而碳、氮足迹较低,平均单位面积活性氮(Nr)损失量为中间水平且年际间变化不大。辽宁省的平均氮肥投入量为198 kg·hm^(-2),Nr损失量为20.8 kg N·hm^(-2),碳、氮足迹为493 kg CO_(2)eq·Mg^(-1)和3.53 kg N·Mg^(-1),均为最高。单产为5966 kg·hm^(-2),处于中等水平,GHG排放量年际间变化不大。黑龙江省平均施氮量为149 kg·hm^(-2),单产水平为5318 kg·hm^(-2),Nr损失量和GHG排放量等均为三省最低,碳、氮足迹均处于中等水平。时间尺度上,2008—2015年东北三省玉米种植面积逐年增大,累积增加了5.73 Mhm^(2)。2015年东北三省玉米产量最高,达91.2 Mt(百万吨);2007—2016年玉米平均总产量占全国的32%,其中黑龙江省、吉林省和辽宁省分别占13.9%、11.7%和6.7%;10年平均种植面积占全国的30%,其中黑龙江省、吉林省和辽宁省分别占14.7%、9.3%和6.4%。东北三省玉米10年平均单产为6116kg·hm^(-2),平均单产最高年份为2013年,为6824 kg·hm^(-2)。2007—2016年10年间东北三省玉米生产的肥料投入整体呈上升趋势,氮肥稳中有降,磷钾肥逐年升高,2014—2016年3年肥料增长趋势大幅减缓,逐渐趋于稳定,10年间氮、磷、钾肥平均用量分别为177、101和70.2 kg·hm^(-2)。2007—2016年,东北玉米生产农药投入量呈现稳步上升趋势;柴油投入量前4年较为稳定,后逐渐上升。东北玉米生产10年间的平均农药用量为10.2 kg·hm^(-2),平均柴油用量为94.6 L·hm^(-2)。10年间玉米生产(2007—2016)平均单位面积Nr损失量和GHG排放量分别为19.0 kg N·hm^(-2)和2770 kg CO_(2)eq·hm^(-2)。Nr损失量10年间较为稳定。2007—2008和2009—2011年玉米生产的平均GHG排放量呈下降趋势,2012—2016年呈稳定上升趋势,2016年达到最高的3045 kg CO_(2)eq·hm^(-2)。氮肥田间施用产生的氨挥发是玉米生产中活性氮损失的主要途径,硝酸盐淋洗损失次之,而氧化亚氮排放占比最低。温室气体的主要排放环节为肥料生产运输与田间施用。10年间,东北玉米生产的平均氮足迹和碳足迹分别为3.16 kg N·Mg^(-1)和459 kg CO_(2)eq·Mg^(-1)。【结论】东北三省玉米生产的资源利用和环境代价在空间尺度上差异较明显,吉林省的平均肥料投入量比黑龙江省高124 kg·hm^(-2),GHG排放量高524 kg CO_(2)eq·hm^(-2);在时间尺度上,10年间东北三省玉米生产的氮肥投入量为170—182 kg·hm^(-2),Nr损失量变化范围为18.4—19.4 kg N·hm^(-2),为我国玉米主产区中较低的氮肥投入与损失量。玉米生产碳、氮足迹的高低主要取决于资源投入(尤其是氮肥投入)与单产水平之间的平衡。东北三省玉米生产资源投入和环境效应的时空特征分析有助于明确现阶段限制因素与主控因子,为优化养分管理实现粮食安全和碳减排的双赢提供理论支撑。

【Objective】The total production of maize is the highest among the three staple grain crops in China,ranking second position in the world.The planting area of maize in the three provinces of northeast China accounts for 39%of China,while the investment of resources is relatively low.The purpose of this study is to clarify the temporal and spatial characteristics of resources input and environmental effects for maize production in the three provinces of northeast China.【Method】In this paper,based on the life cycle assessment(LCA)method,the reactive nitrogen loss model suitable for maize production in the three provinces of northeast China was used to quantitatively evaluate the resources input(fertilizer,pesticide and diesel oil,etc.)and related environmental risks such as reactive nitrogen losses and GHG emissions of maize production systems in Northeast China from 2007to 2016.【Result】The average total fertilizer application rate of maize production in Jilin Province was 400 kg·hm^(-2),the average yield per unit area was 7065 kg·hm^(-2),the average GHG emissions per unit area was 2965 kg CO_(2) eq·hm^(-2),all of the above were the highest in the three provinces,but the carbon and nitrogen footprint was low,and the average reactive N losses per unit area was in the middle level and changed little from year to year.The average nitrogen input of Liaoning Province was 184 kg·hm^(-2),the average N loss per unit area was 20.8 kg N·hm^(-2),and carbon and nitrogen footprint was 493 kg CO_(2) eq·Mg^(-1) and 3.53 kg N·Mg^(-1),respectively,all of which were the highest.The per unit yield of 5966 kg·hm^(-2),was in the middle level,and the GHG emission did not change much from year to year.The average nitrogen application rate in Heilongjiang Province was 149 kg·hm^(-2) per unit yield,the average unit area N losses and GHG emissions were the lowest in the three provinces,while the carbon and nitrogen footprint were in the middle level.From 2008 to 2015,the planting area of maize in the three provinces of northeast China increased year by year,with a cumulative increase of 5.73 million hectares.In 2015,the total maize production of the three provinces was the highest,reaching 91.16 million tons,accounting for 32%of the country’s ten-year(2007-2016)average production,of which Heilongjiang Province,Jilin Province and Liaoning Province accounted for 13.9%,11.7%,and 6.7%,respectively.The ten-year average planting area accounted for 30%of the country,of which Heilongjiang Province,Jilin Province and Liaoning Province accounted for 14.7%,9.3%,and 6.4%,respectively.The ten-year average maize grain yield in the three provinces of northeast China was 6116 kg·hm^(-2),and the highest average yield was achieved in 2013,which was 6824 kg·hm^(-2).During 2007 to 2016,the fertilizer input of maize production in the three provinces of northeast China showed an overall upward trend,nitrogen fertilizer decreased steadily,while phosphorus and potassium fertilizer increased year by year.From 2014 to 2016,the increase trend of fertilizers rate slowed down sharply and gradually became stable.The ten-year average rate of nitrogen,phosphate and potassium fertilizers were 177,101,and 70.2 kg·hm^(-2),respectively.From 2007 to 2016,the pesticide input for maize production in Northeast China showed a steady upward trend,while the diesel input was relatively stable in the first four years,and then gradually increased.During the ten years of maize production in Northeast China,the average rate of pesticide used was 10.2 kg·hm^(-2),and that of diesel was 94.6 kg·hm^(-2).The average N losses and GHG emissions per unit area of maize production in 2007-2016 were 19.0 kg N·hm^(-2) and 2770 kg CO_(2) eq·hm^(-2),respectively.The reactive nitrogen losses per unit area was stable from 2007 to 2016.The average GHG emissions of maize production showed a downward trend in 2007-2008 and 2009-2011,a steady upward trend in 2012-2016,and reached the highest with 3045 kg CO_(2)eq·hm^(-2) in 2016.Ammonia volatilization caused by field application of nitrogen fertilizer was the main way of reactive nitrogen losses in maize production,followed by nitrate leaching loss,and nitrous oxide emission.The main emission sector of GHG emissions was fertilizer production,transportation and field application.During the past ten years,the average nitrogen footprint and carbon footprint of maize production in Northeast China were 3.16 kg N·Mg^(-1) and 459 kg CO_(2) eq·Mg^(-1),respectively.【Conclusion】The resource inputs and environmental cost of maize production in the three provinces of northeast China were significantly different on the spatial scale.The average fertilizer input of Jilin Province was 124 kg·hm^(-2) higher than that of Heilongjiang Province,while the GHG emissions were 524 kg CO_(2) eq·hm^(-2) higher.In 2007-2016,the nitrogen input for maize production in the three provinces of northeast China ranged from 170 to182 kg·hm^(-2),N losses ranged from 18.4 to19.4 kg N·hm^(-2),which played a good demonstration role for the green development of agriculture in China.The carbon and nitrogen footprint of maize production mainly depended on the trade-off between resource input and yield per unit area,noticeably,the nitrogen fertilizer input had a greater impact.The spatial-temporal characteristics analysis of resource inputs and environmental effects for maize production in the three provinces of northeast China contributes to clarify the limiting factors and main controlling factors at present stage,and provides theoretical support for optimizing nutrient management to achieve win-win situation of food security and carbon emission reduction.