耕作方式对小麦-玉米两熟农田生态系统碳足迹的影响

Effect of Tillage Mode on Carbon Footprint in Wheat-Maize Double Cropping Farmland Ecosystem

农田生态系统碳足迹分析有利于找出问题,为低碳农业提供支撑。本文基于碳足迹全循环指标系统,以山东省泰安、滕州、龙口三地的中高产田为例,研究了耕作方式对中高产田耗碳足迹、固碳足迹、净耗碳(△GHG)、单位产值碳足迹(CFv)及单位产量碳足迹(CFy)的影响。结果表明:农田生态系统耗碳足迹中,化合物耗碳中N肥和土壤N_2O耗碳占了79.69%~92.53%,其中仅N肥就占了53.82%~62.49%;机电油耗碳的80%以上是灌溉、耕作、播种和收获产生的;有机耗碳中98.83%以上是秸秆耗碳。农田生态系统中主要是籽粒与秸秆固碳,籽粒固碳占总固碳的39.05%~52.64%;滕州的总固碳比其他两个城市高出196.3~7 801.5 kg CO_2/hm^2(旋耕除外);三地农田生态系统的ΔGHG值在-3 524.7^-8 774.3 kg CO_2/hm^2,均表现为碳汇;夏玉米季的净固碳高于冬小麦季;翻耕的净固碳量明显高于旋耕和耙耕。在冬小麦-夏玉米一年两熟条件下,夏玉米的CFv和CFy均显著高于冬小麦;CFv和CFy均表现为冬小麦翻耕-夏玉米免耕>冬小麦旋耕-夏玉米免耕>冬小麦耙耕-夏玉米免耕;地区间的CFv和CFy规律性不明显。因此,提高农业机械作业效率、减少机电油耗,提高氮肥和水分利用效率,建立合适的土壤耕作制度,提高作物产量,是山东省提高净固碳能力的重要突破方向。同时,继续挖掘夏玉米的固碳潜力、提高冬小麦的固碳能力,是作物育种与栽培应该重点解决的问题。

Carbon footprint analysis in farmland ecosystem was beneficial to find problems and provide the support for the development of low-carbon agriculture. Based on the whole-circle carbon footprint index system,the effects of tillage mode on carbon consumption and sequestration,carbon footprint,net carbon con-sumption（ △GHG）,carbon footprint per unit of output（ CFv） and carbon footprint per unit of production（ CFy） were studied in the high-and middle-yield field in Taian,Tengzhou and Longkou in Shandong Province. The results showed that the carbon consumption from N fertilizer and soil N2 O emission accounted for 79. 69% ~ 92. 53%,in which,that from N fertilizer accounted for 53. 82% ~ 62. 49%,in the carbon consumption from chemical compounds. More than 80% mechanical fuel consumption was used for irrigation,tillage,sowing and harvest. The carbon consumption of straw accounted for 98. 83% in the organic carbon consumptions. In the farmland ecosystem,the carbon was mainly sequestrated in grain and straw,in which,the carbon sequestration in grain accounted for 39. 05% ~ 52. 64% of the total carbon sequestration. The total carbon sequestration in Tengzhou was 196. 3 ~ 7 801. 5 kg CO_2/hm^2 higher than those of the other two cities,except under the rotary tillage mode. The △GHG in the 3 cities were between-3 524. 7 and-8 774. 3kg CO_2/hm^2,which showed that the farmland ecosystem was a carbon sink. The carbon sequestration of summer maize was higher than that of winter wheat. The carbon sequestration under plough tillage was higher than those under rotary tillage and harrow tillage. Under the winter wheat-summer maize double cropping farmland ecosystem,the CFv and CFy of summer maize both were significantly higher than those of winter wheat,the CFv and CFy were winter wheat with plough tillage-summer maize with no-tillage winter wheat with rotary tillage-summer maize with no-tillage winter wheat with harrow tillage-summer maize with no-tillage. But there were no significant rules in the CFv and CFy of different cities. Thus,in order to improve the net carbon sequestration in Shandong Province,we should improve the agricultural mechanical efficiency,reduce the mechanical and electronic consumption,increase the nitrogen and water use efficiencies,build the suitable tillage system,and increase the crop yield. Meanwhile,to excavate the carbon sequestration potential of summer maize and to improve the carbon sequestration capacity of winter wheat were important for crop breeding and cultivation.