秸秆还田配施氮肥对黑土玉米田土壤CO2排放与碳平衡的影响

Effects of Straw Returning Combined with Nitrogen Fertilizer on Soil CO2 Emission and Carbon Balance in Black Soil Maize Field

摘要:

为探寻不同秸秆还田方式配施氮肥对黑土玉米田土壤CO2排放与碳平衡的影响，于2023年开展大田试验，设置秸秆离田（S0，对照）、秸秆覆盖还田(S1)、秸秆旋耕还田（S2）3种秸秆还田方式，同时设置常规施加氮肥（N, 250kg/hm2）与不施加氮肥（W，0kg/hm2，对照）2种施氮模式，共计6个处理。测定不同处理下玉米生育期土壤CO2排放通量以及玉米收获后土壤有机碳（SOC）、可溶性有机碳（DOC）、微生物量碳（MBC）含量，探究土壤CO2累积排放量与SOC、DOC、MBC含量的关系，并分析黑土玉米田生态系统碳平衡状况。结果表明：各处理中土壤CO2累积排放量从大到小依次为S2N、S1N、S0N、S2W、S1W、S0W，其中S2N处理土壤CO2累积排放量较S0W处理显著增加70.31%（P<0.05）。在相同施氮模式下，秸秆还田能够有效增加SOC、DOC、MBC含量，且土壤CO2累积排放量与SOC、DOC、MBC含量呈正相关关系。不同秸秆还田方式配施氮肥下，S1N处理玉米产量最高，为13534.4kg/hm2，作物碳排放速率最低，为0.122kg/kg。不同秸秆还田方式配施氮肥下黑土玉米田生态系统碳平衡值均为正值，表现为较强的碳“汇”，其中S1N处理碳平衡值和土壤固碳潜力最大，较其他处理分别增加13.12%~94.05%、3.49%~25.32%。综上所述，在本试验条件下，秸秆覆盖还田+常规施氮（S1N处理）可以实现黑土玉米田土壤固碳减排和作物增产目的。

Abstract:

Field experiment was conducted in 2023 to investigate the effects of different straw returning methods with N fertilization on soil CO2-emission and carbon balance in black soil maize fields. The experiment included three straw return methods: straw leaving the field (S0, control), straw mulching returning to the field (S1), and straw rotary tillage returning to the field (S2), and two modes of N fertilization: regular N fertilizer application (N, 250kg/hm2) and no N fertilizer application (W, 0kg/hm2, control), totaling six treatments. The soil CO2-emission flux and the contents of soil organic carbon (SOC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) after maize harvest were measured under different treatments, and the relationship between soil CO2-emission and the contents of SOC, DOC, MBC were explored, and the carbon balance of black soil maize field ecosystem was analyzed. The results showed that the cumulative soil CO2-emissions in each treatment were S2N, S1N, S0N, S2W, S1W,S0W, and the cumulative soil CO2-emissions of S2N treatment were increased significantly by 70.31% compared with S0W treatment (P<0.05). Under the same nitrogen application mode, straw returning to the field effectively increased the contents of SOC, DOC, MBC. Additionally, the cumulative soil CO2-emissions were positively correlated with the contents of SOC, DOC, MBC. Under different straw returning methods and nitrogen fertilizer, the yield of maize in S1N treatment was the highest (13534.4kg/hm2), and the crop carbon emission rate was the lowest (0.122kg/kg). The carbon balance value of black soil maize field ecosystem under different straw returning methods and nitrogen fertilizer application were all positive, showing a strong carbon “sink”, and the carbon balance value and soil carbon sequestration potential of S1N treatment were the largest, which were increased by 13.12%~94.05% and 3.49%~25.32%, respectively, compared with other treatments. In summary, the results of this experiment suggest that straw mulching and returning to the field, in combination with conventional nitrogen application (S1N), can effectively achieve the goals of soil carbon sequestration, emission reduction, and increased crop yield in black soil corn fields.