秸秆分解对两种类型土壤无机氮和氧化亚氮排放的影响

[目的]明确作物秸秆分解对土壤无机氮和氧化亚氮(N2O)排放的影响,为不同土壤类型采用合理的氮肥用量,促进秸秆分解、增加土壤可利用养分、减少N2O等温室气体排放提供理论依据.[方法]室内采用尼龙网袋法,设置秸秆类型(小麦和玉米)、土壤类型(潮土和砂姜黑土)和氮肥用量(N0:0,N1:180 kg N·hm-2,N2:3...

Effects of Crop Residue Decomposition on Soil Inorganic Nitrogen and Greenhouse Gas Emissions from Fluvo-Aquic Soil and Shajiang Black Soil

【Objective】The purpose of this study was to examine the effects of crop residue decomposition on soil available nitrogen (N) and nitrous oxide (N₂O) emissions, and provide a theoretical basis for reasonable N fertilizer rate in agricultural soils to promote residue decomposition, to increase soil available nutrients, and to reduce N₂O emissions. 【Method】The indoor soil incubations with nylon decomposition bag were conducted to study the effects of crop residue types (wheat and maize), soil types (fluvo-aquic soil: AS and Shajiang black soil: LS) and N fertilizer rates (N0: 0; N1: 180 kg N·hm^-2; N2: 360 kg N·hm^-2) on soil N₂O emission. A control (CK) without residue addition and N fertilizer input was also established for the two soil types. Inorganic N content, N₂O and CO₂ flux, and soil enzyme activity were measured in incubated soil. 【Result】Compared with CK, soil inorganic N content under N0 decreased significantly, which was decreased by 0.8 mg·g^-1 for 1 g wheat residue addition or 0.4 mg·g^-1 for 1 g maize residue addition. Compared with AS, soil inorganic N content in LS reduced by 16% with wheat residue addition, by 41% with maize residue addition. Compared with wheat residue addition, soil inorganic N content in AS and LS increased by 111% and 252% with maize residue addition, respectively. Compared with CK, both soil N₂O and CO₂ flux increased with wheat residue or maize residue addition, and the total accumulation of soil N₂O flux under N0 treatment increased by 70% and 47% with wheat residue and maize residue addition, by 346% and 154% for CO₂ accumulation, and by 53% and 71% for global warming potential, respectively. Compared with AS, soil N₂O flux in LS reduced by 38% and 61% with wheat residue and maize residue addition, by 12% and 51% for the accumulation of N₂O flux, and by 28% and 16% for the accumulation of CO₂ flux, respectively. And the global warming potential in LS increased by 13% with the wheat residue addition in comparison with that in AS, while declined by 44% with maize residue addition. Compared with wheat residue addition, the accumulation of soil N₂O flux with maize residue addition increased by 88% in AS, and by 6% in LS, and reduced by 21% and 6% for the accumulation of soil CO₂ flux in AS and LS, respectively. And the global warming potential with maize residue addition was 91% higher than that of wheat residue addition under the conditions of different N fertilizer rates and soil types. Compared with N0 and N2, soil N₂O flux and their global warming potential under N1 treatment reduced significantly with wheat residue or maize residue addition in LS. Compared with CK, soil invertase activity increased with wheat residue or maize residue addition in both AS and LS, while which declined for soil Catalase and O₂ content. Compared with wheat residue addition, soil urease activity, Catalase, and invertase activities declined with maize residue addition. Compared with AS, soil urease and catalase activities in LS reduced with wheat residue or maize residue addition, while soil O₂ content increased. The catalase activities and O₂ content was significantly and negatively related with soil N₂O flux. 【Conclusion】The decomposition of wheat residue and maize residue reduced soil inorganic N content while increasing soil N₂O flux. Soil inorganic N content and N₂O flux with maize residue addition were higher than that of wheat residue. Emissions of N₂O from Fluvo-aquic soil with wheat or maize residue addition was higher than that from Shajiang black soil. When combined with suitable N fertilizer rate, neither residues additions in Shajiang black soil increased N₂O flux and global warming potential. These results suggested that, in the field, comprehensive management methods by returning residue to soil should consider the residue type, soil type and rate of N fertilization.