有机物料添加对淡黑钙土碳平衡的影响研究

The effects of different agricultural treatments on accumulation of soil organic carbon mostly focused on the research of amount and composition of soil organic carbon.The quantitative and mechanism study about transformation of soil organic carbon to inorganic carbon ( CO2 and carbonate ) was seldem.And previous studies were mostly limited to the studies about the effects of single agricultural treatment on carbon sequestration in soil.Because the field environment was complex and changeable, the information about regulation of organic carbon accumulation and transformation to inorganic carbon was difficult to be obtained accurately. It leaded to unclear mechanism of soil carbon sequestration. In this project, the typical black soil and light chernozem soil in Corn Belt of Song Liao Plain were selected and the analyze of field sampling and simulatative experiment were combined to roundly investigate the effects of different agricultural treatments including cultivation, fertilization and straw returning on organic carbon accumulation and transformation to inorganic carbon.The accumulation mechanism of organic carbon in soil was further investigated. The transformation of organic carbon to CO2 and carbonate was quantitatively studied.The reasonable agricultural treatments of carbon sequestration and carbon stock enhancement for Corn Belt of Song Liao Plain will be proposed. The results of this study have important theoretical and practical significance for carbon sequestration in farmland soil of Corn Belt of Song Liao Plain, the sustainable development of agriculture and reduce emissions of greenhouse gas and other aspects.

淡黑钙土是吉林省主要的土壤资源和重要的农牧业生产基地，但由于淡黑钙土有机质含量低，碳酸盐含量高，土壤肥力相对较低，要保证粮食稳产增产，主要途径是提升土壤有机质。目前，淡黑钙土区域主要通过添加有机物料（秸秆还田、施用有机肥）来提升土壤有机质含量。有机物料添加在改良土壤的同时，却对环境具有不可忽视的影响。因为有机物料添加到土壤后部分腐殖化变为有机质，部分经过矿化变为CO2，释放到大气中的CO2对环境产生不利影响，残存于土壤体系中的CO2影响碳酸盐平衡，关于以上问题的详细解读鲜见报道，尤其是新的碳酸盐平衡机制尚不清楚。本项目以吉林省淡黑钙土为对象，通过实验室模拟培养方法，研究有机物料添加对淡黑钙土有机碳累积、CO2释放和碳酸盐平衡的影响，着重探明有机物料添加情况下，土壤中新的碳酸盐平衡是如何建立的以及何种有机物料添加方式能够减少CO2释放，为构建环境友好型的淡黑钙土改良技术体系提供理论支撑。

淡黑钙土是吉林省主要的土壤资源和重要的农牧业生产基地，但由于淡黑钙土有机质含量低，碳酸盐含量高，土壤肥力相对较低，要保证粮食稳产增产，主要途径是提升土壤有机质。本项目以吉林省淡黑钙土为对象，通过实验室模拟培养方法，研究有机物料添加对淡黑钙土有机碳累积、CO2释放和碳酸盐平衡的影响。研究表明秸秆进入土壤后CO2经历快速释放和缓慢释放两个阶段，出现两个释放峰值。在相同秸秆添加量条件下，“秸秆混合”比“秸秆覆盖”可进一步提高土壤有机碳含量、减少CO2的累积释放量，改善土壤团聚体组成。“秸秆覆盖”的土壤碳酸钙含量的增加大于“秸秆混合”。有机无机肥配施对提高土壤固碳能力没有显著作用，反而加速了有机碳的矿化，同时增加了碳酸盐的含量，但是由于矿化后CO2累积释放量与对照并没有显著差异，因此认为有机碳矿化生成的CO2部分与H2O、金属阳离子结合转化为碳酸盐。冻融循环对土壤有机碳及碳酸盐的作用较小，但会增加土壤添加有机物料后的碳矿化量。随秸秆添加量的增加，耕层土壤和母质中的重组有机碳含量、原土有机碳复合量，均呈同步增加趋势，但原土有机碳复合度呈逐步下降趋势。在耕层土壤中，原土有机碳含量越低的土壤，其重组有机碳增量和原土有机碳复合量増率越大，说明原土有机碳含量低的土壤具有更大的固碳潜力。母质层土壤重组有机碳增量、原土有机碳复合量増率和追加复合量均大于耕层，说明母质的固碳潜力远大于耕层土壤，且红土母质的固碳潜力更强。秸秆焚烧仅对0-2cm表层土壤中团聚体组成具有影响。秸秆焚烧处理均使土壤大粒级微团聚体含量显著降低，而小粒级微团聚体含量显著升高。焚烧后土壤分散系数也明显升高。焚烧处理后，各粒级复合体中碳储量均降低，且在粘粒和细砂粒复合体中其有机碳含量降低，而粉粒复合体中其有机碳含量升高。秸秆焚烧会使得土壤团粒结构有向小粒级微团聚体聚集的趋势，从而破坏了土壤微团聚结构，降低了土壤的微结构水稳定性。