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以中国科学院长期定位试验站的红壤为研究对象,通过室内模拟实验,利用δ~(13)C示踪方法,将稳定同位素碳(δ13C)标记的水稻秸秆添加入红壤,研究水稻秸秆添加对红壤水稳性团聚体分布及稳定性的影响,探索水稻秸秆腐解过程中有机碳在不同粒级团聚体中的动态变化以及分布规律.研究结果表明:未添加水稻秸秆的红壤(对照组),微团聚体(<250μm)占主体,>2000μm粒级水稳性团聚体含量最少.与对照相比,添加水稻秸秆后(试验组)促进了>2000μm粒级水稳性团聚体的团聚.不同培养时期,>2000μm水稳性团聚体增加了108.3%~270.3%,促使大团聚体占主体,显著提高了红壤水稳性团聚体的平均重量直径(MWD)、几何平均直径(GMD)、R0.25值,降低了分形维数(D)值,土壤结构明显得到改善.各粒级团聚体有机碳含量也显著得到提高,>2000μm团聚体有机碳含量比对照组增加了14.7%~41.5%.土壤有机碳在>53μm粒级团聚体中分布随着粒级的增大而增大,即>2000μm>2000~250μm>250~53μm.不同粒级团聚体δ13C值动态变化显著,有机碳的周转速率增大.外源新碳前期主要分配在>2000μm、250~53μm粒级团聚体中,并促进了原有机碳的分解,后期主要分配在微团聚体中.红壤大团聚体有机碳含量与团聚体稳定性呈极显著的相关关系(p<0.01).
Using red soil from Long-Term Positioning Station of Chinese Academy of Sciences as the research object, δ13C labeled rice straw was added into red soil by means of δ ~ (13) C tracing method through indoor simulation experiment. The effects of rice straw addition on red soil The distribution and stability of water-stable aggregates, and to explore the dynamic changes and distribution of organic carbon in different size aggregates during the decomposition of rice straw.The results showed that the red soil (control group) without rice straw, Microaggregates (<250μm) accounted for the majority, with> 2000μm particle size water stable aggregates being the least .Compared with the control, the addition of rice straw (experimental group) promoted the agglomeration of> 2000μm particle size water stable aggregates. During the cultivation period,> 2000μm water-stable aggregates increased by 108.3% ~ 270.3%, which promoted the aggregation of large aggregates and significantly increased the average weight diameter (MWD), geometric mean diameter (GMD) (D), the soil structure was obviously improved.The content of organic carbon in aggregates> 2000μm was significantly increased by 14.7% -41.5% compared with the control group, Soil organic carbon is> 53μ The distribution of aggregates increased with the increase of grain size, ie,> 2000μm> 2000 ~ 250μm> 250 ~ 53μm. The δ13C value of aggregates with different size fractions changed significantly and the turnover rate of organic carbon increased. The source new carbon was mainly distributed in> 2000μm, 250 ~ 53μm particle size aggregates and promoted the decomposition of the original organic carbon, which was mainly distributed in the microaggregates in the early stage. The organic carbon content and aggregate stability of the large aggregates Significant correlation (p <0.01).