施肥对不同地下水位水稻土团聚体组成及有机碳分布的影响

Effects of Fertilization on Aggregate Composition and Organic Carbon Distribution in Paddy Soil Under Different Groundwater Level

利用长期定位试验研究施肥（高量有机肥、常量有机肥、化肥）对不同地下水位（低水位80cm,高水位20cm）红壤性水稻土团聚体组成及有机碳分布的影响。结果表明,高、低水位下,各施肥处理的水稳性团聚体均主要分布在〉2mm的大团聚体范围内,分别为58.62%-71.29%和68.66%-80.46%,其数量随粒径的减小而减少。有机肥处理显著提高土壤〉0.25mm水稳性团聚体含量、团聚体平均质量直径（MWD）、几何平均直径（GMD）,降低土壤团聚体的分形维数（D）,且增加（降低）量随有机肥施用量的增加而增加。地下水位也显著地影响土壤团聚体的稳定性,低地下水位下,土壤团聚体的MWD、GMD值均显著高于高地下水位下各施肥处理。土壤有机碳含量深受施肥和水位条件的影响。高、低地下水位下,土壤全量有机碳含量分别为14.45-20.46g/kg和14.16-18.88g/kg,高量和常量有机肥处理的土壤有机碳含量较化肥处理分别增加42%,29%和33%,25%;〉2mm粒径团聚体的土壤有机碳含量最高且数量最多,对土壤有机碳的贡献率最高。

A long-term experiment was utilized to study the effects of applying different amounts（high,normal and none）of crop residue on the organic matter content,aggregate particle size distribution,and aggregate stability in red paddy soil under different groundwater level（80cm,20cm）.The results showed that the water stable aggregate of three fertilization treatment under high or low ground water level were dominated by2mm particle size,the proportion were 58.62%-71.29% and 68.66%-80.46%respectively,and the quantity decreased with decreasing particle size.The application of crop residue increased the amount of soil water stable aggregate（0.25 mm）,aggregate mean weight diameter（MWD）,geometric mean diameter（GMD）,and decreased aggregate fractal dimension（D）.Groundwater level significantly affected soil aggregate stability.The MWD and GMD of soil aggregate under low groundwater level was higher than that under high groundwater level obviously.Soil organic carbon（SOC）content was also influenced by fertilization and groundwater level.The contents of total organic carbon was 14.45-20.46g/kg and 14.16-18.88g/kg under high groundwater level and low groundwater level respectively.The SOC contents of high and normal crop residue application treatments were 44%,29% and 32%,25% higher than that of mineral fertilizer treatment under high and low groundwater level conditions.Water stable aggregate（2mm）had the highest mass proportion and organic carbon contents among different soil particle sizes,and had the most important contribution to improve SOC.