西南地区紫色水稻土颗粒有机质的季节动态

以西南大学试验农场的紫色水稻土试验田为研究对象,探讨颗粒有机质的季节变化。结果表明,在油菜生长季内,颗粒态土质量分数呈现先升高后降低趋势,变化范围为27.38%～32.15%,具有明显的季节变化。颗粒有机碳(POC)与颗粒有机氮(PON)含量具有相同的季节变化趋势,为"U"字形,主要影响因子为TOC、TN及pH值。POC与PON分配比例的季节变化特征大体相似且均较明显,POC分配比例变化范围为24.96%～42.39%,平均值为35.73%,PON分配比例变化范围为17.19%～30.98%,平均值为22.59%。有机质的输入及其矿化分解是造成POC、PON含量及其分配比例变化的主要原因。生长季内POC/PON介于13.96～17.28之间,极显著高于全土碳氮比,表明颗粒有机质更容易被分解和转化。

Seasonal Dynamics of Soil Particulate Organic Matter in Purple Paddy Soil in Southwest China

Seasonal dynamics of particulate organic matter were studied in a purple paddy soil at the farm of southwest university,Chongqing,China.The results showed that the ratio of soil particulate fraction,the concentrations of POC and PON,proportion of POC and PON all had obvious seasonal variation.The ratio of soil particulate fraction ranged from 27.38% to 32.15%,the concentrations of POC and PON had similar trends of seasonal variation with U-shaped.The POC and PON proportion were 24.96%~42.39% and 17.19%~30.98%,with the mean of 35.73% and 22.59%,respectively.The POC and PON content were both positively and significantly correlated with TOC,TN,and pH.The input and mineralization of organic matters caused the seasonal dynamics of the content and proportion of POC and PON.The particulate C/N ratio ranged from 13.96 to 17.28 during rape growing period,which was significantly higher than bulk soil,indicating that particulate organic matter was more likely to be decomposed and transformed.