长期不同施肥制度对红壤性水稻土活性有机质及碳库管理指数的影响

以长期定位试验点的红壤性水稻土为研究对象，研究了长期不同施肥制度对红壤性水稻土活性有机质和碳库管理指数的影响。试验处理为：CK（不施任何肥）；NK（施氮钾肥）；NPK（施氮磷钾肥）；NK+PM（施氮钾肥＋猪粪）；NPK+RS（施氮磷钾肥＋稻草）。结果表明：红壤性水稻土中的活性有机质以中活性有机质为主，施肥对活性有机质组分影响明显。连续种植25年水稻后，CK处理的土壤活性有机质含量降低，CMI(碳库管理指数)下降。施肥能够提高土壤有机质、活性有机质各组份的含量和碳库管理指数，CMI以NPK+RS处理上升最大，NK处理最小，说明有机-无机肥配施对活性有机质组分影响较单施化肥更明显。土壤活性有机质含量和CMI的增幅大于土壤总有机质的增幅，水稻产量与CMI的相关性达到极显著水平。CMI是评价施肥制度对土壤质量影响的良好指标。

Effects of Long-term Fertilization Systems on Soil Labile Organic Matter and Carbon Management Index of Reddish Paddy Soil

OBJECTIVE]Effects of long-term fertilization on labile organic matter and carbon management index(CMI)in reddish paddy soil were studied in order to assess soil quality.METHOD]Soil labile organic matter with three fractionations was measured by oxidation of KMnO4,namely,high labile organic matter(measured by oxidation of 33mmol/L KMnO4),middle labile organic matter(measured by oxidation of 167 mmol/L KMnO4),and labile organic matter(measured by oxidation of 333 mmol/L KMnO4).RESULTS]The results showed that middle labile organic matter was the main part among labile organic matter in the reddish paddy soil.After 25 years,the labile organic matter in soils with long term of no fertilizer application(CK),and CMI were decreased.Soil total organic matter,labile organic matter content and CMI in the treatments with fertilizer applied were higher than those in CK and soil initial value,and there was significantly increase in labile organic matter and CMI.The CMI in the NPK RS treatment was the highest;whereas the lowest in the NK treatment.The increases in range of soil labile organic matter content and CMI were higher than those of soil total organic matter,of which increase range of CMI was the largest.The correlation between CMI and rice yield was highly significant(p<0.01).CONCLUSION]Combined application of organic manure or rice straw with inorganic fertilizer could increase labile organic matter fractions in the reddish paddy soil of southern China and rice yield.The CMI will be a good index to assess influence of fertilization practice on soil quality.