不同耕作制度对紫色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紫色水稻土为研究对象，研究了耕作制度对紫色水稻土活性有机质和碳库管理指数的影响。结果表明：稻田长期垄作免耕0～10cm土层有机质含量比常规平作高，10～60cm土层有机质含量则比常规平作低；表明稻田长期垄作免耕土壤有机质具有表层富集现象；水旱轮作各土层有机质含量均比常规平作低。垄作免耕各土层活性有机质含量普遍增加，水旱轮作表层（0～10cm）活性有机质含量减少，其余土层变化不大。对活性有机质组分含量的研究表明：与常规平作相比，垄作免耕增加了土壤表层活性有机质各个组分的含量，在其余土层增加了低活性有机质含量，而减少了高活性有机质含量；水旱轮作增加了各土层低活性有机质含量而减少了中活性和高活性有机质含量。垄作免耕所有土层的碳库管理指数都在100以上，水旱轮作除表层（0～10cm）小于100以外，其余土层都在100以上。由此可见，农业管理措施对土壤有机质、活性有机质及碳库管理指数有较大影响。

Effects of Different Tillage Systems on Soil Labile Organic Matter and Carbon Management Index of Purple Paddy Soil

Effects of different tillage systems on labile organic matter and carbon management index in purple paddy soil of long term experiment site(since 1990) were studied.Soil labile organic matter was measure by oxidation of KMnO4 with three fractionations,namely,high labile organic matter(oxidized by 33 mmol/L KMnO4),middle labile organic matter(extra carbon oxidized by 167 mmol/L KMnO4),and low labile organic matter(extra carbon oxidized by 333 mmol/L KMnO4).Compared with conventional tillage,long-term no-tillage and ridge culture of paddy field only can increase organic matter in surface soil(0~10 cm), but can increase soil labile organic matter in each soil layer except in 10~20 cm;while rotation of paddy and upland would cause organic matter decrease in each soil layer,but only cause soil labile organic matter decreased in 0~10 cm soil layer.Effects of different cultivation systems on fractionation of soil labile organic matter were also studied.The results showed that no-tillage and ridge culture can increase each faction in soil surface(0~10 cm) and increase oxidative organic matter by 167~333 mmol/L KMnO4 in the other soil layers,but decrease oxidative organic matter by 33 mmol/L KMnO4,and rotation of paddy and upland also can increase oxidative organic matter by 167~333 mmol/L KMnO4 in each soil layer,but decreased oxidative organic matter by 33 mmol/L and 33~167 mmol/L KMnO4.The carbon management index was increased in each layer of no-tillage and ridge culture,while it decreased in 0~10 cm soil layer of rotation of paddy and upland.So significant influence of agricultural management and practices on soil organic matter,labile organic matter and carbon management index were found.