Effects of Tillage Practices on Soil Organic Carbon Distribution and Mineralization in Aggregates of a Brookston Clay Loam Soil

A Brookston clay loam in Southwest Ontario,Canada was selected to analyze impacts of no-till(NT),mouldboard plough(MP) tillage and continuous bluegrass(BG) on the distribution and stability of soil organic carbon(SOC) in two aggregates sizes(0.25~0.5 mm,1~2 mm).Results showed that BG soil contained more SOC relative to MP and NT soils and the SOC was more labile in the former than in the later.Compared with MP soil,NT soil contained more SOC in aggregates,and SOC in 1~2 mm than in 0.25~0.5 mm aggregate.In addition,SOC was more labile in NT than MP soils.The stability of SOC in aggregates varied with tillage practices,with no difference between two classes of aggregates in NT soil and more labile in 0.25~0.5 mm than in 1~2 mm aggregate for MP soil.