土壤颗粒有机碳和矿质结合有机碳对4种耕作措施的响应

以陕西关中平原中部耕作定位试验为研究对象,研究深松、旋耕、免耕和统耕作4种耕作方式在秸秆还田和不还田条件下对土壤颗粒有机碳和矿质结合态有机碳的影响。结果表明,相对于传统耕作,深松、旋耕和免耕处理都使土壤颗粒碳(POC)含量增加,但在秸秆还田下相应增加幅度更大,在0-10cm土层颗粒碳增加20.71%～69.25%,表现出深松>旋耕>免耕>传统耕作的顺序,而对其他10-20cm,20-30cm,30-40cm土层的颗粒碳影响较小。在同一种耕作模式下,秸秆还田的与无秸秆还田的相比,深松、旋耕、传统耕作使土壤POC增加了9.17%～26.61%,其中以传统耕作措施的提高幅度最大。在秸秆不还田条件下,各耕作处理矿质结合态有机碳的差异较小,但在秸秆还田条件下,旋耕促进了土壤矿质结合态有机碳(MOC)的增加,比对照(传统耕作)提高了22.98%。从土壤有机碳的角度考虑,深松和旋耕并结合秸秆还田是较适合于当地土壤条件的耕作模式。

Responses of Soil Particulate Organic Carbon and Mineral-bound Organic Carbon to Four Kinds of Tillage Practices

Particulate organic carbon(POC) and mineral-bound organic carbon(MOC) were investigated in a long-term tillage experiment located in Guanzhong Plain,Shaanxi province.Soil were disturbed by sub-soiling(ST),rotray tillage(RT),no-tillage(NT) and conventional tillage(CT) with and without straw returning.The results indicated that ST,RT and NT were aggressive in increasing contents of POC and MOC under both straw returning conditions in comparison to CT,but the increase effects were better when straw was returned.Specifically,the increase of POC ranged from 20.71% to 69.25% and ranked by ST >RT >NT >CT.Little increase of POC was detected in 10-20 cm,20-30 cm and 30-40 cm soil layer.When the same tillage practice was considered,straw returning increased the content of POC ranging from 9.17% to 26.61%.Among the present tillage treatments,CT was observed with the highest increase of POC when straw was returned.With out straw returning,the variation in content of MOC in different treatments was small,but under the condition of straw returning,RT improved the content of MOC of 22.98% compared with CT.From the perspective of carbon sequestration,ST and RT with straw returning are suitable tillage practices under the local soil condition in Guanzhong plain.