持续棉秆还田对新疆棉田土壤可矿化碳库的影响

Effect of Continuous Straw Returning on Soil Mineralizable Carbon Pool of Long-term Cotton-cropping Field in Oasis of Xinjiang

依据新疆绿洲棉花长期连作的微区定位试验,研究了在秸秆还田和不还田处理下,棉田土壤有机碳矿化特征,以及土壤有机碳释放随棉花秸秆还田年限的变化规律。结果表明:秸秆还田与不还田处理相比增加了0~60 cm土层土壤的总有机碳(TOC)、可矿化碳(MC)的含量和矿化速率(MR),并且随着秸秆还田年限的加长呈上升趋势,但随土层的加深而下降。持续秸秆还田后棉田随着秸秆还田时间增加土壤有机碳矿化速率、累积矿化排放量(CO_2-C排放量)增加,但矿化强度呈降低趋势,而棉花连作但秸秆不还田的棉田变化趋势与之相反。说明棉花秸秆还田措施增加了新疆绿洲棉田土壤有机碳含量,土壤中有机碳虽然不断得到补充,但尚未达到饱和状态,随着秸秆还田时间延长棉田固碳能力下降。

Based on the long-term experiment in long-term cotton-cropping field, this paper analyzed the characteristics ofsoil organic carbon mineralization and the change patterns of soil organic carbon release under the conditions with and withoutstraw returning. The results showed that straw returning increased soil total organic carbon （TOC） and mineralizable carbon （MC）contents and mineralization rate （MR） in 0 - 60 cm soil layer, and trended to increase with the increase of cropping year but todecease with the increase of soil depth. With the increase of continuous cropping years, soil organic carbon MC and cumulativemineralized emissions （CO2-C emissions） showed an increasing tendency, however, mineralization intensity showed a decreasingtendency with straw returning, while showed opposite tendencies without straw returning. It demonstrates that straw returningpromotes soil biological activity, compensates soil organic carbon but not enough to stabilize or increase carbon sequestrationcapacity of long-term continuous cotton-cropping field of Xinjiang Oasis.