中文摘要：

通过设置在陇中黄土高原半干旱区的豌豆-小麦-豌豆（W-P-W）和小麦-豌豆-小麦（P-W-P）轮作系统的长期定位试验,探讨了土壤有机碳及活性有机碳组分对不同耕作措施的响应.结果表明：保护性耕作的3个处理均能不同程度地提高两种轮作次序下土壤SOC、ROC和MBC的含量,其中免耕和秸秆覆盖结合处理效果最佳.同时,各处理土层的含碳量均随土壤深度的增加而降低.与免耕处理相比,免耕秸秆覆盖（NTS）、免耕不覆盖（NT）和传统耕作秸秆还田（TS）处理能够显著增加表层（0～30cm）土壤有机碳的含量,但降低了深层（30～80cm）土壤有机碳的含量,说明与传统耕作相比,3种保护性耕作有利于表层土壤有机碳的积累,而不利于深层土壤有机碳的积累.

英文摘要：

Long term field experiment on the responses of soil organic carbon（SOC）and active organic carbon（AOC）to different tillage patterns were conducted in Dingxi City located on the western Loess Plateau.The experiment was set with two rotation sequences,phase 1started with field pea（Pisum sativum）followed by spring wheat（Triticum aestivum）（P→W）,whereas,phase 2started with spring wheat followed by field pea（W→P）.The effects of conventional tillage and three conservation agriculture patterns,conventional tillage（T）,conventional tillage with stubble incorporation（TS）,no till with no stubble（NT）and no till with stubble retention（NTS）were studied.Readily oxidizable carbon（ROC）and microbial biomass carbon（MBC）were considered as indicators of AOC,and were measured together with SOC in soil layers of 0～5,5～10,10～30,30～50and 50～80cm.It was shown that the conservation tillage patterns,NTS,TS and NT,increased the concentration of SOC,ROC and MBC.In both rotation sequences,NTS treatment showed the highest values in the concentration of carbon among the different tillage patterns.Meanwhile,carbon fractions had a declining trend with the increasing depth along the soil profile.Total SOC content was significantly increased in 0～30cm soil layer,while it decreased in 30～80cm soil layer in NTS,NT and TS treatment.