半湿润偏旱区坡耕地保护耕作土壤碳素转化及增产机理

Soil carbon change and yield increase mechanism of conservation tillage on sloping drylands in semi-humid arid area

利用长期定位试验在豫西半湿润偏旱区坡耕地进行了不同保护耕作下土壤有机碳、微生物量碳及小麦增产机理的研究。结果表明:深松覆盖和免耕覆盖处理耕层土壤有机碳增加较明显,深松覆盖有机碳(SOC)含量最高,为6.79g.kg-1,比传统耕作高13.8%;其次是免耕,较传统耕作高11.6%;而少耕降低了1.4%。随土层加深,土壤有机碳含量降低。土壤微生物量碳(SMBC)对耕作敏感,其含量为免耕>深松>传统耕作>少耕,免耕、深松和少耕较传统耕作增加79.3%、19.9%和-2.5%。土壤有机碳和土壤微生物量碳都有坡下富集现象。免耕和深松的土壤微生物商(SMBC/SOC)较高,分别为3.11%和2.04%。深松覆盖在任何年型均能提高小麦产量,免耕覆盖在欠水年能提高小麦产量,但增产效果低于深松;深松覆盖和免耕覆盖土壤含水量较高,小麦中后期干物质积累量较多,能延缓小麦植株衰老。

A long-term field experiment was conducted in the semi-humid areas of western Henan Province to study the changes of soil organic carbon （ SOC）, soil microbial biomass carbon （SMBC） and yield increase mechanism of wheat. The results show that SOC increases significantly under sub-soiling tillage and no-tillage, especially in cultivated soil layers. SOC （6.79 g. kg-1 ） is highest under sub-soiling, which is 13.8% higher than that under conventional tillage. SOC under no-tillage is 11.6% higher than conventional tillage, which also drops by 1.4% under reduced tillage. The deeper the soil layer, the lower SOC content is. SMBC content occurs in the following order： no-tillage 〉 sub-soiling 〉 conventional tillage 〉 reduced tillage; while SMBC contents under no-tillage, sub-soiling tillage and reduced tillage are 79.3% , 19.9% and - 2.5% higher than that of conventional tillage. Ratio of SMBC to SOC under no-tillage and sub-soiling are 3.11% and 2.04%. Through out the field trial experiments, sub-soi- ling yields the highest. No-tillage increases wheat yield, except in very rainy years. No-tillage and sub-soiling tillage store more water in the soil and improve accumulation of dry matter during the later growing stage of winter wheat, postpone plant co-senes- cence in wheat.