陇中旱地不同保护性耕作方式表层土壤结构和有机碳含量比较分析

Effects of tillage measures on soil structure and organic carbon of surface soil in semi-arid area of the western Loess Plateau

在陇中黄土高原半干旱区进行保护性耕作定位试验,研究了不同保护性耕作措施对表层土壤结构和有机碳含量的影响。结果表明:与传统耕作(T)、传统耕作结合秸秆还田(TS)相比,免耕秸秆覆盖(NTS)土壤容重在作物生长期保持稳定;虽然两种序列NTS处理土壤总孔度较低,但其>30μm的非毛管孔度显著高于其它三种处理,W→P→W序列(2002年小麦→2003年豌豆→2004年小麦)NTS处理分别比T处理、TS处理和NT处理提高3.605%、4.749%、3.338%;P→W→P序列(2002年豌豆→2003年小麦→2004年豌豆)NTS处理分别比T处理、TS处理和NT处理提高2.834%、4.023%、2.728%;就大团聚体(>0.25 mm)含量而言,W→P→W序列下T处理、TS处理、NT处理和NTS处理分别为7.412%、9.493%、9.098%、10.577%,P→W→P序列下分别为7.600%、10.027%、8.085%、9.933%,且统计分析表明两种序列下NTS处理均与T和TS两处理差异显著。同时发现,NTS处理可显著增加土壤有机碳含量,两种序列下分别比T处理增加0.958 g/kg和1.045 g/kg,而单一的免耕(NT)或覆盖(TS)效果并不显著。

Field experiments were conducted in Dingxi on the western Loess Plateau to investigate the effects of conservation tillage on soil structure and organic carbon of surface soil in the rainfed farming system.The results showed that soil bulk density kept steady in no-tillage with straw cover（NTS） compared to conventional tillage（T）,conventional tillage with straw incorporated（TS） and no-tillage（NT）.Soil total porosity was lowest in NTS,but NTS increased 〉30 μm pores content by 3.605%,4.749%,3.338% in W→P→W rotation sequences and 2.834%,4.023%,2.728% in P→W→P rotation sequences compared with T,NT and TS,respectively.As far as water stable macroaggregates（〉0.25 mm） was concerned,it was 7.412%,9.493%,9.098% and 10.577% in W→P→W rotation sequences and 7.600%,10.027%,8.085% and 9.933% in P→W→P rotation sequences for T,NT,TS and NTS,respectively.At the same time,soil organic carbon in NTS was 9.227 g/kg and 9.353 g/kg,being 0.958 g/kg and 1.045 g/kg higher than that of conventional tillage in two rotation sequences,respectively.That is to say,NTS can improve topsoil total organic carbon,which failed to be affected by NT or TS independently.