保护性耕作对太行山前平原土壤质量的影响

Effect of conservation tillage on soil quality in the piedmont plain of Mount Taihang

保护性耕作被认为是华北平原农业可持续发展的重要措施,但目前缺乏这些措施对土壤质量影响的系统报道。本研究以长期定位试验为基础,探讨了太行山前平原两熟制高产农田不同耕作措施对麦田土壤质量的影响。试验始于2001年,设置翻耕玉米秸秆不还田(非保护性耕作对照,CK)、翻耕玉米秸秆粉碎还田(CT)、旋耕玉米秸秆粉碎还田(RT)和免耕玉米秸秆直立还田(NT)4个处理。2007年冬小麦收获后分层测定土壤有机碳(soil organic carbon,SOC)含量、容重(ρb)、水稳性团聚体、水分特征曲线、饱和导水率(Ks)和微生物量碳氮。2008年测定了剖面SOC含量、ρb和蚯蚓数量。结果表明,连续多年保护性耕作后土壤剖面的SOC储量无显著变化,但保护性耕作(RT和NT)下SOC的层化比率(1.74-2.04)显著高于翻耕处理(CK和CT,1.37-1.45);保护性耕作显著提高了表层微生物量碳、氮含量以及单位面积土壤中的蚯蚓数量。NT处理导致耕层(0-20 cm)土壤ρb增加,但提高了土壤团聚体的稳定性。CK和CT处理显著增加了0-5 cm土层裂隙(>500μm)和传输孔隙(500-50μm)的比例,而NT处理则增加储水孔隙(50-0.5μm)的含量。另外,保护性耕作提高了土壤的Ks、田间持水量和有效水含量。对土壤质量指标S的分析结果表明,实施保护性耕作后,太行山前平原地区土壤质量总体上得到改善。

Conservation tillage is a viable option for sustainable agricultural development in the North China Plain.Yet few studies exist on the influences of conservation tillage practices on soil quality.The objective of this study was to investigate soil quality changes as related to the shift from moldboard plow to conservation tillage practices based on a long-term field experiment.The ex-periment was started in 2001 and included four winter wheat tillage treatments — moldboard plow without corn residue（CK）,moldboard plow with corn residue（CT）,rotary tillage with corn residue（RT）,and no tillage with corn residue（NT）.In 2007,the soil organic carbon（SOC） content,bulk density（ρb）,water stable aggregate,water retention curve,soil saturated hydraulic conductivity（Ks） and soil microbial biomass C and N were measured after winter wheat harvesting.Soil samples were also collected in 2008 and analyzed for SOC,ρb and earthworm count.The results indicated no significant（P 0.05） differences in stored SOC among the treat-ments.However,conservation tillage showed SOC stratification in the soil profile.This was indicated by higher SOC stratification ratios（SR） of 1.74-2.04 for RT and NT,and 1.37-1.45 for CK and CT.Earthworm abundance and microbial biomass C and N also increased under RT and NT treatments.Application of NT significantly（P 0.05） increased soil ρb in the upper 0-20 cm soil layer,and also improved soil aggregate stability（measured by mean weight diameter）.Whereas CT and CK treatments significantly increased the proportions of fissures（ 500 μm） and transmission pores（500-50 μm）,NT treatment increased storage pores（50-0.5 μm） in the 0-5 cm soil layer.Tillage management increased soil Ks,field water capacity and plant available water content.The S index suggested that shift from conventional tillage to conservation tillage improved soil quality in the piedmont region of Mount Taihang.