保护性耕作土壤线虫成熟度及区系分析

土壤线虫的生活史和功能多样性能够反映土壤健康质量和生态环境的演变,耕作措施的改变可能通过影响土壤环境进而影响土壤线虫的生活史和功能多样性,然而关于保护性耕作条件下土壤线虫成熟度及区系分析的研究,国内外尚鲜见报道。为了深入揭示土壤线虫对保护性耕作土壤生态环境变化的生物指示作用,以辽宁彰武县保护性耕作示范推广基地土壤为研究对象,通过实地调查和取样分析,对比研究了传统犁耕和6年保护性耕作（免耕秸秆覆盖）条件下的土壤线虫成熟度指数及区系分析。研究发现,与犁耕相比,保护性耕作显著降低了表层土壤自由生活线虫成熟指数MI、总成熟指数MMI、c-p值为2~5的自由生活线虫成熟指数MI2–5和总成熟指数MMI2–5,降低幅度分别为11%、9%、9%和10%,然而对植物寄生线虫成熟指数PPI以及PPI/MI比值的影响不明显。线虫区系分析结果表明,保护性耕作土壤线虫的富集指数EI和结构指数SI,比犁耕土壤分别显著降低56%和24%。保护性耕作造成的土壤pH降低和可能带来的土壤农药污染,可能是导致其上述影响的主要原因。简单相关分析和主成分分析结果证明,线虫成熟指数MI、MMI、MI2–5和MMI2–5以及结构指数SI与土壤pH关系密切。综上,土壤线虫生活史多样性和功能多样性对于揭示保护性耕作对土壤环境的影响具有良好的作用。

Soil nematode maturity and faunal analysis under conservation tillage

Soil nematode life history and functional diversity are thought to be useful for indicating soil health and environment changes. Changing tillage practices may affect soil nematode life history and functional diversity through altering soil environment. However, there are few reports on soil nematode maturity and faunal analysis under conservation tillage. In this paper, soil nematode maturity indices and faunal analysis were compared under traditional plow tillage （PT） and 6-yr conservation tillage of no-tillage with straw mulch （CT） in Zhangwu county of Liaoning Province, in order to examine effectiveness of soil nematode in indicating soil eco-environment change under conservation tillage. Obtained results showed that, the conservation tillage significantly decreased maturity indexes for free-living nematodes （MI, 11%）, for total nematodes （MMI, 9%）, for free-living nematodes with c-p values of 2 5 （MI2-5, 9%） and for total nematodes with c-p values of 2 5 （MMI2-5, 10%）, as compared to plow tillage. Soil nematode faunal analysis suggested that, enrichment index El and structure index SI were both significantly lower under the conservation tillage than under plow tillage. Soil acidification and possible soil pesticide pollution induced by the conservation tillage may be responsible for those effects. Simple linear correlation analysis and principle component analysis （PCA） conformed that maturity indices of MI, MMI, MI2-5 and MMI2-5 and structure index SI were closely correlated with soil pH and they can be good indicators for evaluating the conservation tillage effects on soil environmental quality.