保护性耕作下土壤动物群落及其与土壤肥力的关系

保护性耕作不仅能改善土壤特性，增加作物产量，也是缓解农田生物多样性损失的重要措施之一。为了探讨保护性耕作下土壤动物群落结构及其与土壤肥力的关系，试验采用裂区设计，主区为翻耕和免耕，副区为3种秸秆还田处理。结果表明：秸秆还田显著增加了土壤动物优势类群弹尾目和蜱螨目，耕作方式和秸秆还田量之间存在显著的交互效应。免耕和秸秆还田的结合增加了土壤有机质含量，但pH值下降；秸秆还田增加了土壤全氮和速效磷；与初始条件相比，过氧化氢酶和蔗糖酶活性下降，而尿酶活性有所增加。土壤有机质和全氮对土壤动物特别是弹尾目和蜱螨目有显著的正效应，土壤速效磷含量也与优势类群表现为正相关；鞘翅目、双尾目和唇足纲表现了能适应相对较高pH值的土壤环境。总之，保护性耕作在一定程度上增加土壤碳库，缓解温室效应，同时也提高了土壤动物丰富度；土壤动物与土壤养分密切相关，表现其在作物对养分利用的有效性上起着重要的作用。

Relation of agricultural soil fauna and soil fertility under conservation tillage systems

Conservation tillage improves soil conditions, increases crop yield, and is also one of the key measures in lessening biodiversity loss of agricultural soils. A Field trial with split-plot design was conducted to investigate soil fauna and soil fertility under conservation tillage systems, the relation of which was discussed in this study. The results showed that straw returning significantly increased the amounts of agricultural soil fauna, especially for collembola and acari. The interaction between tillage type and straw returning amount was significant. Application of no-tillage added straw returning significantly improved soil organic matter content, but lowered soil pH value. Straw returning increased in soil available phosphorus content and soil total nitrogen and soil urinary activity, but decreased in catalase and invertase activity when compared to the initial condition of experiment. The dominant groups (collembola and acari) of soil fauna were highly correlated with soil organic matter content, and Coleoptera, Diplura and Chilopoda might be adapted to reside in relatively high pH value soils. In conclusion, conservation tillage can improve soil organic matter content and increase soil carbon pool which is beneficial to lessen greenhouse effect, and also increase the abundance of soil fauna. The abundance of soil fauna is well correlated to soil nutrients, which shows that soil fauna plays an important role in availability of soil nutrients utilized by plants in the agro-ecosystem.