免耕对农田土壤生物学特性的影响

农业管理对土壤群落水平下各种生物之间复杂的相互作用的影响是土壤生态学研究的一个热点。土壤生物和酶活性在改善土壤结构、养分循环、有机质分解和保持中起重要作用。与常规耕作系统比,免耕系统中作物残体和土壤矿物质的机械混合要少得多,因此免耕系统更接近于未受扰动的自然生态系统,可能更加依赖于土壤生物体的固有作用。综合有关文献讨论了耕作实践对一些土壤生物学特性的影响。总体看来,土壤线虫总量及功能类群对免耕既可能是正响应也可能是负响应,与常规耕作相比免耕系统中土壤微生物的丰富度或生物量增加,土壤酶活性增强,土壤呼吸作用减弱。最后还对免耕系统中有关土壤生物学特性研究的重要性和需要解决的问题进行了小结。

Effects of No-Tillage on Soil Biological Properties in Farmlands:A Review

One of the challenges of research in soil ecology is to understand the impacts of management on the complex interactions of all organisms at the soil community level. Soil organisms as well as enzyme activities perform important functions in soil, including structure improvement, nutrient cycling, and organic matter decomposition and retention. No-tillage (NT) systems have less mechanical mixing of crop residues into the mineral soil than do conventional tillage (CT) systems. From this standpoint, the no-tillage systems are a little more like undisturbed natural ecosystems and may depend on soil organisms for proper functioning. This paper discusses the effects of tillage practices on some soil biological properties through reviewing literatures. Although there is a wide range of responses among total and functional groups of nematodes, microflora in general have greater abundance or biomass in NT than in CT systems. Enzyme activities,in general,appear to be greater, while soil respiration to be less in NT than in CT systems. This paper also concludes with discussion,in brief,of the importance and research challenges of soil biological properties in NT systems.