农田土壤食物网管理的原理与方法

土壤食物网在维持生态系统生产力和健康等方面起着重要作用,但现代农业中,化肥农药等外部投入已经改变或部分替代了土壤食物网的功能,由此也造成一系列的环境问题。为了协调作物高产与环境保护的利益,需要对土壤食物网进行管理,使土壤食物网符合作物生长的需要,即建立健康土壤食物网。管理土壤食物网有两种方式:(1)直接方式,即通过调节食物网各个功能群的组成来管理土壤食物网;(2)间接方式,即根据农田土壤食物网以自下而上调控方式为主、强调低营养阶层的资源限制的原理,通过调节碎屑的数量和质量来管理食物网。在这两种调控方式中,都需要对被管理的食物网进行监测,监测的方式也分两种,一种是直接测定食物网各功能群的数量和生物量,另外一种方式即以线虫为工具来反应土壤食物网的结构。

Managing farmland soil food web: principles and methods

The soil food web consists of assemblage of interactions within soil organisms. Most ecological researches focused on the theory with respect to connectedness web, energy flow web and functional web. However, practical applications for established theories to guide the agriculture practice were seldom used. In nature ecosystem, the soil food web play an important role of maintaining both productivity and ecosystem health. In farmland, however, most of these functions were replaced by agrochemicals such as fertilizer and pesticides, which result in many environment problems. In order to maintain high crop yield and protect environmental disturbances, effective soil food web management is necessary. This paper reviewed mechanisms of controlling the soil food web, direct and indirect methods of measuring the soil food web, and how to regulate the soil food web to healthy status. Understanding these mechanisms provide the theory support and practice guide of achieving a healthy soil food web. To address the mechanism of controlling the soil food web, the paper argued the top-down and bottom-up regulation of soil food web structure and emphasized that bottom-up effects maybe more important in farmland. Also the bacterial and fungi channel within the soil food web were compared. Regarding the methods of measuring the soil food web, mainly focused on the indirect method that uses nematodes as bio-indicators of soil food web structure, enrichment and decomposition channels. Finally, we discussed mechanisms describing how to get the healthy soil food web by regulating the quantity and quality of debris or functional groups by compos tea and a concept mode of managing soil food web are discussed.