Biodiversity in agricultural soils, sustainable plant production and control of plant pathogens

Abstract

Pathogens Soils are very heterogeneous substrates providing an environmental matrix with varying spatial and temporal gradients of pH, organic carbon, particle size distribution and moisture content. Chemical, physical as well as biological factors are operational and soil includes a vast variety of soil-dwelling invertebrates and microbes that interact with each other and the environment to influence plant productivity directly and indirectly. A review of recent literature on the role of soil biodiversity highlights the important role of soil invertebrates, notably earthworms, in influencing soil characteristics and soil borne plant pathogens. Earthworms are widely recognized as having critical functions in soil in regulating key processes that impact favourably on plant productivity and simultaneously eliminating or reducing soil borne diseases. The aim of this review is firstly to contribute towards a clarification of the role of soil biodiversity in general and to focus specifically on that of earthworms and their role in influencing plant pathogens and parasites. Evidence is provided that their activities can support plant productivity and suppress pathogens. Once the nature and extent of their role is better known and they are confirmed to support plant productivity to the extent that many soil biologists believe, the next logical step is to utilize knowledge of their ecology to create and manage favourable environmental conditions to ensure their survival and activity in agricultural soils. Agricultural management practices that favour soil organisms are also reviewed. Implementing these will make the services of soil biota available to improve and sustain agro-ecosystems. This requires a better understanding of the preferences and tolerance ranges of these organisms and their interactions before we can apply methodologies in general to manipulate environmental conditions to maximise the benefits that they may offer.