Soil microorganisms

Abstract

Soils are discontinuous and heterogeneous ecosystems, with properties determined by environmental factors (i.e. climate, parent material, organisms and time factor). Different soils reflect the impact of the various factors involved in their genesis and, as their physicochemical characteristics shift in different axes (surface and subsurface horizons), variability exists from site to site, and within a given site varies in the range of micro niches. These peculiar characteristics convert/transform soils into a composite of very diverse ecosystems making its study very challenging, since very diverse communities may coexist in a very small scale of the same sample. Soil organisms include macro/megafauna, mesofauna, microfauna/flora, and although comprising less than 1% of the total mass of a soil, they play vital functional roles in supporting the soil ecosystem. This chapter presents different approaches to structurally and functionally characterize key soil microorganisms, namely bacteria, archaea, plant growth promoting bacteria, arbuscular mycorrhizas and nematodes.