Microorganisms Cycling Soil Nutrients and Their Diversity

References.................................................................................................... 260 The vast majority of nutrient cycling processes in soil are carried out by microorganisms. Organic nutrients and some inorganic compounds are supplied through animal excreta, death of plants and animals, and exudation by plant roots of plant-derived photosynthetic material. In agricultural ecosystems, nutrient input is also provided by fertilizer application. This material must be recycled. Some nutrients are returned to plants through uptake by roots, while others are released to groundwaters, to runoff or to atmospheric gases. Although soil macrofauna (nematodes, worms, enchytraeids) play a role in these recycling processes, most of them are carried out by soil bacteria, archaea, fungi and protozoa, for the purpose of this chapter collectively called soil microorganisms.