Soils are filled with microbial life. In fact, soil houses the most diverse and complex microbial community of any environment known. Soil is a globally important reservoir of biodiversity containing between a quarter and a third of all living organisms on the planet. A single handful of healthy soil can contain over 50km of fungal networks, more than 100 million bacteria and 100,000 protozoa. This soil microbiota diversity brings with it enormous functional potential, and is a rich source of genetic and pharmaceutical resources. Indeed, many of the antibiotics used in modern medicine today have been derived from the soil microbiota.

Soil microorganisms are critically important to agriculture, food production, and in climate regulation. They are the main drivers of nutrient cycles in soils. Thus, they play an active role in soil fertility and several important nutrient transformations are carried out exclusively by microorganisms for e.g. fixing nitrogen from the air or making the nutrients tied up in complex organic matter available for plants. The soil microbiome is intrinsic for the establishment and productivity of crops. The microbes in soil and on plant roots provide essential nutrients, vitamins and plant growth regulators to plants, and prevent pathogen invasions by both stimulating plant defences and being antagonistic to invading pathogens. Greenhouse gases result from microbial processes and understanding their function is key to reducing gaseous emissions that contribute to climate change.

Despite the importance of the soil microbiome very little is known about it. However, with new technologies this is beginning to change and we are now achieving a better understanding of the important role of the soil microbiome. Increasing our knowledge of what organisms are present in soil and what they are doing will enable us to manage soils in such a way as to harness the natural capacity of soil microorganisms to provide nutrients for plants, while at the same time limiting losses that can be damaging to the environment. This has the potential to lead to a more economically and environmentally sustainable agriculture into the future.