From a biological point of view, soil is one of the most complex ecosystems on nature, containing different microbial communities that interact and are involved in the global cycles that make possible all forms of life. Metagenomics has the potential to answer some fundamental questions of microbial ecology and is especially useful for the study of soils. Among the Earth's ecosystems, soils show the greatest microbiological diversity, with an estimate of 5,000 to 10,000 species of microorganisms per gram of soil.
The biota of the soil also includes the roots that grow in it and interact with other species on and beneath the soil. The availability of inorganic phosphorus (the only form of P that is directly accessible to plants) is influenced by the biogeochemical properties of the soil and limits the production of about 70% of the soils of the world. Only 20-30% of P applied as fertilizer is used by plants, and it is estimated that the global reserve of phosphate rock will be exhausted in the next 70-200 years. Improving the acquisition of P and the efficient use of P by plants is a complex challenge that involves the integration of interdisciplinary knowledge. Soil microorganisms are an integral part of the phosphorus cycle and, therefore, play an important role in the phytoavailability of this element. The development of microbial biofertilizers represents a technological alternative to increase the levels of available phosphorus in the soil and improve phosphate nutrition in production systems.