Soil microbiology

Soil microbiology is the study of microorganisms in soil, their functions, and how they affect soil properties.^[1] It is believed that between two and four billion years ago, the first ancient bacteria and microorganisms came about on Earth's oceans. These bacteria could fix nitrogen, in time multiplied, and as a result released oxygen into the atmosphere.^[2][3] This led to more advanced microorganisms,^[4][5] which are important because they affect soil structure and fertility. Soil microorganisms can be classified as bacteria, actinomycetes, fungi, algae and protozoa. Each of these groups has characteristics that define them and their functions in soil.^[6][7]

Up to 10 billion bacterial cells inhabit each gram of soil in and around plant roots, a region known as the rhizosphere. In 2011, a team detected more than 33,000 bacterial and archaeal species on sugar beet roots.^[8]

The composition of the rhizobiome can change rapidly in response to changes in the surrounding environment.