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They are the most abundant microorganisms in the soil, and serve many important purposes, including nitrogen fixation. [9] Some bacteria can colonize minerals in the soil and help influence weathering and the breaking down of these minerals. The overall composition of the soil can determine the amount of bacteria growing in the soil.
Nitrogen is an essential element needed for the creation of biomass and is usually seen as a limiting nutrient in agricultural systems. Though abundant in the atmosphere, the atmospheric form of nitrogen cannot be utilized by plants and must be transformed into a form that can be taken up directly by the plants; this problem is solved by biological nitrogen fixers.
The plant microbiome, also known as the phytomicrobiome, plays roles in plant health and productivity and has received significant attention in recent years. [1] [2] The microbiome has been defined as "a characteristic microbial community occupying a reasonably well-defined habitat which has distinct physio-chemical properties.
Soil microbial communities are characterized in many different ways. The activity of microbes can be measured by their respiration and carbon dioxide release. The cellular components of microbes can be extracted from soil and genetically profiled, or microbial biomass can be calculated by weighing the soil before and after fumigation.
In young plants, growth allocation is often quite similar to the actual biomass allocation. But especially in trees, there may be a high yearly turnover in leaves and fine roots, and a low turnover in stems, branches and thick roots. In those cases, the allocation of growth and the final biomass allocation may diverge quite strongly over the years.
Soil biology is the study of microbial and faunal activity and ecology in soil. Soil life , soil biota , soil fauna , or edaphon is a collective term that encompasses all organisms that spend a significant portion of their life cycle within a soil profile, or at the soil- litter interface.
So, where "active" soil organic matter is a key to productive soil, soil with low microbial activity provides significantly fewer nutrients to plants; this is true even though the quantity of biomass left in the soil may be the same. Soil microorganisms also decrease pathogen and pest activity through competition. In addition, plants produce ...
Biological soil crusts cover about 12% of the earth's landmass. [8] They are found on almost all soil types, but are more commonly found in arid regions of the world where plant cover is low and plants are more widely spaced. This is because crust organisms have a limited ability to grow upwards and cannot compete for light with vascular plants.