centipedes , essential for decomposing organic matter and aerating soil . Mesofauna , like springtails and dwarf millipedes are often large enough to see . Most numerous are the microfauna — the protozoa , small nematodes , rotifers and tardigrades that are only visible with a microscope . All play a role in decomposition of organic matter . When pesticides are sprayed to control a particular pest on garden plants or farm crops , many of these vital invertebrates will die as well . Neonicotinoids , the most widely used insecticide in the world , pose a particular risk to soil invertebrate communities due to their high toxicity , systemic properties , and persistence in soils .
Even more plentiful are the microflora ; myriad bacteria — so abundant that a teaspoon of soil can hold a billion ! They can fix nitrogen , solubilize phosphorus , and help suppress pests and pathogens . They cluster near plant roots , an area dubbed the “ rhizosphere .” How does this happen ? First , the plants grab the carbon from the atmosphere , photosynthesizing it into carbohydrates ( molecules
comprised of carbon , hydrogen and oxygen ). The bacteria are recruited by the “ free food ” the plant roots exude including carbohydrates , amino acids , vitamins and phytochemicals . The plants give all that away because , in return , the microbes they attract help to keep pathogenic soil fungi and bacteria at bay and provide other nutrients that plants need but cannot acquire on their own .
Last — but definitely not least — are the fungi ; eighty to ninety percent of land plants have a symbiotic relationship with mycorrhi-
Eighty to ninety percent of land plants have a symbiotic relationship with mycorrhizal fungi ! The term “ mycorrhizae ” refers to the joining together of fungus and plant root systems . The fungi form long filaments , or hyphae , that integrate with the plant roots and extend their reach , enhancing water and nutrient uptake .
Top : Earthworms thrive in healthy soil ; above : mycelium ; the filamentous , root-like structure of a fungus . When they partner symbiotically with plant roots , they are known as mycorrhizae . zal fungi ! The term “ mycorrhizae ” refers to the joining together of fungus and plant root systems . The fungi form long filaments , or hyphae , that integrate with the plant roots and extend their reach , enhancing water and nutrient uptake , like phosphorus and nitrogen . They acquire nutrients from decomposing plant litter and heighten a plant ’ s ability to tolerate environmental stresses like drought and high soil temperature . In return , the fungi receive photosynthesisderived carbon and sequester it for their own use . Carbon and nutrients are also sometimes exchanged
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