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Biological fixation is a process that microorganisms use to convert nitrogen gas into ammonia in soil and legumes.

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Biological Fixation

Biological Fixation

Photo by Derek, Lena and Mike

Biological Fixation

Location: ISU Agronomy Farms, West of Ames, IA
Featuring: Dr. Kathleen

Unlike their counterparts in conventional agriculture, organic farmers can't use synthetic nitrogen fertilizer. Using legumes is one way they can add nitrogen to their system.

About 80% of the atmosphere in Nitrogen (N2), which is a good thing because all plants need nitrogen for growth. In agriculture, nitrogen is a key ingredient in fertilizer. When it and other gases enter soil pores they encounter rhizobium bacteria, which infect the root hairs of leguminous plants and produce nodules. It's here that nitrogen is converted into ammonia, which it then exchanges with plants for energy. Plants such as soybeans, peas and alfalfa have a symbiotic relationship with rhizobium bacteria. Once they are tilled into the soil they release nitrogen, which other plants can uptake. Using less nitrogen fertilizer can help keep nitrogen out of the rivers, and keep our environment clean and safer.

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