Alphabetical Plant Listing

Nitrogen-Fixing Plants to Enrich your Soil

Alfalfa, Beans, Clover, Esparsette, Kudzu, Lespedeza, Peas, Peanuts, Soybeans, Winter Hairy Vetch


Nitrogen is among the top 3 vital nutrients for plants and crops, alongside potassium and phosphorus. It is responsible for chlorophyll and photosynthesis and is also a major component of amino acids.

What Is Nitrogen Fixation?

  • Though nitrogen makes up 80% of the volume of the atmosphere, it is unusable by most living organisms. It needs to be transformed into a digestible compound before it can be used. 
     
  • Nitrogen-fixing plants are those with rhizobia bacteria that live on their roots and convert the atmospheric nitrogen into nitrogen compounds for their own use. Thanks to this relationship with this bacteria, these nitrogen-fixing plants increase the nutrients in the soil, making them also available to the plants nearby – a perfect relationship for companion planting. 
     
  • Using nitrogen-fixing plants is a natural way to enrich your soil without using chemical fertilizers. A successful practice is to use nitrogen-fixing plants in intercropping. Heavy-feeding plants are intermixed with crops that add nitrogen to the soil. As an example, peas and beans benefit potatoes, carrots, cucumbers, cauliflower, cabbage, summer savory, turnips, radishes, corn, and most other herbs and vegetables.
     
  • Using nitrogen-fixing plants in crop rotation also allows nitrogen fixation for succeeding plants - because the nutrients are also available to plants grown in the soil after the nitrogen-fixing plants are pulled.
     
  • Legumes are known as the best nitrogen-fixing plants. These soil improvers collect nitrogen on their roots and restore it to the soil.
     
  • Some legumes are better at fixing nitrogen than others. The magnitude of biological nitrogen fixation and associated contribution varies across legume species, soil properties, climatic conditions, and cropping systems.
     
  • Perennial and forage legumes, such as alfalfa, clovers, and vetches, are the best crops for companion planting as they can fix substantial amounts of surplus nitrogen under the right conditions. However, they only add significant nitrogen for the following crop if the entire biomass (stems, leaves, roots) is incorporated into the soil. If a forage is cut and removed from the field, most of the nitrogen fixed by the forage is removed. Roots and crowns add little soil nitrogen compared with the aboveground biomass.
     
  • Grain legumes, such as peanuts, cowpeas, soybeans, and fava beans, are good nitrogen fixers as opposed to common beans.

By Koxae Sun, Shutterstock

While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.


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