Soybeans obtain nitrogen primarily through the process of N fixation.
The Unique Way Soybeans Get Nitrogen
Unlike many other common crops grown in North America, such as corn and wheat, soybeans possess a special ability to acquire nitrogen from the environment. They don't rely solely on nitrogen present in the soil or applied as fertilizer.
Nitrogen Fixation: The Soybean's Secret
The key to the soybean's nitrogen supply is a process called nitrogen fixation (N fixation). This is an intricate biological partnership between the soybean plant and specific types of soil bacteria.
- The Partnership: This remarkable relationship occurs in nodules that form on the roots of the soybean plant.
- The Bacteria: The main bacterial partner for soybeans is a particular species known as Bradyrhizobium japonicum.
- The Process: Inside the root nodules, the Bradyrhizobium japonicum bacteria convert nitrogen gas (N₂), which is abundant in the atmosphere but unusable by plants, into a form of nitrogen that the soybean plant can readily absorb and use for growth.
This natural process provides a significant amount of the nitrogen needed by the soybean plant, reducing the need for external nitrogen fertilizer application compared to non-leguminous crops.
