Flint on Crops: Nitrogen Fixation Can Be Supercharged

    Many miracles occur in nature, more in fact than we will ever know about. However one that we depend upon for a great quantity of our food supply is that of nitrogen fixation in legumes which are more commonly known as the pea and bean family of plants.

    The member of this plant family that is most common in our area is the soybean although other crops like peas and beans that are grown for direct consumption also take advantage of this method of drawing nitrogen from the air.

    The invasive plant called kudzu that grows wild along the highways all over the South also utilizes nitrogen fixation for its nitrogen supply.

    The process of nitrogen fixation involves the relationship between the legume plant and a bacteria that is capable of removing some of the abundant nitrogen from the atmosphere and making it available to the plant. These bacteria form colonies called nodules on the roots of the host plants and go about their work of “fixing” nitrogen which involves converting it from the gaseous form found in air to the nitrate form that is utilized by plants.

    Farmers who grow other crops like corn, cotton, and wheat, as well as forage grasses that require the application of synthetic nitrogen have to purchase the nitrogen needed for these crops and apply it directly to the soil from which these crops draw it for their use in growth and the production of grain, fiber, sugars, and starches that we utilize and that we need to feed the animals that produce our milk, eggs, and meat products.

    A corn crop may require over 200 pounds of nitrogen per acre, and this seems like a lot to the farmer who has to buy it. However an acre of soybeans may require almost double that amount in the development of the crop and the formation of proteins and oils that are the end products of that crop. The farmer does not have to buy this nitrogen because it is drawn directly from the air by these amazing bacteria.

    When we think of this dramatic process that we depend upon so much for our food it quickly becomes apparent that whenever possible we should support it in any way we can. And there are several things that can improve the environment that best suits the growth of healthy soybean plants and this necessary mechanism for providing nitrogen for their use.

    First, all of the soil fertility and moisture needs of the plants have to be met since the presence of a healthy host plant is paramount. All the factors we talk about in soil fertility come to bear on this subject just they do with any crop only with soybeans there is the second consideration for supporting the nitrogen fixing bacteria as well.

    Soil pH is extremely important as well as good supplies of plant nutrients in the correct proportions. Good drainage of the field and the soil immediately surround the roots is a big issue since in order for the bacteria to extract nitrogen from air there must be an abundant supply of fresh air moving into the soil through pores formed by other microorganisms, earthworms, and other soil organisms.

    Aggregation of soil particles is extremely important to prevent the soil from sealing over and preventing the movement of air into the soil profile.

    The beneficial fungi we call mycorrhizae that we have talked about before interact with all these systems to provide nutrients and water. They also help the bacteria find the right places to develop nodules and support them as they go to work making the nitrate that fuels the engine of the growing plant.

    We go about our lives every day without really stopping to think about how all this great world came to be. We look out into the universe on a clear night and wonder at the magnitude of the outer world when under our feet miracles just as great are taking place every second.

    Thanks for your time.

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