Nitrogen Fixation

When you were a young child you probably built things out of blocks. You used blocks of different colours and sizes to create a structure such as a house. Did you know that you are also made of blocks ? The blocks that you (and all living things) are made from are protein, fat and carbohydrate. Your whole body is a mixture of these protein, fat and carbohydrate blocks stacked in millions of different ways.

One of the blocks you are made of is the protein block. Without protein you would not survive. Proteins are used to make up your muscles. They also make all the enzymes that 'push-start' the millions of reactions which take place in your body.

Making protein requires nitrogen. Where do you get it from?

The nitrogen that makes up the proteins in your body was once nitrogen gas in the air that you breathe. Bacteria called rhizobia living inside the roots of plants called legumes, take the nitrogen gas from the air and turn it into ammonia. This process is called "nitrogen fixation". The legume plant then uses this ammonia to make protein. When you eat a legume such as beans, peas or lentils, your body uses the protein in the seeds to make the proteins your body needs.

Or when a cow grazing a legume pasture eats clover plants, it converts the protein in the plant to meat in its body. Then when you have some steak for dinner, your body takes the protein in the meat and turns it into some of your muscle (see below). Either way, whether you eat the legume directly or you eat an animal which has eaten a legume, a little bit of nitrogen that once floated in the air is trapped in the muscles of your body !