How Does Nitrogen Fertilize a Plant?

Importance

• Plants need nitrogen to grow. Nitrogen is an essential component of protein, which is the main building block of cells and tissue. Also, plants need the nitrogen in the chlorophyll in their leaves to perform the important metabolic process photosynthesis. Lastly, nitrogen in the plant's roots enables the plant to absorb water and other nutrients from the soil. Without nitrogen to build cells, absorb water and perform photosynthesis, beautiful green plants turn yellow, stop growing and can even die.

Absorption

• The air we breathe is made up of 78 percent nitrogen. Only a few types of plants, such as legumes, can absorb nitrogen from the air. Most plants must absorb the nutrient from the soil, taking it up through their roots. Even plants in nitrogen-rich soil may show signs of nitrogen deficiency because the nitrogen in the soil is in a form the plants cannot absorb. Organic material such as manure and compost add plenty of nitrogen to the soil, but only a little is available to the plants immediately. More plant-ready nitrogen is slowly released into the soil as the manure and compost continue to decompose over the years.

Too Much and Too Little

• Nitrogen deficiencies affect foliage density and crop yields. Too much nitrogen fertilizer causes problems for plants, and too little applied too soon burns the root systems of young, developing plants. Over-fertilizing, especially before a heavy rain, contaminates local water supplies as the fertilizer hasn't absorbed into the soil and been picked up by the plants, causing the excess to run off into local water supplies.

Application

• Before applying nitrogen fertilizers, test the soil and check how much nitrogen the plants need. Different species have different nutrient needs. Check the weather, and never apply fertilizers before a heavy rain. Although most synthetic fertilizers need moisture to release plant-ready nitrogen into the soil, a light watering is sufficient.