Nitrogen is an important component of soil, but it can be depleted through water runoff, erosion, crop removal and other processes. Water movement always takes some nitrogen with it, and it’s impossible to stop all nitrogen loss, but you can take steps to prevent too much nitrogen loss and to attempt to put some back into the soil. Nitrogen is produced by plants, animals and other natural processes, so there are several ways of organically replenishing the nitrogen supply in your soil. Natural fertilizers such as manure and compost are environmentally friendly and nutrient-rich.
While natural processes can remove nitrogen from the soil, other natural processes can increase it. Nitrogen from the atmosphere can be taken in from some plants such as legumes, but not by others. This is because symbiotic bacteria live on the roots of these plants and convert the nitrogen from the air to a type that is usable by the plant. For other plants, precipitation can help put more nitrogen in the soil. Rain and thunderstorms can also decrease the amount of nitrogen in the soil if it is highly erodible.
One of the best ways to increase nitrogen in the soil organically is through the use of manure fertilizers. These are rich in nitrogen, although the exact amount varies depending on the type of livestock and what it was fed. You may want to get an analysis of the manure so you can determine the amount of nitrogen content as well as the amounts you should use and how often.
Another organic method of replenishing soil's nitrogen is to use crop residue. Nitrogen is in the crop residue, but it must decay in order to become usable by the new plants. Plants can use only inorganic nitrogen. Inorganic nitrogen is formed from organic nitrogen by chemical processes. This can be accomplished by composting your dead plant matter. Legumes are particularly rich in nitrates and are an important source of nitrates in organic fertilizers. Composting takes time, but the end product can be full of nitrogen and other nutrients to replenish your soil. Starting a compost pile can add many other nutrients to the soil as well, and it is a useful and environmentally friendly method to fertilize your crops with the waste material from your other crops.
Nitrogen Loss Prevention
You also can try to prevent some nitrogen loss by minimizing erosion. Loose soil washes away and loses nitrogen more easily, which is another reason that crop removal encourages nitrogen loss. The roots of plants and other barriers to soil movement can help keep soil from eroding. Some plants also encourage less nitrogen loss, such as soybeans and peanuts. These can be planted in the area, or waste materials from them can be used in compost to add to your soil.