You can return nitrogen to the soil without using fertilizer by planting clover in your lawn and beans in your garden. These plants naturally bring nitrogen back into the soil, making it available to nitrogen-hungry plants and grasses.
If you want to avoid using commercial fertilizers, natural solutions such as compost, grass clippings, and fallen leaves make excellent natural fertilizers that add nitrogen to the soil as they break down. Some so-called nitrogen boosters, such as coffee grounds, fish emulsion, manure, and eggshells should not be added to the soil unless they have been composted first.
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5 Ways to Add Nitrogen to Soil Without Fertilizer
Nitrogen is essential for keeping plants green and growing. Without nitrogen, plants will yellow, wither, and die. It’s an essential nutrient for the production of chlorophyll, as well as fuel for the DNA replication needed for plant cell division and continued life. There’s no way around it: your lawn and garden need nitrogen.
If you want to learn how to add nitrogen to soil without fertilizer, the following methods are perfect for you.
Seed Your Lawn with a Clover Mix
Clover naturally adds nitrogen to the soil and boosts green color and growth. This is because nitrogen collects in clover roots as it grows. When clover dies back in fall, or when it is mowed, the dead roots release nitrogen into the soil, feeding the grass growing there.
- Nitrogen collects in clover roots.
- When clover dies in fall or is mowed, this nitrogen enters the soil.
- Planting your lawn with this grass and clover seed mix naturally adds nitrogen to the soil and drastically reduces your lawn’s fertilizer needs.
Although clover has long been considered a pest weed, it can actually be highly beneficial. A lawn where clover and grass thrive together maintains a natural nitrogen balance that allows you to have nitrogen-rich soil without fertilizer.
Plant Legumes in Your Garden
Beans, peas, peanuts, and soybeans are all part of the legume family, along with clover. Much like clover, other legumes also collect nitrogen in their roots and release it into the soil. By planting your garden with these varieties, you can get a vegetable crop and increase your soil’s nitrogen content without purchasing any fertilizer.
- Vegetables in the legume family (green beans, peas, soybeans) introduce nitrogen back into the soil.
- Plant legumes among your herbs and vegetables to maintain nitrogen levels without fertilizer.
There are also some herbs and flowers, such as licorice and vetch, that serve as nitrogen-fixing plants. By mixing nitrogen fixers with nitrogen-hungry plants, you can create a natural, sustainable garden with little to no fertilizer needs.
Rather than shop for chemical fertilizers, use manure compost in your garden to boost nitrogen levels. Manure compost combines animal manure with plant material and other ingredients (coffee grounds, eggshells, etc.) to create a natural fertilizer.
- Mix manure compost into garden soil for a natural nitrogen boost.
- Do not simply spread compost on top of your garden or lawn—exposure to sunlight evaporates the uric acid that provides the nitrogen in compost
- Never use uncomposted manure. It can carry dangerous bacteria and weed seeds.
True compost is created when manure and other ingredients are piled and turned. The decomposition process then generates heat, which destroys E. coli bacteria and weed seeds. Either purchase compost from a reputable dealer or make your own compost at home. Using fresh manure is harmful and won’t provide nitrogen to your crops.
There’s a use for the grass clippings you create when you mow. Those grass blades contain nitrogen and other nutrients. Either allow grass clippings to fall back onto the lawn to feed the soil, or bag and spread them on your garden as a natural fertilizer.
- Grass blades contain nitrogen—it is the nutrient that gives them their green color.
- Grass clippings decompose quickly when left on the lawn or spread in the garden.
- By leaving grass clippings on the lawn to decompose, a high percentage of the nitrogen the grass used to grow returns to the soil.
Think of grass clippings as nitrogen storage units. As they break down over the course of 3–4 weeks, the nitrogen they took from the soil is returned back to where it came from, fueling your lawn all over again. If you bag and trash grass clippings, you’re throwing away nitrogen and increasing the need to fertilize your lawn.
Much like grass blades, leaves contain nitrogen pulled from the soil. Additionally, mulched and shredded leaves decompose quickly, providing a natural nitrogen boost to the soil. To get the most out of fallen leaves:
- Mow over fallen leaves. Perform multiple passes if necessary, until the leaves are cut into quarter-sized pieces.
- Do not allow fallen or mulched leaves to pile in drifts. They will smother grass and plants.
- Spread mulched leaves evenly through your yard, or use a leaf blower to blow them into your garden as natural mulch.
- As the leaves decompose over 1–2 months, they will return nitrogen to the soil.
Bagging, burning, or trashing leaves prevents the nitrogen stored in them from returning to the soil. Properly mulched leaves decompose in just a few months and provide a natural nitrogen boost. If you mulch leaves in the fall, they will decompose by spring, which will feed your lawn and garden.
Natural Nitrogen Sources to Avoid
Some sources tout additional natural sources of nitrogen, but beware. Natural nitrogen fertilizer still must come from safe and usable sources. Using the wrong source will not combat nitrogen deficiency. Instead, you may introduce dangerous bacteria to the soil or damage your plants.
Coffee grounds are often claimed as a natural way to increase levels of nitrogen in soil. However, this is only true if the grounds are properly composted with other ingredients. Whole coffee grounds dumped on plants or grass are extremely acidic. The increased acid can actually prevent plants from absorbing nutrients, including nitrogen. If you want to use coffee grounds as fuel, compost them first.
Fish emulsion is a byproduct of fish oil and fish factory processes. This means that in many cases it is not a sustainable, eco-friendly fertilizer. Additionally, it has very low nutritive value compared to other natural fertilizers. Because it has such low nitrogen levels, fish emulsion is not a powerful enough solution to correct nitrogen deficiency on its own.
While it’s true that urine contains nitrogen, the collection, handling, and distribution of urine is not sanitary or safe. It is a waste product that contains salt, uric acid, and other compounds that are detrimental to plants. It is not advised to use urine as a nitrogen source for your lawn, trees, or garden.
Much like urine, manure is waste material. Whether it’s cow, horse, or sheep manure, in its uncomposted form it may contain dangerous E. coli bacteria that can make walking in your garden or eating any food grown there dangerous. For the same reason, pet waste from your yard should not be used as a fertilizer.
When added to compost and allowed to break down, manure can be beneficial. If it has not been composted, it won’t add much nitrogen to your soil or provide a boost to your plants.
How Can You Add Nitrogen to Your Soil Naturally?
The best way to add nitrogen to your soil without fertilizer is by planting varieties that naturally perform nitrogen fixation. Clover in your yard and legumes in your garden will pull nitrogen into the soil for other plants and grasses to feed on. Other natural nitrogen sources include composted manure, grass clippings, and shredded leaves. All of these are natural alternatives to chemical fertilizers and are organic, sustainable, and guaranteed to boost nitrogen levels in your soil.