How to Increase Nitrogen in Soil

Loosen the top 8 to 10 inches of soil in your planting site. Rake up any uprooted weeds, vegetative debris, soil clumps and rocks. Remove these items from your planting site.

Plant a legume crop the year before using the planting site for flower beds, garden vegetables or lawns. Broadcast legume seeds, such as clover, vetch or alfalfa, over the planting site. Cover with a fine layer of soil that equals about twice the depth of the seed's diameter. Keep the soil slightly moist as the seeds germinate and grow. Depending on your climate and soil type, you may need to give mature legume crops about 1 inch of water every week to 10 days. Till the legume crop under the soil in the late fall.

Ready your planting site in the springtime, after the ground begins to warm. Loosen the soil with a garden tiller. Rake up any uprooted plants.

Spread a 2-inch layer of organic compost over the surface of the tilled and raked soil. Work this into the loosened topsoil with a garden tiller or a hoe, creating a smooth, even planting medium. Plant your grass seed, vegetables, flowering plants or shrubs into the prepared soil, according to each variety's individual planting instructions.

Mulch the area around perennial plants, shrubs and trees with a 2-inch layer of sterile compost. Do this every spring to maintain a healthy level of nitrogen in the existing soil. Plants that exhibit rapid rates of growth may also require supplemental fertilization using a plant food formulated for your specific variety of plants.

Apply a nitrogen fertilizer with of a 3:1:2 ratio of nitrogen, phosphorus and potassium on your lawn grass three or four times each year during the growing season. Use a time-release, granulated fertilizer to keep your grass plants green and help them ward off weed infestations. Apply the fertilizer on a calm, dry day, according to the manufacturer's directions.