How to Use Soybean Seed as a Nitrogen Fertilizer

Sowbeans can be used as a green manure, cover crop or a living mulch which keeps weeds down among other crops.

Nitrogen is one of the three main macro-nutrients that plants require. It is a compound that promotes the healthy development of plant cells and green leafy growth. Every plant needs it in fairly high amounts along with potassium and phosphorus. These are the base nutrients listed on fertilizer packaging as the NPK (nitrogen, phosphorus and potassium) ratio. Legumes are known to be nitrogen fixers. This means that they take nitrogen from the air and then when composted they yield nitrogen that is absorbed into the soil. Cover crops are often legumes because of this feature. The nitrogen is leached out of the soil by growing plants and is replaced by the legume organic matter.

Things You'll Need

• Tiller
• Rake
• Soy beans
• Compost
• Water
• Hoe

Instructions

1. Prepare the bed that will be sown. Spring after the last expected frost date is the optimal time to plant soybeans. Till the soil to break up clods and incorporate clay and hard soils. Churn up the earth at least 8 inches below the surface. Soybeans will increase the tilth of the soil, but first they need to have plenty of oxygen already captured in the soil and enough room for their roots to grow.

2. Rake the bed smooth and remove any roots or rocks. Plant the soybeans immediately not days later or competing weeds will have shown up. Sow the soybeans on the surface of the soil and then pass over the area with the rake to give them some contact with the dirt. Strew the seed thickly for maximum coverage. Cover the entire crop with 1 1/2 to 2 inches of compost.

3. Water the bed until 2 inches of the soil feels damp. You can simply stick a finger in the soil to check. Keep the bed evenly moist until germination. When the seedlings are all up, reduce watering.Stick your index finger into the soil and water when the soil feels dry up to the second knuckle. You will see the seedlings in five to ten days.

4. Allow the crop to grow until it has the first bean pods. This means the roots have had time to produce nodules. The nodules are where the nitrogen concentrates and will disperse it to the soil in the decomposition process. If you wanted a green manure you would till the soybeans in before the pods formed to add balanced nutrition and texture to soil.

5. Pull the plants up and allow them to dry on the surface of the soil for two weeks. Then till the plants into the ground. You may need to use a hoe to chop them up better. As the plants decompose the nitrogen in the roots becomes available for other plants. Plant a cover crop annually in areas like vegetable gardens which can become depleted of nitrogen.

References

• University of Minnesota: Green Manure Cover Crops for Minnesota
• National Sustainable Agriculture Information Service: Overview of Cover Crops and Green Manures
• Washington State University Extension: Plant and Manage Cover Crops for Maximum Weed Suppression
• National Soybean Research Laboratory: Planting, Growing and Harvesting Soybeans
• Texas Gardener: Soybeans- An Edible Cover Crop You Can Plant Now.