What Is the Difference Between Nitrogen and Organic Fertilizer?
- Along with phosphorus and potassium, nitrogen is one of the three macronutrients soil needs to support healthy plants. Nitrogen helps plants achieve optimal growth and develop healthy stems and leaves, according to the University of Florida's Institute of Foods and Agricultural Sciences. Plants growing in nitrogen-depleted soil may exhibit this deficiency with yellow leaves, poor yield or slower-than-average growth. Backyard soils often have a deficiency in at least one of the three major elements, so homeowners provide fertilizer for lawns, trees, shrubs, vegetable patches and flower gardens. Bagged chemical fertilizer is often labeled with a series of three numbers, such as 10-10-10 or 10-20-5. The first number always refers to the amount of nitrogen in the mix in relation to the phosphorus, the second number, and potassium, the third number.
- Organic fertilizer and "nitrogen" are not synonymous, because fertilizer might provide more of the other macronutrients or trace elements than nitrogen. Bone meal and rock phosphate contribute phosphorus, for example, while green sand and granite meal add potassium. Additionally, nitrogen fertilizer is available in both organic and non-organic versions, so specifying "nitrogen" as your garden fertilizer of choice won't guarantee that you'll be using organic nitrogen.
- Manure remains a popular choice as an organic fertilizer. Nurseries offer bagged cow and other aged animal wastes. You may also choose to add aged manure from local sources of cow, chicken, rabbit or horse droppings. The manure should be at least six months old to ensure the absence of harmful bacteria such as e. coli. Other organic nitrogen sources include cottonseed meal, blood meal, coffee grounds, fish meal, soybean meal and liquid fish emulsion. Corn gluten mix is both an organic nitrogen fertilizer and an organic herbicide. Some organic gardeners and farmers also plan ahead by planting "green manure," also known as cover crops that provide nitrogen when they are tilled into the soil. Red clover is an example of a cover crop organic growers plant at least several weeks before the main growing season, then plow under so that the decomposing crop organically releases nitrogen into the soil.
- Gardeners use organic nitrogen fertilizer to enrich new gardens, establish plants or seeds and as mid-season fertilizers. Bagged manure, corn gluten mix and organic nutrient mixtures will generally tell you how much to add per square foot of garden soil or lawn, as well as how much to use around individual trees or shrubs. Liquid nitrogen fertilizers make better choices for feeding plants rather than enriching soil. Follow the directions on the bottle to determine how much water to add to the concentrated substance to meet your plants' nitrogen needs. Rodale's "Ultimate Encyclopedia of Organic Gardening" warns that corn gluten mix kills seedlings as they emerge, so it makes a poor choice for freshly seeded lawns or gardens. Use it at the recommended rates around existing plantings to enrich soil and keep weed seeds from sprouting.
