Organic Fertilizer Options

What counts as an organic fertilizer?

The term covers materials from plant, animal or mineral sources with little processing: compost, manure, plant meals, animal by-products, cover crops and natural mineral materials. Each supplies different nutrients in different amounts.

If you farm under an organic certification or sell as organic, check which inputs your program permits before you buy anything.

Be clear about what organic means for you. Gardening with natural inputs at home has no certification requirement, while selling products labeled organic is governed by a national program with its own rules on inputs and records. Ask your extension office or the USDA Agricultural Marketing Service which applies to you before you buy.

How do compost and manure compare?

Compost is stable, easy to handle and builds soil structure, but it is usually modest in nutrients. Manure can supply more nutrients, with big differences by animal, bedding and age. Fresh manure can burn plants and may carry harmful bacteria.

Food safety rules about the time between applying manure and harvesting produce are specific, so ask your extension office and the USDA for current guidance for your crops.

Plant-based and animal-based meals, bone and feather products and similar materials supply nutrients in different ratios. Check labels for the guaranteed analysis and source. Because release depends on soil warmth and moisture, a product that works in a warm spring may seem slow in a cold one.

• Use composted, not fresh, manure on food beds.
• Ask where bedding or hay came from, since herbicide residue can persist.
• Wash all produce well before eating.

What about cover crops and green manure?

Cover crops add organic matter and, with legumes, can add nitrogen to the system. They also protect soil and suppress weeds. They take planning, since you need to grow, manage and turn them under at a suitable stage.

Timing depends on your frost dates and soil temperature. Your extension office can suggest species for your region.

Plan the cover crop into your rotation so it does not take space from a food crop. A quick summer cover between crops, or a winter cover after harvest, fits many small farms. Ending the cover crop at the right stage matters, so ask your extension office when to turn it under in your area.

How fast do organic sources release nutrients?

Release depends on warmth, moisture and soil life. In cold, dry soil, release is slow. In warm, moist soil it speeds up. Part of the nutrients become available in the first season, and the rest over several years.

This means you cannot match a bag of organic material to a crop need as exactly as with a quick source. A soil test and some patience help you adjust.

Keep track of how plants respond. Pale growth early in a cold spring does not always mean a deficiency, since soil may simply be too cool for release. Compare with your soil test and wait for warmth before adding more.

How do I pick and apply them?

Begin with a soil test and decide which nutrient is actually short. Pick a material whose profile fits and apply it before planting where you can, so nutrients are available when plants need them. Keep it off frozen, saturated and sloping ground.

Follow the label on any bagged product, because the label is the law, and do not exceed what the soil test supports. Too much of even an organic source can cause nutrient imbalance and water pollution.

Store organic materials well. Bagged meals can attract rodents, pets and wildlife, and wet piles can smell and leach. Keep them in sealed containers in a dry place, and use manure and compost piles that sit on a firm surface away from water and neighbors.

What costs and sources should I consider?

Cost categories include the material itself, delivery, equipment for spreading and your labor. Local sources such as a neighbor's stable or a municipal compost site can be low in cost, but quality varies, so ask what went into the material.

Compare options by nutrients delivered, not by weight alone, and keep notes on what worked.

How do I build a simple organic fertility plan?

Start with a soil test and a list of what each bed will grow. Choose a base of compost or cover crops for general fertility, then add a targeted source only for the nutrients the test shows are short. Write the plan as a short table by bed and season.

Review it every year. Compare your records with soil tests and plant performance, drop what did not help and keep what did. A plan built this way stays affordable and is easy to explain to a certifier or buyer if you ever need to.

Last reviewed: November 12, 2026. Written by the Homestead & Small Farm Editorial Team. See our editorial policy.