Animal-Based Fertilizers for Organic Gardens
Animals, fish, and birds all provide organic fertilizers that can help plants grow. Animal-based fertilizers contain nitrogen, phosphorous, and potassium ¯ the primary nutrients plants need to grow. They each play a critical role in plant growth and development.
If your soil is deficient or if you're growing vegetables, fruits, or other demanding crops, you may want to supplement the soil's nutrients with these animal-based fertilizers:
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Manures: Animal manures provide lots of organic matter to the soil, but most have low nutrient value. A few, such as chicken manure, do have high available nitrogen content. In general, use only composted manures, because fresh manures can burn tender roots.
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Bat/seabird guano: Yes, this product is what it sounds like ¯ the poop of bats and seabirds. Guano comes in powdered or pellet form and is high in nitrogen (10 to 12 percent).
Bat guano provides only about 2 percent phosphorous and no potassium, but seabird guano contains 10 to 12 percent P, plus 2 percent K. The concentrated nitrogen in these products can burn roots if they're not used carefully.
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Blood meal: Blood meal is the powdered blood of slaughtered animals. It contains about 14 percent nitrogen and many micronutrients. Leafy, nitrogen-loving plants such as lettuce grow well with this fertilizer. Reportedly, blood meal also repels deer (but may attract dogs and cats).
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Bonemeal: A popular source of phosphorous (11 percent) and calcium (22 percent), bonemeal is derived from animal or fish bones and is commonly used in powdered form on root crops and bulbs. It also contains 2 percent nitrogen and many micronutrients. It may attract rodents.
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Fish products: Fish by-products make excellent fertilizers, and you can buy them in several forms:
Fish emulsion is derived from the fermented remains of fish. This liquid product can have a fishy smell (even the deodorized version), but it's a great complete fertilizer (5-2-2) and adds trace elements to the soil. When mixed with water, it's gentle yet effective for stimulating the growth of young seedlings.
Hydrolyzed fish powder has higher nitrogen content (12 percent) than fish emulsion; it's mixed with water and sprayed on plants.
Fish meal, which is high in nitrogen and phosphorus, is applied to the soil.
Other animal-based organic fertilizers include crab meal, dried whey, earthworm castings, feather meal, and leather meal.
Using composted human waste (euphemistically called night soil) to fertilize gardens has been a common practice in countries such as China for generations. In many Western countries, our version of this practice is using composted sewage sludge as fertilizer. Modern sewage treatment plants, however, receive waste from many sources, including industries. Although sludge has fertilizer and soil-building value, sewage sludge is not generally considered to be an organic fertilizer, because it may contain toxic heavy metals that accumulate in the soil. Although you can buy granular fertilizers made from sludge, organic gardeners generally avoid them.
Gardening Glossary
annuals
Plants that complete their entire life cycle within one growing season. The plant germinates from seed, grows and blooms, and then produces seed and dies.
Gardening Glossary
biennials
A plant that take two growing seasons to complete its life cycle. It germinates and grows leaves and stems in the first year; produces flowers and fruit (seed) in the second, and then dies.
Gardening Glossary
bolt
When a plant flowers or produces seed prematurely.
Gardening Glossary
cold frame
A wooden or concrete block box in which you can grow plants or hold dormant during the cold winter months.
Gardening Glossary
cole crops
A family of vegetables, including broccoli, cabbage, cauliflower, kale, and Brussels sprouts. They thrive in cooler weather.
Gardening Glossary
complete fertilizer
Any fertilizer that contains all three of the primary nutrients, N-P-K (nitrogen, phosphorus, potassium). Phrase is based on regulations governing the fertilizer industry. Does not mean that the fertilizer literally contains everything a plant needs to thrive.
Gardening Glossary
deadheading
The practice of pinching or cutting off spent flowers
Gardening Glossary
evaporative-pad humidifier
A humidifier in which fans blow across a moisture-laden pad that sits in a reservoir of water.
Gardening Glossary
harden off
The process of acclimating plants grown indoors gradually to the brighter light and cooler temperatures of the outside world.
Gardening Glossary
hardiness
The ability of a plant to survive is called its hardiness.
Gardening Glossary
humus
A stable end product of organic-matter decomposition that's believed to increase microbial activity in soil, improve soil structure, and enhance the root development of plants.
Gardening Glossary
Bacillus thuringiensis Bt
An effective bacteria that attacks only the larvae of caterpillar family insects. It is safe to other insects, animals, and humans.
Gardening Glossary
macronutrients
Mineral nutrients that plants need in the largest quantities: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.
Gardening Glossary
mulch
Organic or inorganic material placed over the surface of soil, usually directly over the root zone of growing plants. Used to conserve moisture, kill weed seedlings, modify soil temperature, provide attractive covering to garden beds.
Gardening Glossary
organic matter
Once-living stuff like compost, sawdust, animal manure, ground bark, grass clippings, and leaf mold (composted tree leaves). Used to enrich soil and improve soil texture.
Gardening Glossary
perennials
Any plant with a life cycle of three or more years. Herbaceous (non-woody) perennials include flowering plants and herbs, mainly. Woody perennials include trees and shrubs. Longevity depends on the plant and growing conditions.
Gardening Glossary
pH
The measure of soil's acidity. Soil with low pH means it's too acidic; soil with high pH means it's alkaline. Most plants grow best in soil with a pH value between 6.5 and 7.2. Neutral soils measure 7.
Gardening Glossary
photosynthesis
The process through which plants take nutrients from the air and from the water in the soil to produce sugars that fuels the plant's growth.
Gardening Glossary
primary nutrients
Nitrogen, phosphorous, and potassium are the three nutrients plants need in the largest quantities.
Gardening Glossary
root crops
Plants with edible underground roots such as onions, carrots, beets, potatoes, turnips. Most root crops are cold-weather crops.
Gardening Glossary
self-blanching
A type of cauliflower with leaves that naturally curl over the head and exclude light. Requires cool temperatures for leaves to curl effectively.
Gardening Glossary
sets
Small onion bulbs, about 1/2-inch wide, that were started from seed the previous year. Grow onion sets with the pointy end up.
Gardening Glossary
side-dressing
The act of adding a small amount of fertilizer around or "on the side" of plants after they're growing.
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succession planting
Planting small, 2-to-4-foot patches of plants every two weeks throughout the growing season so that you can harvest a crop over an extended period of time.
Gardening Glossary
thinning
The act of cutting the least robust seedlings in your garden to give the healthier plants more room to grow.
Gardening Glossary
vining crops
Crops that grow on vines, such as cucumbers, melons, pumpkins, and winter squash. They usually require support (staking, trellising, etc.) to keep them off the ground.
