Dried blood is a byproduct from beef processors. As blood is drained from recently killed animals, it is dried and ground into a powder. It is a rich source of nitrogen and supplies certain essential trace elements including iron. The gardener must be careful not to use more than the amount recommended on the label.

Fish emulsion is a partially decomposed blend of finely pulverized fish. The odor is intense, but dissipates within a day or two. Fish emulsion contains up to 5 percent readily available nitrogen and is a source of several trace elements. Contrary to popular belief, too strong a solution of fish emulsion can burn plants, particularly those in containers.

Animal manure is also a complete fertilizer but is low in nutrients. Manures vary in nutrient content according to the animal source and what the animal has been eating. A nutrient ratio of 1-1-1 is typical. The amount of nitrogen in manure varies but is normally around 0.5 percent (poultry litter is higher in nitrogen). This is 1/20 of the nitrogen found in an equal amount of 10-10-10 fertilizer.

Commonly available manures include horse, cow, chicken, and sometimes sheep. The actual nutrient content varies widely: the highest concentration of nutrients is found when manures are fresh. As it is aged, leached, or composted, nutrient content is reduced. However, the subsequent reduction in salts will reduce the chances of burning plants. Fresh manure should not be used where it will contact tender plant roots. Manures are good soil conditioners. Manures should be incorporated into the soil to conserve nitrogen. If left on the soil surface, up to 25 percent of the ammonia nitrogen can be lost within 2 days and 75 percent or more can be lost within 1 month after application.

Sewage sludge is a recycled product of municipal sewage treatment plants. Two forms are commonly available: activated and composted. Activated sludge has a high concentration of nutrients (approximately 6-3-0) and may contain significant amounts of lime. Composted sludge is usually sold in a dry, granular form for use as a general purpose, long lasting, nonburning fertilizer. Composted sludge is used primarily as a soil amendment and has a lower nutrient content (approximately 1-2-0). There is some question about the long term effects of using sewage sludge products in the garden, particularly around edible crops. Heavy metals, such as cadmium, are sometimes present in the sludge and may build up in the soil. Possible negative effects vary, not only with the origin of the sludge, but also with the characteristics of the soil where it is used. It would be desirable to have the sludge analyzed for heavy metals.

Rock phosphate is ground rock that contains as much as 30 percent phosphate. It is not in a readily available form and is released very slowly.

Granite dust contains about 5 percent potassium but little of it is available for plant growth.

Greensand contains 6 percent potassium. It is also available very slowly.

Wood ashes are often used as a soil amendment. They contain potash (potassium), phosphate, boron, and other elements. Wood ashes can be used to raise soil pH; use twice as much wood ash as limestone for the same effect as lime. Ashes should not come into contact with germinating seedlings or plant roots as they may cause root damage. Spread a thin layer during the winter and incorporate into the soil in the spring. Check pH yearly if you use wood ashes. Never use coal ashes or large amounts of wood ash (no more than 20 pounds per 1,000 square feet), as toxicity problems may occur.

Consumer Horticulture | Quick Reference

© Erv Evans, Consumer Horticulturist
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