Organic Fertilizers Developed

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Organic fertilizers Designing

Organic fertilizers are used to improve soil quality and tilth, and to provide nutrients for plant growth. They provide nitrogen, phosphorus, and potassium, as well as other elements essential for plant development and overall good health.

Nutrient values vary greatly among organic fertilizers. They also vary greatly for a given organic fertilizer. For example, as the table on the following three pages shows, the nitrogen in raw bone meal ranges from 2 to 6%, and the phosphorus from 15 to 27%. Differences reflect variations in the age of organic material, its decomposition rate, application method and timing, incorporation time, time exposed to the elements (rain, sun), the percentages of organic matter and water the material contains, carbon-to-nitrogen ratio, microbe population, and soil type. Values for manures vary according to the time of year, time in the open air, the percentage of added straw, and rate of incorporation. The speed of release shown in the table indicates how quickly nutrients are made available to plants.

Some materials are regulated by Oregon Tilth. To be considered organic, they must result from organic farming methods.

For example, cocoa shell meal and cottonseed meal must not be contaminated with pesticide residues. Raw manure is also regulated; composted manure is not. Wood ashes must not be from treated wood.

Nitrogen, phosphorus, and potassium are represented by N, P, and K in the table headings, to conform to standard commercial practice in labeling fertilizers. Phosphorus is actually present in the form of P2O5, potassium as K2O.

Top Sources of Nitrogen, Phosphorus, and Potassium

  • Nitrogen (N): bat guano; blood/blood meal; crab waste, feather meal; fish meal (dry), hair, hood, horn meal, shrimp waste
  • Phosphorus (P): bat guano; bone meal; crab waste; cucumber skins (burned); hair; mushroom compost; phosphate; shrimp waste
  • Potassium (K): crab waste; cucumber skins (burned), granite (dust); greensand; kaolinite (clay); kelp; sulfate of potash magnesia; wood ashes
Material%N%P%KRelease SpeedEfftivenessComments
Alfalfa2.50.5 2Slow2 to 6 monthsCover crop
Animal Tankage (dry)710 0.5Medium
Bat Guano5.5 to 8 4 to 8.6 1.5Medium to fast
Bat Guano (Peruvian)12.38 to 112.5Medium
Blood (dried)121.50.6Medium to fast
Blood Meal12.51.5 0.6Medium6 to 8 weeks
Bone Meal (raw)2 to 615 to 270Slow to medium6 weeksCan burn plants.
Bone Meal (steamed)0.7 to 718 to 240Slow to medium2 to 4 months
Castor Pomace51.81Slow
Clover, Crimson20.52SLow2 to 6 MonthsCover crop
Cocoa Shell Meal2.512.5Slow
Compost1.5 to 3.50.5 to 11 to 2Slow
Cottonseed Meal (dry)4 to 62.5 to 31.6Slow to Medium4 to 6 monthsAcidic
Crab Meal100.250.05Slow4 to 6 months
Crab Waste30215.5
Cucumber Skins (burned)01127Fast
Eggshells (burned)00.50.3Fast
Feather Meal1500Slow4 to 6 monthsBest if ground up
Fish Emulsion511Fast2 WeeksSpray foliage or apply dilute solution to soil
Fish Meal (dry)104 to 60Medium4 tp 6 months
Fish Scrap (dry)3.5 to 121 to 121 to 1.5SlowBury deep; attracts 4-legged pests.
Granite (dust)003 to 6Very slow 3 to 5+ years
Greensand 01.55Very slow5+ years. Improves water retention
Hair12260Very Slow4 to 12 months
Hoof/Horn Meal9 to 141.5 to 20
Kaolinite (clay) z0012Medium
Kelp10.5 4 to 13Slow4 to 6 monthsContains potassium chloride,
sodium carbonates, sodium
sulfates, potassium sulfates.
Manure (fresh)
Cattle0.5 to 1.50.2 to 0.70.5 to 2Medium2 years
Cattle (dairy)0.5 to 20.3 to 0.50.4 to 1.5Medium2 years
Duck2.60.8 to 1.40
Goat40.61 to 2.8MediumConcentrated; compost first
Goose3.30.40.6MediumConcentrated; compost first
Horse0.7 to 1.50.2 to 0.70.6 to 0.8Medium2 years
Pig04 to 20.5 to 10.5
Pigeon6.3 to
Poultry (75% water)1.510.5
Poultry (50% water)1.5 to 2.01.8 to 21Medium to fast
Poultry (30% water)3 to 42.51.5Medium to fast2 yearsBest when composted.
Poultry (15% water)643Medium to fast2 years
Rabbit3 to 4.81.5 to 2.81 to 1.3Medium
Sheep2.2 to 3.60.3 to 0.60.7 to 1.7Medium
Turkey50.506 to 0.9Medium to Fast
Marl024.5Very Slow
Mushroom Compost05 to 0.840 to 550.5 to 0.8SlowOften has high salt content
Peas, Austrian Winter2 to 301Slow2 to 6 monthsCover top
Peat and Muck1.5 to 30.25 to 0.50.5 to 1Very slow
Phosphate, Colloidal017 to 250Slow3 years
Phosphate, Rock017 to 300Very Slow5+ years
Rye, Annual101Slow2 to 6 monthsCover crop
Sawdust0.10.05 to 0.12 to 4Very Slow2 to 4 yearsCauses nitrogen deficiency.
Seaweed0 to 200.5 to 1FastFoliar spray
Shrimp Shells1.31.00
Shrimp Waste25200
Sodium Nitrate1600Fast
Soybean Meal (dry) to medium
Sulfate of potash magnesia002222% sulfur, 11% magnesium
Urine soaked bedding36 to 4200Fast
Wine Grape Compost1.52.00.5
Wood Ashes053 to 7Fast1 to 4 monthsAlkaline; contains 32% CaCO3.
Fireplace ashes may contain
toxic metals.
Wool Wastes5 to 62t o 41 to 3Very Slow4 to 9 monthsMay mat into layers.
Worm Castings152.51.3