Nutrient Value of Organic Matter
Fertilizer selection, whether for organic fertilizers or chemical fertilizers, should be done judiciously. You should try to know the nutrient content of the organic fertilizers before purchasing them. Like chemical fertilizers, organic fertilizers also have N-P-K (nitrogen potassium and phosphorus) value.
The NPK value for organic fertilizers depends on the organic matter used for preparing them. Organic matter such as dried blood and fish meal are rich in nitrogen. Fish meal is also rich in phosphorus. Kelp, on the other hand is rich in potassium. The ability of the different types of organic matter to release nutrients is also not same. Hence availability of nutrients is also an important criterion in selecting the type of organic fertilizer.
The Cornell Cooperative Extension and The Utah State University Extension have provided the nutrient value of different organic matters, in their guides Fertilizing Garden Soils and Selecting and Using Organic Fertilizers respectively. Some of these values are tabulated below:
|
Organic Matter |
% Nitrogen |
% Phosphorus |
% Potassium |
Availability of Nutrients |
|
Alfa Alfa Hay |
2-3 |
0.5-1 |
1-2 |
Medium |
|
Bone Meal |
1 |
11 |
0 |
Slow |
|
Cottonseed Meal |
6 |
3 |
1 |
Slow |
|
Compost |
1.5 |
0.5 |
1 |
Slow |
|
Dried Blood |
12 |
1.5 |
0.5 |
Rapid |
|
Feather Meal |
12 |
0 |
0 |
Medium |
|
Fish Meal |
10 |
4 |
0 |
Slow |
|
Grass Clippings |
1-2 |
0-0.5 |
1-2 |
Medium |
|
Horn Meal |
12-14 |
1.5-2 |
0 |
Medium |
|
Kelp |
1 |
0.5 |
9 |
Rapid |
|
Leaves |
1 |
0-0.5 |
0-0.5 |
Slow |
|
Legumes |
2-4 |
0-0.5 |
2-3 |
Medium |
|
Cow Manure |
0.25 |
0.15 |
0.25 |
Medium |
|
Horse Manure |
0.3 |
0.15 |
0.5 |
Medium |
|
Sheep Manure |
0.6 |
0.33 |
0.75 |
Medium |
|
Swine Manure |
0.3 |
0.3 |
0.3 |
Medium |
|
Pine Needles Manure |
0.5 |
0 |
1 |
Slow |
|
Poultry Manure |
2 |
2 |
1 |
Rapid |
|
Saw Dust Manure |
0-1 |
0-0.5 |
0-1 |
Slow |
|
Sewage Manure |
2-6 |
1-4 |
0-1 |
Moderate |
|
Seaweed Manure |
1 |
2 |
5 |
Rapid |
|
Straw Manure |
0-0.5 |
0-0.5 |
1 |
Slow |
|
Wood Ashes |
0 |
1-2 |
3-7 |
Rapid |
