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NPK Values of Manures & Compost Etc

Different fertilisers will provide different percentages of various nutrients so the quantity added will depend on the content. For example, if you want to add 10g of nitrogen per square metre you would need to add 83g of dried blood (12% nitrogen) or 50g of sulphate of ammonia (20% nitrogen) but if you wanted to supply that nitrogen from cow manure you would need 1,660g at its average 0.6% supply.

Of course, your cow manure will supply valuable humus that the fertilisers will not.

NPK Values of Common Farmyard Manures

Let's take a look at the N-P-K values of the most common farmyard manures. These are pretty variable according to the diet the animals have had, how long it has been rotted for etc but it gives a reasonable idea.

NPK Values of Animal Manures
	N Nitrogen %	P Phosphorus %	K Potassium (Potash) %
Cow Manure	0.6	0.4	0.5
Horse Manure	0.7	0.3	0.6
Pig Manure	0.8	0.7	0.5
Chicken Manure	1.1	0.8	0.5
Sheep Manure	0.7	0.3	0.9
Rabbit Manure	2.4	1.4	0.6

More information on farmyard manures

NPK Value of Home Made Compost

Your own home made compost has NPK values quite similar to those of animal manure:

NPK Value of Home Made Compost
	N Nitrogen %	P Phosphorus %	K Potassium (Potash) %
Average Home Made Compost	0.5	0.27	0.81

Having covered manures and compost, the next thing to look at is a fertiliser you make yourself, comfrey tea. Following the recipe of 6 Kg (14lbs) of wilted comfrey in 90 litres (20 gallons) of water in a barrel, produces a liquid feed with these values:

NPK Values of Comfrey Liquid Fertiliser
	N Nitrogen %	P Phosphorus %	K Potassium (Potash) %
Comfrey Liquid	0.014	0.0059	0.0340

Although the percentage NPK values are relatively low in comparison with manures, being in liquid form, nutrients are immediately available to the plants.

More information on growing comfrey and comfrey tea or liquid fertiliser

In organic systems there is qualified acceptance of using 'natural' fertilisers to supplement nutrient levels achieved by composts and manures. These are

NPK Levels in Natural Fertilisers
	N Nitrogen %	P Phosphorus %	K Potassium (Potash) %
Bloodmeal	12	0	0
Bonemeal	3.5	18	0
Hoof and Horn	12	0	0
Fish, Blood & Bone	6	6	6
Chicken Manure Pellets	4	2.5	2.3

Unlike artificial fertilisers, the 'natural' fertilisers tend to dissolve slowly and thereby release their nutrients more slowly. More information on natural fertilisers.

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