Organic nitrogens (from proteins and amino acids) do not tend to be immediately available to plants and must be first broken down by bacteria into ammonium, and then nitrate. Distribution of this nitrogen is spread out over a period of time. Popular organic nitrogen sources include blood meal (12-0-0), alfalfa meal (2-1-2), and compost (3-1-2).
Phosphorus can be obtained naturally from organic composts or bone meal, although crushed rock phosphate is often considered an acceptable organic alternative.
Organic sources of potassium (also known as potash) include powdered kelp (1-0-4) compost (3-1-2), and greensand (0-0-3).
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