Table 7. Average Plant Food Content of Natural and Organic Ferilizer Materials (Percentage on a Dry-Weight Basis.)
Organic Materials	% N	% P	% K	Availability	Acidity
Fish Scrap	5.0	3.0	0	slowly	acid
Fish Meal	10.0	4.0	0	slowly	acid
Guano, Peru	13.0	8.0	2.0	moderately	acid
Guano, Bat	10.0	4.0	2.0	moderately	acid
Sewage Sludge	2.0-6.0	1.0-2.5	0.0-0.4	slowly	acid
Dried Blood	12.0	1.5	0.8	mod. slow	acid
Soybean Meal	7.0	1.2	1.5	slowly	v. sl. acid
Tankage, Animal	9.0	10.0	15.5	slowly	acid
Tankage, Garbage	2.5	1.5	1.5	very slowly	alkaline
Tobacco Stems	1.5	0.5	5.0	slowly	alkaline
Seaweed	1.0	---	4.0-10.0	slowly	---
Bone Meal, Raw	3.5	22.0	---	slowly	alkaline
Castor Pomace	6.0	1.2	0.5	slowly	acid
Wood Ashes	---	2.0	4.0-10.0	quickly	alkaline
Cocoa Shell Meal	2.5	1.0	2.5	slowly	neutral
Cotton Seed Meal	6.0	2.5	1.5	slowly	acid
Ground Rock Phosphate	---	33.0	---	very slowly	alkaline
Green Sand	---	1.0	6.0	very slowly	---
Basic Slag	---	8.0	---	quickly	alkaline
Horn and Hoof Meal	12.0	2.0	---	---	---
Milorganite	6.0	2.5	---	---	---
Peat and Muck	1.5-3.0	0.25-0.5	0.5-.10	very slowly	acid
Spent Mushroom Compost	2.0	.74	1.46	moderately	6.4