Table 17. List of commonly used organic manure and inorganic fertilizers used for milkfish culture and their calcium and NPK content
Type of fertilizers		N:P ratio and Ca and NPK content (%)
Organic manure		N:P ratio	Calcium	Nitrogen	Phosphorus	Potassium
	Poultry manure	2.8		1.2	0.4	0.4
	Cow dung	7		0.5	0.1	0.3
	Pig dung	3.3		0.5	0.2	0.5
	Rice straw compost	5	0	1.2	0.2
	Commercial compost*		0.9	1.3	2.97**	0.8
Inorganic fertilizers		N:P ratio	Calcium	Nitrogen	Phosphorus as P2O5	Potassium
	Urea			46	0	0
	Ammonium sulfate			21	0	0
	Ammonium phosphate	0.9		16	20	0
	Dimmonium phosphate	0.4		18	46	0
*Compose of decomposed rice hull, manure, ash, guano, lime
**as phosphoric acid