Table 11. Liming (a and b) and fertilizatrion (c,d  and e) rates
a. Suggested liming rates in kg/100 m2 CaCO3, for ponds based on pH and soil texture
Soil/mud pH	Heavy loams or clays	Sandy loam	Sand
4	143	72	45
4�4.5	107	54	45
4.6�5.0	90	45	36
5.1�5.5	54	36	18
5.6�6.0	36	18	9
6.1�6.5	18	18	0
Source: Tacon (1988)
b. Suggested liming rates for the treatment of low soil pH
Soil pH	Liming material (kg/100 m2)
	Agricultural lime	Slaked or quick lime	Caustic lime
4	17	16	11
4.5	15	14	10
5	11	10	7
5.5	7	7	5
6	4	3	3
6.5	0	0	0
Source: Tacon (1988)
Note: De Graaf and Janssen (1996) proposed liming rates for Clarias gariepinus nursery ponds that fall within the rates as shown here
c. Options for chemical fertilization rates  (kg/100 m2)
Fertilizer	Option 1	Option 2	Option 3	Option 4
Single super-phosphate	0.6	0.4		0.15
Triple super-phosphate			0.3	0.3
Urea
Ammonium sulphate	0.6	0.3	0.6
NPK�
Interval:	Every 2 weeks	Monthly in 2 equal doses	Every 2�3 weeks	Every 2 weeks
Source: Tacon (1988)
d. Suggested organic/manure fertilization rates (dry kg/100 m2)
Fertilizer	Rates (dry weight manure)
Poultry manure	25 kg initially and then 3�5 kg every 10 d�
	5 kg every 2nd d or 10 kg every 10 d
Pig manure�	7 kg every 2nd d or 14 kg every 10 d
Cow dung	10 kg every 2nd d or 20 kg every 10 d
Source: Tacon (1988)
e. Suggested combination fertilization rates (kg/week/100 m2)
Manure / Fertilizer	Option 1	Option 2
Dry poultry manure	10�20	1
Urea�	0.4�0.8	0.56
Triple super-phosphate	0.1�0.2	0.25
Source: Option 1: Janssen (1985b); Tacon (1988)