Cat manure contains roughly 2.5 times the nitrogen cattle manure contains. However, cat waste also contains the intestinal parasitic disease toxoplasmosis, which is transmissible to humans. Because of the high risk of transmission, the veterinarian and soil experts at the University of Minnesota advise against using cat waste as a fertilizer. However, if carefully handled, cat feces can be sterilized through the composting process and safely used in home gardens.
Avoid handling cat waste, even with garden gloves, if possible. Use a small shovel, disposable plastic bag, or other implement to pick it up.
Add the cat waste to the center of a freshly turned compost pile.
Insert a compost thermometer into the pile. The cat manure will be sterilized when the temperature of the compost heap exceeds 165 degrees Fahrenheit for 5 days.
Turn and add to your compost pile as usual once the cat feces is sterilized. The humus is ready for use when it is dark brown and crumbly like rich garden soil. The amount of time that this will take largely depends on the size of your compost pile and its contents.