Manure naturally fertilises vegetable plants, increasing their growth and yield. When used incorrectly, manure can transmit diseases to the plants, which will infect you when you eat the vegetables. Chicken manure is the best type of manure to use when growing vegetables, both to reduce the risk of disease and to promote plant growth.
Raw Versus Composted
Manure can be applied to a vegetable garden in both raw and composted forms. Composted manure should be used when possible, because it reduces the risk of transmitting diseases. If you use raw manure, apply the manure to the soil early in the growing process. This will allow the manure to mix with the soil, and decrease the chance of passing diseases to plants. If you are growing vegetables which touch the ground, apply raw manure at least four months before harvest. For vegetables which do not touch the ground, you can wait until three months before harvest. Allow as much time as you can for the manure to mix with the soil. The best time to add the manure is immediately after your previous harvest.
Composted manure has a lower risk of disease, and can be used close to harvest time. The manure should be completely composted before you use it, which could take up to one year.
Regardless of the type of manure you use, you should wash the vegetables before eating them. Vegetables grown in raw manure should be cooked to further reduce the risk of disease, but vegetables grown in composted manure can be eaten raw.
Pig, dog and cat manure are the types of manure most likely to pass diseases onto vegetables. These should not be used as raw or composted manure. Cow manure and chicken manure are both less likely to transmit diseases to vegetables. Composted chicken manure is the best type of manure to use for growing vegetables, because it has a very low risk of passing disease and it contains more nutrients which help vegetables grow than most manure.
Chicken manure should always be composted, because in its raw form it contains high levels of nitrogen which can kill plants. This nitrogen level lowers during composting. Composting chicken manure can take as little as half a year, or as long as one year. You can compost the bedding from a chicken coup with the manure.
Although composted chicken manure is normally safe to use, you must still avoid using manure from sick chickens. This manure is much more likely to carry parasites and diseases, which will not always die during the composting process.