Using poultry manure for fertilizer has many pros and a few cons. Poultry manure has more of the three components needed in a fertilizer — nitrogen, phosphorus, and potassium — than does manure from other animals. Using manure rather than commercial fertilizers may have environmental benefits and may be less expensive, especially if poultry manure is readily available for collecting. Using poultry manure is more labor intensive than buying a commercial fertilizer. There may also be some chance of contaminating vegetables with manure if the proper processes aren’t followed and if produce isn’t thoroughly washed before it is eaten.
One of the pros of using poultry manure for fertilizer is also the cause of one of the cons. Poultry manure contains large amounts of nitrogen, which plants need to grow. The level of nitrogen in poultry manure is so high, however, that the manure must go through a process before it can be applied to plants. If fresh poultry manure is applied directly to plants, the nitrogen content is so high that poultry manure can burn the plants and even kill them. This means using poultry manure as fertilizer is much more labor intensive than using a commercial fertilizer or even some other types of animal manure for fertilizer.
The nitrogen content means that poultry manure must go through a composting or aging process before it is applied to plants. This process brings nitrogen levels to a point that plants can use it without causing the plants harm. In the composting process, the poultry bedding, including the manure, is put into a composting bin for six to 12 months. It must be watered and turned periodically during this time. Once the composting process has been completed, the compost is spread over the garden, and a natural fertilizer is in place to help plants thrive.
The composted poultry manure for fertilizer will likely increase carbon in the soil, may help to reduce soil erosion, and can reduce nitrate leaching from the soil. Nitrates are necessary for plants to grow. Nitrate leaching refers to the nitrates in soil being removed from plants as water moves through the roots.
The risks of contaminating produce by using poultry manure as fertilizer are low, especially if the manure is composted. To further reduce this risk, poultry manure for fertilizer should be applied to plants at least two months before harvesting the food for consumption. It is also important that foods grown with manure fertilizer be thoroughly washed before serving.