Chicken manure is the primary fertilizer used in aquaculture, the farming of fish and plants. Chickens are typically confined and eat commercial-grade feed; their manure is higher in nutrient content than manure from grass-fed cows and horses, making it ideal for application in aquaculture practices, especially fish and shellfish farming.
Using Organic Fertilizers in Aquaculture
Like other organic fertilizers, chicken manure decomposes into nitrogen, phosphorous and potassium, which in turn feeds algae and phytoplankton. Fish then feed upon the phytoplankton and algae; in some cases, the fertilizer may contribute directly to the nutrition of the fish.
Chicken manure fertilization of fish-farming ponds offers excellent opportunities for sustainable, cyclical agricultural practices. Farmers who own chicken coops as well as aquaculture ponds can reap great benefits from using chicken manure fertilizer to feed fish and plants.
How to Apply Fertilizer
Some fish farmers build chicken coops over fish ponds; manure and uneaten chicken feed can then be washed into the pond. Pens may also be built with flooring that allows waste to fall or be swept directly into the pond.
Chicken manure can also be purchased, or removed from coops built elsewhere and used to irrigate the pond. Recommended application of chicken manure fertilizer is six to eight times per week per hundred square meters of pond (assuming 10 to 15 chickens are producing manure).
The first application should be made two weeks prior to stocking the pond with fish or crop plants; this will increase the food supply prior to their arrival, especially if the pond was previously unfertilized. Maintain a fertilization schedule -- regular amounts should be applied at regular intervals. If fish eat the fertilizer directly, consider daily application of smaller doses (as opposed to weekly application). If fertilizing daily, apply the manure mid-morning to stave off oxygenation problems.
Problems and Considerations
As chicken manure and other organic fertilizers degrade, they consume oxygen from water. Fish in oxygen-depleted water will come to the surface to gulp air. If signs of oxygen depletion are observed, immediately suspend fertilization and add fresh water to the pond to revive the fish. You may also drain water from the bottom of the pond, where the oxygen levels are lowest.
Note that low-oxygen problems tend to occur at night when phytoplankton are not producing oxygen. Keeping track of the phytoplankton can help farmers prevent oxygen depletion; Secchi disks give readings of how many phytoplankton populate a particular sample of water; readings of 20 cm or below indicate that the number of phytoplankton is too high and oxygen depletion has begun.