As the weather gets warmer, the question of whether to fertilize ponds or not is common.
Fertilizer provides nutrients for any plant life inside the pond and for any algae that is growing. This is not necessarily always good. Fertilization will also grow the planktonic population that will then serve as the beginning of the food chain for smaller fish that will eventually grow into larger fish or be eaten by larger fish.
The clarity of the water is going to serve as a major indicator of whether a pond needs to be fertilized. Utilize a Secchi disk to determine the need of fertilization depending on the depth at which one can see the disk. The disk can also notify if there are too many nutrients that will rob the water of oxygen and potentially cause a fish kill or restrict sunlight that can cause oxygen depletion. Also, consider how much water is draining out of the pond. If a considerable amount of water is draining then it is possible that whatever fertilizer is applied will just end up downstream. Unlike soil, there is not a lab analysis that can indicate if or how much fertilizer is necessary for a pond. The Extension office does test water hardness in-office to determine lime needs, but that does not give an indication of the pond’s fertility. Therefore, the Secchi disk and/ or water clarity may be the best indicators.
Improper fertilization can have severe negative impacts on a pond’s ecosystem. If ar pond does require fertilization then applications should be made monthly between March and October. Applying fertilizer once per year is not the best practice. It is better to not fertilize at all than to make one application because inconsistent fertilization will disrupt the forage base for bass and bream due to inconsistency. With soil, the levels of nitrogen or potassium is usually the major concern, but with ponds the emphasis is on phosphorus. The Extension office has information on which formulation of fertilizer should be used and how much per application.
Lastly, consider what the goal of the pond is. Fertilizing will increase the carrying capacity for the pond which will bring about bigger fish, but the desire for a healthy pond may not need fertilization.
For any questions about pond fertilization or other aspects of pond management call 478-4454394 or email brennan4@uga.edu.