Fertilizing lakes and ponds will increase fish production two to threefold and is an extremely valuable component of a highly productive lake management program. Infertile ponds will seldom produce more than 50 to 100 pounds of fish per acre, but fertilized lakes are different. Well-managed, fertile ponds can maintain up to 300 to 400 pounds of fish per acre!
If, however, the pond is naturally fertile and is not going to receive much fishing pressure, it may not require fertilizer. If the pond receives only minor harvest pressure, do not fertilize or fertilize at only half the recommended rate. There is no need to produce fish mass if it is not going to be removed.
Once fertilization is started it should always be continued. If fertilization is stopped, the fish in the lake will become stunted because of the reduced food supply. Not only does a lack of phytoplankton and zooplankton lead to a declining food supply, but all this makes fish more susceptible to disease. Although lake fertilization can be very beneficial, if the lake manager does it improperly, the result could be an extreme algae bloom, low dissolved oxygen, and a pond full of dead fish.
Not all fertilizers work well in lakes and ponds. Phosphorus is the nutrient most needed in lakes and ponds. Given time, phosphorus will be absorbed and trapped in the mud of the pond through chemical processes. Once trapped, however, it is not available to planktonic algae but can promote the growth of weeds and filamentous algae.
Nitrogen is seldom needed in older ponds because it develops naturally, but occasionally new lakes and ponds need nitrogen. Once a lake is established nitrogen usually is abundant and will not require further attention or input.
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