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From Zooplankton to Your Bass: Pond Fertilization Made Simple for GameKeepers

Don C. Keller | Originally published in GameKeepers: Farming for Wildlife Magazine. To subscribe, click here.

zooplanktonMany existing lakes and ponds containing both bass and bluegill may benefit significantly from a few basic and cost-effective management techniques. A little knowledge coupled with some common sense will turn your lake into a great place to fish. One of the most important and economical management techniques to improve the fishing in your lake is pond fertilization. I will explain why this is important, what types of fertilizer to use, and how pond fertilizer works to improve your fishing. 

Pond Fertilization 

Applying proper pond fertilizer to a lake has the same effect as fertilizing your garden, your lawn or agricultural crops; it increases your production. In fact, research into ponds has proven that pounds of fish produced may be increased 300 percent or more by proper fertilization. Clear, infertile ponds and lakes may have a total carrying capacity (total pounds of all species and sizes of fish) of less than 50 pounds per acre. Well-fertilized lakes may produce 250 pounds or more of total fish per acre, providing many more opportunities for catching quality-size fish. How does this happen? Pond fertilizer increases the small, green, single-cell plants called phytoplankton (this is what gives your pond a green tint). Tiny insects called zooplankton eat phytoplankton. These little insects are eaten by larger insects, which are then eaten by bluegill. The bluegill are eaten by bass and BAM! You have a great fishing hole. The more food you produce from fertilization, the more fish you can grow. It is a simple and cost-effective way to boost the growth and numbers of bluegill and bass in a lake. As with fertilizing your garden or an agricultural crop, soil pH can play an important part in determining how effectively the fertilization program works. In many soil types throughout the southeast, agricultural limestone should be applied to lakes to neutralize acidic pond bottoms and make the fertilizer produce more food. Have the total alkalinity of your water tested to see if your lake requires liming.

pond algae
Fertilizer does not kill aquatic weeds or algae. Do
not fertilize if significant weed growth is present.
Adding pond fertilizer to aquatic weeds is like
adding gasoline to a fire. Treat weeds with an
herbicide and fertilize as the weeds begin to

Types of Fertilizers 

There are several types of pond fertilizers. Granular fertilizers were developed for ponds during the early 1950s and the standard 40-pound bag of 20-20-5 (N-P-K) is still used by many pond owners. Granular fertilizer should never be broadcast or poured from a boat because the phosphorus can become chemically bound by the bottom mud and will not dissolve. Granular fertilizer should be placed on a platform about 18 inches below the pond surface. It would take 200 pounds of granular fertilizer for a five-acre pond. 

Liquid fertilizers, such as the green 10-34-0, have been used with good success. This fertilizer is much heavier than water (13 pounds per gallon) and must be mixed with water before being applied to the pond, otherwise it will layer on the bottom. Although effective, it is very messy and usually requires mixing one gallon of fertilizer with four gallons of water. Once mixed, it can be poured from a boat or broadcast from the bank. A five-acre pond would require five gallons of liquid fertilizer (65 pounds) plus 20 gallons of water (160 pounds). 

That means you would have to handle 225 pounds of material. There is a new type of concentrated, totally-dissolvable powder or crystalline fertilizer which requires no mixing, no platforms and only recommends five pounds per acre to apply. Pond fertilization could not be easier. Formulations vary from 10-52-4 to 12-48-8 and one of them, BioLogic’s Perfect Pond Plus (12-48-8), contains a micronutrient package beneficial for many crops. This fertilizer, which has the consistency of powdered sugar, can be broadcast from the bank or a pier or may be poured from the side of a boat. A five-acre pond requires only 25 pounds as compared to 200 pounds of granular or 65 pounds of liquid, plus 20 gallons of water (160 pounds). With the new powdered fertilizer, a five-acre pond could be fertilized from a single location if applied with a breeze at your back. This fertilizer dissolves in the upper two feet of the pond and can be distributed throughout the pond by wind currents. Most ponds require applications during March through October. Fertilize when the water visibility is greater than 18 to 24 inches. Do not fertilize if the water visibility is less than 18 inches as the pond may develop a heavy and potentially dangerous plankton bloom. 

pond fertilizer
With powdered fertilizer, a five-acre pond could be fertilized
from a single location if applied with a breeze at your back.

Aquatic Weeds
Do not fertilize your lake or pond if there is a significant population of aquatic weeds or algae. Why is it important to control these plants? Because they can reduce the nutrients used for producing phytoplankton (the basis of the food chain for your fish) and they increase your risks of an oxygen-related fish kill. A clear, weedy or slime-infested pond is not productive, is difficult to fish, and cannot be properly fertilized. Fertilizing aquatic weeds or algae makes them grow more rapidly. Weeds have to be controlled before an effective pond fertilization program can be initiated. 

Fishing can be enjoyable for the entire family, especially in well-fertilized ponds. Even small ponds of an acre or two can produce plenty of harvestable fish for your family and friends. Don’t be afraid to keep bluegill and bass to eat. Harvest is an important part of any management plan. In most fertilized ponds and lakes, bass harvest should be 15 to 25 pounds per acre per year. More than 75 percent of lakes today have too many small bass because there has been an inadequate harvest. Bass harvest should be selective. Remove the size bass that is most abundant. For the average lake in the southeast, bass 14 inches and under should be harvested. Bluegill should also be harvested; however, the old adage that you can’t catch too many bluegill is not true. Allow you and your friends to take the bluegill you want to eat, but do not harvest more than 50 pounds per acre if you want to continue to catch big bluegill. Managing your lake is not complicated or expensive. Put a little effort into improving your lake and utilize that wonderful resource you have on your property. For specialty fisheries, such as trophy bass or trophy bluegill, consult a professional fisheries biologist.

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