Pond Assistance

Do not fertilize if your pond exhibits any of the following conditions:

• The pond has muddy water.
• There are any species other than bluegill, redear, channel catfish, or largemouth bass in the pond. (These fish would be crappie, bullheads, green sunfish or pond perch, gizzard shad, carp, or gar.)
• There is an undesirable amount of green algae or other aquatic plants in the pond.
• The pond has crowded or stunted bream populations (most of them will be 3-5" in length).
• Catfish are the only fish in the pond.
• There is excessive water flow. (The fertilizer will be diluted and not produce the desired result.)
• The pond is only fished by a few families or individuals, and/or most fish are released.
• Swimming and skiing are frequent pond activities.
• You want to use fertilization to kill aquatic plants. (This is a myth.)
• You intend to fertilize only once or twice a year or not fertilize every year.
• You don't fish enough or don't want to harvest 20-40 pounds of largemouth bass per acre per year under 14 inches long.
• You don't intend to do a soil test every other year to determine if your pond needs lime.
• You don't intend to apply or have your farm cooperative store deliver and spread 1-3 tons of agricultural limestone ($30-50/ton) per pond surface acre every 3-4 years.
• You don't intend or cannot afford to apply 4-12 pounds per acre of 0-46-0 granular fertilizer on a fertilizer platform or 1/2 - 1 gallon of liquid fertilizer or 2-8 pounds of powdered fertilizer every 3-5 weeks from March through September each year in your pond.

In all areas of Mississippi except the Delta and Loess Bluff (east of the Delta to the Hill region), the soils are acidic. Acidic soils will bind or hold the phosphorus contained in the fertilizer you apply, and it will not be dissolved into the water column, where it is needed by the tiny plants (phytoplankton) in your pond that are at the base of the food chain. So if your soil needs lime and you fertilize, the fertilizer will not work, and you will be wasting your money.

Methods of Testing Your Soil/Pond

The most accurate method is to have a soil sample tested. Call your county cooperative extension service office and ask them to mail you a soil test kit (a box and a form). Take several soil samples from the pond bottom or along the shoreline of your pond--the more samples the better. Mix all the samples together and let the soil dry out. Check "fish pond" in the "crop grown" section of the form and send it off after filling the box with soil from your pond. The results will be sent back to you indicating how many tons of agricultural limestone you should apply. You really can't overlime a pond.

A less accurate way to determine your lime requirement is to locate your pond location on the soil-type map located on page 28 of the publication Managing Mississippi Ponds and Small Lakes. Liming rates range from zero in the Delta to 3 tons per acre in the Lower Coastal Plain along the Gulf Coast.

Another way of determining your lime requirement is to test your water for its alkalinity. Alkalinity test kits are inexpensive and easy to use. If your alkalinity is 20 or less, apply 2 tons of lime per surface acre. Waters with alkalinity less than 15 are in desperate need of lime. Waters with alkalinity between 20-30 will have a good response to fertilizer applications. The most you can increase your water's alkalinity is to 35-40 with proper lime application.

Applying Lime

Call your county farm cooperative store or garden supply store and determine if they will deliver and spread the amount of lime you need. Lime is cheap, but the transportation of it is not. Expect to pay between $40-60 per ton. All limestone sold in Mississippi must have a Relative Neutralizing Value (RNV) of at least 63 percent. The higher the RNV number, the better the lime in terms of purity and fineness of the grind in terms of particle size. Lime with a high RNV value dissolves quickly and changes the soil pH faster, so it is worth the money paid for it. Never use liquid lime, quick lime, hydrated lime, or other more potent liming agents. If the pH of the water is raised too quickly, you will kill your fish.

Lime should be added in the fall and winter so that it has enough time to react with the soil before you begin fertilizing in March or April. Ideally, limestone should be applied directly to the pond surface. If access is good around a pond, this is not a problem. If the spreader trucks can't get to the pond edge or on the levee, have them apply the lime on land adjacent to the pond where it will wash into the water. If the lime supplier has a minimum quantity you have to purchase that exceeds your lime requirement, don't worry--overliming will not hurt your pond. All it will do is prolong the time before the next lime application is needed.

Applying Fertilizer

Fertilization should begin in the spring when the water temperatures are 60F or higher. This usually means about March 15th in south Mississippi and April 1 in central and north Mississippi. Fertilization rates depend upon your soil type. Again, find your pond location on the Mississippi soil-type map located on page 28 of the publication Managing Mississippi Ponds and Small Lakes. Rates depend on the type of fertilizer you select to use. Fertilizers are sold containing different levels of nitrogen, phosphorus, and potassium. The product will have a number on it like "10-52-4", meaning it contains 10% nitrogen, 52% phosphorus, and 4% potassium. Freshwater ponds do not normally need more nitrogen. Phosphorus is the limiting nutrient.

Three types of fertilizer are recommended for Mississippi farm ponds:

• Liquid fertilizers, which must be stirred or shaken before application, with rates ranging from 1/2 to 1 gallon per acre per application. Dilute them with 2 parts water to 1 part fertilizer prior to application.
• Granular 0-46-0 (Triple Phosphate) fertilizer is the cheapest type, but it must placed on a platform to keep it off the bottom so it can slowly dissolve. If you throw 0-46-0 directly out into your pond, you are wasting two-thirds of it. 0-46-0 application rates range from 4-12 pounds per acre per application.
• Powdered fertilizers (10-52-4) will totally dissolve before they reach the bottom if thrown in water at least 2 feet deep. They are the easiest to use but will cost more than granular fertilizers. Powdered fertilizer rates range from 2-8 pounds per acre per application.

If you have a new pond that has been limed, and you use the recommended rate of 0-46-0 for your location but don't get a plankton bloom (greenish water color), use 20-20-5 at 40 pounds per acre for the first few applications until you get a plankton bloom, then switch to one of the 3 recommended types at the appropriate application rates. Older ponds should respond well to the recommended fertilizer formulations (0-46-0 or 10-52-4). The first three fertilizer applications can be made at least every 2 weeks, or you can wait to fertilize until your water visibility indicates that you need to.

Using a Secchi Disc

You can easily check your water clarity by purchasing or making a Secchi disc. This is a round plate about 8 inches in diameter. An end of a #10 can works well, as does a piece of plywood. Divide the disc into 4 equal sections. Paint 2 of the sections black and 2 white. The colors should alternate so that the same colors should not touch each other. Drill a hole through the center of the disc. Run an eyebolt through the hole and attach some washers or weights to the eyebolt on the underside of the disc to help it sink. Attach a section of rope 4 feet or longer that has been marked at 6, 12, 18, 24, and 30 inches through the top of the eye bolt.

To check your water clarity, slowly lower the disc into the pond until you can no longer see a difference between the colored sections. Then raise it until you can first see the different colored sections of the disc. Mark the surface of the water on the rope by grabbing it at that location. Measure the distance from the surface of the water to the disc. If the distance is 18 inches or more, it's time to fertilize. If the distance is less than 18 inches, wait a week and check it again.

Important:

• Don't fertilize until your water clarity is more than 18-24 inches.
• Don't apply more fertilizer than the recommended rate per acre.
• Don't fertilize in an attempt to kill aquatic plants or algae.

Fertilization can be used to limit the depth to which sunlight penetrates in your pond, which may help you limit the establishment of aquatic plants. If sunlight cannot reach the bottom of your pond, then plants can't get established.

If undesirable amounts of aquatic plants develop, stop fertilizing until you treat those aquatic plants to reduce their coverage.

Don't fertilize ponds in Mississippi from October to the end of February.

This section contains resources for aquatic plant identification and methods of control (biological, chemical, and physical means). Prior to attempting any control measure, it is very important that you identify the plants in your pond that you want to treat. The Southeastern Aquatic Plants: Identification, control and management book published by the Mississippi State University (MSU) Extension Service provides this information.  This publication was funded by the Aquatic Nuisance Species Program of the U.S. Fish and Wildlife Service, Grant Award F18AP00260 and the Mississippi Department of Environmental Quality. Additional funding and support was provided by the MSU Extension Service.

The Texas A&M University AquaPlant site is another resource for identifying plants. Various means of control are discussed, and there are links to chemical product labels.

Remember that all the chemicals listed on the sites linked in the previous section are safe and approved for aquatic use when applied according to the product label directions. Fish kills resulting from aquatic plant chemical control applications are due to a lack of oxygen--not the chemical applied. Low oxygen levels result from the breakdown and decay that occurs once the plants are killed.

To avoid low oxygen levels in ponds with excessive amounts of plants, never treat more than 1/4 to 1/3 of the plants at a time. Treat an area of plants, wait 10-14 days, then treat the next section of plants. Remember that several treatments will usually be necessary to kill the plants. Treatments are most effective when plants are treated early in the growing season, when they are actively growing and before they have produced seeds.