You are here

Fertilizing Farm Ponds: What You Need to Know

Filed Under:
March 25, 2019

Announcer: Farm and Family is a production of the Mississippi State University Extension Service.

Amy Myers: Today we're talking about Fertilizing Farm Ponds: What You Need to Know. Hello, I'm Amy Taylor Myers, and welcome to Farm and Family. Today we're speaking with Wes Neal, associate extension professor for the Department of Wildlife, Fisheries, and Aquaculture and fisheries extension specialist.

So, Wes, why should someone want to fertilize a fish pond?

Wes Neal: Well, Amy, it's much like your garden. If you add fertilizer to it, it tends to grow bigger and better whatever. In this case, you can grow more fish in a pond via fertilization.

Amy Myers: Should all of our listeners be fertilizing their ponds?

Wes Neal: That's the catch-22. The reality is most people shouldn't fertilize their ponds because I always tell people to build their pond right, stock their pond right, and fish their pond right. And usually people fail on the fishing their pond right, because they don't take enough fish out. When you fertilize a pond, you're actually increasing the amount of fish you need to remove from the pond, and most people can't remove enough fish. It also can bring a lot of other problems we'll discuss in a minute.

Amy Myers: Okay. Now for those that want to fertilize their ponds, what do they need to know?

Wes Neal: Well first of all, they need to know that they are taking a little bit more of a risk by fertilizing because it will increase the risk of water quality problems and potentially fish kills down the road, but if they really are dead set on doing it, the reason why they would want to do it would be because either they're managing for trophy bass, in which case fertilizing the pond will help them reach that goal. Or if they have incredibly high fishing pressure, such as a community fishing lake where there's a lot of fishing pressure and harvest, they may want to fertilize.

But the first two things they should do is have their pond water tested for alkalinity and hardness. Alkalinity will determine how well the phosphorous and the fertilizer is utilized, and hardness will tell them how much fertilizer they need to add to the water.

Amy Myers: How should fertilization be performed?

Wes Neal: Well, fertilization's not as easy as it sounds. Some people think they can just dump the fertilizer in the water, and that's certainly not what you want to do. First of all, fertilization, once you start it, it's something you need to continue indefinitely. You can't stop. It's like feeding your chickens too much. You get more chickens, and then if you stop feeding them as much, they're going to starve. The same thing's going to happen in your pond, so once you start it, you need to continue it.

Usually we tell people to start fertilizing as soon as water temperatures reach about 60 degrees Fahrenheit, and fertilize throughout the year until they go below that temperature. When you put out the fertilizer, you need to make sure it doesn't come into contact with the bottom, because the bottom sediment will tie up the fertilizer and make it useless for the pond. And you need to follow a schedule.

Basically, we tend to fertilize ponds every two to four weeks once we get a bloom going, a bloom being an algal when the pond turns green, and we use the water clarity to determine when to fertilize. Basically, you want bloom to be about 18 inches of visibility, so if you stick your hand in the water and you see your fingertips barely when your elbow's at the water surface, then that's about 18 inches for most people. That's okay, but once you can see your fingertips really well and it's gotten too clear, it's time to fertilize again.

But you need to follow that schedule, and you can't stop it. You have to continue with it until the water temperatures go down and start it up again next year.

Amy Myers: Now how exactly should we know when we do need to fertilize?

Wes Neal: Well, we usually start the fertilization in late February to mid-March when the water temperatures exceed 60 degrees, and once you get a bloom going, what you'll do is you'll use the visibility of the water. So you can do something as simple as taking a yardstick and putting a white board on the end of it and measuring the depth at which you can see it, or you can stick your hand in the water, like I said before. But really, your goal is to have about 18 inches of visibility. If you have more than 24 inches of visibility, it's time to fertilize again.

Amy Myers: So if your pond is too clear, then it needs fertilizing?

Wes Neal: If you're choosing to fertilize, yes. We want to make sure you do it consistently.

Amy Myers: How do we get a pond sample to the right person who can test it?

Wes Neal: To test alkalinity and hardness, you can take it to your local county extension agent. They can test the alkalinity, generally. You can also send it to me. I would test the alkalinity. You can send it to the state chem lab. You could even run it by a local pool and spa store.

Hardness is a little bit more of a challenge to measure. You can also take a soil sample from the bottom of the pond and send that to the extension soil lab, and they can test it and tell you what's necessary.

Amy Myers: Okay, and all of that can be found here at Mississippi State Extension Service here at the Bost Building on campus.

Wes Neal: Yes.

Amy Myers: Okay, and there's a really good MSU Extension publication for folks. Where can they find that?

Wes Neal: Well, it's called Managing Mississippi Ponds and Small Lakes: A Landowner's Guide. You can go by your local county extension office and request a copy, or you can go online to, and then you'll find it there.

Amy Myers: Today we've been speaking with Wes Neal, professor for the Department of Wildlife, Fisheries, and Aquaculture. I'm Amy Taylor Myers, and this has been Farm and Family. Have a great day.

Announcer: Farm and Family is a production of the Mississippi State University Extension Service.

Department: Wildlife, Fisheries & Aquaculture

Select Your County Office