Pond Boss Forums MANAGING AN EXISTING POND Fertilization fertilizing an existing pond

This is a 12 acre lake that has been actively managed every year in south Mississippi. . Biologist surveys once a year, and has recommended a fertilization program after surveying in feb/march. When the pond was built, the owner trucked in lime and tested soil before it was filled. I would guess the lake is 14 years old.

I have been attempting to manage it over the past 3 years. The first year, I fertilized end of march, April, and by May the lake was green, and visibility was around 14 inches so I stopped fertilizing. During June and July, the bloom became significant to the point I did not like it, so I did not fertilize the rest of the year. The bloom did not subside until late October.

By the following February, the lake had cleared and biologist again recommended fertilizing through October. I explained the heavy bloom, and he said ferlize march and April, and if it is heavy then resume in September and October. It went to pea green soup in June and July, and I thought no need to fertile in September/October because it was still thick and green water.

This march, after the survey, biologist recommended again fertilizing every month. For the first time, he came in May with a load of crawfish and said he could see a little bloom, but thought fertilizing was necessary.

I am very hesitant to fertilize because of what the water looks like in June/July/August. It's 8-12 inches visibility on the sechi disk and very green. I don't like it, and I have wanted to fertilze less in march and April with hopes that the water in June/July/august does not appear so thick.

The lake has 5 bream feeders spread around it, and an excellent population of bream.

Is my theory correct to reduce ferliztion in late march and April in hopes of not having too much of a bloom in the summer - or are the 2 unrelated? I would like to get to a point I can fertilize in sept/oct to help with winter months. I have bream fry in February, and I want them to have the right water conditions. I know that sounds crazy, but I have been in the boat with him shocking and bream fry come up everywhere in February.

Currently, the lake is a bit stained in color due to the abnormal rain. I think the runoff in the lake would prevent the fertilizer from working properly at this point, but I am no expert.

I share your concern, and I also agree that your water is carrying too much bloom when the secchi falls below 18". Inorganic fertilization is practically immediately available and can quickly ramp up to more bloom than desired. Once there, it will take time to dissipate as the nutrients are recycled as organisms eat the phytoplankton and discharge wastes. As those organisms are consumed, then the fish recycle nutrients in their waste. So it ramps up faster than it ramps downs.

I see you are feeding. Feeding rates in excess of 5 lbs/acre-day will also sustain heavy blooms and there is absolutely no reason to fertilize, if you are feeding fish at per acre rates like that.

There is one thing I would like to mention. Metabolism is driven by temperature. Even phytoplankton have metabolism and they reproduce and grow slower in cooler water. In terms of your native nutrients that remobilize each year in a cycle. Temperature plays a big role there to. The warmer the water gets, the more organisms responsible for nutrient cycling return nutrients to the water column. In the cooler months, the slowing of this activity will cause a corresponding decline in bloom. This isn't a problem ... at least in my way of thinking. In cooler water, the fish need less consumption and do in fact consume less. Its a cycle where water should be clearer in winter and ramp its bloom as temperatures and metabolic activity increases for all of the pond's life (whether phytoplankton, zooplankton, insects or fish). This is a natural annual cycle.

Your biologist is making a judgment if February or March that is influenced by a cycle that is only beginning to ramp up at that time. Maybe, don't bring him out next year in March. Maybe, bring him out in May or June and see if he says to cut back on fertilizer?

One last thing. Sechi depth is not the only measure of productivity. Sometimes water is more productive than the secchi depth would otherwise suggest. Common reasons for this are vibrant periphyton communities and/or abundance of phytoplankton grazers.

What are the main goals for this lake?

Is it LMB catch rates, trophy LMB, BG catch rates, trophy BG, etc.?

How is the pond performing relative to the goals?

For example, the bass spawn should be over by the time kids are out of school in Mississippi. If they can only catch low numbers of bass during the peak summer fishing season due to low visibility, then the pond is failing (if that is the goal).

Add some more info, and you should get some more feedback.

It is trophy largemouth. Your post prompted another question. Does a heavy summertime bloom affect your ability to catch fish - as in will the fish bite less with the bloom on the water?

My fear is if I fertlize it now - even though it looks like it needs it, will I be doing harm as to what will happen in the end of June, July, and August based on my past experience.

Any ideas?

Jbass,

Heavy blooms can limit fish activity if DO is in the margins. That is counter-productive to growth because there will be less consumption under such a condition. I have seen a study on strike radius for SMB in turbid water. It is reduced by turbidity. Success per predatory strike was not affected by turbidity (evidently SMB will not launch a predatory strike unless the there is a good chance of success). So when visual reach is reduced, the chances per unit time are lower than when water is clearer. If reduced visual reach is a consequence of bloom, it is at least to some degree offset by higher prey density. But for fishing? I could see it making an impact ... just don't know what that would be for sure. Sometimes, ultra clear water is difficult to fish, so it is probably a balance.

Two of life's biggest mistakes are thinking "it will be different this time" and "ignoring your gut". Ultimately, you are captain of the ship (your wonderful lake) and are the only one who will accept responsibility if something goes wrong. Also, it would be you paying the price not only for the cause of what went wrong but also paying the consequences of it. Not just the loss of population structure but all the costs of remedy.

Use your best judgment and follow your gut is the best advice I can give you and the only advice that I will.

That said, I will share my philosophy and what my goals will be for my pond(s).

Water is a beautiful and I wouldn't want to be at war with it. A new pond is usually very nutrient poor and it may have water parameters that are not conducive to native nutrient mobilization and uptake. A new pond really needs assistance so that it can support a good biomass of fish. It needs good water parameters, it needs a combination of fertilization and feed (even only one or the other).

With fertilization only, a pond is going to be limited to around 500 to 600 lbs of an LMB/BG combination. If one has other fish that feed lower on the food chain than BG, then this weight can be higher. If one's feeds the BG, then combined LMB/BG weight can exceed the weight that fertilization alone would support.

A bloom is self-shading, so I understand that there is a limit to the amount of food that can be generated by fertilization alone. My particular goal for support of an LMB/BG biomass? About 1/2 to 2/3 of that. If nature itself can only achieve 500 to 600 lbs at the limits of fertility ... then I would personally want to have some room for natural eutrophication to bring the pond to that limiting hyper-eutrophic condition (over many years) and I would not want to hurry that along. In fact, if I could, I would try to remove nutrients to slow down eutrophication once the native nutrients could support the goaled standing weight.

This is a very conservative philosophy and it isn't shared by many here. Most are trying to get every little bit they can from their water and some are trying to get much more than that (more than water could support by fertilization and self-shaded blooms alone). I am not being critical of this approach of pushing water past its natural limits. Just from your description, I know that your water supports more LMB/BG than what nature could support with a self-shading bloom. This may be goal, and if it is, then you are doing what you should be doing to achieve that goal.

On the other hand, if you are doing all these things for a different goal, then I would question the wisdom of keeping the water at this trophic level. For example, let's say all you want to do is grow some fish into the 8 to 10 lb range. You can do that with much less expense and risk by managing the population to balance that goal with the current status of native nutrients.

One thing I know, if I were to push my water into hyper-eutrophic condition. It's all on me, the expense of it, the risk of it, the cost of remediation of it. The only one with no risk and all the profit is the one selling me on the idea of pushing my water hard. Something goes wrong? A profit opportunity that wouldn't have otherwise been there for the person selling me on the idea of pushing my water hard. It's always going to be on me, the cost and the risk and it will always benefit the person making the sales (unless I give up). So your advisor really needs to be worthy of your trust, especially when he profits if you fail.

Back to the only advice I am giving you. Follow your gut and use your best judgment.

Get the dirt and water tested. You need facts not opinions from people who have never seen your lake. The only expert that has seen your lake and who should (assume has) tested the water first has made a recommendation. I have worked with a number of lakes in the same area for years with similar results and issues. One thing to keep in mind is that fertilization is not an all or nothing event. If it needs nutrients then cut the total application rate by 60-75 %. Just because you can't see and quantify (by visual) the effects does not mean they aren't there. You may be way over fertilizing. Consider much lower application rates more often - a little at a time and then wait and watch.

See the archive on fertilization.
https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=96127#Post96127