Pond bio-matter

I have a small "koi pond" that constantly collects wind blown leaves, twigs, lily pads, water plant material, and anything else that  might fall in. Every few years i drain it to clean out the organic black sludge collected at the bottom.
Can this sludge be used in my garden? I'm guessing its anaerobicly produced, since its been 4ft down in the water, and smells somewhat sulfurous. It would be a shame to just dump it in the adjacent field it i couldn't find a good use for it.
Suggestions please?

Hi Zeo,

I would think it is an excellent soil amendment. But if you are not so sure, maybe it offers an excellent opportunity to experiment?  Maybe plant two plants at the same time, and dress one with pond sludge, and see which does better?  Might be fun!

Pond sludge is great stuff! I've been using it for years. I'll spread it atop my garden soil and till it in. Or I'll use it layered in my compost piles.

The sludge is awesome. Flotsam that collects from day today is also great. Some things, like leaves from trees will need time to break down. Other things like duckweed, azolla and hyacinth, break down very quickly and enrich the soil. Ponds containing fish can become too nutrient-rich. The growth of these plants and their removal, will help lower those nutrient levels.

Many fish can benefit from creation of a shaded spot where they are hidden from predators. A floating net which protects floating plants from being eaten by the fish, will quickly fill to the point where it becomes an effective shade and predator blocker. When the plants become overcrowded either feed them to the fish or use them in the garden. The pond will grow less free floating algae and it will stay a little cooler. That can be a real benefit with koi.

I add it occasionally to compost cages as an additional layer.   I use the pond water to make compost tea.  Of course,  returning the tadpoles back.  I use a pool net to gather the muck and they get caught in every scoop.  It's a rich, under utilized resource.  Never enough hours in the day.

Last year, I made a little temporary pond for my 15 ducks. It had to be cleaned up every 4-5 days, which was messy.
With the help of a transfer pump, I could empty it in about 20 minutes in the evening, after the duckies were asleep and refill it for them to have their fresh water in the morning. It is in an orchard, so the richer water was watering the nearby apple trees. I had a hose handy to flush the last of the rich water while the transfer pump was going.
The best way to not have to deal with sludge is to prevent sludge from forming in the first place. Now, to be fair, I only had 15 ducks and the pons was 10' X 10' and just a tad deeper than a 2X4 placed on its edge. It was deeper because I took advantage of a 6" depression in the center of the pond.
This year, I am building a deeper one about 20'X10' and the depth will be the diameter of a phone pole laying down, so I was happy to hear you say it is still possible to deal with sludge, as I might get some!
I plan to build a low Roman pluvium to collect rainwater automatically and give them shade at the same time. I'll tell you later this year how I came out on it.

We have about an acre-sized pond that has a lot of muck in the bottom.  We also have piles of brush and cut-up dead pines near the pond.  I have been wondering about pumping or using a rake and wheelbarrow to remove the sludge and then covering the brush piles with the sludge in a sort of Huegelkultur fashion.  But really unsure if this is a good idea.  The piles are mostly shaded so it wouldn't create a great growing space.  Just thinking it might speed decomposition of the wood and reduce the fire hazard.  I have also read online that, for ecological reasons, it is better to treat the muck with enzymes than to pump it out.  Has anyone tried using sludge on brush piles?

In our previous residence, we had a garden pond that had to be re-done after a hurricane came through.  The sludge was pumped out into an area of the garden.  I found that plants did not do well when planted directly into the sludge.  My guess is it needed aerating.  

Greta Lee wrote:
In our previous residence, we had a garden pond that had to be re-done after a hurricane came through.  The sludge was pumped out into an area of the garden.  I found that plants did not do well when planted directly into the sludge.  My guess is it needed aerating.  

There is an anaerobic decomposition that occurs at the bottom of a pond, so you are correct, the material needs aerating: the plants would not do well when planted directly in pond muck, which is just organic matter that has fallen apart, after all. Just like horse and chicken manure has to "age" before being used on our plants, I think something similar is at work here, although I'm sure that chemically, it is not for the same reason.  
Or think of it as flour that needs yeast to "work" and rise.
That is probably why we turn the compost pile over once in a while too: aeration]. We just have to get beyond the smell, but exposed to the air it will get a chance of becoming great compost.
There is a product made of beneficial bacteria in tablet forms [A bit like Rid-Ex for your septic tank], where an anaerobic decomp occurs as well. Here is the link. I would be weary of using it around ducks [that could dive to the bottom and eat the tablets before they have a chance to work!], but it seems to be effective at decomposing muck under water.
https://www.thepondguy.com/product/airmax-muckaway/#:~:text=MuckAway%20is%20all%2Dnatural%20and,%2C%20wildlife%2C%20and%20the%20environment.
Of course, companies never say anything negative about their own product, so you have to make the part of that. It seems to be horribly expensive, though, so well beyond my means [plus I do not own a large pond].
Water, because it makes oxidation difficult has preserved logs at the bottom of lakes and oceans for centuries and we can still find boats that sunk long ago whose wood has not deteriorated very much.

Cécile Stelzer Johnson wrote:

Greta Lee wrote:
In our previous residence, we had a garden pond that had to be re-done after a hurricane came through.  The sludge was pumped out into an area of the garden.  I found that plants did not do well when planted directly into the sludge.  My guess is it needed aerating.  

There is an anaerobic decomposition that occurs at the bottom of a pond, so you are correct, the material needs aerating: the plants would not do well when planted directly in pond muck, which is just organic matter that has fallen apart, after all. Just like horse and chicken manure has to "age" before being used on our plants,...

I'm thinking along those lines also. Organic pond sludge is potentially a massive (and stinky) resource,  but I'm sure it will need thoughtful handling and time before it's ready for the garden. I have access to a pond with geese and ducks; maybe I can grab a few specimens of pond goo and see if my compost pile finds it tasty.