Duck pond water NPK test

I'm still a newbie when it comes to ducks but I started hearing quite a bit about how great the old pond water is for plants. I started out as a pepper guy and wanted to see what I was working with before I applied it to my plants. I got some odd results with a soil test from a big box store.

Zero trace of nitrogen and low/med levels of phosphorus and potassium.

I took the sample from a 50 gallon pond that hadn't been drained in ~5 days. Made sure to stir up the water a bit prior. It did rain last night quite a bit but it doesn't seem to have affected the P/K results.

Any ideas? Anyone ever try to test their pond water?

I was expecting them ALL to show trace...or even the exact opposite of what I got... getting such high marks on the other two had me curious.

A better test would probably be solid manure but pond water is much easier to contain and collect. Maybe another day.

I have not tested “pond water” and I don’t have ducks, but I do grow things. I’ll offer a few thoughts.

I’ve never used that tester. I’ve actually used very few over-the-counter testers like that. I’m generally greatly disappointed in their consistency and accuracy on the rare occasions I’ve tried one. I don’t know how accurate that tester really is.

Was that pond water in a swimming pool, bath tub, or some type of container or was it dug into and exposed to the ground? Did you have enough ducks swimming in it and pooping in it to be truly noticeable as far as the tester is concerned? Perhaps the dilution was so great those readings were pretty accurate. From a dilution aspect, I’d suspect your P and K readings were pretty high unless maybe that stuff was leaching from the ground and not necessarily coming from the duck poop.

You mention “old” pond water. To me five days isn’t very old but I haven’t studied up on using pond water or fish aquarium water directly on plants. For plants to be able to use nutrients the nutrients have to be in a useable chemical form. Maybe they have to be in a certain chemical form for that tester to detect them? When you compost things, the bugs break the nitrogen and carbon down into a useable form. Chemically I’m not sure what’s going on with that duck poop in the water.

I would expect nitrogen to at least show a trace if there was any real volume of duck poop in that water, you not getting any is a bit of a surprise. But just from a dilution effect I’d be surprised if there was anything much more than a trace of any of those. If you are going to put that directly on your plants, you want it to be really weak anyway, otherwise you could burn your plants.

I don’t know how much poop is actually in that water, but I think you will get some benefit over time using it. It may need to break down in the ground after you use it, especially if you try using it after only 5 days. The effect may not be miraculous with everything doubling in size overnight, but I think you will get some benefit.

I'll continue to let it sit and test again after its 2 weeks old.

I only have 6 1 month old ducks and they are mostly on starter still. Their poop looks almost exactly like the feed half the time even though they are out during the day foraging. The kicker is... I don't think they have taken up to eating vegetation from the ground. They will eat weeds and such all day if I feed them by hand and they destroy bugs if they can catch em. Maybe the P/K is a result of all the undigested grain etc in the pond... I don't know. Maybe their poop will gain nitrogen as they turn adult, forage more of their diet, and eat more digestible food?

The pond is a 50 gallon hard plastic liner that I got from lowes.


I figured if dilution was going to be an issue id see very low N and non existent P/K. Then I'd test again as the weeks pass. Also, the test is for soil..... but they also have you dilute the soil at a 5:1 ratio to the point where you are testing ...basically compost tea. Should be close enough to pond water i'd think.

Interesting. Any plants in this pond? any filtration? Any mechanical aeration? I can speak to the issue as it relates to aquarium water: When an aquarium has been up and running for a while, with an active filtration system, the bacteria in the system actually keep the nitrogen to negligible levels. Those bacteria convert the nitrogen to a form that can be used by the plants, thus continuing to keep the N level low. In your pond situation, unless it is a balanced system with filtration and plants to consume the nitrogen, that nitrogen (ammonia) level should be off the charts with the input of all of that duck poo. Here's my suggestion to you: Take a sample of that water to a local pet store, and have them test the water for you. I'm guessing that your N reagent is defective. Perhaps you could try testing it by putting a few drops of straight, unscented ammonia into a pint of water and testing that. It won't tell you how accurate the test is, but it will tell you if that reagent is working at all. BTW, aquarium water, especially the deitrus siphoned from the gravel at the bottom of the tank is incredible plant fertilizer.

No plants, no filter, no aeration other than the ducks. No rocks at the bottom either. Only a drain for quick water dumping.

No algae either. It has probably only been used by the ducks for a few weeks.

I'll have check out that aquarium test idea... lol I cant imagine the looks on their faces after testing duck manure tea...

Just did a PH test since the kit also included one. Also did another nitrogen test.

PH was 7.5 / Alkaline and nitrogen was the same. No color at all. I'll have to test on some compost I have to see if it registers anything at all...