# Nitrate leaching into well/groundwater



## MDJoe (Sep 16, 2019)

I am on a well. Nitrates test just over the max recommend already, so we use a reverse osmosis system for drinking water.

My concern is adding annual N to my lawn will make that worse. Slow release is better, but prohibitively expensive for a large yard.

Has anyone got experience here?


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## LeeB (Jul 1, 2019)

I also have this problem, nitrates tested at 24 ppm. My lot was a former farm field, and is adjacent to an active field. Depending on the depth of your well, annual rainfall, and soil composition the nitrate level in your groundwater is typically a long term average of nitrogen use near your well. Decades of fertilizer overuse by the farmer are likely to blame in my case rather than my lawn fertilizing. Farmers like to megadose N before planting to give enough nitrogen for the whole season. In some cases if they are worried about yields and sandy soil they might put down the equivalent of 10 lbs N/k ft (400+ lbs N per acre). If a big rain hits early in the season a huge amount of that may be leached down into the groundwater. Alas, farmers don't care about groundwater nitrate levels when they fertilize, only yields. Personally I think there should be stricter fertilizing regulations for farmers because of the long-term damage they can cause to groundwater systems and watersheds, but that's another story...

In terms of best practices for turf fertilization, the research supports common sense, fertilize as little as needed, and use as much slow release N as you can. In one study, 4 lbs N per year was the max before increased leaching was noted. The type of fertilizer N source is also important, ammonium nitrate (what farmers use) leaches significantly more than urea which is what most consumer lawn fertilizers use. Organic nitrogen has very little leaching unless it's overused. Time of year is also important, you want to apply N when the grass is going to be able to use it. In particular, you should be careful with late fall apps because if the grass goes dormant before using all the N, a lot of it will leach down into the groundwater from snow melt and early spring rains. Same thing with very early spring apps, or if you apply during hot weather when the grass isn't growing.

I also have a big yard so I understand the cost and practicality aspects (whole lawn Miloragite apps are likely out of the question). What I would do is stick to 4 lbs N or less per year, and only apply 0.5 lbs at a time if you're worried. Smaller apps are going to be more efficient anyway, so you might be able to get away with 2-3 lbs a year which will save you some money. Use a fert with as much polymer coated urea as possible (typical consumer ferts have 20-30% coated urea). If you have trouble spots then you can do spot treatments with Milo or more urea. Don't be afraid of fertilizing though because getting the lawn to be dense and healthy reduces leaching and runoff. You may leach a bit more in the first year or two until the lawn is fully established. But overall, nitrate contamination of groundwater from turfgrass fertilization is very minimal compared to agricultural sources. I would be surprised if you were to blame for your high nitrate levels unless you've been doing extreme levels of N for some time or you have a really shallow well.

In my case I am hoping the nitrate level will drop with time since the land is no longer being over-fertilized. It may take a few decades for it to dilute out in the groundwater and return to safe levels. I am using a reverse osmosis system as well.

Sources:
https://www.golfdom.com/twenty-years-of-measuring-nitrogen-leaching-from-turfgrass/
https://pdfs.semanticscholar.org/e297/c8ef4cd501162ec3938a2ca609532f1c3ce9.pdf
https://www.mgcsa.org/resources/Documents/RevisedTurfFertBMPs.pdf
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.939.4079&rep=rep1&type=pdf
http://archive.lib.msu.edu/tic/mitgc/article/199180.pdf


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## MDJoe (Sep 16, 2019)

Nice information, thanks for all that!

My well isn't shallow, it's actually 310 feet.


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## mowww (Jan 16, 2018)

Slow release and stabilized nitrogen products UMaxx, UFlexx, STN, EXN, XCU can all help prevent nitrification and leaching as opposed to urea or AMS when applied properly. I'd take a look at some of the enhanced stuff above.


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## MDJoe (Sep 16, 2019)

I did a quick search, and I'm already finding that these products (UMaxx, UFlexx) come up in a bunch of Google search results, but nobody actually sells it to the end user! Lots of links to spec sheets etc.

I found one supplier of UFlexx but they don't ship here.


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## mowww (Jan 16, 2018)

What part of WI? there are quite a few distributors in WI for stabilized N. Reinders has a web store.


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## MDJoe (Sep 16, 2019)

I'm in Maryland.


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## mowww (Jan 16, 2018)

I am sorry, clicked on LeeB's profile on mobile. SiteOne will probably sell to you if you walk in, ask for the product specifically, and throw down some cash.


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## GrassFarmer (Sep 21, 2017)

LeeB seems pretty anti farmer. Im not sure who puts down 400lbs of actual nitrogen up front on corn but does not sound very profitable. Also urea is cheaper per pound than ammonium nitrate for nitrogen percentage so why would a farmer use that?
anhydrous ammonia is more likely the form used since its the cheapest nitrogen source cost vs nitrogen percentage.


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