Too much nitrogen

I’m hoping for some help as my research hasn’t been successful.

I live in zone 9 and despite adequate watering and care have had all my newly planted shrubs die in the five years we have lived here. They get burnt/brown looking leaves that die off until the whole plant dies. (Our lawn doesn't do well either.) The plants do ok in the spring with regular rainfall but start dying pretty quickly once I switch to irrigating. We are on a well and had the water tested when we purchased the home. We have excessively high nitrate levels and were told that it was due to so many years of farming/fertilizing in the area. I recently purchased a soil test kit and the results were excessive levels of nitrogen and depleted phosphorous and potassium. I know that sawdust/mulch can help reduce the nitrogen and plan to add some to the areas where I’d like to grow some shrubs.

1. I’m not sure how well I can reduce the nitrogen if my irrigation water has such high nitrate levels. I’ve searched for zone 9 shrubs that might help reduce the nitrogen levels but all the “nitrogen fixing” plants that I find say that they increase nitrogen. Are there any shrubs or small trees that tolerate/thrive in high nitrogen (zone 9) and/or help reduce it?

2. Any recommendations for increasing potassium and phosphate without increasing nitrogen?

3. Any recommendations for helping my lawn?

Any advice is greatly appreciated! Thank you!!!

Welcome to Permies!

Nitrates can be tricky to pull out of water. Sand filters or other simple to build aren't effective in the process.

Would you consider rain water harvesting in order to have a different source of water to utilize for your crops?

What kind of soil are you working with if I may ask? What is your average rainfall?

Here is a thread for plants that consume excess nirotgen:

It starts off with these, Mike said:

Grass
Corn (yes I know it's a grass)
Nettle
Rhubarb
Asparagus

https://permies.com/t/137078/Plants-consume-excess-nitrogen

Thanks!

We have sandy loam soil and our area gets about 12 inches of rain annually. Our property does back up to a canal with irrigation water that we can use, so I’ve been considering getting a small pump and going that route. The downside to that though is that water only comes once every ten days and it’s at the back of our property and we’d have to install all new pipes to get it where it’s needed. That might be our only option though…