you can try def
diesel exhaust fluid
"Diesel DEF" refers to Diesel Exhaust Fluid (DEF), a solution made of 32.5% urea and 67.5% deionized water
Yes, DEF can be used as a fertilizer because it is a solution of urea and water, and urea is a common nitrogen source in fertilizers. To use it for your lawn, dilute it with water to prevent burning the grass. For example, a common recommendation is to mix about 14 to 21 fluid ounces of DEF with one gallon of water and spray it over 1,000 square feet, then water the lawn within an hour after application
Interesting, I never knew that. Did some checking and there is info everywhere about using it for lawns.
Definitely has me thinking....
If DEF is 32.5% urea, and DEF weighs ~ 9#/ gal, and urea is 46% nitrogen then there is ~1.3# actual N per gallon.
At tractor supply, you can get a 5 gallon bucket of DEF for $17.00 so, you are getting your nitrogen for ~$2.62 per pound actual N.
For comparison, a bag of 13-13-13 is currently $25/50#. So you are getting 6.5# actual N for $25 or $3.85/# actual N.
Economics certainly work well, and if you only need a small amount, this may be the way to go. However, I'd be sure to dilute any that you try, more dilution the better to help spread small amounts evenly over large areas. I'd also be careful using this on foliage.
A note: I know nothing about the actual manufacture/formulation of DEF, so have no idea if impurities could be present or not. I haven't seen any University studies using DEF as fertilizer on food crops so I won't publicly recommend it, but.....
Edit, just found this article talking about the possibility of using DEF as fertilizer.
https://azurechemical.com/blog/can-diesel-exhaust-fluid-be-used-as-fertilizer/
As I pointed out above, it might be economical for small areas, but unknown potential contaminants means that I won't be using it on any food crops.