This is a pic of the fertilizer calculator I'm using to select the best formula based on the soil sample recommendation from the lab.
The recommendation was 100 lbs N; 40 lbs P; 90 lbs K
The highest rated product (score of 84) was 10-10-10. I also entered 13-13-13 because it is a very common formula and easily found, but the calculator did not list it as a recommended option. The grade entered, at the suggested rate yields -.23 N; +1.15 P; 0.0 K.
If I choose 10-10-10 from the suggested list, I get the exact same numbers for deficit and surplus, etc. in the NPK. Keep in mind that the numbers for NPK are % of nutrients in the bag.
Hoping to offset the deficit and surplus by adding another mixture with the 10-10-10, I chose 13-0-0 (Bloodmeal). when the two are calculated together it yields a total % of: N = 0 %; P = +.23 %; K = 0 %. So I evened out my Nitrogen and reduced the surplus for P by a lot.
Oddly enough, even though the expressed percentages are the same for both formulas, if I put 10-10-10 into the calculator (rather than 13-13-13) and add Bloodmeal to it, the final % is different. I get N = 0.0; P = 0.0; K = -1.15 AND the overall score is 85.
Both are good scores but I'm confused on the statistics. Any ideas?

I don't understand why 10-10-10 would "score" well when you don't need a balanced blend. You need roughly the same amount of N and K per acre and roughly 1/2 as much P.

If you can find a 20-5-20 blend but that would be about an ideal fertilizer for your application. It would take 10 bags per acre to get your N & K correct and that would leave you short on P but.... You could put out one bag of triple super phosphate per with the 20-5-20 and be real close to dead on, on all three nutrients.

Remember that the numbers recommended are pounds per acre of the nutrient and the numbers on a bag of fertilizer are the pounds of actual nutrient per 100 pounds of product, NOT pounds per bag.

To get 100 lbs of N and K to the acre using 10-10-10 you'd have to put out 1000 lbs per acre. That would be absurd.

I'm guessing this is for a food plot? If so, don't over complicate it, it's not rocket surgery.

You're right, Fur, I tend to overthink these things. This is for a food plot.
Last year we used ? - 0 - 8 because it was the local feed store's recommendation for Deer Magnet and AL Blend. It appeared to do fine. But we were thinking there was an ideal formula we had to find to bring down the pH. Probably splitting hairs unnecessarily.

The TSP that I recommended has calcium in it. It won't help the pH much, but it will help it.


Just an FYI, feed store people usually don't know jack squat about fertiizer. For a food plot you needs lots of N and lots of K.

If you can't find what I suggested above, just get 15-5-10 and put it out at 400 lbs per acre and you'll be fine.

Thanks for that advice!
If I was responsible for growing all my own food, I'm sure I'd starve to death.

I'd suggest you start working on correcting that. Your families life could one day depend on it.

...sooner rather than later, too.