Combining fertilizers

These are weight percentages so you just take the average for 50/50 blend or proportion for any other blend.

Indeed, the numbers represent percentages by weight. If you mix equal weights of these two, you will get 2.5-5.5-5.5.

That is, if you take 10 lbb of the first, you will have 0.5 lb nitrogen and 0.1 lb each of phosphorus and potassium. Then, if you take 10 lbb of the second, you will have 1 lb each of phosphorus and potassium. Combining them, you will have 20 lbb of fertilizer with 0.5 lb nitrogen (2.5% of 20 lbb) and 1.1 lbb each of phosphorus and potassium (each 5.5% of 20 lbb).

So I thought.

Close to the standard all-purpose 5-10-10 ratio, ideal 1/2 strength.