I've tested my soil and it is very low in N and P. What is the best way to solve this problem? In a 10' by 20' garden, I added 40 lbs of 16-10-16 last year and it tested the same this year.
Certified GKH Gardening Expert
You may want to try some rotted manure. It is one of the best ways to add nitrogen as it also adds organic material (good for water retention) and trace micro-nutrients as well. Potash is typically used to replace potassium.
Chemical fertilizers have a tendency to leech out faster than other sources. This may be why the soil did not test any better this year.