A nitrogen profile test is done with a sample taken at 24 inches. This will tell you about your nitrogen and micronutrient levels in detail. Make sure not to mix the upper level sample with the deeper ones. Take sample from 6 or 7 locations in the same general garden area. If you have several different gardens take a group of samples from each area and do a separate test.
All gardens have microclimates and a varying degree of nutrient levels.
Take the 7 different samplings from an area and mix together in a plastic bag. Place one cup of the mixture into a paper bag. Clearly label the bags so you know which garden it represents. And take them down to your local cooperative extension for analysis. All rights reserved.