All soils have NPK in them. You have to test them to know how much. Most people don't want to be bothered, so they either dig a hole - then fill it with store bought soil (NPK printed right on the bag) or grow in containers with store bought soil.
.
The test kits to test soil, are cheap & available at most Garden Centers, Lowes, Home Depot, Wally World..etc.. They cost between $ 4 - $ 12 and you can do dozens of tests with the bigger more expense one. If you can read, you can use them.
.
Botanicare makes a Soil Grow Sampler sold by Wormsway, which is the best I've seen in 30 years of growing. Here is a link to that site:
Pure Blend Pro Soil Kit - Worm's Way
.
The price is fair on these nutes, there is enough for a good grow & the directions on the bottles are good. Even if you don't buy one, the recommended NPK for each stage of growth is good.
.
The two biggest mistakes made by new growers are Overwatering & Overfertilizing.
Water weekly, Fertlize every two weeks. Don't use more than directed to, on the label. More is not better. The reason they suggest certain amounts, is becasue those amounts work & work properly.
.
Hope this helps... For Real Growing Info... Surf on over to the Orangics Threads..
.
.