The NPK only measurement is a not a healthy way to grow crops, it is actually an error that Von Liebig tried to correct after understanding that chemical fertilization is a mistake.

I recommend reading with "Teaming with microbes" by Jeff Lowenfels, he also made two other books after this one, Teaming with nutrients and Teaming with fungi, he recommends to read them in order, and I too:
https://loadaverage.org/url/6140478