have you tried a CGS meter?

calahan measured the level of paramagnetic force in various soils using a CGS meter. most cost several thousand dollars. so he pateneted a simplified version of the CGS called the PCSM (paramagnetic count soil meter) that costs a few hundred dollars. you can use it to measure the paramegnetic force of your soil and learn what does, and does not, positively and negatively affect your soil health.

a few CGS reading he gives in the book of individual elements

calcium +40
potassium +20
magnetite +4,420
oxygen (gas) +3,349

you can see why magnetite, when added in very small amounts to your soil can dramatically boost its paramagnetic count.