First I'll aim you at the 3 lb's Why you should reuse your soil, or Soil heresy by the 3LB's.

Now I'll my 2 cents if your growing outdoor mixing with the native soil has proven to work best I think it's due the soil mixes we use being light weight compared to the native soils which in my area is mostly clay base soils. when making the big holes to grow in we make it big and deep but leave no soil weight to anchor the plants in during the grow.

If your planning to bring the soil inside bake it first bring the temp up to 200F to 250F this kills the bugs and their eggs.

in either case you will see you need less nutes because there are more than you think still left in the old soil mix

those nutes are broken down by now to a more basic compounds and imo are usable by the microherd. Now I think the main reason the synthetic nutes are harmful to the microherd is because the synthetic are in the form the mcroherds excrement(sh it} is. They take the organic compounds in the soil and break it down to a more plant usable form the form the synthetic are supposed to be in for plant uptake