There are many reasons we need to remineralizing our depleted soils. Here are a few methods that I find the most effective and ecological.
Free Choice Mineralization
I was first drawn to Permaculture because of the idea of letting nature do the work for us. Free Choice Mineralization is a perfect example of this. We can use our animals’ exquisite sensitivity to their bodies’ mineral needs to tell us what minerals we need to replace. But we let them do all the work for us. Here is how it works…
We put livestock (cattle, sheep, pigs, etc.) out in our pastures. If a certain mineral is deficient in our soil, then the plants growing in that soil will also be deficient. This is the mineral our animals will crave. Instead of using mineral blocks containing mixtures of minerals, we can put out our minerals in individual containers, cafeteria style. The animals walk up to the mineral trough and decide what they want. Sometimes an animal will take mouthfuls of a certain mineral. Other times, an animal will just touch its nose to the mineral, lick it off, and walk away. We check back often and replace what is being eaten.
The animals are unable to absorb everything that they eat. Much of it passes through their gastrointestinal tract and is deposited in their manure. This process actually makes many minerals more readily absorbed by soil life and plants. But even if it is not immediately taken up by the plants, the soil now has been given a dose of exactly the minerals it was missing or was deficient.
I have spoken with a number of people who use this method, and they are strong proponents. They relate how when they start rotating their animals on new pastures, they spend quite a bit of money on the free choice minerals. However, this cost does not continue. Over time, sometimes within only two to three years, their mineral requirements become almost negligible. The same thing occurs when they introduce new animals to their farm. The animals often dive into certain minerals like it was candy. These minerals (and the specific mineral change from year to year and can change based on where the animal was previously) need to be replaced on a daily basis sometimes. After a few months, the rate of consumption slows down. The animal has restocked its required/desired mineral stores.
So without doing a single soil test, we can remineralize our soils by using animals. The animals and the soil become remineralized to right where they need to be.
Of course, things are not always as simple as we may initially think. This method only works with animal systems. Some plants, trees for instance, may desire different minerals than the animals need, and so animal systems may not provide the required minerals.
Cited from TC Permaculture