You can think of the soil as the food for the plants that grow on it. In the case for our olive oil, the soil is the food for the olive trees. A nutritious soil contains lots of minerals like calcium, calium, oxygen, nitrogen, phosphorous, and so on. Just like we know it's important for us people to have a rich and varied diet, the same is true for the trees.
In a natural and healthy eco-system, these nutrients are used and are replenished continuously.
Natural ways to healthy soil
Plants use and produce different minerals. Each variety has different needs and when decaying also leaves behind different byproducts. It's the same with animals. They like to eat certain plants and their droppings serve as natural fertilizer to the land.
We have sheep grazing the lands because they help contain the weeds and unwanted olive sprouts, they keep the grass nice and short whilst fertilizing the soil. This is the traditional way here in the Alentejo. It means we don't need to use any chemicals to control weeds or pests and we don't need to artificially add any fertilizers or herbicides.
If we find that the soil is deficient in some nutrients, then we plant some specific grasses, clover or flowers that help to bring what is missing. If we notice a surge in some insects that could be harmful, we welcome in bats or other natural enemies to help contain them. It's that simple. Well, it is and it isn't. It means we have to be very aware of the health of the land and we have to be very knowledgeable so that we support the eco-system whilst never upsetting the balance.