The plants they grow and products they harvest from it exhaust the ground, because the plants need minerals to grow but the minerals dont return to the ground when they die. Instead, (part of) the plant is harvested and the ground is left exhausted from minerals. Farmers add fertiliser to the soil to artificially make it rich of nutrients for the plants.
Mercury is a barren planet with little atmosphere. In many regards it is similar to our own moon. However, it is also very close to the Sun, so humans will have to set up bases in craters or near the Poles to avoid being blinded.
