In a word or two is not possible, but we can try to summarise.
Soil is different than dirt. Dirt is inert and soil complies much more than the soil textural triangle we learn at school/university. There is a wide range of macro and micronutrients that interact with biological activity. And this activity occurs below and above ground, with nano, micro meso and macro biota, such as bacteria, fungi spores, mycorrhizae, paramecia, earthworms, ants, snakes, plants, birds, insects and mammals… When soil is tilled, almost all the relationships, occurring since the last disruption, are broken and a) soil becomes exposed to variables and radiation, b) galleries and soil structure is broken, c) becoming homogeneous and impermeable, d) promoting run-off depleting top nutrients, e) carbon is released by decomposition of plant material. Soil f) becomes exposed to water erosion, especially in more “drastic event” driven rain patterns, and g) also exposed to wind erosion, an understated depletion that specialises on top soil nutrients, where they are more needed. Then, some more depletion processes start to build up. When vegetation is removed, wind speed increases and more radiation is reaching the soil. These two together, cause higher vapour pressure deficit (so called evaporative demand), that “pulls” water into the atmosphere (check the Penman-Monteith equation, on one of the best FAO report ever made!), h) depleting even more the current scarce water resource. And we haven’t mentioned all the biological activity impact that a) to h) have. But we don’t want to deplete your patience on all these physical impacts on micro-meso-macro biodiversity (actually very little is known or understood!). But be assured that every “small” living being can have an impact on all relationships and trophic chain balances, under and above-ground.