Plants require a root system that is equal in mass to the top growth, and vice versa. So without a good “understanding” your plants can never reach their potential and provide a harvest worthy of your efforts.
Here in the Ozarks we’re usually faced with a clay soils of marginal fertility that’s more appropriate to pines and oaks rather than corn and tomatoes. The standard recommendation for improving the soil is to add organic matter in the form of manure or compost. In truth this doesn’t actually improve the soil – which technically can only be comprised of sand, silt, and clay – but organic matter, or humus, does make the soil more friable and increases its ability to hold nutrients.