These days we have professionals who dedicate their careers to studying it. We call them, simply, soil scientists. To prepare, they take courses in biology, chemistry, math, physics and lots of other disciplines. They' ve written volumes and volumes that explain why we should give a rip about dirt. Only they'd never use that vulgar, but common, term.
Scientists much prefer that other four-letter word, soil.
Oregon State University professors Herb Huddleston and Jerry Kling wrote it. Instead, we depend completely on green plants, which take nutrients and water from soil and combine them with air and sunlight to provide our food supply. Some of those plants, such as wheat and corn, we eat directly. Others, such as alfalfa hay and range grasses, we process through livestock first. Even the fish we eat depend on plants that grow in the sea using nutrients that have been washed out of the soil and carried to the sea in rivers and streams.