What Goes Into Soil: Minerals, Air, Water, and Living Organisms

Soil begins as rock worn down by wind and water over eons. A shovelful is ~50% mineral particles; the rest is roughly equal parts air and water in pore spaces, plus a tiny fraction of organic matter (decaying plants).

The upper inches teem with life: hundreds of earthworms, a million mites, 10+ million nematodes and protozoans per square yard. They process minerals for plant uptake, suppress harmful fungi, and their waste/remains form humus—a soft, dark material that improves soil structure.

Because these organisms live near the surface, scraping or constant tilling destroys their habitat. Reviving depleted soil takes years as microbial colonies re-establish.