How does organic material enter soil

Through the decay of tiny life forms (organic matter).

Through the decay of tiny life forms (organic matter). For example, diatoms are microscopic single-celled algae. So their fossilized remains would be called Diatomaceous Earth. Basically, this is an organic nutrient-rich "soil" (& is used commercially as a fertilizer & as a natural pesticide - aka - Mother Nature's product w / no harm to the environment, pets or to people).