Question

forms the largest share, around 45%. air and water make up about 25% each, and organic matter constitutes 5%, including humus and living organisms. this combination of biotic and abiotic factors makes soil an ecosystem. what is humus? mineral matter or pieces of rock in the soil substance from decaying organic material a type of worm that only lives in the soil

Explanation:

Humus is formed from decomposed organic matter. It enriches soil with nutrients.

Answer:

B. substance from decaying organic material