Humus is dark organic matter formed from plant and animal decomposition. Contains nutrients, especially nitrogen, with C:N ratio between 8:1 and 15:1. Has amorphous structure lacking cellular organization. Composed of lignin, polyphenols, proteins, and carbohydrates
Soil is the loose layer of earth covering planet's surface. Soil formation takes 500 years or more from rocks. Soil has three stages: solid, air-filled, and water-filled
Humus is the rich brown or black substance left after organic matter decomposes. It contains essential nutrients like nitrogen, phosphorus, and calcium. High-quality farmland soil contains 3-6% humus