Why is humus important?

That it's a source of nutrients and that it improves soil structure are two reasons why humus is important. Humus is dark brown, fresh smelling, nutrient rich organic matter. That it contains such important elements as nitrogen makes it a source of nutrients for plant roots, soil, and soil food web members. That it encourages the formation of air and water pore spaces makes it a facilitator of soil structure. The soil that has adequate air and water pore space has appropriate moisture levels and adequate drainage. Both of these contributions from the presence of humus in soil account for the improved well being of soil, soil food web critters, and plant parts above and below ground surface levels.