Humus is the dark organic matter formed in the soil from the decayed plant and animal matter. It is a component of soil organic matter. It is of great importance due to its ability to retain soil moisture, to loosen the soil and maintain soil aeration, to maintain soil microorganisms population and nutrient recycling ability which altogether maintains the soil fertility and promotes good crop production. This article will cover the topic of genesis of humus, its composition and properties of humus and its role in maintaining soil fertility.