Answer – Humus is formed by the decomposition of plant and animal matter and is usually dark brown or black in color.
Explanation:
As plants drop leaves, twigs, and other materials to the ground, they accumulate as organic waste. When animals die, their remains also contribute to organic waste. Over time, these materials decompose, providing essential nutrients to the soil. The decomposed mixture that is dark brown or black in color is called humus.
Humus is a kind of soil organic matter that is rich in nutrients and retains moisture in the soil. It is important for soil health because it improves the soil’s capacity to stay moist, moderates soil acidity or alkalinity, and helps to warm cold soils in spring.
Humus formation is a biological process, and only 4-12 inches of humus-containing soil are available in the Earth’s upper crust. It is made up of approximately 60% carbon, 6% nitrogen, and small amounts of sulfur and phosphorus. The carbon to nitrogen (C:N) ratio of humus ranges between 8:1 or 15:1, with an average ratio of about 12:1. Humus is also important for climate change mitigation due to its ability to remove carbon dioxide from the air.
