In the study of soil profiles, which master horizon is predominantly composed of organic matter such as decomposing leaves, needles, twigs, and moss in various stages of decomposition?

💡 Solution & Explanation

The O horizon represents the uppermost organic layer of a soil profile, consisting predominantly of decomposing leaves, twigs, moss, and other organic matter in various stages of decay. Below this layer lies the A horizon, which is the topsoil rich in humified organic matter mixed with mineral particles, followed by the B and C horizons. This organic-rich surface layer is essential for nutrient cycling and sustaining terrestrial biological activity.