Explanation
The soil horizon that contains litter is the O horizon.
The O horizon, or organic horizon, is made up mostly of organic matter such as leaf litter and decomposed plant material. This layer can be thin, thick, or not present at all, depending on how a soil forms. In soil science, soil litter is classified in three layers, which form on the surface of the O Horizon. These are the L, F, and H layers: L – organic horizon characterized by relatively undecomposed plant material. F – organic horizon found beneath L characterized by accumulation of partly decomposed organic matter. This detritus or dead organic material and its constituent nutrients are added to the top layer of soil, commonly known as the litter layer or O horizon ("O" for "organic")
