Forest Soil vs. Grassland Soil Forest Soil • Thick litter layer from fallen debris such as leaves, twigs, and branches. • Thinner A Horizon layer due to less extensive root system. Grassland Soil • Thin litter layer because only grass contributes to dead material. • Deep organic topsoil because of extensive root systems. • High in clay due to less rain leeching the clay away, so it holds water better for plants.