Final answer:
The statement is false; grassland soils have much thicker A horizons than forest soils due to the accumulation of organic matter from extensive grass root systems.
Step-by-step explanation:
The statement that soils developed in forest settings tend to have thinner surface horizons than those developed in grasslands is false. Forest soils generally have a thin, organic-rich A or O horizon due to the annual shedding of leaves and needles from trees. In contrast, grassland soils, thanks to their extensive root systems and surface masses of grasses that die and add to the soil each year, tend to have much thicker A horizons with high organic matter content, making them more agriculturally productive than forest soils. The thickness and development of soil layers, or horizons, depend on various factors such as climate, parent material, soil type, and vegetation.