spongy topsoil的用法和樣例：
例句
- Loss of topsoil by erosion and a reduction in soil fertility by not replacing nutrients, turn a renewable resource into a non-renewable one.
侵蝕造成的表土流失以及不補充養分造成的土壤肥力下降使一種可再生資源變成不可再生的資源。 - Midwestern topsoil, some of the finest cropland in the world, is made up of loose, heterogeneous clumps with plenty of air pockets between them.
美國中西部的表土堪稱全世界最優良的耕地，由各種不同的鬆散土塊組成，土塊之間還有大量的氣潭。
