spongy topsoil的用法和样例：
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.
侵蚀造成的表土流失以及不补充养分造成的土壤肥力下降使一种可再生资源变成不可再生的资源。 - Midwestern topsoil, some of the finest cropland in the world, is made up of loose, heterogeneous clumps with plenty of air pockets between them.
美国中西部的表土堪称全世界最优良的耕地，由各种不同的松散土块组成，土块之间还有大量的气潭。
