topsoil

n.

表土（层），耕作（层）；耕层；

1. Heavy rains washed the topsoil away.
   大雨把表层土冲蚀掉了
2. This topsoil tends to wash away.
   表层土壤要冲掉了。

The carbon content of topsoil and its geographical distribution in France
Distribution of Clostridium tetani in topsoil from Sagamihara, central Japan
Storage and sequestration potential of topsoil organic carbon in China's paddy soils.
Scale-dependent correlation between topsoil copper and cobalt concentrations in Scotland
Assessment of heavy metals contamination in urban topsoil from Changchun City, China
Restoration of Wet Fen Meadows by Topsoil Removal: Vegetation Development and Germination Biology of Fen Species
Restoration of a species-rich flood meadow by topsoil removal and diaspore transfer with plant material
Heavy metal contamination of roadside topsoil in Osogbo, Nigeria: its relationship to traffic density and proximity to highways
Changes in soil physical properties and organic carbon status at the topsoil horizon of a vertisol of central India after 28 years o...
Microbial biomass responses to seasonal change and imposed drying regimes at increasing depths of undisturbed topsoil profiles