英文文献：Regional Differences In The Relationship Between Erosion And Crop Yields: Some Implications For Soil Conservation Policy
英文文献作者：McElyea, David E.,Christensen, Lee A.
英文文献摘要：
Differences in the relationship between topsoil depth and crop yields are explored for typical soils in the northwestern and southeastern United States using agronomic and economic models. Important distinctions in the slopes of the yield/topsoil depth functions were foond. These differences have significant implications for the economic of soil conservation and also indicate a need for more heterogcneouc soil conservation policies.