(black earth) A type of zonal alkaline *soil
) found in regions with light summer rainfall, as in the pampas of South America and the prairies of North America. The top of the A horizon is very thick, rich in humus, and black, and the brown lime-rich layer beneath merges into, and is often indistinct from, the B horizon. The slight leaching due to the spring and summer rains is counteracted by surface evaporation in the hot summer resulting in the accumulation of lime in the A horizon. Such soils are very fertile over a long period of time.