chernozem

noun

1. (countable, uncountable)A fertile black soil containing a very high percentage of humus (3% to 15%) and high percentages of phosphoric acids, phosphorus and ammonia.

   “The experiments made by the beet-root growers of the extensive tract of land in Russia, known as the Tschernosem or 'Black soil', whose fertility for corn plants is proverbial, show that this earth, though analytically proved to contain upon the whole, to the depth of twenty inches, 700 to 1000 times the quantity of potash required for a full beet-root crop, is, after three or four years' cultivation, so exhausted, that without manuring it will no longer yield a remunerative crop of beetroot.”