Complex sentence: Chernozem, or Black Earth (from Russian чернозём, "black soil") is the black-coloured soil that contains a very high percentage of humus--3% to 15%, rich in phosphoric acids, phosphorus and ammonia.
Split into simpler sentences: Chernozem, or Black Earth (from Russian чернозём, "black soil"), a kind of soil. This black-coloured soil contains a very high percentage of humus--3% to 15%, rich in phosphoric acids, phosphorus and ammonia.