Rotational cultivation
Usually 'conventional' ploughing, where the topsoil is turned down to a depth of 15-45 cm. The top aerated (aerobic) soil layer is deposited at the bottom and the bottom anaerobic layer is deposited at the top, or mixed together, thus damaging and destroying the established soil life. The agitated layer loosens, but this is only temporary or often excessive. Meanwhile, below the cultivation depth, a thick, compacted layer, known as the ectal layer, is formed. This is often impenetrable to plant roots.