Over cultivation of the soil, partially mechanical (constant use of a rotavator) physically breaking down the crumb structure, possibly creating a cultivation pan (non-dig concept); Loss of Humus by not adding it to the soil. Example - American dust bowl Also burnt up by over-aeration of the soil by cultivating (see above). Example -Fen peat loss. Burnt up if applied with lime; Compaction caused by walking on wet soil (puddling) physically breaking the structure, driving out the air; Use of heavy irrigation, breaking down the crumb.