poor vegetation cover on dry clay soils devoid of a layer of humus

ecosystem procariotic waterholding organic contamination desertification degradation erosion smectites community competition mutualism biocoenosis revegetation poor vegetation clay soil sandy depleted weathering burnout fertility chernozem alumina sod humus scarce dry arid survival restoration selfhealing euphorbia dandelion bindweed melioration rough dryness disaster bad rainfall botany