Bulk density of mineral soils commonly ranges from 1.1 to 1.5 g/cm3 in surface horizons. It increases with depth and tends to be high in sands and compacted pan horizons, and tends to be low in soils with abundant organic matter. Tillage operations looen soils and temporarily lower bulk density, while compaction processes raise bulk density. High bulk densities correspond to low porosity.Natural soil-forming processes that increase aggregation reduce bulk density, but excessive tillage and raindrop impact on bare soil destory aggregation and increase bulk density.