The arrangements of soil aggregates gives soil its structure. The principal types of soil structure are platy, prismatic, columnar, blocky, granular, and crumb. The aggregates in these structure types vary in size and degree of stability. Bulk Density Bulk density of a soil is defined as the weight per unit volume of soil. The volume includes both the solids and the pore space.
Bulk density is important because it reflects the porosity of a soil.
Loose, porous soils have lower bulk densities than tight, compacted soil. The bulk density of a soil increases with compaction. Bulk density indicates how easily a soil will till, how easily water will infiltrate, how it will hold water, and its suitability for growing plants. Typical soil bulk densities for fine sands, silt loams, and silty clay loams are 1.5, 1.35, and 1.25 grams per cubic centimeter, respectively. Soil porosity depends on soil texture and structure.