Solum average bulk density (Mg/m3)

Bulk density is a measure of a soils mass per unit volume of soil and depends on the mineral composition of the soil and degree of compaction. Uncertainty in bulk density estimates will be greater than for texture as data are not available for many groups of soils. Bulk density is inversely related soil porosity: the more pore space in a soil the lower the value for bulk density. Soils high in organics and some friable clay may have a lower bulk density. Derived from McKenzie et al. (2000). The solum average bulk density is the A and B horizon estimates weighted by the depth of each horizon.

容重（bulk density）是单位体积土壤的质量度量，其取值取决于土壤的矿物组成与压实程度。由于多数土壤类群缺乏相关数据，容重估算的不确定性高于土壤质地。容重与土壤孔隙度呈负相关关系：土壤孔隙空间越大，容重数值越低。富含有机质的土壤以及部分疏松黏土的容重通常更低。本数据集源自McKenzie等人（2000）的研究。土壤发生层（solum）平均容重为A层与B层土层估算值按各土层厚度加权得到的结果。