Soils Exam 4-Bulk Density

% porosity=

(1- (BD/PD)) x 100 BD=Bulk density PD=Particle density

high organic matter

low bulk density

strong structures (well granulated topsoil)

low bulk density

high pore space

low bulk density (sponge)

bulk density=

mass of dry soil/ volume of soil

particle density=

mass of solids/ volume of solids mass of solids=bulk density

soil bulk density is affected by both ___ and ___.

nature of solids and the volume of the pores

soil strength increases because...

pore space decreases and soils become more compact

sandy soils

range from 1.2-1.8 g/cm3

as bulk density increases

soil strength increases

as bulk density increases...

the amount of pore space decreases

porosity

the percentage of a soil that is pore space or voids

the average soil has a porosity of about ____, and the pores are filled with ______ or ____ depending on the moisture content.

50%, air or water

low pore space

high bulk density (brick)

Soil bulk density

a measure of how compact or dense a soil is -relates weight of solids to total volume of soil including solids and pores

fine textures: silt loams, clay, clay loams

generally lower bulk density (1-1.6 g/cm3)