mass of water

The mass water content of the soil (w) is the amount of water per unit oven dry mass of soil.

Volume of pores

Question 1 of 12

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Volume of air

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Volume of water

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Volume of solid

Total volume

text

Mass of air ( = 0 )

=

Mass of water

mass water content (w)

Mass of solid

?

unitless

g g-1

Question 2 of 12

kg kg-1

mass of water mass of solid

The appropriate units for mass water content are:

The appropriate SI units are kg kg-1. Even though these units cancel out, they are necessary to discriminate mass water content from volumetric water content.

Question 4 of 12

The appropriate SI units are m3m-3. Even though these units cancel out, they are necessary to discriminate volumetric water content from mass water content. The units m m-1 are incorrect. because we are using a volume of soil rather than a depth.

m3m-3

m m-1

volumetric water content (θ)

volume of water

total volume

Question 3 of 12

The volumetric water content of the soil (θ) is the volume of water per unit volume of soil (i.e. total volume).

The bulk density of the soil (pb) is the amount of solid per unit volume of soil (i.e. total volume).

bulk density (Pb)

Question 5 of 12

kg m-3

Question 6 of 12

The appropriate units for bulk density are:

mass of solid

The appropriate SI units are kg m-3

kg kg-1

The air-filled porosity of the soil (fa) is the proportion of gaseous volume within the soil, it will vary with moisture content.

volume of air

air-filled porosity (fa)

Question 7 of 12

The appropriate units for air-filled porosity are:

Question 8 of 12

air-filled porosity (fa)

Air-filled porosity has no units. It is also often expressed as a percentage. The units are not m3 m-3 because, unlike water content, there can be no confusion between volumetric and mass water content.

m3 m-3

particle density (Ps)

Question 9 of 12

The particle density of a soil (Ps) is the density of the solid soil particles. Most soils would be within the range 2600 to 2700 kg m-3

kg m-3

The appropriate SI units are kg m-3.

Question 10 of 12

The appropriate units for particle density are:

volume of solid

total porosity (f)

Question 11 of 12

The total porosity of the soil (f) is the volume of pores (both water- and air-filled) within a given volume of soil.

Question 12 of 12

Total porosity has no units. It is also often expressed as a percentage. The units are not m3 m-3 because, unlike water content, there can be no confusion between volumetric and mass water content.

The appropriate units for total porosity are:

All done! Again?!

volume of pores

m3 m-3