Garden with Insight v1.0 Help: porosity
Soil porosity is a measure of how much of the soil volume is made up of pore space (air) as opposed to
solid materials. Some of this pore space may be filled with water, so the amount of water a soil can hold is
partly determined by its porosity. Typically the constituents of soil volume look like this:
(Redrawn from Troeh & Thompson 1993)
Porosity is often described in units of percent pore space. In this
simulation we describe porosity in units of depth of water over depth of soil (as in m/m or a fraction) over a constant soil area. This is the same as percent pore space
divided by 100.
In this simulation porosity is maintained in a close relationship with bulk
density, which is also related to soil pore space. It changes when the bulk density changes (when the
soil settles with rain, when the soil is mixed with a tool, and when the soil is aerated with a tool). When
the soil is mixed, the porosity of some layers may change due to mixing of the soil particles. Wilting
point, field capacity, and porosity are used extensively in the model as standards against which to compare the soil's current water
content.
How it works:
mixing soil
aerating soil
soil settling with rain
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