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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Water content</span></span>

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<p><b>Water content</b> or <b>moisture content</b> is the quantity of <a href="Water" title="Water">water</a> contained in a material, such as <a href="Soil" title="Soil">soil</a> (called <i><a href="Soil_moisture" title="Soil moisture">soil moisture</a></i>), <a href="Rock_(geology)" title="Rock (geology)">rock</a>, <a href="Ceramic" title="Ceramic">ceramics</a>, <a href="Crops" class="mw-redirect" title="Crops">crops</a>, or <a href="Wood" title="Wood">wood</a>. Water content is used in a wide range of scientific and technical areas. It is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' <a href="Porosity" title="Porosity">porosity</a> at saturation. It can be given on a volumetric or gravimetric (mass) basis.

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<div class="mw-heading mw-heading2"><h2 id="Definitions">Definitions</h2></div>

<p><b>Volumetric water content</b>, θ, is defined mathematically as:

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<annotation encoding="application/x-tex">{\displaystyle \theta ={\frac {V_{w}}{V_{\text{wet}}}}}</annotation>

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</math></span><img src="./1fb81086bbba1750736f2a484e52f2958078b177.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:9.169ex; height:5.676ex;" alt="{\displaystyle \theta ={\frac {V_{w}}{V_{\text{wet}}}}}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{w}}">

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<annotation encoding="application/x-tex">{\displaystyle V_{w}}</annotation>

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</math></span><img src="./8b3417115633747e6616d838e82fdcb92f1e76cb.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.764ex; height:2.509ex;" alt="{\displaystyle V_{w}}" loading="lazy"></span> is the volume of water and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{\text{wet}}=V_{s}+V_{w}+V_{a}}">

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<annotation encoding="application/x-tex">{\displaystyle V_{\text{wet}}=V_{s}+V_{w}+V_{a}}</annotation>

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</math></span><img src="./e3a156e4b46caaaac605f44b45f4eeeea5d538b0.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:20.503ex; height:2.509ex;" alt="{\displaystyle V_{\text{wet}}=V_{s}+V_{w}+V_{a}}" loading="lazy"></span> is equal to the total volume of the wet material, i.e. of the sum of the volume of solid host material (e.g., soil particles, vegetation tissue) <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{s}}">

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<annotation encoding="application/x-tex">{\displaystyle V_{s}}</annotation>

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</math></span><img src="./57d5d0bb9d326d015df44456d7c0648f80c0f1f5.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.359ex; height:2.509ex;" alt="{\displaystyle V_{s}}" loading="lazy"></span>, of water <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{w}}">

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<annotation encoding="application/x-tex">{\displaystyle V_{w}}</annotation>

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</math></span><img src="./8b3417115633747e6616d838e82fdcb92f1e76cb.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.764ex; height:2.509ex;" alt="{\displaystyle V_{w}}" loading="lazy"></span>, and of air <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{a}}">

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<annotation encoding="application/x-tex">{\displaystyle V_{a}}</annotation>

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</math></span><img src="./b26205fe6c67ed47c72959a921fe7fd9c1c250ed.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.457ex; height:2.509ex;" alt="{\displaystyle V_{a}}" loading="lazy"></span>.

</p><p><b>Gravimetric water content</b><sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> is expressed by mass (weight) as follows:

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<annotation encoding="application/x-tex">{\displaystyle u={\frac {m_{w}}{m_{s}}}}</annotation>

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</math></span><img src="./759120c6916b9d6b37207264d37b2ed16c54ea05.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.171ex; width:8.714ex; height:5.009ex;" alt="{\displaystyle u={\frac {m_{w}}{m_{s}}}}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{w}}">

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<annotation encoding="application/x-tex">{\displaystyle m_{w}}</annotation>

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</math></span><img src="./1bd173f48c4afc862b28f62d46b4ff220e64f016.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.449ex; height:2.009ex;" alt="{\displaystyle m_{w}}" loading="lazy"></span> is the mass of water and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{s}}">

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<annotation encoding="application/x-tex">{\displaystyle m_{s}}</annotation>

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</math></span><img src="./488560816fccdf62695552ac8bf0611a0d5c09b4.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.044ex; height:2.009ex;" alt="{\displaystyle m_{s}}" loading="lazy"></span> is the mass of the solids.

</p><p>For materials that change in volume with water content, such as <a href="Coal" title="Coal">coal</a>, the gravimetric water content, <i>u</i>, is expressed in terms of the mass of water per unit mass of the moist specimen (before drying):

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<annotation encoding="application/x-tex">{\displaystyle u'={\frac {m_{w}}{m_{\text{wet}}}}}</annotation>

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</math></span><img src="./054681fc39ab2e113ee4238f9c7a511605d3af5c.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.171ex; width:10.778ex; height:5.009ex;" alt="{\displaystyle u'={\frac {m_{w}}{m_{\text{wet}}}}}" loading="lazy"></span></dd></dl>

<p>However, <a href="Woodworking" title="Woodworking">woodworking</a>, <a href="Geotechnics" class="mw-redirect" title="Geotechnics">geotechnics</a> and <a href="Soil_science" title="Soil science">soil science</a> require the gravimetric moisture content to be expressed with respect to the sample's dry weight:

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<annotation encoding="application/x-tex">{\displaystyle u''={\frac {m_{w}}{m_{\text{dry}}}}}</annotation>

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</math></span><img src="./7d1d0184c4293ce6b5c803931f99e2729b5a06b3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:11.101ex; height:5.343ex;" alt="{\displaystyle u''={\frac {m_{w}}{m_{\text{dry}}}}}" loading="lazy"></span></dd></dl>

<p>And in <a href="Food_science" title="Food science">food science</a>, both <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle u'}">

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<annotation encoding="application/x-tex">{\displaystyle u'}</annotation>

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</math></span><img src="./bee645f272e64333868e2baa275419eca4ee0718.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.014ex; height:2.509ex;" alt="{\displaystyle u'}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle u''}">

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<annotation encoding="application/x-tex">{\displaystyle u''}</annotation>

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</math></span><img src="./75057c7f0c536c8aa2f1df42cfddcfd96985c4f9.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.467ex; height:2.509ex;" alt="{\displaystyle u''}" loading="lazy"></span> are used and called respectively <b>moisture content wet basis</b> (MC<sub>wb</sub>) and <b>moisture content <a href="Dry_basis" title="Dry basis">dry basis</a></b> (MC<sub>db</sub>).<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>Values are often expressed as a percentage, i.e., <span class="nowrap"><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle u}">

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<annotation encoding="application/x-tex">{\displaystyle u}</annotation>

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</math></span><img src="./c3e6bb763d22c20916ed4f0bb6bd49d7470cffd8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.33ex; height:1.676ex;" alt="{\displaystyle u}" loading="lazy"></span> × 100%</span>.

</p><p>To convert gravimetric water content to volumetric water content, multiply the gravimetric water content by the bulk <a href="Specific_gravity" class="mw-redirect" title="Specific gravity">specific gravity</a> <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle SG}">

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<annotation encoding="application/x-tex">{\displaystyle SG}</annotation>

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</math></span><img src="./6910f93458a60f1fb5457f21f7054c32fbc347d6.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:3.326ex; height:2.176ex;" alt="{\displaystyle SG}" loading="lazy"></span> of the material:

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<annotation encoding="application/x-tex">{\displaystyle \theta =u\times SG}</annotation>

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</math></span><img src="./b3ff94e6e7023c6cfb68cd61882b1c2672648dce.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:11.685ex; height:2.176ex;" alt="{\displaystyle \theta =u\times SG}" loading="lazy"></span>.</dd></dl>

<div class="mw-heading mw-heading3"><h3 id="Derived_quantities">Derived quantities</h3></div>

<p>In <a href="Soil_mechanics" title="Soil mechanics">soil mechanics</a> and <a href="Petroleum_engineering" title="Petroleum engineering">petroleum engineering</a> the <b>water saturation</b> or <b>degree of saturation</b>, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S_{w}}">

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<annotation encoding="application/x-tex">{\displaystyle S_{w}}</annotation>

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</math></span><img src="./727e2945c3e0a54e22c86ed12ec1205a358961a7.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.834ex; height:2.509ex;" alt="{\displaystyle S_{w}}" loading="lazy"></span>, is defined as

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<annotation encoding="application/x-tex">{\displaystyle S_{w}={\frac {V_{w}}{V_{v}}}={\frac {V_{w}}{V\phi }}={\frac {\theta }{\phi }}}</annotation>

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</math></span><img src="./6911e4ffb5154563c08e6c58e70b1170d33c5d14.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:21.96ex; height:5.843ex;" alt="{\displaystyle S_{w}={\frac {V_{w}}{V_{v}}}={\frac {V_{w}}{V\phi }}={\frac {\theta }{\phi }}}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi =V_{v}/V}">

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<annotation encoding="application/x-tex">{\displaystyle \phi =V_{v}/V}</annotation>

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</math></span><img src="./4c9ccb2db6bcacdc3bb8fa33108cc9dd5f8169c2.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:9.818ex; height:2.843ex;" alt="{\displaystyle \phi =V_{v}/V}" loading="lazy"></span> is the <a href="Porosity" title="Porosity">porosity</a>, in terms of the volume of void or pore space <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{v}}">

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<annotation encoding="application/x-tex">{\displaystyle V_{v}}</annotation>

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</math></span><img src="./cd10bf605dca1100ddb95dd0a175b020a756d9bd.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.385ex; height:2.509ex;" alt="{\displaystyle V_{v}}" loading="lazy"></span> and the total volume of the substance <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V}">

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<annotation encoding="application/x-tex">{\displaystyle V}</annotation>

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</math></span><img src="./af0f6064540e84211d0ffe4dac72098adfa52845.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.787ex; height:2.176ex;" alt="{\displaystyle V}" loading="lazy"></span>. Values of <i>S<sub>w</sub></i> can range from 0 (dry) to 1 (saturated). In reality, <i>S<sub>w</sub></i> never reaches 0 or 1 - these are idealizations for engineering use.

</p><p>The <b>normalized water content</b>, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Theta }">

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<annotation encoding="application/x-tex">{\displaystyle \Theta }</annotation>

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</math></span><img src="./bc927b19f46d005b4720db7a0f96cd5b6f1a0d9b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.808ex; height:2.176ex;" alt="{\displaystyle \Theta }" loading="lazy"></span>, (also called <b>effective saturation</b> or <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S_{e}}">

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<annotation encoding="application/x-tex">{\displaystyle S_{e}}</annotation>

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</math></span><img src="./3c116b38a936976c554aaf49bddf5c6476313dab.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.423ex; height:2.509ex;" alt="{\displaystyle S_{e}}" loading="lazy"></span>) is a dimensionless value defined by van Genuchten<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> as:

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<annotation encoding="application/x-tex">{\displaystyle \Theta ={\frac {\theta -\theta _{r}}{\theta _{s}-\theta _{r}}}}</annotation>

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</math></span><img src="./c87e5d62f4fe9a6ad1c527387ed6c00b5188d05b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:12.741ex; height:5.843ex;" alt="{\displaystyle \Theta ={\frac {\theta -\theta _{r}}{\theta _{s}-\theta _{r}}}}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }">

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<annotation encoding="application/x-tex">{\displaystyle \theta }</annotation>

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</math></span><img src="./6e5ab2664b422d53eb0c7df3b87e1360d75ad9af.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }" loading="lazy"></span> is the volumetric water content; <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta _{r}}">

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<annotation encoding="application/x-tex">{\displaystyle \theta _{r}}</annotation>

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</math></span><img src="./8150e6ff5705574752b8a69aa3da335179961b5e.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.064ex; height:2.509ex;" alt="{\displaystyle \theta _{r}}" loading="lazy"></span> is the residual water content, defined as the water content for which the gradient <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d\theta /dh}">

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<annotation encoding="application/x-tex">{\displaystyle d\theta /dh}</annotation>

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</math></span><img src="./b8bc981715e70f8443e4ba65ab1615b4e04db350.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:6.024ex; height:2.843ex;" alt="{\displaystyle d\theta /dh}" loading="lazy"></span> becomes zero; and, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta _{s}}">

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<annotation encoding="application/x-tex">{\displaystyle \theta _{s}}</annotation>

</semantics>

</math></span><img src="./835141623ca41c8deb23ca33ec7e84a858566b57.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.094ex; height:2.509ex;" alt="{\displaystyle \theta _{s}}" loading="lazy"></span> is the saturated water content, which is equivalent to porosity, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \phi }</annotation>

</semantics>

</math></span><img src="./72b1f30316670aee6270a28334bdf4f5072cdde4.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.385ex; height:2.509ex;" alt="{\displaystyle \phi }" loading="lazy"></span>.

</p>

<div class="mw-heading mw-heading2"><h2 id="Measurement">Measurement</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Direct_methods">Direct methods</h3></div>

<p>Water content can be directly measured using a drying <a href="Oven" title="Oven">oven</a>.

The <b>oven-dry method</b> requires drying a sample (of soil, wood, etc.) in a special oven or kiln and checking the sample weight at regular time intervals. When the drying process is complete, the sample's weight is compared to its weight before drying, and the difference is used to calculate the sample's original moisture content.

</p><p>Gravimetric water content, <i>u</i>, is calculated<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> via the mass of water <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{w}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle m_{w}}</annotation>

</semantics>

</math></span><img src="./1bd173f48c4afc862b28f62d46b4ff220e64f016.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.449ex; height:2.009ex;" alt="{\displaystyle m_{w}}" loading="lazy"></span>:

</p>

<msub>

</mrow>

</msub>

<msub>

</mrow>

</msub>

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle m_{w}=m_{\text{wet}}-m_{\text{dry}}}</annotation>

</semantics>

</math></span><img src="./fcd5780006840c7cdf0fd8301e1bc91c386c128d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:18.916ex; height:2.676ex;" alt="{\displaystyle m_{w}=m_{\text{wet}}-m_{\text{dry}}}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{\text{wet}}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle m_{\text{wet}}}</annotation>

</semantics>

</math></span><img src="./191c7bfb693352fc5db41d214bba7201000ed92a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:4.829ex; height:2.009ex;" alt="{\displaystyle m_{\text{wet}}}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{\text{dry}}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle m_{\text{dry}}}</annotation>

</semantics>

</math></span><img src="./6aefb795a1564d26ebcc65c705e80b5fca497f79.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:4.699ex; height:2.343ex;" alt="{\displaystyle m_{\text{dry}}}" loading="lazy"></span> are the <a href="Mass" title="Mass">masses</a> of the sample before and after drying in the oven.

This gives the numerator of <i>u</i>; the denominator is either <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{\text{wet}}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle m_{\text{wet}}}</annotation>

</semantics>

</math></span><img src="./191c7bfb693352fc5db41d214bba7201000ed92a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:4.829ex; height:2.009ex;" alt="{\displaystyle m_{\text{wet}}}" loading="lazy"></span> or <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{\text{dry}}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle m_{\text{dry}}}</annotation>

</semantics>

</math></span><img src="./6aefb795a1564d26ebcc65c705e80b5fca497f79.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:4.699ex; height:2.343ex;" alt="{\displaystyle m_{\text{dry}}}" loading="lazy"></span> (resulting in <i>u'</i> or <i>u"</i>, respectively), depending on the discipline.

</p><p>On the other hand, volumetric water content, <i>θ</i>, is calculated<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> via the volume of water <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{w}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle V_{w}}</annotation>

</semantics>

</math></span><img src="./8b3417115633747e6616d838e82fdcb92f1e76cb.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.764ex; height:2.509ex;" alt="{\displaystyle V_{w}}" loading="lazy"></span>:

</p>

<msub>

</mrow>

</msub>

<mfrac>

<msub>

</mrow>

</msub>

<msub>

</mrow>

</msub>

</mfrac>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle V_{w}={\frac {m_{w}}{\rho _{w}}}}</annotation>

</semantics>

</math></span><img src="./cc7099396dada4bdbb49c66252d97f039b67ac1e.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:10.148ex; height:5.176ex;" alt="{\displaystyle V_{w}={\frac {m_{w}}{\rho _{w}}}}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho _{w}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \rho _{w}}</annotation>

</semantics>

</math></span><img src="./3ba05ad86dbe23f819d2b17a77fd2187e98251f8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:2.611ex; height:2.176ex;" alt="{\displaystyle \rho _{w}}" loading="lazy"></span> is the <a href="Density_of_water" class="mw-redirect" title="Density of water">density of water</a>.

This gives the numerator of <i>θ</i>; the denominator, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{\text{wet}}}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle V_{\text{wet}}}</annotation>

</semantics>

</math></span><img src="./3c63032d49d565834c3deea4cc88439e3ccfa04c.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:4.144ex; height:2.509ex;" alt="{\displaystyle V_{\text{wet}}}" loading="lazy"></span>, is the total volume of the wet material, which is fixed by simply filling up a container of known volume (e.g., a <a href="Tin_can" class="mw-redirect" title="Tin can">tin can</a>) when taking a sample.

</p><p>For <a href="Wood" title="Wood">wood</a>, the convention is to report moisture content on oven-dry basis (i.e. generally drying sample in an oven set at 105 deg Celsius for 24 hours or until it stops losing weight). In <a href="Wood_drying" title="Wood drying">wood drying</a>, this is an important concept.

</p>

<div class="mw-heading mw-heading3"><h3 id="Laboratory_methods">Laboratory methods</h3></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Moisture_analysis" title="Moisture analysis">Moisture analysis</a></div>

<p>Other methods that determine water content of a sample include chemical <a href="Titration" title="Titration">titrations</a> (for example the <a href="Karl_Fischer_titration" title="Karl Fischer titration">Karl Fischer titration</a>), determining mass loss on heating (perhaps in the presence of an inert gas), or after <a href="Freeze_drying" title="Freeze drying">freeze drying</a>. In the food industry the <a href="Dean-Stark_apparatus" class="mw-redirect" title="Dean-Stark apparatus">Dean-Stark method</a> is also commonly used.

</p><p>From the Annual Book of <a href="ASTM" class="mw-redirect" title="ASTM">ASTM</a> (American Society for Testing and Materials) Standards, the total evaporable moisture content in Aggregate (C 566) can be calculated with the formula:

</p>

<mfrac>

<mrow>

</mrow>

</mfrac>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle p={\frac {W-D}{W}}}</annotation>

</semantics>

</math></span><img src="./4c2b7e0af40a1fcb8d6b10ab01ff3d9d649bff9b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; margin-left: -0.089ex; width:12.393ex; height:5.343ex;" alt="{\displaystyle p={\frac {W-D}{W}}}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle p}</annotation>

</semantics>

</math></span><img src="./81eac1e205430d1f40810df36a0edffdc367af36.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; margin-left: -0.089ex; width:1.259ex; height:2.009ex;" alt="{\displaystyle p}" loading="lazy"></span> is the fraction of total evaporable moisture content of sample, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle W}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle W}</annotation>

</semantics>

</math></span><img src="./54a9c4c547f4d6111f81946cad242b18298d70b7.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.435ex; height:2.176ex;" alt="{\displaystyle W}" loading="lazy"></span> is the mass of the original sample, and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle D}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle D}</annotation>

</semantics>

</math></span><img src="./f34a0c600395e5d4345287e21fb26efd386990e6.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.924ex; height:2.176ex;" alt="{\displaystyle D}" loading="lazy"></span> is mass of dried sample.

</p>

<div class="mw-heading mw-heading3"><h3 id="Soil_moisture_measurement">Soil moisture measurement</h3></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="Soil_moisture" title="Soil moisture">Soil moisture</a></div>

<p>In addition to the direct and laboratory methods above, the following options are available.

</p>

<div class="mw-heading mw-heading4"><h4 id="Geophysical_methods">Geophysical methods</h4></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="Soil_moisture_sensors" class="mw-redirect" title="Soil moisture sensors">Soil moisture sensors</a></div>

<p>There are several <a href="Geophysics" title="Geophysics">geophysical</a> methods available that can approximate <i>in situ</i> soil water content. These methods include: <a href="Time-domain_reflectometry" class="mw-redirect" title="Time-domain reflectometry">time-domain reflectometry</a> (TDR), <a href="Neutron_probe" title="Neutron probe">neutron probe</a>, <a href="Frequency_domain_sensor" title="Frequency domain sensor">frequency domain sensor</a>, <a href="Capacitance_probe" title="Capacitance probe">capacitance probe</a>, <a href="Amplitude_Domain_Reflectometry_(ADR)" class="mw-redirect" title="Amplitude Domain Reflectometry (ADR)">amplitude domain reflectometry</a>, <a href="Electrical_resistivity_tomography" title="Electrical resistivity tomography">electrical resistivity tomography</a>, <a href="Ground_penetrating_radar" class="mw-redirect" title="Ground penetrating radar">ground penetrating radar</a> (GPR), and others that are sensitive to the <a href="Water_(molecule)" class="mw-redirect" title="Water (molecule)">physical properties of water</a> .<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Geophysical sensors are often used to monitor soil moisture continuously in agricultural and scientific applications.

</p>

<div class="mw-heading mw-heading4"><h4 id="Satellite_remote_sensing_method">Satellite remote sensing method</h4></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="Remote_sensing" title="Remote sensing">Remote sensing</a></div>

<p>Satellite microwave remote sensing is used to estimate soil moisture based on the large contrast between the dielectric properties of wet and dry soil. The microwave radiation is not sensitive to atmospheric variables, and can penetrate through clouds. Also, microwave signal can penetrate, to a certain extent, the vegetation canopy and retrieve information from ground surface.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> The data from microwave remote sensing satellites such as WindSat, AMSR-E, RADARSAT, ERS-1-2, Metop/ASCAT, and SMAP are used to estimate surface soil moisture.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading3"><h3 id="Wood_moisture_measurement">Wood moisture measurement</h3></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="Moisture_meter" title="Moisture meter">Moisture meter</a></div>

<p>In addition to the primary methods above, another method exists to measure the moisture content of wood: an electronic <i><a href="Moisture_meter" title="Moisture meter">moisture meter</a></i>.

Pin and pinless meters are the two main types of moisture meters.

</p><p>Pin meters require driving two pins into the surface of the wood while making sure that the pins are aligned with the grain and not perpendicular to it. Pin meters provide moisture content readings by measuring the resistance in the electrical current between the two pins. The drier the wood, the more resistance to the electrical current, when measuring below the fiber saturation point of wood. Pin meters are generally preferred when there is no flat surface of the wood available to measure

</p><p>Pinless meters emit an electromagnetic signal into the wood to provide readings of the wood's moisture content and are generally preferred when damage to the wood's surface is unacceptable or when a high volume of readings or greater ease of use is required.

</p>

<div class="mw-heading mw-heading2"><h2 id="Classification_and_uses">Classification and uses</h2></div>

<p>Moisture may be present as adsorbed moisture at internal surfaces and as capillary condensed water in small pores. At low relative humidities, moisture consists mainly of adsorbed water. At higher relative humidities, liquid water becomes more and more important, depending or not depending on the pore size can also be an influence of volume. In wood-based materials, however, almost all water is adsorbed at humidities below 98% RH.

</p><p>In biological applications there can also be a distinction between physisorbed water and "free" water — the physisorbed water being that closely associated with and relatively difficult to remove from a biological material. The method used to determine water content may affect whether water present in this form is accounted for. For a better indication of "free" and "bound" water, the <a href="Water_activity" title="Water activity">water activity</a> of a material should be considered.

</p><p>Water molecules may also be present in materials closely associated with individual molecules, as "water of crystallization", or as water molecules which are static components of protein structure.

</p>

<div class="mw-heading mw-heading3"><h3 id="Earth_and_agricultural_sciences">Earth and agricultural sciences</h3></div>

<p>In <a href="Soil_science" title="Soil science">soil science</a>, <a href="Hydrology" title="Hydrology">hydrology</a> and <a href="Agricultural_science" title="Agricultural science">agricultural sciences</a>, water content has an important role for <a href="Groundwater_recharge" title="Groundwater recharge">groundwater recharge</a>, <a href="Agriculture" title="Agriculture">agriculture</a>, and <a href="Soil_chemistry" title="Soil chemistry">soil chemistry</a>. Many recent scientific research efforts have aimed toward a predictive-understanding of water content over space and time. Observations have revealed generally that spatial variance in water content tends to increase as overall wetness increases in semiarid regions, to decrease as overall wetness increases in humid regions, and to peak under intermediate wetness conditions in temperate regions .<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup>

</p><p>There are four standard water contents that are routinely measured and used, which are described in the following table:

</p>

<th>Name

</th>

<th>Notation

</th>

<th>Suction pressure<br>(J/kg or kPa)

</th>

<th>Typical water content<br>(vol/vol)

</th>

<th>Conditions

</th></tr>

<tr>

<td>Saturated water content

</td>

</td>

<td align="right">0

</td>

<td align="center">0.2–0.5

</td>

<td>Fully saturated soil, equivalent to <a href="Effective_porosity" title="Effective porosity">effective porosity</a>

</td></tr>

<tr>

<td><a href="Field_capacity" title="Field capacity">Field capacity</a>

</td>

</td>

<td align="right">−33

</td>

<td align="center">0.1–0.35

</td>

<td>Soil moisture 2–3 days after a rain or irrigation

</td></tr>

<tr>

<td><a href="Permanent_wilting_point" title="Permanent wilting point">Permanent wilting point</a>

</td>

</td>

<td align="right">−1500

</td>

<td align="center">0.01–0.25

</td>

<td>Minimum soil moisture at which a plant wilts

</td></tr>

<tr>

<td>Residual water content

</td>

</td>

<td align="right">−∞

</td>

<td align="center">0.001–0.1

</td>

<td>Remaining water at high tension

</td></tr></tbody></table>

<p>And lastly the <a href="Available_water_capacity" title="Available water capacity">available water content</a>, θ<sub>a</sub>, which is equivalent to:

</p>

<p>which can range between 0.1 in <a href="Gravel" title="Gravel">gravel</a> and 0.3 in <a href="Peat" title="Peat">peat</a>.

</p>

<div class="mw-heading mw-heading4"><h4 id="Agriculture">Agriculture</h4></div>

<p>When a soil becomes too dry, plant <a href="Transpiration" title="Transpiration">transpiration</a> drops because the water is increasingly bound to the soil particles by suction. Below the <a href="Wilting_point" class="mw-redirect" title="Wilting point">wilting point</a> plants are no longer able to extract water. At this point they wilt and cease transpiring altogether. Conditions where soil is too dry to maintain reliable plant growth is referred to as <a href="Agriculture" title="Agriculture">agricultural</a> <a href="Drought" title="Drought">drought</a>, and is a particular focus of <a href="Irrigation" title="Irrigation">irrigation</a> management. Such conditions are common in <a href="Arid" class="mw-redirect" title="Arid">arid</a> and <a href="Semi-arid" class="mw-redirect" title="Semi-arid">semi-arid</a> environments.

</p><p>Some agriculture professionals are beginning to use environmental measurements such as soil moisture to schedule <a href="Irrigation" title="Irrigation">irrigation</a>. This method is referred to as <i>smart irrigation</i> or <i>soil cultivation</i>.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading4"><h4 id="Groundwater">Groundwater</h4></div>

<p>In saturated <a href="Groundwater" title="Groundwater">groundwater</a> <a href="Aquifer" title="Aquifer">aquifers</a>, all available <a href="Porosity" title="Porosity">pore</a> spaces are filled with water (volumetric water content = <a href="Porosity" title="Porosity">porosity</a>). Above a <a href="Capillary_fringe" title="Capillary fringe">capillary fringe</a>, pore spaces have air in them too.

</p><p>Most soils have a water content less than porosity, which is the definition of unsaturated conditions, and they make up the subject of <a href="Vadose_zone" title="Vadose zone">vadose zone</a> hydrogeology. The <a href="Capillary_fringe" title="Capillary fringe">capillary fringe</a> of the <a href="Water_table" title="Water table">water table</a> is the dividing line between <a href="Aquifer#Saturated_versus_unsaturated" title="Aquifer">saturated and unsaturated</a> conditions. Water content in the capillary fringe decreases with increasing distance above the <a href="Phreatic" title="Phreatic">phreatic</a> surface. The flow of water through and unsaturated zone in soils often involves a process of fingering, resulting from <a href="Saffman%E2%80%93Taylor_instability" title="Saffman–Taylor instability">Saffman–Taylor instability</a>. This results mostly through <a href="Drainage" class="mw-redirect" title="Drainage">drainage</a> processes and produces and unstable interface between saturated and unsaturated regions.

</p><p>One of the main complications which arises in studying the vadose zone, is the fact that the unsaturated hydraulic conductivity is a function of the water content of the material. As a material dries out, the connected wet pathways through the media become smaller, the hydraulic conductivity decreasing with lower water content in a very non-linear fashion.

</p><p>A <a href="Water_retention_curve" title="Water retention curve">water retention curve</a> is the relationship between volumetric water content and the <a href="Water_potential" title="Water potential">water potential</a> of the porous medium. It is characteristic for different types of porous medium. Due to <a href="Hysteresis" title="Hysteresis">hysteresis</a>, different wetting and drying curves may be distinguished.

</p>

<div class="mw-heading mw-heading2"><h2 id="In_aggregates">In aggregates</h2></div>

<p>Generally, an aggregate has four different moisture conditions. They are Oven-dry (OD), Air-dry (AD), <a href="Saturated-surface-dry" title="Saturated-surface-dry">Saturated surface dry (SSD)</a> and damp (or wet).<sup id="cite_ref-:0_11-0" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Oven-dry and Saturated surface dry can be achieved by experiments in laboratories, while Air-dry and damp (or wet) are aggregates' common conditions in nature.

</p>

<div class="mw-heading mw-heading3"><h3 id="Four_Conditions">Four Conditions</h3></div>

<ul><li><b>Oven-dry</b> (OD) is defined as the condition of an aggregate where there is no moisture within any part of the aggregate. This condition can be achieved in a laboratory by heating the aggregate to 220 °F (105 °C) for a period of time.<sup id="cite_ref-:0_11-1" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></li>

<li><b>Air-dry</b> (AD) is defined as the condition of an aggregate in which there are some water or moisture in the pores of the aggregate, while the outer surfaces of it is dry. This is a natural condition of aggregates in summer or in dry regions. In this condition, an aggregate will absorb water from other materials added to the surface of it, which would possibly have some impact on some characters of the aggregate.<sup id="cite_ref-:0_11-2" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></li>

<li><b>Saturated surface dry</b> (SSD) is defined as the condition of an <a href="Aggregate_(composite)" title="Aggregate (composite)">aggregate</a> in which the surfaces of the particles are "dry" (<i>i.e.</i>, they will neither absorb any of the mixing water added; nor will they contribute any of their contained water to the mix<sup id="cite_ref-:0_11-3" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup>), but the <a href="Porosity" title="Porosity">inter-particle voids</a> are saturated with water. In this condition aggregates will not affect the free water content of a <a href="Composite_material" title="Composite material">composite material</a>.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup></li></ul>

<p>The water adsorption by mass (A<sub>m</sub>) is defined in terms of the mass of saturated-surface-dry (M<sub>ssd</sub>) sample and the mass of oven dried test sample (M<sub>dry</sub>) by the formula:

</p>

<mfrac>

<mrow>

<msub>

</mrow>

</msub>

<msub>

</mrow>

</msub>

</mrow>

<msub>

</mrow>

</msub>

</mfrac>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle A={\frac {M_{ssd}-M_{dry}}{M_{dry}}}}</annotation>

</semantics>

</math></span><img src="./a894bc2e337ac84c14bed280b091ed9b4c487bbe.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:18.311ex; height:6.176ex;" alt="{\displaystyle A={\frac {M_{ssd}-M_{dry}}{M_{dry}}}}" loading="lazy"></span></dd></dl>

<ul><li><b>Damp</b> (or wet) is defined as the condition of an aggregate in which water is fully permeated the aggregate through the pores in it, and there is free water in excess of the SSD condition on its surfaces which will become part of the mixing water.<sup id="cite_ref-:0_11-4" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></li></ul>

<div class="mw-heading mw-heading3"><h3 id="Application">Application</h3></div>

<p>Among these four moisture conditions of aggregates, saturated surface dry is the condition that has the most applications in laboratory experiments, research, and studies, especially those related to water absorption, composition ratio, or shrinkage tests in materials like concrete. For many related experiments, a saturated surface dry condition is a premise that must be realized before the experiment. In saturated surface dry conditions, the aggregate's water content is in a relatively stable and static situation where its environment would not affect it. Therefore, in experiments and tests where aggregates are in saturated surface dry condition, there would be fewer disrupting factors than in the other three conditions.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup>

</p>

<ul><li><a href="Humidity" title="Humidity">Humidity</a>, "water content" in air</li>

<li><a href="Moisture" title="Moisture">Moisture</a></li>

<li><a href="Viscous_fingering" class="mw-redirect" title="Viscous fingering">Viscous fingering</a></li>

<li><a href="Moisture_analysis" title="Moisture analysis">Moisture analysis</a></li>

<li><a href="Soil_moisture_sensors" class="mw-redirect" title="Soil moisture sensors">Soil moisture sensors</a></li>

<li><a href="Water_activity" title="Water activity">Water activity</a></li>

<li><a href="Water_retention_curve" title="Water retention curve">Water retention curve</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div>

<ul><li><cite id="CITEREFRobinson2008" class="citation cs2">Robinson, David A. (2008), <a rel="nofollow" class="external text" href="http://www-pub.iaea.org/mtcd/publications/pdf/tcs-30_web.pdf">"Field Estimation of Soil Water Content: A Practical Guide to Methods, Instrumentation and Sensor Technology"</a> <span class="cs1-format">(PDF)</span>, <i>Soil Science Society of America Journal</i>, <b>73</b> (4), Vienna, Austria: International Atomic Energy Agency: 131, <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2009SSASJ..73.1437R">2009SSASJ..73.1437R</a>, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2136%2Fsssaj2008.0016br">10.2136/sssaj2008.0016br</a>, <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1018-5518">1018-5518</a>, IAEA-TCS-30</cite></li>

<li><a rel="nofollow" class="external text" href="https://www.schweizerbart.de/9783443011093">Wessel-Bothe, Weihermüller (2020): Field Measurement Methods in Soil Science.</a> New practical guide to soil measurements explains the principles of operation of different moisture sensor types (independent of manufacturer), their accuracy, fields of application and how such sensors are installed, as well as subtleties of the data so obtained. Also deals with other crop-related soil parameters.</li></ul>

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</style><div id="Physical_aquifer_properties_used_in_hydrogeology56" style="font-size:114%;margin:0 4em">Physical <a href="Aquifer" title="Aquifer">aquifer</a> properties used in <a href="Hydrogeology" title="Hydrogeology">hydrogeology</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Hydraulic_head" title="Hydraulic head">hydraulic head</a></li>

<li><a href="Hydraulic_conductivity" title="Hydraulic conductivity">hydraulic conductivity</a></li>

<li><a href="Specific_storage" title="Specific storage">storativity</a></li>

<li><a href="Permeability_(earth_sciences)" class="mw-redirect" title="Permeability (earth sciences)">permeability</a></li>

<li><a href="Porosity" title="Porosity">porosity</a></li>

</ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Geotechnical_engineering316" style="padding:3px"><table class="nowraplinks mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Geotechnical_engineering316" style="font-size:114%;margin:0 4em"><a href="Geotechnical_engineering" title="Geotechnical engineering">Geotechnical engineering</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div><a href="Offshore_geotechnical_engineering" title="Offshore geotechnical engineering">Offshore geotechnical engineering</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Geotechnical_investigation" title="Geotechnical investigation">Investigation</a> <br>and<br>instrumentation</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;">Field (<i>in situ</i>)</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"><div class="div-col" style="column-width: 33em;">

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Core_drill" title="Core drill">Core drill</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Cone_penetration_test" title="Cone penetration test">Cone penetration test</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> Geo-electrical sounding</li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Permeability_(Earth_sciences)" class="mw-redirect" title="Permeability (Earth sciences)">Permeability test</a></li></ul>

<ul><li><a href="Static_load_testing" title="Static load testing">Static</a></li>

<li><a href="Dynamic_load_testing" title="Dynamic load testing">Dynamic</a></li>

<li><a href="Statnamic_load_test" title="Statnamic load test">Statnamic</a></li></ul></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> Pore pressure measurement

<ul><li><a href="Piezometer" class="mw-redirect" title="Piezometer">Piezometer</a></li>

<ul><li><span class="noviewer" typeof="mw:File"></span> Ram sounding</li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> Rock control drilling</li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Rotary-pressure_sounding" title="Rotary-pressure sounding">Rotary-pressure sounding</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> Rotary weight sounding</li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Soil_test#Soil_testing" title="Soil test">Sample series</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> Screw plate test</li></ul>

<ul><li><a href="Deformation_monitoring" title="Deformation monitoring">Deformation monitoring</a>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Inclinometer" title="Inclinometer">Inclinometer</a></li>

<li><span class="noviewer" typeof="mw:File"></span> <a href="Soil_consolidation" title="Soil consolidation">Settlement recordings</a></li></ul></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Shear_vane_test" title="Shear vane test">Shear vane test</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> Simple sounding</li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Standard_penetration_test" title="Standard penetration test">Standard penetration test</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Total_sounding" title="Total sounding">Total sounding</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Trial_pit" title="Trial pit">Trial pit</a></li></ul>

<ul><li><span class="noviewer" typeof="mw:File"></span> <a href="Bedrock" title="Bedrock">Visible bedrock</a></li></ul>

<ul><li><a href="Nuclear_densometer" class="mw-redirect" title="Nuclear densometer">Nuclear densometer test</a></li></ul>

<ul><li><a href="Exploration_geophysics" title="Exploration geophysics">Exploration geophysics</a></li></ul>

<ul><li><a href="Crosshole_sonic_logging" title="Crosshole sonic logging">Crosshole sonic logging</a></li></ul>

<ul><li><a href="Pile_integrity_test" title="Pile integrity test">Pile integrity test</a></li></ul>

<ul><li><a href="Wave_equation_analysis" title="Wave equation analysis">Wave equation analysis</a></li></ul></div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;"><a href="Soil_test" title="Soil test">Laboratory <br>testing</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<li><a href="Soil_classification" title="Soil classification">Soil classification</a></li>

<li><a href="Atterberg_limits" title="Atterberg limits">Atterberg limits</a></li>

<li><a href="California_bearing_ratio" title="California bearing ratio">California bearing ratio</a></li>

<li><a href="Direct_shear_test" title="Direct shear test">Direct shear test</a></li>

<li><a href="Hydrometer" title="Hydrometer">Hydrometer</a></li>

<li><a href="Proctor_compaction_test" title="Proctor compaction test">Proctor compaction test</a></li>

<li><a href="R-value_(soils)" title="R-value (soils)">R-value</a></li>

<li><a href="Sieve_analysis" title="Sieve analysis">Sieve analysis</a></li>

<li><a href="Triaxial_shear_test" title="Triaxial shear test">Triaxial shear test</a></li>

<li><a href="Oedometer_test" title="Oedometer test">Oedometer test</a></li>

<li><a href="Hydraulic_conductivity#Experimental_approach" title="Hydraulic conductivity">Hydraulic conductivity tests</a></li>

<li><a class="mw-selflink-fragment" href="#Measurement">Water content tests</a></li>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Soil" title="Soil">Soil</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;">Types</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<li><a href="Gravel" title="Gravel">Gravel</a></li>

<li><a href="Loess" title="Loess">Loess</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;">Properties</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Hydraulic_conductivity" title="Hydraulic conductivity">Hydraulic conductivity</a></li>

<li><a href="Void_ratio" title="Void ratio">Void ratio</a></li>

<li><a href="Bulk_density" title="Bulk density">Bulk density</a></li>

<li><a href="Thixotropy" title="Thixotropy">Thixotropy</a></li>

<li><a href="Reynolds'_dilatancy" class="mw-redirect" title="Reynolds' dilatancy">Reynolds' dilatancy</a></li>

<li><a href="Angle_of_repose" title="Angle of repose">Angle of repose</a></li>

<li><a href="Friction#Angle_of_friction" title="Friction">Friction angle</a></li>

<li><a href="Cohesion_(geology)" title="Cohesion (geology)">Cohesion</a></li>

<li><a href="Porosity" title="Porosity">Porosity</a></li>

<li><a href="Permeability_(earth_sciences)" class="mw-redirect" title="Permeability (earth sciences)">Permeability</a></li>

<li><a href="Specific_storage" title="Specific storage">Specific storage</a></li>

<li><a href="Shear_strength_(soil)" title="Shear strength (soil)">Shear strength</a></li>

<li><a href="Soil_liquefaction" title="Soil liquefaction">Sensitivity</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Structures <br>(<a href="Soil-structure_interaction" title="Soil-structure interaction">Interaction</a>)</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;">Natural features</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Topography" title="Topography">Topography</a></li>

<li><a href="Vegetation" title="Vegetation">Vegetation</a></li>

<li><a href="Terrain" title="Terrain">Terrain</a></li>

<li><a href="Topsoil" title="Topsoil">Topsoil</a></li>

<li><a href="Water_table" title="Water table">Water table</a></li>

<li><a href="Bedrock" title="Bedrock">Bedrock</a></li>

<li><a href="Subgrade" title="Subgrade">Subgrade</a></li>

<li><a href="Subsoil" title="Subsoil">Subsoil</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;"><a href="Earthworks_(engineering)" title="Earthworks (engineering)">Earthworks</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<ul><li>Shoring structures

<ul><li><a href="Retaining_wall" title="Retaining wall">Retaining walls</a></li>

<li><a href="Gabion" title="Gabion">Gabion</a></li>

<li><a href="Ground_freezing" title="Ground freezing">Ground freezing</a></li>

<li><a href="Mechanically_stabilized_earth" title="Mechanically stabilized earth">Mechanically stabilized earth</a></li>

<li><a href="Pressure_grouting" title="Pressure grouting">Pressure grouting</a></li>

<li><a href="Slurry_wall" title="Slurry wall">Slurry wall</a></li>

<li><a href="Soil_nailing" title="Soil nailing">Soil nailing</a></li>

<li><a href="Tieback_(geotechnical)" title="Tieback (geotechnical)">Tieback</a></li></ul></li>

<li><a href="Land_development" title="Land development">Land development</a></li>

<li><a href="Landfill" title="Landfill">Landfill</a></li>

<li><a href="Digging" title="Digging">Excavation</a></li>

<li><a href="Trench" title="Trench">Trench</a></li>

<li><a href="Embankment_(earthworks)" title="Embankment (earthworks)">Embankment</a></li>

<li><a href="Causeway" title="Causeway">Causeway</a></li>

<li><a href="Terrace_(earthworks)" title="Terrace (earthworks)">Terracing</a></li>

<li><a href="Tunnel#Cut-and-cover" title="Tunnel">Cut-and-cover</a></li>

<li><a href="Grading_(engineering)" class="mw-redirect" title="Grading (engineering)">Grading</a></li>

<li><a href="Land_reclamation" title="Land reclamation">Land reclamation</a></li>

<li><a href="Track_bed" title="Track bed">Track bed</a></li>

<li><a href="Erosion_control" title="Erosion control">Erosion control</a></li>

<li><a href="Earth_structure" title="Earth structure">Earth structure</a></li>

<li><a href="Expanded_clay_aggregate" title="Expanded clay aggregate">Expanded clay aggregate</a></li>

<li><a href="Crushed_stone" title="Crushed stone">Crushed stone</a></li>

<li><a href="Geosynthetics" title="Geosynthetics">Geosynthetics</a>

<ul><li><a href="Geotextile" title="Geotextile">Geotextile</a></li>

<li><a href="Geomembrane" title="Geomembrane">Geomembrane</a></li>

<li><a href="Geosynthetic_clay_liner" title="Geosynthetic clay liner">Geosynthetic clay liner</a></li>

<li><a href="Cellular_confinement" title="Cellular confinement">Cellular confinement</a></li></ul></li>

<li><a href="Infiltration_(hydrology)" title="Infiltration (hydrology)">Infiltration</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;"><a href="Foundation_(engineering)" title="Foundation (engineering)">Foundations</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Shallow_foundation" title="Shallow foundation">Shallow</a></li>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Soil_mechanics" title="Soil mechanics">Mechanics</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;">Forces</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Effective_stress" title="Effective stress">Effective stress</a></li>

<li><a href="Pore_water_pressure" title="Pore water pressure">Pore water pressure</a></li>

<li><a href="Lateral_earth_pressure" title="Lateral earth pressure">Lateral earth pressure</a></li>

<li><a href="Overburden_pressure" title="Overburden pressure">Overburden pressure</a></li>

<li><a href="Preconsolidation_pressure" title="Preconsolidation pressure">Preconsolidation pressure</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:10.0em;font-weight: normal;">Phenomena/<br>problems</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Permafrost" title="Permafrost">Permafrost</a></li>

<li><a href="Frost_heaving" title="Frost heaving">Frost heaving</a></li>

<li><a href="Consolidation_(soil)" class="mw-redirect" title="Consolidation (soil)">Consolidation</a></li>

<li><a href="Soil_compaction" title="Soil compaction">Compaction</a></li>

<li><a href="Earthquake" title="Earthquake">Earthquake</a>

<ul><li><a href="Response_spectrum" title="Response spectrum">Response spectrum</a></li>

<li><a href="Seismic_hazard" title="Seismic hazard">Seismic hazard</a></li>

<li><a href="S_wave" title="S wave">Shear wave</a></li></ul></li>

<li><a href="Landslide" title="Landslide">Landslide</a> analysis

<ul><li><a href="Slope_stability_analysis" title="Slope stability analysis">Stability analysis</a></li>

<li><a href="Landslide_mitigation" title="Landslide mitigation">Mitigation</a></li>

<li><a href="Landslide_classification" title="Landslide classification">Classification</a></li>

<li><a href="Sliding_criterion_(geotechnical_engineering)" title="Sliding criterion (geotechnical engineering)">Sliding criterion</a></li>

<li><a href="Road#Slab_stabilization" title="Road">Slab stabilisation</a></li></ul></li>

<li><a href="Bearing_capacity" title="Bearing capacity">Bearing capacity</a> * <a href="Stress_distribution_in_soil" title="Stress distribution in soil">Stress distribution in soil</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Software" title="Software">Numerical analysis <br>software</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li>STABL</li>

<li><a href="SVFlux" title="SVFlux">SVFlux</a></li>

<li><a href="SVSlope" title="SVSlope">SVSlope</a></li>

<li><a href="UTEXAS" title="UTEXAS">UTEXAS</a></li>

<li><a href="Plaxis" title="Plaxis">Plaxis</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Geoprofessions" title="Geoprofessions">Related fields</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Geology" title="Geology">Geology</a></li>

<li><a href="Geochemistry" title="Geochemistry">Geochemistry</a></li>

<li><a href="Petrology" title="Petrology">Petrology</a></li>

<li><a href="Earthquake_engineering" title="Earthquake engineering">Earthquake engineering</a></li>

<li><a href="Geomorphology" title="Geomorphology">Geomorphology</a></li>

<li><a href="Soil_science" title="Soil science">Soil science</a></li>

<li><a href="Hydrology" title="Hydrology">Hydrology</a></li>

<li><a href="Hydrogeology" title="Hydrogeology">Hydrogeology</a></li>

<li><a href="Biogeography" title="Biogeography">Biogeography</a></li>

<li><a href="Earth_materials" title="Earth materials">Earth materials</a></li>

<li><a href="Archaeology" title="Archaeology">Archaeology</a></li>

<li><a href="Agricultural_science" title="Agricultural science">Agricultural science</a>

<ul><li><a href="Agrology" class="mw-redirect" title="Agrology">Agrology</a></li></ul></li></ul>

</div></td></tr></tbody></table></div>

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