 Felly we've talked about properties or parameters that describe the mass of the soil. Let's talk about properties that describe the liquid phase of the soil. The first parameter that we can define for this is something called the water content. Sometimes also described as the moisture content and it's given the symbol little w. Llywodraeth ychydigau yn ddechrau ddysgrifedigd Gwydraeth Mw, ddechrau Cyfrifiad Llywodraeth Mw. Mae Llywodraeth arall o Gwydraeth a chyfrifiad Llywodraeth. Mae hwn yn gallu i wedi cyfrifiadau arall y rhai, oeddaeth eich rhai, oeddaeth eich rhai, oeddaeth eich cyfrifiad Llywodraeth o Gwydraeth, oeddaeth eich ddysgrifedig, felly yna'r myddwch ei ddysgrifedigol yddyddai'r hyn, a ydych chi'n tyfnol i Ied cuzu'r hyn? water over the total mass of the soil but in this case it would be MS plus Mw and that's wrong it's not the total mass so it's not a fraction of the total mass it's just a ratio between the mass of the water and the mass of the solid so it's not a percentage of the total mass and that's a common misconception so make sure you don't you don't confuse that another parameter to describe the the liquid in a soil there's something called the saturation ratio now what the saturation ratio describes is how much of the volume of the voids so vv in this case how much of the volume of the voids is taken up by the volume of water um so saturation ratio SR is really the volume of the water divided by the volume of the voids so you can see that the as the volume of the water approaches the volume of the voids so this ball grows bigger and bigger this ratio tends towards one so for a fully saturated soil SR would equal one and that's saturated and the inverse is true is SR closer to zero it's dry you have a dry soil and again this is sometimes expressed as a ratio between zero and one or as a percentage so you can just multiply that by 100 and you get SR between zero and 100 so a question that I'd like you to to to read up on or or try and answer is can you get a water content or moisture content of greater than 100 or greater than one if we're just talking about the ratio and in what soils might that might that be possible so earlier we said that the the essentially the dry density was equivalent to the bulk density with the water or the mass of the water removed so you might be left thinking is there a way to to describe bulk density dry density together with water content is there a relationship that that binds these three things together and well the answer is yes there is and you might want to to try and do this yourself first you can use this three phase model so the parameters as described volume and and mass and use those to relate the bulk density dry density and water content into one equation but I'll go through that now you might want to try that yourself first okay so I've wrote the the three relationships out here in terms of their three phase the base unit on the three phase model now the first thing that we can do is remove this this V value this the total volume value by dividing the bulk density by the dry density and we can see that if we do that this V moves on to the top here and it cancels out so what this looks like is if I take the the bulk density and we divide it by the dry density that equals the bulk density divided by the volume so that's the bulk density and divided by the dry density we just multiply the bottom here by ms and multiply the top by V and you can see that both these Vs cancel out so what we're left with is the mass of the water plus the mass of the solid all over the mass of the solid so that's if we take the bulk density and we divide it by the dry density that's what the the relationship looks like in terms of this three phase parameter model well we can separate out the denominator here into the into the top part of the equation so we can rewrite this in terms of just mw over ms plus ms over ms so that's really just separating out these two on the top now what you can see here is this what we've got here is mw over ms which is in fact the water content so we can replace this value here with just w the water content and you can see that we've got ms over ms here which must be one that equals the bulk density over the dry density