Difference between soil Water Holding Capacity and soil pore volume?

I have got confused

I took 100g soil in a funnel with filter paper. poured 100 ml water and collected the drained water in a calibrated cylinder.

Water added in funnel = 100 ml Water collected in cylinder = 39 ml. Water retained by soil = 61ml. Thus soil WHC = 61ml/100g soil

Is this same as Soil Pore volume? If not how should I calculate soil pore volume by water volume method?

• I am not a soil scientist, but the test procedure above would adversely affect the porosity of the soil being tested. If you could have a constrained soil sample, such as a core sample that fits the container exactly, you could gradually add a measured amount a water till the soil was saturated. Alternatively, take a know volume of saturated soil, weigh it, then bake it at a low enough temperature to ensure you don't lose any organic material. Finally weight it again, the weight difference would give the amount of water in the soil of a known volume. – user824 May 1 '19 at 18:39

As Friddy says, if it's not constrained and relatively intact you're going to have issues with pore volume calculations. Generally the saturate-and-dry method, using a soil core, will give you both the water mass and the mass of sediment. Then you'd use the average density of soil (which will depend somewhat on the minerology, and if it's got lots of organic matter--which can be calculated by burning off OM in a 400 C oven) to get at the particle volume. The known volume of the core minus the estimated particle volume would give you the pore volume.

Googling bulk density and particle density should find lots of info on how exactly to do this calculation.