How does one go about making Hydrophobic soil?

Question

For a science fair coming up that my school is hosting, my bio teacher asked us if we wanted to take a part in it. Naturally, we all agreed, with our competitivness with other schools in science. We are trying to come up with ideas to try and I would like to know how to cause normal soil to become hydrophobic. I know it has something to do with Phobic acid, and more than natural levels of it, but not much else. Any help? Need to know in the next day or 2 please. Thanks for the help.

Answer 1

the ash coating the soil particles is hydrophobic and this surrounds water drops so they are not adsorbed and they are reluctant to coagulate even with each other

Answer 2

Hydrophobic soil should repel water, it really has nothing to do with a "phobic acid", perhaps you mean humic acid.  Fires in nature cause soil to temporarily become hydrophobic and water runs off rather than soaking  in.

Answer 3

Easy way to get it is to buy it..it's called magic sand

But if you wanna make it you just get some soil, run it through a seive(sp?) to get similar sized particles and then coat it with a hydrophobic material like a fat or lipid or scotchgaurd.