I guess plant sap in general is probably effective. Manure teas would be good for similar reasons (cowpoo soaked in water makes a very soapy mix - that might just be the washdown mixture used in dairies though).

Adding organic matter (particularly humic acids) is very effective. We just pile tip mulch on at about 30cm thick and let it get digested by worms. Within 6 months our soil has gone from hydrophobic, dead and dusty to rich black, clumping and full of worms. And tip mulch is the cheapest there is.

Another strategy is to water the ground very slowly (drip irrigation is good).

just put a bit of detergent in the water.
i have had no problems, although I imagine you couldnt do it regularly. i have tried it on natives, the vegie patch, succulents etc.
nothing has died so far.

how about some heavy mulching?

i've never used wetting agents or been concerened with drying out but then i do use grey water around the gardens so i expect there is some wetting capacity there, but then i mulch pretty heavily as well.

len

I find saturaid a quick solution to hydrophobia. But I agree getting the organic content up is the long term solution

Molasses is often applied to soils to control some nematodes. It is also thought to increase the decay of organic matter by providing food for micro-organisms. There is a recent theory that Molasses can help assist in the remediation of sodic soils ie. salt affected soils.

I've bought some Hydraflo2 to try out.
Despite mulching I'm finding the soil still drying out in places and not holding water.
So I'll give this stuff, which apparently also contains Osmocote, a go with the mulching, to see what happens.
Will let you know in a month or so.

Over the past 2-3 years I have been observing the instances of hydrophobic soils and trying to make a connection.

In a very large proportion of cases I have noticed that the landscape soil mixes are involved. If you have ever looked closely at these they contain a great deal of organic matter, a small amount of sand but very little or no clay.

The sand particles become coated in a layer of fine organic matter which renders them water repellent once they dry out.

Detergents and all that will no doubt alleviate the situation temporarilly but if you really want to solve the problem then you must permanently increase the clay content of your soil. Clay particles are very hydrophillic or water loving, are very minute and will eventually penetrate and disrupt the coating of organic matter over the sand particles.

I always use granitic sand as a top soil and I never have problems with it becoming water repellent, even when it is bone dry.

So you can either mix your top soil with granitic sand or you can use a product called Volclay Bentonite.

This is pure refined clay that is used a clarifying agent by the wine industry and by farmers to seal leaks in their dams. It comes in 20kg bags and can be rotary hoed into your top soil in much the same way as gypsum.

It is not a partucularly easy product to find however I know of one source in Melbourne and will get it in for people if they wish to try it.

Here is a link that might be useful: Greg's Indigenous Plants & Landscapes