50% water crystals 50% dirt, is clearly not good. from what I can see. you end up with dirt still wet but 25% smaller because the water crystals stay wet but shrink. so I would try putting like 10% water crystals 90% soil. maybe i should run another experiment 5% 10% and 20% water crystals and see what happens.
@adam.ca because your losing seeds mate...I suggest asking Kazza the amount of soil she uses to one nappy and that way try in from there and see how it goes
When I taught in Texas I used fake snow, in the classroom. Someone told me that this is what it was.The kids loved it! I had winter animals in it.