Chick grid? Does ordinary soil do the same work ?
It does if it's sandy soil. We have heavy clay here and they'd struggle to find anything useful in it. So, I used the very small bits from our gravel driveway (it's granite scrap -- same thing they use to make commercial chick grit). Now that they are big enough to range, they can get to the driveway on their own and that's where they go for their grit.