SOIL SPONGE, should be add to the root zone of any planting area. When you water, the loss of water through the soil profile will be reduced by SOIL SPONGE, then released back as required. With SOIL SPONGE added you can reduce the soil depth required, as moisture holding ability is increased. This will reduce soil costs and installation costs. Over a longer period your water usage will be reduced, another saving. SOIL SPONGE is a natural Australian product, very strong and tends not to break down. Forget adding chemical based moisture retention products (that have limited life spans), use SOIL SPONGE it’s ORGANIC.