The sand-sized and smaller waste material left from lava gravel is an excellent, highly paramagnetic soil-amendment material, It can be used in potting soils and bed preparation for all landscaping and food crops. Use once a year as a mineral supplement. Can also be used to top dress new sod installations. It increases the water-holding capacity of the soil and increases the paramagnetism. 40 -80 pounds per 1000 square feet. Or 80 - 150 pounds per 1000 square feet for new flowerbeds.