This is a relatively new soil amendment requiring no mining or land destruction to produce. Many growers agree, it's the perfect replacement for perlite. Extremely light weight, it produces the optimum air-filled pore space, water-holding capacity and drainage. Uniquely processed, the rice hulls are steralized by par boiling, giving their name "PBH" (par boiled hulls), steaming and hot air drying. This assures there are no rice kernel residues, weed seeds or diseases. It's now being introduced in a wide variety of growing applications by adding it with peat, coir and bark at the rate of 10-30% of total growing media, so the higher the (PBH) ratio, the lighter the growing media will be, offering better drainage and better root development. It has a pH range of 6.2 to 6.6 and provides less than 1% nitrogen content so fertilize accordingly.