The Andersons formulated Black Gypsum DG with natural chelated gypsum and humic substances. This unique bio-amendment features both a plant-derived carbon source as well as a bio-organic derived source. Sold in 50-pound bags. Black Gypsum DG utilizes Dispersing Granular (DG) technology. With irrigation or precipitation, this technology delivers calcium directly into the soil. It does this without altering soil pH levels. Black Gypsum DG provides several benefits to your plants. In addition to supplying calcium, it also adds sulfur and humate (a rich source of carbon) to the soil. Gypsum also acts as a soil conditioner, loosening hard-packed soil and flushing out harmful salts and excess sodium. For new seedlings, apply at a rate of 6 to 12 pounds per 1,000 square feet. For established trees and shrubs, apply 4-3/5 to 11-1/2 pounds per 1,000 square feet. For established lawns, apply at a rate of 3 to 12 pounds per 1,000 feet. For bulk mixes, use 8 to 12 pounds per cubic yard.