Dec 29, 2017 Decomposed Granite 3 Types and Their Best Uses. December 29, 2017 david. Decomposed Granite or DG is a natural byproduct of the weathering and erosion of solid granite rocks. DG is a combination of small granite pieces ( inch or smaller) and fine granite, which can resemble sand. It is like gravel, but finer and more stable. Baytens vineyards, planted on a variety of ancient decomposed granite soils, are dry farmed, with an average yield of five tons per hectare. The farm embraces a variety of holistic farming practices, and even allows free running baboons to perform a natural green cropping of sorts.