Complex sentence: Some composting textbooks narrowly define composting as being an aerobic form of decompostion, primarily by microbes, but to a general audience composting is used to refer to several different types of biological process.
Split into simpler sentences: Some composting textbooks narrowly define composting as being an aerobic form of decompostion, primarily by microbes. For many people, however, composting is used to refer to several different types of biological process.