How does temperature or moisture change how fast soil microbes break down food? Decomposer organisms (tiny living things in soil) recycle nutrients by breaking down organic matter. You can measure their speed. Bury carrot pieces in sealed plastic bags with potting soil. Set up one bag as your experimental chamber and one as the control. Change one condition between them. Try different temperatures or wet versus dry soil. You can also test soil from different locations. Weigh the carrots before and after. Cold temperatures slow decomposition. Waterlogged soil may produce a foul smell from anaerobic bacteria (microbes that work without oxygen). These microbes can break down carrots just as fast as aerobic ones.