In this study, scientists compared how fast organic matter breaks down in shallow and deep soil layers from farmlands in China. They found that although the topsoil breaks down organic matter faster due to having more easily degradable carbon, the deep subsoil layer breaks down carbon more quickly when it gets warmer. This means that deeper soil layers release more carbon as temperatures rise, which is important to consider when predicting how farming practices may impact the amount of carbon released into the air as the climate warms.