The study looked at how different types of fertilizers affect crop yield and soil health in a region of China. They tested six treatments, including using no fertilizer, chemical fertilizers, organic manure, and a mix of both. The results showed that using a balanced mix of chemical fertilizers and organic manure significantly increased crop yield and soil organic carbon content. The yields of maize and wheat increased by up to 147% compared to using no fertilizer. The study also found that applying chemical fertilizer every other year with straw returning to the field had similar crop yield values with reduced fertilizer use. Overall, the study suggests that a combination of chemical fertilizers and organic manure can improve crop yield and soil health in the long term.