The study looked at how reducing nitrogen fertilizer while returning straw to the soil affects crop yields and soil health in a wheat-maize rotation system. They tested different nitrogen levels over four years and found that a 15% reduction increased crop yields without affecting soil carbon or active organic carbon. A 30% reduction did not decrease yields either. The soil's nitrate nitrogen levels decreased with nitrogen reduction, showing that less nitrogen can be used without harming crop production. Overall, reducing nitrogen fertilizer with straw returning can boost soil health by increasing organic carbon and decreasing nitrate nitrogen accumulation.