The study looked at how using a cover crop called hairy vetch, along with mineral nitrogen fertilizer, can help improve crop yields and soil health in different areas of farmland. They found that hairy vetch, when used with the right amount of fertilizer, can help increase crop yields, especially in areas with lower yields. This combination was more effective than just using fertilizer alone. Overall, using hairy vetch and adjusting fertilizer rates based on soil conditions can help boost crop yields, protect the environment, and keep the soil healthy.