Chinese agricultural systems have changed a lot in the past 20 years, affecting greenhouse gas emissions and soil carbon storage. A study looked at seven major crop systems in China and found that overall, croplands in China release more carbon than they store. Paddy fields emit a lot of methane, while uplands store carbon in the soil. Changes in crop types and yields can either increase or decrease carbon emissions, depending on the region. To reduce carbon emissions from croplands, it's important to choose the right crops and fertilizers for each area.