Cover Cropping with Reduced Nitrogen Fertilization Enhances Soil Carbon but Not Nitrogen Stock

Strategic Insights -

Fresh data from a recent study by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) sheds light on the effects of cover cropping and reduced nitrogen fertilization rate on soil carbon and nitrogen stocks. The research, conducted in the US northern Great Plains, evaluated the impact of oat cover cropping and nitrogen fertilization rates on soil carbon and nitrogen stocks from 2013 to 2019. The study found that cover cropping with reduced nitrogen fertilization rate can enhance soil carbon but not soil nitrogen stock at surface layers in the malt barley-pea rotation.

Key Takeaways:

  • The study evaluated the effect of winter cover cropping (oat vs. none) and N fertilization rate (0, 40, 50, 60, 70, and 80 kg N ha-1) on soil C and N stocks at 0- to 120-cm depth.
  • Carbon and N stocks were significantly higher for 40 kg N ha-1 than other nitrogen rates, and crop residue C and N were greater in 2016 than other years.
  • Soil total C (STC) and soil organic C (SOC) at 0-15 and 15-30 cm increased by 0.02 and 0.06 Mg C ha-1 kg-1 N in 2016 and 2019, respectively.
  • The study concluded that cover cropping with reduced nitrogen fertilization rate can enhance soil C but not soil N stock at surface layers in the malt barley-pea rotation.
  • The research has been peer-reviewed and published in the Soil Science Society of America Journal.

Statistics:

  • Soil total C (STC) and soil organic C (SOC) at 0-15 and 15-30 cm increased by 0.02 and 0.06 Mg C ha-1 kg-1 N in 2016 and 2019, respectively.
  • Carbon and N stocks were significantly higher for 40 kg N ha-1 than other nitrogen rates.
  • Crop residue C and N were greater in 2016 than other years.
  • The study was conducted from 2013 to 2019 in the US northern Great Plains.

Sources:

  • "Cover Cropping With Reduced Nitrogen Fertilization Rate Enhances Soil Carbon but Not Nitrogen In the Malt Barley-pea Rotation," Soil Science Society of America Journal, 2025;89(3).
  • USDA Agricultural Research Service (ARS)
  • Upendra M. Sainju, Northern Plains Agricultural Research Laboratory, Sidney, MT 59270, United States