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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #422099
Research Project: Climate-resilient Sustainable Irrigated and Dryland Cropping Systems in the Semi-arid Northern Great Plains

Location: Agricultural Systems Research

Title: Cover cropping with reduced nitrogen fertilization rate enhances soil carbon but not nitrogen in the malt barley-pea rotation

Author
item Sainju, Upendra

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2025
Publication Date: 6/13/2025
Citation: Sainju, U.M. 2025. 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. 89(3):Article e70086. https://doi.org/10.1002/saj2.70086.
DOI: https://doi.org/10.1002/saj2.70086

Interpretive Summary: Soil carbon and nitrogen sequestrations are effective means of mitigating greenhouse gas emissions and climate change. Novel management strategies are needed to enhance carbon and nitrogen sequestrations in dryland soils in arid and semiarid regions. An ARS scientist in Sidney, MT evaluated the effect of winter cover cropping and nitrogen fertilization rate on dryland soil carbon and nitrogen stocks from 2013 to 2019 in the malt barley-pea rotation. He found that reduced nitrogen fertilization rate with cover cropping increased soil carbon stock more than higher nitrogen fertilization rates with or without cover cropping. Soil nitrogen stock increased with cover cropping and increasing N fertilization rate compared with no cover cropping and N fertilization rate. He also reported that soil total carbon was a better measure of carbon sequestration than soil organic carbon in dryland soils, which can reduce cost of soil analysis. These findings can help producers, industrialists, and policy-makers to mitigate greenhouse gas emissions from agroecosystems, claim carbon credits, and reduce the costs of nitrogen fertilization and soil sample analysis.

Technical Abstract: Increased C and N supplied by cover crop and crop residues and N fertilization may enhance soil C and N in the malt barley (Hordeum vulgaris L.)-pea (Pisum sativum L.) rotation. The effect of winter cover cropping (oat [Avena sativa L.] vs. none) and N fertilization rate (0, 40, 50, 60, 70, and 80 kg N ha-1) for malt barley (NR) were evaluated on soil C and N stocks at the 0-120 cm depth from 2013 to 2019 in the dryland malt barley-pea rotation in the US northern Great Plains. Carbon and N stocks were soil total C (STC), soil organic C (SOC), soil inorganic C (SIC), and soil total N (STN). Cover crop C and N were greater for 40 kg N ha-1 than other NRs and crop residue C and N were greater in 2016 than other years. The STC and 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 (p = 0.10). The STC at 0-15 and 15-30 cm was greater at 40 than 50 and 70 kg N ha -1 in 2019. The STN at 15-30 cm increased by 0.004 Mg N ha-1 kg-1 N with cover cropping. The STC, SOC, and STN at 0-15 and 15-30 cm also increased at greater rates from 2013 to 2019 with than without cover cropping. Cover cropping with reduced NR can enhance soil C more than soil N stock at surface layers in the malt-barley pea rotation.