Adaptive multi-paddock grazing enhances soil carbon and nitrogen stocks and stabilization through mineral association in southeastern U.S. grazing lands.

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Publisher: Elsevier B.V.
Document Type: Report
Length: 492 words

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Keywords Adaptive multi-paddock grazing; Soil carbon sequestration; Mineral-associated organic matter; Soil nitrogen Highlights * Adaptive multi-paddock grazing (AMP) can increase soil carbon (C) stocks. * We found 13% more soil C on farms under AMP compared to conventional grazing (CG). * In AMP, C shifted to more persistent organic matter, suggesting long-term C storage. * We found 9% more soil nitrogen on farms practicing AMP compared to CG. * Findings show that AMP grazing is a management strategy to sequester C and retain N. Abstract Grassland soils are a large reservoir of soil carbon (C) at risk of loss due to overgrazing in conventional grazing systems. By promoting regenerative grazing management practices that aim to increase soil C storage and soil health, grasslands have the potential to help alleviate rising atmospheric CO.sub.2 as well as sustain grass productivity across a vast area of land. Previous research has shown that rotational grazing, specifically adaptive multi-paddock (AMP) grazing that utilizes short-duration rotational grazing at high stocking densities, can increase soil C stocks in grassland ecosystems, but the extent and mechanisms are unknown. We conducted a large-scale on-farm study on five "across the fence" pairs of AMP and conventional grazing (CG) grasslands covering a spectrum of southeast United States grazing lands. We quantified soil C and nitrogen (N) stocks, their isotopic and Fourier-transform infrared spectroscopy signatures as well as their distribution among soil organic matter (SOM) physical fractions characterized by contrasting mechanisms of formation and persistence in soils. Our findings show that the AMP grazing sites had on average 13% (i.e., 9 Mg C ha.sup.-1) more soil C and 9% (i.e., 1 Mg N ha.sup.-1) more soil N compared to the CG sites over a 1 m depth. Additionally, the stocks' difference was mostly in the mineral-associated organic matter fraction in the A-horizon, suggesting long-term persistence of soil C in AMP grazing farms. The higher N stocks and lower .sup.15N abundance of AMP soils also point to higher N retention in these systems. These findings provide evidence that AMP grazing is a management strategy to sequester C in the soil and retain N in the system, thus contributing to climate change mitigation. Author Affiliation: (a) Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO, USA (b) Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA (c) Applied Ecological Services, Brodhead, WI, USA (d) School of Sustainability, Arizona State University, Tempe, AZ, USA (e) Walter Cronkite School of Journalism, Arizona State University, AZ, USA (f) USDA-ARS, Central Plains Research Station, Akron, CO, USA (g) Texas A&M University AgriLife Research Center, Vernon, TX, USA * Corresponding author. W.K. Kellogg Biological Station, Michigan State University, 3700 East Gull Lake Dr. Hickory Corners, MI, 49060, USA. Article History: Received 25 February 2021; Revised 15 March 2021; Accepted 16 March 2021 Byline: Samantha Mosier [] (a,b,*), Steven Apfelbaum (c), Peter Byck (d,e), Francisco Calderon (f), Richard Teague (g), Ry Thompson (c), M. Francesca Cotrufo (a,b)

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Gale Document Number: GALE|A659174343