Hope Below Our Feet: Featured Publications on Grazing that is Regenerative

---

Grazing facilitates litter-derived soil organic carbon formation in grasslands by fostering microbial involvement through microenvironment modification

"Accordingly, mowing treatment increased the exposure of litter to UV radiation (+38 %) and therefore facilitated the microbial assimilation of litter C (+20 %) and the SOC formation (+15 %). Trampling treatment promoted the transformation of litter C to SOC pools by mixing litter and soil (+34 %).  ... Collectively, our results suggest that grazing facilitates litter-derived SOC formation by regulating microbial involvement through changes in the microenvironment. Our study indicates that grazing promotes SOC formation from plant litter, which maintains SOC storage in grasslands. Accurate quantification of the contribution of plant C input to SOC pools in different grasslands under various utilization is the next step to better predict SOC dynamics."

Yuqi Wei, Bin Wei, Masahiro Ryo, Yixian Bi, Xiangyun Sun, Yingjun Zhang, Nan Liu,

Grazing facilitates litter-derived soil organic carbon formation in grasslands by fostering microbial involvement through microenvironment modification, CATENA, Volume 232, 2023, 107389, ISSN 0341-8162,

https://www.sciencedirect.com/science/article/abs/pii/S0341816223004800?dgcid=coauthor

Agricultural land is a scarce resource globally and will continue to encounter challenges to sustainably increase food production in the face of global change. Adaptations that make use of livestock should ideally incorporate agroecological principles (e.g., improved circularity), while limiting feed-food competition. However, they should also remain respectful of the diversity of ecosystem contexts, availability of resources, and the various social and economic needs of local populations.

Finds that, "The potential for carbon sequestration comes via two key mechanisms: 1) restoration of degraded landscapes through the introduction of livestock, and 2) use of adaptive grazing to improve ecological function."

Logan Thompson, Jason Rowntree, Wilhelm Windisch, Sinéad M Waters, Laurence Shalloo, Pablo Manzano, Ecosystem management using livestock: embracing diversity and respecting ecological principles, Animal Frontiers, Volume 13, Issue 2, April 2023, Pages 28–34, https://doi.org/10.1093/af/vfac094

Evaluating the impacts of alternative grazing management practices on soil carbon sequestration and soil health indicators

“... The objective of this study was to identify the impacts of alternative grazing management practices, including heavy continuous (HC), light continuous (LC), and adaptive multi-paddock (AMP) grazing, on SOC and soil health indicators at the ranch and watershed scales in the Lower Prairie Dog Town Fork Red River Watershed in Northwest Texas.  …  The study results indicated that when grazing management at the study ranch was changed from the current AMP grazing to hypothetical HC grazing, simulated average annual SOC decreased from 84 to 81.8 Mg/ha (a 2.6% decline). At the watershed-scale, when the grazing management was changed from the baseline HC grazing to AMP grazing, the simulated average annual SOC increased from 35.6 to 38.3 Mg/ha (a 7.5% increase) … These results indicate that compared to HC, AMP grazing performed better with respect to SOC increase, and improvement of soil ecosystem and hydrological functions at both the ranch and watershed scales in the study watershed. Our findings suggest the need to shift from continuous to AMP grazing in order to improve soil health at multiple spatial scales.”

JungJin Kim, Srinivasulu Ale, Urs P. Kreuter, W. Richard Teague, Stephen J. DelGrosso, Steven L. Dowhower, Evaluating the impacts of alternative grazing management practices on soil carbon sequestration and soil health indicators, Agriculture, Ecosystems & Environment, Volume 342, 2023, 108234, ISSN 0167-8809, https://doi.org/10.1016/j.agee.2022.108234.

Grassland soil carbon sequestration: Current understanding, challenges, and solutions

“Grasslands store approximately one third of the global terrestrial carbon stocks and can act as an important soil carbon sink. Recent studies show that plant diversity increases soil organic carbon (SOC) storage by elevating carbon inputs to below ground biomass and promoting microbial necromass contribution to SOC storage. …  Improved grazing management and biodiversity restoration can provide low-cost and/or high-carbon-gain options for natural climate solutions in global grasslands. The achievable SOC sequestration potential in global grasslands is 2.3 to 7.3 billion tons of carbon dioxide equivalents per year (CO2e year−1) for biodiversity restoration, 148 to 699 megatons of CO2e year−1 for improved grazing management … “

“Under moderate grazing intensity, the average SOC stock increase (28.4%) is substantially greater with rotational grazing than that with continuous grazing. In the southeast United States, grassland soils managed with adaptive multi-paddock grazing that used a high-density- short-duration rotational grazing had more carbon (72.49 Mg C ha−1) and nitrogen (9.26 Mg N ha−1) stocks compared with continuous grazing (64.02 Mg C ha−1 and 8.52 Mg N ha−1) in the 0 to 100 cm soil layer … optimizing grazing intensity (e.g., rotational grazing) is projected to increase soil carbon sequestration potential by 148 to 699 megatons (Mt) CO e year−1 in global grazing lands … with the greatest SOC sequestration potential occurring in Central and South America, Africa, and Asia.”

Yongfei Bai M. Francesca Cotrufo, Grassland soil carbon sequestration: Current understanding, challenges, and solutions. Science 4 Aug 2022 Vol 377, Issue 6606 pp. 603-608  377,603-608(2022).DOI:10.1126/science.abo2380 https://www.science.org/doi/10.1126/science.abo2380

Adaptive Multi-paddock Grazing Management’s Influence on Soil 

Food Web Community Structure for: Increasing Pasture Forage Production, Soil Organic Carbon, and Reducing Soil Respiration Rates in Southeastern USA Ranches. 

A comparative study of Adaptive Multi-Paddock (AMP) and conventional grazing (CG) operations by New Mexico State University molecular biologist, Dr. David Johnson, finds that AMP ranches have on average a 46% increase in standing crop biomass (SCB) - representing similarly higher photosynthetic capacity - and a 20.6% increase in soil organic carbon (SOC) in the top 10 cm of soil profile coupled with a 19.52% decrease in soil CO2 respiration (meaning more C is staying in the ground). The paper calculates that if applied over 1.25 billion hectares of savannahs and grasslands globally, the increased photosynthetic capacity and decreased soil C respiration would remove 9.82 and 6.66 billion tonnes CO2 year or 26.8% and 18.19% respectively of the global 36.6 billion tonnes of global anthropogenic emissions.  AMP stocking density can be 2.38 times higher than CG systems. 

Johnson DC, Teague R, Apfelbaum S, Thompson R, Byck P. 2022. Adaptive multi-paddock grazing management’s influence on soil food web community structure for: increasing pasture forage production, soil organic carbon, and reducing soil respiration rates in southeastern USA ranches. PeerJ 10:e13750 https://peerj.com/articles/13750/

Loss of Grazing by Large Mammalian Herbivores can Destabilize the Soil Carbon Pool

16-year study (2006-2021) in India’s Himalayan region shows far greater stability in soil-C and soil-N stocks in grazed plots versus exclusion plots,  “fluctuations in soil-C and soil-N were 30 to 40% higher after herbivore exclusion than under grazing … Overall, we conclude that herbivores exert strong influence on both the stability and the size of the soil-C pool, and their persistence is essential for decarbonization services derived from grazing ecosystems.” 

Naidu, Roy, Bagchi (2022) Loss of grazing by large mammalian herbivores can destabilize the soil carbon pool. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES (PNAS) Vol. 119 | No. 43 October 25, 2022 https://doi.org/10.1073/pnas.2211317119

Persistent soil carbon enhanced in Mollisols by well-managed grasslands but not annual grain or dairy forage cropping systems

"Soil organic carbon (C) responses to agricultural management are highly uncertain, hindering our ability to assess the C sequestration potential of croplands and develop sound policies to mitigate climate change while enhancing other ecosystem services. Combining experimental evidence from a long-term field experiment and a meta-analysis of published literature, we show that the accrual of mineral-associated soil C in intensively managed Mollisols was only achieved by managing ruminant grazing on perennial grasslands. …  Compared to conventional continuous maize monocropping with annual tillage, systems with reduced tillage, diversified crop rotations with cover crops and legumes, or manure addition did not increase total SOC storage or MAOM-C, whereas perennial pastures managed with rotational grazing accumulated more SOC and MAOM-C (18 to 29% higher) than all annual cropping systems after 29 y of management.“

Yichao Rui, Randall D. Jackson, M. Francesca Cotrufo , +5, and Matthew D. Ruark. Edited by William Schlesinger, Cary Institute of Ecosystem Studies, Millbrook, NY; received October 20, 2021; accepted January 10, 2022. February 10, 2022. 119 (7) e2118931119 https://doi.org/10.1073/pnas.2118931119

"Biological regulation of planetary temperature has been explained with the Daisyworld model, in which reflective-cooling white daises balance absorbing-warming black daisies. This article advances the proposition that cooling 'daisies' of Daisyworld represent carbon sequestration and consumption by productive soils and ecosystems, such as grasslands expanding into deserts and tropical forests migrating toward the poles. ... These hypotheses are quantified and tested by new global soil maps derived from paleosols of the last extremes of atmospheric CO2: middle Miocene (16 Ma) and last glacial maximum (20 ka), when CO2 levels were 588 ± 72 and 180 ppm, respectively. Observed expansion of productive soils curbed large atmospheric injections of CO2 in deep time and observed expansion of unproductive soils during ice ages of low CO2 was thwarted by continued metamorphic and volcanic degassing."

Retallack GJ. Soil Carbon Dioxide Planetary Thermostat. Astrobiology. 2022 Jan;22(1):116-123. doi: 10.1089/ast.2020.2415. PMID: 35020414. https://pubmed.ncbi.nlm.nih.gov/35020414/

Vegetation, water infiltration, and soil carbon response to Adaptive Multi-Paddock and Conventional grazing in Southeastern USA ranches

“On average, surface water infiltration was higher on AMP than paired CG ranches. Averaged over all locations, soil organic carbon stocks to a depth of 1 m were over 13% greater on AMP than CG ranches, and standing crop biomass was >300% higher on AMP ranches. AMP grazing supported substantially higher livestock stocking levels while providing significant improvements in vegetation, soil carbon, and water infiltration functions. AMP grazing also significantly increased available forage nutrition for key constituents …” 

Apfelbaum SI, Thompson R, Wang F, Mosier S, Teague R, Byck P. 2022. Vegetation, water infiltration, and soil carbon response to Adaptive Multi-Paddock and Conventional grazing in Southeastern USA ranches. Journal of Environmental Management 308:114576 https://www.sciencedirect.com/science/article/pii/S0301479722001499?via%3Dihub

Soil carbon stocks and nitrous oxide emissions of pasture systems in Orinoquía region of Colombia: Potential for developing land-based greenhouse gas removal projects

Comparing permanent grasslands (PG) which are degraded from improper grazing and burning with improved grasslands (IG) “managed through rotational grazing of introduced, productive and deep-rooted pasture grass species promote soil organic carbon (SOC)”  … “Improving grassland conditions under grazing has the potential not only to accumulate carbon in soils, but also to reduce nitrous oxide (N2O) emissions from animal urine deposition. … Estimated SOC stocks (0–100 cm) were in the range of 224.8 Mg C ha−1 for the PG and 259.0 Mg C ha−1 for the IG, with a significant (p < 0.05) average accumulation of 2.0 Mg C ha−1 y−1 (0–20 cm) in the IG area. N2O emissions were 10 times lower in the IG compared to the PG. … Compared to the reference default value of IPCC for, the SOC stock found in PG was almost 40% higher, whereas the N2O emission factor (5%) was within the uncertainty range (0.7–6%). The Orinoquía region shows significant potential for SOC storage and reduced N2O emissions in improved pastures with deep root systems. Thus, scaling the implementation of land-based SOC storage practices/projects could significantly contribute to reducing net emissions from beef production from this region.”

Costa  et al. 2022, Soil carbon stocks and nitrous oxide emissions of pasture systems in Orinoquía region of Colombia: Potential for developing land-based greenhouse gas removal projects, Frontiers in Climate, vol 4, 2022, 10.3389/fclim.2022.916068, https://www.frontiersin.org/articles/10.3389/fclim.2022.916068/full

“Climate change will cause a substantial future greenhouse gas release from warming and thawing permafrost-affected soils to the atmosphere enabling a positive feedback mechanism. Increasing the population density of big herbivores in northern high-latitude ecosystems will increase snow density and hence decrease the insulation strength of snow during winter. As a consequence, theoretically 80% of current permafrost-affected soils (<10 m) is projected to remain until 2100 even when assuming a strong warming using the Representative Concentration Pathway 8.5. Importantly, permafrost temperature is estimated to remain below −4 °C on average after increasing herbivore population density. Such ecosystem management practices would be therefore theoretically an important additional climate change mitigation strategy. Our results also highlight the importance of new field experiments and observations, and the integration of fauna dynamics into complex Earth System models, in order to reliably project future ecosystem functions and climate.”

Beer, Christian & Zimov, Nikita & Olofsson, Johan & Porada, Philipp & Zimov, S.. (2020). Protection of Permafrost Soils from Thawing by Increasing Herbivore Density. Scientific Reports. 10. 10.1038/s41598-020-60938-y.
https://www.researchgate.net/publication/339982637_Protection_of_Permafrost_Soils_from_Thawing_by_Increasing_Herbivore_Density  

2020 paper by Rowntree et al. documents the soil carbon increases from “holistic planned grazing” in a multi-species pasture rotation (MSPR) system on the USDA-certified organic White Oak Pastures farm in Clay County, Georgia. Over 20 years, the farm sequestered an average of 2.29 metric tonnes of carbon per hectare per year (2.29 Mg C/ha/yr).  The paper also shows that the area required to produce food in this regenerative way was 2.5 times that of conventional farming (which would have resulted in soil degradation and toxic chemicals impact). It notes that production efficiency comes at a cost of “land-use tradeoffs” that  must be taken into consideration.

Rowntree JE, Stanley PL, Maciel ICF, Thorbecke M, Rosenzweig ST, Hancock DW, Guzman A and Raven MR (2020) Ecosystem Impacts and Productive Capacity of a Multi-Species Pastured Livestock System. Front. Sustain. Food Syst. 4:544984. doi: 10.3389/fsufs.2020.544984 https://www.frontiersin.org/articles/10.3389/fsufs.2020.544984/full

Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in Midwestern USA beef finishing systems

2018 Michigan State University study in Agricultural Systems finds 1.5 metric tons of carbon per acre per year drawdown via adaptive multi-paddock grazing, more than enough to offset all greenhouse gas emissions associated with the beef finishing phase.

Stanley, P. L., Rowntree, J. E., Beede, D. K., DeLonge, M. S., & Hamm, M. W. (2018). Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in Midwestern USA beef finishing systems. Agricultural Systems, 162, 249-258. doi:https://doi.org/10.1016/j.agsy.2018.02.003

2016 Texas A&M study in Journal of Soil and Water Conservation finds 1.2 metric tons of carbon per acre per year drawdown via adaptive multi-paddock grazing and the drawdown potential of North American pasturelands is 800 million metric tons of carbon per year. 

Teague, W. R., Apfelbaum, S., Lal, R., Kreuter, U. P., Rowntree, J., Davies, C. A., R. Conser, M. Rasmussen, J. Hatfield, T. Wang, F. Wang, Byck, P. (2016). The role of ruminants in reducing agriculture’s carbon footprint in North America. Journal of Soil and Water Conservation, 71(2), 156-164. doi:10.2489/jswc.71.2.156 http://www.jswconline.org/content/71/2/156.full.pdf+html

Global Cooling by Grassland Soils of the Geological Past and Near Future

2013 paper in Annual Review of Earth and Planetary Sciences by University of Oregon Department of Geological Sciences professor Gregory J. Retallack shows the co-evolution of ruminants and grassland soils (mollisols) was essential for geologic cooling of the past 20 million years – leading to the conditions suitable for human evolution – and can be an instrumental part of the necessary cooling in the future to reverse global warming.

Retallack, G. (2013). Global Cooling by Grassland Soils of the Geological Past and Near Future (Vol. 41, pp. 69–86): Annual Review of Earth and Planetary Sciences. https://doi.org/10.1146/annurev-earth-050212-124001