GHG Mitigation Potential of Different Grazing Strategies in the United States Southern Great Plains

Abstract

Abstract:The possibility of reducing greenhouse gas (GHG) emissions by ruminants using improved grazing is investigated by estimating GHG emissions for cow-calf farms under light continuous (LC), heavy continuous (HC) and rotational grazing, also known as multi-paddock (MP), management strategies in Southern Great Plain (SGP) using life cycle assessment (LCA). Our results indicated a GHG emission with these grazing treatments of 8034.90 kg·CO2e·calffor cow-calf farms in SGP region, which is high, compared to that for other regions, due to the high percentage (79.6%) of enteric CH4 emissions caused by relatively lower feed quality on the unfertilized rangeland. Sensitivity analyses on MP grazing strategy showed that an increase in grass quality and digestibility could potentially reduce GHG emission by 30%. Despite higher GHG emissions on a per calf basis, net GHG emissions in SGP region are potentially negative when carbon (C) sequestration is taken into account. With net C emission rates of −2002.8, −1731.6 and −89.5 kg C ha −1 ·year −1 after converting from HC to MP, HC to LC and from LC to MP, our analysis indicated cow-calf farms converting from continuous to MP grazing in SGP region are likely net carbon sinks for decades.

Do Differences in Livestock Management Practices Influence Environmental Impacts?

“…LCA studies by Pelletier et al (2010) and Lupo et al (2013) support these observations, suggesting a 24-30% reduction in net GHG production as a function of sequestration from grass-fed beef production. These observations are consistent with an LCA analysis by Wang et al (2015) for beef production in Texas, and they track well with empirical observations (Teague et al, 2011;Dowhower et al, 2019;Rowntree et al, 2019). The importance of C-sequestration by grasslands is clearly critical to the efficacy of agriculture as a vehicle for GHG removal.…”

A Global Meta‐Analysis of Grazing Impacts on Soil Health Indicators

“…Previous work also suggests grazing exclusion can decrease soil C pools, due to reduced root C inputs, decreased grazer‐driven plant growth, and increased microbial respiration (Shao et al, 2013). Notably, considerable disagreement exists regarding the potential C sequestration gains and subsequent mitigation benefits to be made via specialized grazing systems (Joyce et al, 2013; Wang et al, 2015). Meeting the simultaneous demands for soil restoration (Six, 2013) and animal protein production (Thornton, 2010; Herrero et al, 2016) requires an improved understanding of the complex relationships between livestock grazing and soil function and health at regional and global scales.…”

Managing Grazing to Restore Soil Health, Ecosystem Function, and Ecosystem Services

“…Paleo records provide evidence that management of grassland agroecosystems can create a large C sink (Retallack, 2013). Equally, changing management approaches in ruminant-based production chains can improve soil health and thereby create net C sinks (Wang et al, 2015;Rowntree et al, 2016;Stanley et al, 2018). Given that most agricultural producers have not used conservation practices outlined by Delgado et al (2011), applying such practices more broadly could lead to substantial soil health improvements and, therefore, a significant increase in C sink (Conant and Elliott, 2001;Liebig et al, 2010;Teague et al, 2011;Machmuller et al, 2015;Dowhower et al, 2019;Hillenbrand et al, 2019).…”

“…Life cycle analyses that include all GHG emissions associated with the production of grain-based feeds, including the production and application of inorganic fertilizers and irrigation water to produce grain, show that the C footprint as well as soil erosion associated with grain-finished beef substantially exceeds the C footprint of grass-finished beef (Teague et al, 2016;Stanley et al, 2018). Additionally, C sequestered by plants grazed by cattle exceeds the enteric emissions of the grazing animals (Wang et al, 2015;Rowntree et al, 2016). The C footprint of the beef production chain can be substantially reduced when ruminants are finished on forages and grains produced using regenerative cropping practices that have a negative C footprint (Gattinger et al, 2012;Aguilera et al, 2013).…”