The ambitious UK greenhouse gas emissions (GHGe) net-zero target for 2050 added to the known large effect that livestock has on GHGe have led to the search for more sustainable production systems. Regenerative grazing management (RGM) uses sustainable management practices that aim to implement soil conservation strategies to regenerate the ecosystem and, at the same time, provide ecosystems services. Thus, RGM has gained increased attention in the UK livestock sector. However, while some research has shown RGM potential to improve soil health and to abate GHGe through carbon sequestration under continental (Steele et al., 2018) or tropical climate conditions (Pinheiro Machado et al., 2021), information is scarce for temperate British conditions. The data on the impact of RGM effects on farm biodiversity are inconsistent and depend on the species and taxa being investigated (Morris 2021). Despite recent efforts to assess the relationship between RGM soils’ and GHGe in the US (Dowhower et al, 2020), it is not clear how RGM may affect soil GHGe under temperate micro-climates and soil types. The positive effects of RGM on soil structure has been reported though (e.g. Pinheiro Machado et al., 2021), but scarce evidence of RGM effect on soil compaction has been found.
Aims and Objectives
This PhD project aims to assess the effects of regenerative grazing management under different micro-climates and soil types across the UK on: 1) soil health characteristics (soil C content, soil structure, compaction and greenhouse gas emissions), 2) system biodiversity and, 3) to model the effect that soil compaction from regenerative grazing management may have on soil greenhouse gas emissions. We hypothesise that, regardless of the soil type, when compared to soils from continuously grazed systems, regenerative grazing management will improve soil carbon content and reduce compaction, enhance biodiversity and reduce soil greenhouse gas emissions.
Methodology
We are a multidisciplinary supervisory team working in sustainable livestock production (Enriquez-Hidalgo, Bristol Veterinary School), ecology (Memmott, School of Biological Sciences), soil greenhouse gas emissions (GHGe) (Cárdenas, Rothamsted Research) and soil compaction and GHGe modelling (Romero-Ruiz, Rothamsted Research). We will work closely with our partner, the Pasture-Fed Livestock Association (PFLA) to identify regenerative grazing management (RGM) farms with characteristics according to the aims of the study. We will characterise farms under different soil types which have neighbouring fields where RMG and continuous grazing management have been applied. Sampling stations will be identified within the assessment fields and will evaluate soil characteristics (chemical and physical characteristics, soil C content, etc.), on field soil GHGe, soil compaction and herbage and soil biodiversity (taxonomic groups and biomass quantification). Soil samples will be tested in an adapted version of the Rothamsted specialised laboratory incubation system (Cardenas et al., 2003) to evaluate how the different soil types under RGM respond to manure application in terms of GHGe. Finally, a soil compaction-focused agro-ecosystem model developed at Rothamsted Research will be used to help interpreting observations of GHGe in terms of the associated grassland management strategies (continuous vs RMG), soil compaction and impacts on key soil processes.
Keywords
Regenerative agriculture, sustainable livestock, greenhouse gases, carbon sequestration, soil compaction
How to apply for this project
This project will be based in Bristol Veterinary School in the Faculty of Health Sciences at the University of Bristol.
Please visit the Faculty of Health Sciences website for details of how to apply
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