Project Overview
Information Products
Commodities
- Animals: bovine, sheep, swine
Practices
- Animal Production: grazing - multispecies
- Education and Training: on-farm/ranch research
- Soil Management: soil microbiology
Summary:
Small-scale livestock farmers are looking for innovative ways to manage their lands for environmental sustainability and economic profitability, while ensuring animal well-being. Multi-species rotational grazing (MSRG) has been suggested as a promising approach, since it allows high grazing intensity and stocking density without negatively impacting pasture quality or animal health. However, the potential effects of MSRG on soil microbial communities are poorly understood. To address this knowledge gap, we collected soil microbial samples before, during, and after one season of MSRG by cattle, sheep, and swine. Nine paddocks experiencing MSRG, as well as three paddocks experiencing monospecies grazing (one paddock per species) and one with no grazing, were sampled. Soil samples were sent to the University of Oregon Genomics & Cell Characterization Core Facility for shotgun metagenomic analysis to identify taxonomic, phylogenetic, and functional characteristics of the microbial communities from each paddock.
Results demonstrated broad microbial diversity in all paddock soil microbiomes. Samples collected early in the season tended to have greater archaeal and bacterial alpha diversity than samples collected later for all grazing treatments, while no effect was observed for fungi or viruses. Beta diversity, however, was strongly influenced by both grazing treatment and month for all microbial kingdoms, suggesting a pronounced effect of different livestock on microbial composition. Cattle-only and swine-only paddocks were more dissimilar from multi-species paddocks than those grazed by sheep. We identified a large number of differentially abundant taxa driving community dissimilarities, including Methanosarcinaspp., Candidatus Nitrocosmicus oleophilus, Streptomyces spp., Pyricularia spp., Fusarium spp., and Tunggulvirus Pseudomonas virus phi-2. In addition, a wide variety of antibiotic resistance genes (ARGs) were present in all samples, regardless of grazing treatment; the majority of these encoded efflux pumps and antibiotic modification enzymes (e.g., transferases).
In addition to posting results on the farm website, we shared the outcomes of our study with other farmers and agricultural professionals at the Oregon State University Extension Small Farms Conference in 2021. This project substantially improves our understanding of soil microbial communities under MSRG and provides information for other farmers following sustainable agriculture practices.
Project objectives:
Objective 1: Measure the impact of MSRG on soil microbial diversity, composition, and function.
We collected soil samples before, during, and after MSRG and use shotgun metagenomics to identify taxonomic, phylogenetic, and functional characteristics of soil microbial communities (bacteria, fungi, and archaea). We hypothesized that each livestock species has a different effect on soil microbial communities (due to distinct foraging/grazing strategies and unique manure composition), and that MSRG would lead to higher microbial taxonomic and functional diversity, as well as different taxonomic composition, in comparison to monospecies grazing or no livestock.
Objective 2: Assess changes in livestock health and pasture forage quality following MSRG.
Since MSRG can effectively break livestock parasite cycles, we hypothesized that animal health would improve following MSRG. Additionally, we hypothesized that pasture productivity and plant diversity would increase after MSRG, due to changes in manure deposition and grazing patterns.
Objective 3: Share study outcomes with other farmers, agricultural professionals, and the general public.
We disseminated our project methods and results by presenting at the Oregon State University Extension Small Farms School in 2021 and posting results on our farm website.