Rotational grazing strategies minimally impact soil microbial communities and carbon dynamics—a Texas case study

Authors: Moore, Jennifer; Manter, Daniel; MACZKO, KRISTIE - University Of Wyoming

Submitted to: Land
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2023
Publication Date: 7/30/2023
Citation: Moore, J.M., Manter, D.K., Maczko, K.A. 2023. Rotational grazing strategies minimally impact soil microbial communities and carbon dynamics—a Texas case study. Land. 12(8). https://doi.org/10.3390/land12081517.
DOI: https://doi.org/10.3390/land12081517

Interpretive Summary: Privately owned rangelands and pasture lands form the largest single land use type in the US. The ecosystem services these grasslands provide are numerous and include supporting biodiversity, carbon (C) storage, forage production, nutrient cycling, and water filtering, capture, and storage. These systems support unique animal-plant-soil-microbe communities that contribute to ecological sustainability. In this study we evaluated vegetation, soil health, and soil microbial responses at three working ranches in Texas under different management strategies (HSHF: high stocking density and herd rotation frequency; MSMF: medium stocking density and herd rotation frequency; and LSCG: low stocking density and continuous grazing). All three ranches which utilize differing approaches to manage grazing intensity did not appear to show any obvious signs of soil or vegetation degradation. However, we did observe significant differences in vegetation composition and soil properties between ranches. Gradients of soil and vegetation across the landscape were more important in shaping the microbial composition and associated functions than ranch management strategy. Our results suggest that there are multiple approaches to achieve ecological sustainability and thus, the goals of the rancher, their resources, and willingness to alter practices should be the focus of any rangeland management plan.

Technical Abstract: The goal of our study was to investigate the linkages between changes in vegetation and soil health on soil microbial community structure and function on three working ranches in Texas under different management strategies. The first ranch followed a high stocking density and high frequency (HSHF) rotation where cattle were moved multiple times each day. The second ranch utilized a medium stocking density and rotation frequency (MSMF) where herds were moved every 2-3 weeks. The third ranch used a low stocking density with continuous grazing (LSCG). Vegetation and soil samples (0-15 cm) were collected and analyzed for plant species composition and biomass, 15 soil properties (eight soil health indicators, six nutrients, and texture), and soil microbial community composition and function using lipid profiling and 16S amplicon sequencing. Vegetation composition and key soil health indicators were significantly different between ranches with slightly higher values of soil health indicators at MSMF. Although rangeland management had a marginal impact on microbial community composition, taxa were associated with specific vegetation and soil properties. Gradients of soil and vegetation across the landscape were more important in shaping microbial composition and function than overall differences in rangeland management. Our results suggest that there are multiple approaches to achieve ecological sustainability in rangeland systems, and thus, the goals of the rancher, their resources, and willingness to alter practices should be the focus of any rangeland management plan.