Long-term pasture management impacts on eolian sand soils in the southern mixed-grass prairie

Authors: Follett, Ronald; Stewart, Catherine; Bradford, James; Pruessner, Elizabeth; Sims, Phillip; Vigil, Merle

Submitted to: International Union for Quaternary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2020
Publication Date: 7/28/2020
Citation: Follett, R.F., Stewart, C.E., Bradford, J.A., Pruessner, E.G., Sims, P.L., Vigil, M.F. 2020. Long-term pasture management impacts on eolian sand soils in the southern mixed-grass prairie. International Union for Quaternary Research. https://doi.org//10.1016/j.quaint.2020.07.019.
DOI: https://doi.org/10.1016/j.quaint.2020.07.019

Interpretive Summary: Mixed grass pastures, which occupy the eolian sand dunes of the southern Great Plains, are a critical resource for livestock production. This study determined the soil age and development from these eolian sands and evaluated long-term grazing of native and improved pasture on vegetative C inputs, soil C, stable isotopes, and other soil properties. Pasture treatments included grazed and ungrazed (50+yrs), improved grasses (28-50 yrs), and winter wheat or go-back grass (for 28-30yrs). Grass species included both native (switchgrass and sand bluestem) and non-native (weeping lovegrass and caucasian bluestem) species. Long-term moderate grazing had relatively little impact compared to ungrazed pastures. Soil C was dependent on plant root biomass across all treatments, but with few differences among individual grasses or long-term pastures. Improved pasture management maintained soil properties under switchgrass, weeping lovegrass, caucasian bluestem, and go-back grass species, but were maintained or lower under sand bluestem and winter wheat compared to long-term grazing. We show here that improved pasture, when moderately grazed, can be a sustainable practice for the conservation of eolian dune soils compared to wheat production.

Technical Abstract: Mixed grass pastures, which occupy the eolian sand dunes of the southern Great Plains, are a critical resource for livestock production. These mixed grass pastures also provide soil cover and are important to soil carbon (C) storage in the southern prairies of the Great Plains. This study determined the soil age and development of eolian sandy soils and evaluated long-term grazing of native and improved pasture on vegetative C inputs, soil C, stable isotopes, and other soil properties. Pasture treatments included grazed and ungrazed (50+yrs), improved pastures (28-50 yrs), and winter wheat or go-back grass (for 28- 30yrs). Grass species included both native (switchgrass and sand bluestem) and non-native (weeping lovegrass and caucasian bluestem) species. The Eda soil age ranged from present at the surface to <1200 to <1600 yr BP (by luminescent or 14C dating, respectively) at the bottom of the soil profile (~130 cm). Long-term moderate grazing had relatively little impact compared to ungrazed pastures. Soil C was dependent on plant root biomass across all treatments, but with few differences among individual grasses or long-term pastures. Comparisons of treatments against grazed pastures indicated SOC, SON, Cmin-C, POM-C, and % silt+%sand were maintained or lower under sand bluestem and winter wheat but increased or maintained under switchgrass, weeping lovegrass, caucasian bluestem, and go-back grass. Soils under winter wheat had the lowest C and N. Long-term grazing is a resilient practice that can increase soil health. Soil protection is necessary should climate changes result in drought and/or high temperatures and winds, and increased potential for reactivation of eolian sand movement.