Impacts of winter grazing on soil health in southeastern cropping systems

Authors: CROWELL, HAYLEY - North Carolina State University; GAMBLE, AUDREY - Auburn University; FENG, YUCHENG - Auburn University; Balkcom, Kipling; YANG, ANNA - Anhui Agricultural University

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2021
Publication Date: 4/13/2022
Citation: Crowell, H., Gamble, A., Feng, Y., Balkcom, K.S., Yang, A. 2021. Impacts of winter grazing on soil health in southeastern cropping systems. Agrosystems, Geosciences & Environment. 5:e20240. https://doi.org/10.1002/agg2.20240.
DOI: https://doi.org/10.1002/agg2.20240

Interpretive Summary: Coastal Plain soils are often characterized by low soil organic carbon (SOC) contents. A conventional tillage cotton/peanut rotation is typical in the region, but increasing SOC and improving soil health with winter grazing of cover crops exists for producers with row crop and livestock operations. Scientists at Auburn Univ. in conjunction with USDA in Auburn, AL evaluated winter grazing impacts on soil health in the US Coastal Plain. Three cattle removal dates and an ungrazed control were evaluated for impacts on selected soil health indicators: SOC, permanganate oxidizable carbon (POXC), water stable aggregates (WSA), penetration resistance (PR), microbial biomass-carbon (MBC), and arbuscular mycorrhizal fungi (AMF) colonization rates. After two years, MBC was highest in the control treatments, likely due to greater cover crop biomass on the soil surface at termination. No differences were observed between treatments for SOC, POXC, WSA, PR, or AMF. Lack of differences in soil health indicators suggests that integrating winter grazing livestock does not negatively nor positively impact selected dynamic soil properties in the short-term. More time under grazing treatments is needed to thoroughly evaluate how winter grazing livestock impact soil health.

Technical Abstract: Coastal Plain soils are often characterized by low soil organic carbon (SOC) as a result of natural and anthropogenic factors. A rotation of cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) under conventional tillage is typical in this region, but an opportunity to increase SOC and improve soil health by incorporating winter grazing of cover crops exists for producers with row crop and livestock operations. A study to assess winter grazing impacts on soil health was established in the US Coastal Plain. Three cattle removal dates and an ungrazed control were evaluated for impacts on selected soil health indicators: SOC, permanganate oxidizable carbon (POXC), water stable aggregates (WSA), penetration resistance (PR), microbial biomass-carbon (MBC), and arbuscular mycorrhizal fungi (AMF) colonization rates. After two years, MBC was highest in the control treatments, likely due to greater cover crop biomass on the soil surface at termination. No differences were observed between treatments for SOC, POXC, WSA, PR, or AMF. Increased cotton lint yield was observed in control and mid-February treatments in 2019, likely due to greater cover crop residues on the soil surface following grazing which may have conserved soil moisture during the growing season. Peanut yields were unaffected by treatments in 2020. Lack of differences in soil health indicators suggests that integrating winter grazing livestock does not negatively nor positively impact selected dynamic soil properties in the short-term, but more time under grazing treatments is needed to thoroughly evaluate how winter grazing livestock impact soil health and crop yield.