Effects of grazing winter cover crops on soil health in the southeastern U.S.

Authors: REITER, WADE - Auburn University; GAMBLE, AUDREY - Auburn University; CROWELL, HAYLEY - Auburn University; FENG, YUCHENG - Auburn University; Balkcom, Kipling

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/12/2022
Publication Date: 11/10/2022
Citation: Reiter, W., Gamble, A.V., Crowell, H., Feng, Y., Balkcom, K.S. 2022. Effects of grazing winter cover crops on soil health in the southeastern U.S. [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. Baltimore, MD. Nov. 6-9, 2022.

Interpretive Summary:

Technical Abstract: Introducing integrated crop-livestock systems into row crop production systems may provide incentive for producers to plant cover crops and promote soil health benefits on degraded soils of the southeastern United States, but the effects of these practices on crop yields and soil health in southeastern Ultisols are not well established. A four-year study was established at the Wiregrass Research and Extension Center in Headland, Alabama to test the effects of different grazing regimes on soil health and crop productivity. Three cattle grazing regimes (mid-February, mid-March, and mid-April cattle removal dates) and an ungrazed control were included in a randomized complete block design and replicated three times. Chemical soil health indicators (soil organic carbon, permanganate oxidizable carbon), physical soil health indicators (water stable aggregates, penetration resistance), biological soil health indicators (microbial biomass carbon, arbuscular mycorrhizal fungi colonization), crop yield, and cover crop biomass were evaluated. Cover crop biomass at termination was reduced for all grazed treatments compared to the ungrazed control, and the mid-March and mid-April treatments resulted in the lowest amount of cover crop biomass. No treatment effects were observed for arbuscular mycorrhizal fungi, microbial biomass carbon, soil organic carbon, and permanganate oxidizable carbon. Penetration resistance was significantly higher for the mid-April treatment compared to the other treatments in 2021 and for the mid-March and mid-April treatments than the other treatments in 2022, indicating that longer grazing periods can result in soil compaction. Grazing also had a negative impact on water stable aggregates in some instances. The results from this study suggest that grazing cover crops has no effect on biological and chemical soil health indicators but can negatively impact some physical soil health indicators. Shorter grazing periods allowed for regrowth of cover crop biomass, leaving more residues to prevent soil erosion and reduce soil compaction.