Soil health and root-zone enrichment characteristics between paired grassland and cropland fields in the southeastern USA

Authors: Franzluebbers, Alan; VAN VLIET, STEPHAN - Utah State University; YOUNG, SIERRA - Utah State University; POORE, MATT - North Carolina State University

Submitted to: Grassland Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2023
Publication Date: 12/31/2023
Citation: Franzluebbers, A.J., Van Vliet, S., Young, S., Poore, M.H. 2023. Soil health and root-zone enrichment characteristics between paired grassland and cropland fields in the southeastern USA. Grassland Research. 2(4):299-308. https://doi.org/10.1002/glr2.12066.
DOI: https://doi.org/10.1002/glr2.12066

Interpretive Summary: Soil health conditions under privately managed grassland farms in the southeastern US has not received much attention. We hypothesized that beef cattle grazing on diverse composition of forage throughout their life cycle might lead to changes in meat quality compared with grain-finished beef. An ARS scientist in Raleigh North Carolina collaborated with investigators from North Carolina State University and some presently at Utah State University to determine soil health conditions under grazed pastures compared with neighboring grain cropping fields in three different physiographic regions. Soil aggregation characteristics were greater under grazed pastures than cropland at all three locations. Soil chemical characteristics were variably affected by land use. Total organic carbon and nitrogen were greater under pasture than under cropland at two of the three locations. However, the biologically active fractions of carbon and nitrogen were greater under pasture than under cropland at all three locations. These results will be useful for farmers, agricultural advisors, and scientists to understand the benefits of well-managed grazing systems on productivity and environmental outcomes.

Technical Abstract: Grasslands are a conservation land use that can be expected to sequester soil organic C and N compared with annual cropland, thereby improving soil health and minimizing soil erosion. Data to support these changes from privately managed pastures in the southeastern US are relatively scant. We deployed a paired-farm approach to determine how a variety of soil health parameters related to nutrient and water cycling might be altered under grazed pastures compared with annual croplands in three Major Land Resource Areas – Blue Ridge, Piedmont, and Blackland Prairie of the southeastern USA. Soil was sampled at depths of 0-10, 10-30, and 30-60 cm from four pastures and four areas on neighboring cropland fields. Soil stability index averaged 0.64 mm/mm under cropland and 0.91 mm/mm under pasture, suggesting that pastures had a highly stable soil surface that was resistant to erosion and contributed to high water infiltration. Surface-soil organic C and N fractions (i.e., total, particulate, and mineralizable fractions at 0-10-cm depth) were all significantly greater under pasture than under cropland, indicating greater soil C and N storage and soil biological activity. Across locations, root-zone enrichments (0-30-cm depth) of organic C and N fractions were greater under pasture than under cropland. Root-zone enrichment of total soil N was greater (p < .05) under pasture than under cropland in the Blue Ridge (2.87 vs 1.10 Mg N/ha, respectively) and the Piedmont (2.80 vs 2.10 Mg N/ha), but not in the Blackland Prairie (2.40 vs 2.12 Mg N/ha). This study provides evidence that well-managed grasslands can sequester soil organic C and N and improve soil surface stability conditions.