Managing beef backgrounding residual soil contaminants by alum and biochar amendments

Authors: NETTHISINGHE, ANNESLY - Western Kentucky University; Cook, Kimberly - Kim; GILFILLEN, REBECCA - Western Kentucky University; WOOSLEY, PAUL - Western Kentucky University; Sistani, Karamat

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2018
Publication Date: 8/30/2018
Citation: Netthisinghe, A., Cook, K.L., Gilfillen, R., Woosley, P., Sistani, K.R. 2018. Managing beef backgrounding residual soil contaminants by alum and biochar amendments. Journal of Environmental Quality. https://doi.org/10.2134/jeq2018.02.0088.
DOI: https://doi.org/10.2134/jeq2018.02.0088

Interpretive Summary: Contamination of soils on intensively managed beef backgrounding operations can serve as nonpoint sources for environmental contaminates. Site management practices like forage harvesting are slow to remediate manure contaminated soils. In situ soil contaminant stabilization has been proposed as an alternative management strategy with a focus on lowering contaminant availability and limiting their release to the environment. Contaminant stabilizing soil amendments employ various sorption, complexation, and precipitation processes to immobilize contaminants. This two year study examined the short-term effects of in situ management of contaminants in soils on a beef background operation. Soils had no amendment (control) or were treated with alum (AL) or biochar (BC). The effect on soil extractable P, Cu, and Zn content, antimicrobial monensin concentrations, total bacteria and those carrying antibiotic resistance genes was measured. The AL decreased soil pH (7.3 to 6.4) and the BC caused slight soil pH increase (7.2 to 7.4). The AL reduced all soil nutrients (1374 to 1060 mgPkg-1; 7.7 to 3.2 mgCukg-1; 52.4 to 19.6 mgZnkg-1), total bacterial cells (5.3x 109 to 5.5x 108 cells g-1), and monensin (1.8 to 0.7 ng g-1) concentrations. However, antibiotic resistance genes as a portion of total cells increased. Amendment with BC reduced Zn content (37.8 to 17.4 mg kg-1) and monensin concentration (2.1 to 1.1 ng g-1), but not other nutrients or microbial parameters. In the short-run, amendment with AL has higher potential than BC in remediating environmental contaminates in calcareous beef backgrounding soils.

Technical Abstract: Heavy manure derived contamination of soils can make intensively managed beef backgrounding operations nonpoint sources for environmental contaminates. Site management practices exhibit slow impact in remediating manure contaminated soils. In situ soil contaminant stabilization has been proposed as an alternative contaminant management strategy with a focus on lowering contaminant availability and limiting their release to the environment. Contaminant stabilizing soil amendments employ various sorption, complexation, and precipitation processes to immobilize contaminants. This two year study examined the short-term effects of adding no amendment (control; CT) or treating with alum (Al2 (SO4)3.18H2O) (AL) or biochar (BC) as soil amendments on extractable soil P, Cu, and Zn content, antimicrobial monensin concentrations, total bacteria (16S rRNA gene), antibiotic resistance genes (sul1, ermB) and class one integrons (intl1) in a semi intensively managed abandoned beef backgrounding site. The AL decreased soil pH (7.3 to 6.4) and the BC caused slight soil pH increase (7.2 to 7.4). The AL reduced all soil nutrients (1374 to 1060 mgPkg-1; 7.7 to 3.2 mgCukg-1; 52.4 to 19.6 mgZnkg-1), total bacterial cells (5.3x 109 to 5.5x 108 cells g-1), and monensin (1.8 to 0.7 ng g-1) concentrations. Antibiotic resistance genes as a portion of total cells increased in the AL treated soils (sul I: 6.3x 10-4 to 1.5x10-3; ermB; 4.8x10-5 to 4.2x10-4; intI I: 1.3x10-4 to 2.3x10-3). Amendment with BC reduced Zn content (37.8 to 17.4 mg kg-1) and monensin concentration (2.1 to 1.1 ng g-1), but not other nutrients or microbial parameters. In the short-run, amendment with AL has higher potential than BC in remediating environmental contaminates in calcareous beef backgrounding soils.