Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2007
Publication Date: 5/1/2007
Citation: Pachepsky, Y.A., Guber, A.K., Shelton, D.R., Yu, O.T. 2007. Effect of Manure on Fecal Coliform Attachment to Soil and Soil Particles of Different Sizes. Applied and Environmental Microbiology. 73(10):3363-3370. Interpretive Summary: Manure-borne pathogens move in the overland flow after being released from manure. The overland flow also carries soil particles and manure particulates. The travel distances of soil particles depend on the particle size. A substantial attachment of pathogens to soil particles, if present, may limit their spread in the environment. Not much, if anything, is known about the attachment of pathogenic microorganisms to soil particles of different sizes. We studied the attachment of E. coli to three soils and to sand, silt, and clay fractions from these soils in the presence and absence of manure colloids. In the absence of manure colloids, attachment to soil, silt, and clay particles was much stronger than to sand particles that did not have an organic matter coating. However, attachment to sand particles coated with organic matter was similar to the attachment to silt and clay. Manure colloids in suspensions drastically decreased bacteria attachment to soils, clay and silt fractions. Because silt and clay particles can move in the overland flow significant distances, the low attachment of bacteria to silt and clay particles in the presence of manure colloids may cause predominantly free-cell transport of manure-borne fecal coliforms in agricultural runoff.
Technical Abstract: It has been recognized that bacteria transport in runoff can be different for free cells, cells attached to soil particles, and cells attached to manure particles. Objectives of this work were to compare attachment of fecal coliforms (FC) to different soils and soil fractions, and to assess effect of manure on FC attachment to soil and soil fractions. Three sand fractions of different sizes, silt fraction, and clay fraction of loam, sandy clay loam, and clay loam soils were separated and used along with soil samples in batch attachment experiments with water-FC suspensions and water-manure-FC suspensions. In absence of manure colloids, attachment was much higher for soil, silt, and clay particles than to sand particles that have not had organic coating. Attachment to sand particles coated with organic matter was similar to the attachment to silt and clay. Manure colloids in suspensions decreased bacteria attachment to soils, clay and silt fractions and to the coated sand fractions, but did not decrease attachment to sand fractions without organic matter coating. The low attachment of bacteria to silt and clay particles in presence of manure colloids may cause predominantly free-cell transport of manure-borne FC in runoff.