Fecal Coliform Transport as Affected by Surface Condition

Land application of manure is recommended to recycle organic matter and nutrients, thus enhancing the soilquality and crop productivity. However, pathogens in manure may pose a human health risk if they reach potable orrecreational water resources. The objective of this study was to observe and quantify the effects of vegetated filter strips (VFS)on surface and vertical transport of fecal coliform (FC) bacteria, surrogates for bacterial pathogens, released fromsurface-applied bovine manure. A two-sided lysimeter with 20% slope on both sides was constructed with a sandy loam soilon one side and a clay loam soil on the other. Each side of the lysimeter was divided into two subplots (6.0 6.4 m), one withgrass and the other with bare soil. Plots were instrumented to collect runoff samples along a 6.0 m slope at three equidistanttransects. Samples of runoff were also collected in a gutter at the edge of each plot. All plots were equipped with multi-sensorcapacitance moisture probes to monitor water content through the soil profile. Bovine manure was applied at the top of eachplot in a 30 cm strip. Rainfall was simulated at a 61 mm h-1 intensity using a portable rainfall simulator. Surface runoff ratewas measured and water quality sampled periodically throughout the simulation. Soil samples were taken at incrementaldepths (0-60 cm) after each simulation. Runoff (as % of total rainfall) decreased from 93% to 12% in the bare vs. vegetatedclay loam plots and from 61% to 2% in the bare vs. vegetated sandy loam plots. The reduced runoff from vegetated plotsdecreased the surface transport of FC while increasing its vertical transport. The amount of FC in runoff (as % of applied)decreased from 68% to 1% in the bare vs. vegetated clay loam plots and from 23% to non-detectable levels in the bare vs.vegetated sandy loam plots. These data indicate that VFS can reduce surface transport of FC, even for slopes as high as 20%,especially in soils with high infiltration (e.g., sandy loam).