title: Composition and design of vegetative filter strips instrumental in improving water quality by mass reduction of suspended sediment, nutrients andEscherichia coliin overland flows in eastern escarpment of Mau Forest, Njoro River Watershed, Kenya.
abstract: This study assessed the effect of vegetative filter strip (VFS) in removal of suspended sediment (SS), total nitrogen, total phosphorus andEscherichia coli(E. coli) in overland flow to improve receiving water quality standards. Four and half kilograms of cowpat manure was applied to the model pasture 14 m beyond the edge of vegetated filter strip (VFS) comprising 10-m Napier grass draining into 20-m Kikuyu grass (VFS II), 10-m Kikuyu grass draining into 20-m Napier grass (VFS III) and native grass mixture of Couch-Buffel (VFS I-control). Overland flow water samples were collected from the sites at positions 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25 and 30 m along the length of VFSs.E. coliremoval by Napier grass VFS was on the order of log unit, which provided an important level of protection and reduced surface-flow concentrations ofE. colito below the 200 (CFU 100 mL-1) recommended water quality standards, but not for nutrients and SS. The Napier grass showed highest efficiency (99.6 %), thus outperforming both Kikuyu grass (85.8 %) and Couch-Buffel grasses VFS (67.9 ± 4.2 %) in removingE. colifrom overland flow. The low-level efficiency of native Couch-Buffel grasses in reducingE. coliin overland flow was because of preferential flow. Composition and design of VFS was instrumental and could be applied with a high potential of contracting the uncertainty in improving water quality standards through mass reduction of SS, nutrients andE. coliload in watersheds.
authors.affiliation: Department of Environmental Science, Egerton University, Nakuru, Kenya.
authors.forename: C O
authors.initials: CO
authors.lastname: Olilo
authors.affiliation: Department of Agricultural Engineering Technology, Egerton University, Nakuru, Kenya.
authors.forename: J O
authors.initials: JO
authors.lastname: Onyando
authors.affiliation: Department of Environmental Science, Egerton University, Nakuru, Kenya.
authors.forename: W N
authors.initials: WN
authors.lastname: Moturi
authors.affiliation: Department of Biological Sciences, Egerton University, Nakuru, Kenya.
authors.forename: A W
authors.initials: AW
authors.lastname: Muia
authors.affiliation: University of California, School of Veterinary Medicine, Davis, CA, USA.
authors.forename: Amber F
authors.initials: AF
authors.lastname: Roegner
authors.affiliation: Kisumu Research Centre, Kenya Marine and Fisheries Research Institute, Mombasa, Kenya.
authors.forename: Z
authors.initials: Z
authors.lastname: Ogari
authors.affiliation: Department of Crops, Horticulture and Soil Science, Egerton University, Nakuru, Kenya.
authors.forename: P N
authors.initials: PN
authors.lastname: Ombui
authors.affiliation: Department of Biological Sciences, Masinde Muliro University of Science and Technology, Kakamega, Kenya.
authors.forename: W A
authors.initials: WA
authors.lastname: Shivoga
keywords: E. coli; Mass reduction; Nutrients; Overland flow; Suspended sediment; Vegetated filter strips