Performance Evaluation of Three Vegetative Filter Strip Designs for Controlling Feedlot Runoff Pollution

Abstract

A vegetative filter strip (VFS) is designed to reduce transport of sediments and nutrients downstream mainly through settling, infiltration (into soil profile), adsorption (to soil and plant materials), and by plant uptake. However, the performance of a VFS greatly depends on a VFS design and climatic conditions of a region. In this paper, relative performance of three VFSs (hereafter Cass County-CC, Sargent County-SC, and Richland County-RC buffers) was evaluated and compared in the context of VFS design for feedlot runoff pollution control and management under agro-climatic condition of North Dakota. Buffer at CC feedlot was established with broadleaf or common cattail (Typha latifolia) grass filter, SC feedlot buffer had Garrison creeping foxtail (Alopecurus arundinaceus Poir.) and reed canary grass (Phalaris arundinaceus), and RC feedlot buffer had mixed grasses. Automatic samplers were installed to collect runoff samples at each inflow and outflow locations. Collected runoff samples were analyzed for total suspended solids (TSS), ortho-phosphorus (ortho-P), total phosphorus (TP), ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), total Kjeldahl nitrogen (TKN), total nitrogen (TN), and potassium (K). Cass County (CC) VFS with cattails grass filter had the longest runoff-flow length (65 m) and resulted in better conducive environment for restricted TSS and TP transports reduction and better adsorption of ortho-P, NH4-N, and K compared to SC and RC feedlot buffers. Overall TSS, ortho-P, TP, NH4-N, and K removal efficacies were 88%, 90%, 89%, 91% , and 90%, respectively, at CC VFS. At SC feedlot VFS resulted in the highest NO3-N reduction. Relatively poor performance was observed for the RC feedlot which was due to smaller runoff-flow length (12 m). Overall, CC feedlot outperformed the SC and RC VFSs in respect of TSS, ortho-P, TP, NH4-N, TKN/TN transport reductions.