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Vegetative Filter Strips for Agricultural Nonpoint Source Pollution Control
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1989
Year
Precision AgricultureEnvironmental MonitoringEngineeringEnvironmental Impact AssessmentPollution MonitoringPollution MitigationVegetative Filter StripsSoluble NutrientsPublic HealthSoil FertilitySoil RestorationPollution ReductionSurface RunoffSoil ScienceAbstract Arainfall SimulatorSediment TransportEnvironmental EngineeringCrop ProtectionEnvironmental RemediationNutrient Management
The study used a rainfall simulator to assess the effectiveness of vegetative filter strips in removing sediment, nitrogen, and phosphorus from cropland runoff. Nine plots on eroded silt loam were subjected to simulated rainfall with VFS lengths of 0, 4.6, or 9.1 m, fertilizers applied at 222 kg /ha N and 112 kg /ha P₂O₅, and water samples collected for sediment and nutrient analysis. The 9.1‑m and 4.6‑m VFS removed 84 % and 70 % of suspended solids, 79 % and 61 % of phosphorus, and 73 % and 54 % of nitrogen, but soluble nutrients were sometimes higher in the effluent, potentially causing eutrophic growth, and on‑farm VFS were less effective due to flow concentration problems.
ABSTRACT Arainfall simulator was used to evaluate the effective-ness of vegetative filter strips (VFS) for the removal of sediment, nitrogen (N), and phosphorus (P) from cropland runoff. Simulated rainfall was applied to nine experimental field plots on an eroded Groseclose silt loam soil (clayey, mixed, mesic Typic Hapludalt) with a 5.5 by 18.3 m bare cropland source area and either a 0, 4.6, or 9.1 m VFS located at the lower end of each plot. Fertilizers were applied to the plots at rates of 222 kg/ha of liquid N and 112 kg/ha of P2O5 and K2O. Water samples were collected from the base of each plot and analyzed for sediment and nutrient content. One set of plots was constructed to encourage concentrated rather than shallow uniform flow. The 9.1 and 4.6 m VFS with shallow uniform flow removed an average of 84 and 70% of the incoming suspended solids, 79 and 61% of the incoming P, and 73 and 54% of the incoming N, respectively. Soluble nutrients in the filter effluent were sometimes greater than the incoming soluble nutrient load, presumably due to lower removal efficiencies for soluble nutrients and the release of nutrients previously trapped in the filters. Concentrations of soluble inorganic N and P in filter strip effluent were sufficient to cause eutrophic plant growth in aquatic ecosystems. Observation of existing VFS showed that on-farm VFS were not likely to be as effective as experimental VFS because of problems with flow concentrations.