Technical Abstract: Use of manure on cropland in association with large confined animal feeding operations has raised concern about nutrient contamination of surface and groundwaters. Warm-season perennial grasses may be useful in filter strips to trap nutrients from manure application and as biomass feedstock for nutrient removal. Our objective was to determine the nutrient uptake of 'Alamo' switchgrass (Panicum virgatum L.) used in a combination biomass- filter strip system treated with dairy manure. We measured changes in extractable N and P in the soil, NO3-N in soil solution, and changes in ortho-P and chemical oxygen demand (COD) of runoff water before and after a switchgrass filter strip. Five rates of dairy manure (target rates of 0, 56, 112, 167, and 224 kg N ha-1 in 1995; 0, 56, 167, 280, and 560 kg N ha-1 in 1996 and 1997) were surface applied to field plots of switchgrass (5.2 by 16.4 m) with a 5.2- by 16.4-m switchgrass filter strip below the manured darea. Yield of switchgrass from the manured area increased linearly with increasing manure rate in each year. Analysis of soil water samples collected at 46 or 91 cm below the soil surface on 30 dates (417 samples total) indicated < 3 mg L-1 of NO3-N in plots treated with up to 1389 kg N ha-1 total during 3 yr. Concentrations of P and COD were reduced an average of 47% for the 167 kg N rate and 76% for the 560 kg N rate in 1996 and 1997 after passing through a 16.4-m switchgrass filter strip. Manure could effectively substitute for inorganic fertilizer in switchgrass biomass production with dual use of the switchgrass as a vegetative filter strip.