Fig. 4. Concentrations of total reactive P in surface runoff water from the manure-treated areas and vegetative filter strips. Effluent was applied on 16 Apr., 1 May, 20 May, and 25 June 1996 (Days 106, 121, 140, and 176; not shown on figure). Arrows indicate dates of effluent application in 1997. Data are means of four replicates plus one standard error