Sprinkler irrigation often causes runoff and erosion. Relatively high application rates under center pivot outer spans usually exceed the infiltration rates of medium-textured soils, leading to runoff and sediment loss, particularly from sloping fields. We hypothesized that incorporated fresh or composted dairy manure would reduce runoff and sediment loss, possibly by improving surface soil structure. Our field study had six treatments in each of six blocks, each of the latter being one span of a lateral-move sprinkler system. In October 1999, we incorporated 0, 29, or 72 Mg/ha of dry manure or 0, 22, or 47 Mg/ha of dry compost into Portneuf silt loam (Durinodic Xeric Haplocalcid) on slopes from 0.8 to 4.4%. In Spring of 2000 and 2001 before irrigating and Fall of 2001 after irrigating, we collected surface soil (0-5 mm) from bed tops to determine aggregate stability. We applied 22 to 45 mm of water at an average application intensity of 28 mm/h to 6.4- x 36.6-m field plots six times in 2000 and twice in 2001. Using small trapezoidal flumes, we measured runoff rates and collected 1-L runoff samples at 15- to 30-minute intervals to determine sediment loss. In general, neither amendment nor rate significantly affected runoff, sediment loss, or aggregate stability. Runoff did tend, however, to decrease with increasing manure rates and to increase with increasing compost rates. Averaged across amendment and rate, sediment loss per irrigation was 230 kg/ha from plots with slopes >3%. Runoff increased exponentially with slope, exceeding 15% of the water applied on slopes of 3% or more. Sediment loss and runoff were affected more by plot slope than by manure or compost.