Phosphorus (P) in runoff from furrow irrigated fields can impair water quality in streams, lakes and rivers. We conducted a series of whole field studies to identify the factors affecting P transfer and transport during furrow irrigation. Six irrigations were conducted on freshly tilled, fallow fields that varied from 110 to 180-m long, with 0.007 to 0.012 m m^-1 slopes. The soil on all fields was Portneuf silt loam (coarse-silty, mixed superactive, mesic Durinodic Xeric Haplocalcids). Flow rate, sediment concentration and phosphorus concentrations were monitored at four, equally spaced locations in each furrow. Flow rate decreased with distance down the furrow as water infiltrated. Sediment concentration varied with distance and time with no set pattern. Total P concentrations were directly related to sediment concentrations (r²=0.75) because typically >90% of the P was associated with particulates. Dissolved reactive P (DRP) concentrations decreased with time at a specific furrow site but tended to increase with distance down the furrow. DRP concentration correlated better with sediment concentration than extractable furrow soil P concentration. However, DRP concentration was not appreciably affected by changes in suspended sediment concentration later in the irrigation (>2 h). Combining sediment detachment-deposition with P desorption-sorption dynamics and sediment transport in the furrow will be important to predict total P and DRP losses from tilled fields where erosion occurs.