View article

Concern over eutrophication has directed attention to manure management effects on phosphorus (P) loss in runoff. This study evaluates the effects of manure application rate and type on runoff P concentrations from two, acidic agricultural soils over successive runoff events. Soils were packed into 100‐ × 20‐ × 5‐cm runoff boxes and broadcast with three manures (dairy, Bos taurus; layer poultry, Gallus gallus; swine, Sus scrofa) at six rates, from 0 to 150 kg total phosphorus (TP) ha⁻¹ Simulated rainfall (70 mm h⁻¹) was applied until 30 min of runoff was collected 3, 10, and 24 d after manure application. Application rate was related to runoff P (r² = 0.50–0.98), due to increased concentrations of dissolved reactive phosphorus (DRP) in runoff; as application rate increased, so did the contribution of DRP to runoff TP. Varied concentrations of water‐extractable phosphorus (WEP) in manures (2–8 g WEP kg⁻¹) resulted …