| Abstract: | This study was designed to evaluate phosphorus (P) losses from rotationally grazed pastures. Sod of tall fescue was transplanted into boxes 100×18.4 cm2. Treatments (13) imposed in triplicate were a no P control, inorganic P at rotational requirements, inorganic P at seasonal requirements, and 10 plots representing a paddock in a 20‐day, alternate‐day grazing rotation. Treatments were isonitrogenous; three rotations were conducted. Inorganic fertilizers were applied on day 1 of the rotation. Dairy slurry from grazing cows was applied daily to the respective treatments. Rainfall was simulated after each rotation, and continuous runoff was collected for 30 min. Total and dissolved reactive P in runoff were lower from control than from P‐amended treatments. No differences were observed among P‐amended plots. The small size of the boxes and naturally high variability in fescue sod did not allow for an accurate assessment of the risk of P losses from rotationally grazed pasture. |
