Stocking method effects on nutrient runoff from pastures fertilized with broiler litter

Repeated applications of broadcast broiler (Gallus gallus domesticus) litter can increase nutrient runoff from pastures. Rotational stocking (RS) of rattle, as compared with continuous stocking (CS), may be useful in decreasing surface nutrient runoff because of better manure distribution and more uniform forage accumulation to act as filters and trap nutrients, Our objective was to measure nutrient runoff from six 0.75-ha tall fescue (Festuca arundinacea Schreb.)-common bermudagrass [Cynodon dactylon (L.) Pers.] pastures fertilized with 13 to 15 Mg (dry weight) broiler litter per hectare per year and managed under RS or CS. Two cross-bred beef (Bos taurus) steers were maintained on each pasture year around for 2 yr, Kith additional steers added to maintain similar forage availability between stocking methods, In each pasture, surface runoff was directed to a flume where it was sampled by an automatic sampler. Runoff was analyzed for total Kjeldahl N, (NO3- + NO2-)-N, NH4+-N, total Kjeldahl P, and dissolved reactive P (DRP). Grazing method had no effect (P > 0.10) an surface runoff quality or quantity. Average runoff expressed as a percentage of the rain was 15% for the first year and 12% for the second year. Tbe average flow-weighted concentrations of DRP and NH4+-N were 5.08 mg P L-1 and 1.07 mg N L-1 for the first year, and 8.22 mg P L-1 and 10.11 mg N L-1 for the second year (P < 0.10).