FORAGE CHARACTERISTICS, STEER PERFORMANCE, AND WATER-QUALITY FROM BERMUDAGRASS PASTURES FERTILIZED WITH 2 LEVELS OF NITROGEN FROM SWINE LAGOON EFFLUENT

Four .8-ha pastures of bermudagrass (Cynodon dactylon [L.] Pers.) were fertilized with either 456 or 873 kg/ha of nitrogen (N) from swine la goon effluent (two replicates per treatment) and grazed by steers over two summers. Within each pasture, steers received forage only, an ene rgy source (corn), a mixture of corn and soybean meal, or a mixture of corn and blood meal via electronic Calan feeders. All supplements wer e offered at a level of 1.36 kg/d, and the soybean meal and blood meal supplements provided similar quantities of protein. Weight gains were similar among supplemented steers, but supplemented steers gained fas ter (P < .05) than controls. Nitrogen fertilization level had no effec t on steer gains, steer grazing days per hectare, or in vitro dry matt er disappearance, NDF, and ADF of clipped forage samples. Plant protei n and nitrate ion concentrations were greater (P < .06) in clipped for age samples receiving the higher N application rate. Nitrate ion conce ntrations were greater in available forage samples from the pastures w ith the high N application rate. Mean total N and nitrate N concentrat ions were similar in water samples obtained from monitoring wells for the two N treatments over the 2 yr and there were no year x N interact ions. Chloride concentrations were greater (P < .05) and pH and specif ic conductance were less in water samples collected from the 873 kg th an from the 456 kg/ha N treatment. Long-term studies are needed to exa mine the possible cumulative effects of applying various levels of swi ne waste to the same land area.