Selenium concentration of bermudagrass after spraying with sodium selenate

Abstract

An experiment was conducted in North Florida to study pasture fertilization with selenium as a method of increasing intake of this nutrient by livestock. Bermudagrass (Cynodon dactylon) was sprayed with sodium selenate at rates of 0, 24, 120, 240, and 480 g/ha of selenium and forage samples were collected for analyses at 2, 4, 6, 12, and 18 weeks after spraying. The bermudagrass from 24 g/ha selenium plots had non-toxic but adequate levels of selenium for livestock at all clipping dates. The 120, 240, and 480 g/ha selenium application rates resulted in toxic forage levels of selenium up to the sixth week after spraying. However, by the twelfth week, the selenium levels were non-toxic and at the same time adequate to meet livestock reguirements. At 18 weeks after spraying, the levels of selenium in the forage were also non-toxic and adeguate for livestock. The results of this study suggest that spraying with 24 g/ha selenium can be an adeguate means to meet reguirements of this mineral for grazing livestock.