Application of selenium prills to improve the selenium supply to a grass/clover sward

Abstract The effectiveness of a commercially produced prill formulation in enhancing the Se level in a Se deficient grass/clover sward has been assessed. The product which contained 1% Se on a pressure impregnated mineral base was applied in early spring at two levels: 10g Se/ha (the recommended level) and 30g Se/ha. The Se levels in the herbage were subsequently monitored on cut samples taken over a 2 year period. The effect of N fertilisation on the Se status was also investigated. The recommended rate of application maintained Se levels in the pasture at an adequate and safe value throughout the growing season for the first year. Three times the recommended rate gave herbage containing potentially toxic levels at the 1st cut. This decreased to a safe level by the 2nd cut and thereafter was maintained at an adequate level for the season. By the second year Se in the herbage for both rates of Se application had returned to background levels. The N fertilisation decreased the Se concentration in the herba...