Selenium prill applications to pasture: Effect on herbage selenium concentrations: A thesis submitted in partial fulfillment of the requirements for the postgraduate diploma of Agricultural Science at Lincoln University Canterbury, New Zealand

Abstract

Under the conditions of pot and field trials, selenium applied to the soil as prills rapidly raised the selenium content of both ryegrass and clover. The herbage selenium concentrations declined steadily back to control levels after the initial uptake peak. The results of both experiments would indicate that total recovery of applied selenium is dependant on how soon the pasture is first cut (grazed) after the application of the selenium prills. Results of the field trial indicate that an application rate of 10 g Se/ha is sufficient to raise the selenium content of the herbage above the critical value for prevention of deficiency in grazing livestock, but without approaching dangerously high values which might cause toxicity. Timing of selenium fertilizer application favours spring topdressing with up to seven times greater uptake than from autumn topdressings.