EFFECT OF SELENATE VS. SELENITE FORMS OF SELENIUM IN INCREASING THE SELENIUM CONCENTRATION IN FORAGES AND CEREALS
A greenhouse study was conducted on a fine sandy loam to determine the effect of adding different sources of Se on the Se concentration of forages and cereals. The three sources of Se were: NH4NO3 prills containing (i) 1.20% Se as sodium selenate, (ii) 1.02% Se as sodium selenite and (iii) urea prills containing 1.00% Se as sodium selenite. Application of 20 g Se ha−1 as sodium selenate (source i) produced Se concentrations of 1.02 and 1.05 mg kg−1 in timothy and 1.04 and 0.55 mg kg−1 in alfalfa in the two cuts, respectively, and 0.78 mg kg−1 in barley grain. This application rate of Se in the form of selenite resulted in 0.07–0.09 mg Se kg−1 in the two forages and barley grain. At similar application rates of Se, the ammonium nitrate doped with sodium selenate produced about 5–18 times more Se in the forages and barley than when doped with sodium selenite. Overall no significant difference was found in the plant Se concentration between ammonium nitrate or urea prills as the carrier for selenite. Key words: Sodium selenate and selenite doped NH4NO3, greenhouse, Se in forages and cereals