THE EFFECT OF TIME OF APPLICATION AND PLACEMENT OF SULFUR FERTILIZER SOURCES ON YIELD OF WHEAT, CANOLA, AND BARLEY

Most experiments with elemental S (So) have shown that spring applicat ion does not benefit annual crops, and it should be applied at least o ne year in advance so the prills are dispersed and oxidized to the sul phate (SO4) state. Because preliminary work had indicated that placeme nt of S prills appeared to affect prill dispersion and oxidation, a se ries of experiments were conducted to determine how placement and time of application affect yields of canola (Brassica napus L.), wheat (Tr iticum aestivum L.) and barley (Hordeum vulgare L.). Response of crops to S was variable and generally, similar for both So and SO4 sources. Response to So was better when there was shallow incorporation of the prills in the spring by harrows before planting or the placement of t he prills in a shallow band (2.5 cm depth) and then planting the seed with the hoe-opener the next day in the same track of the fertilizer b and. Elemental S increased the yield of wheat as much as 0.46 t/ha and canola, 0.99 t/ha. Prill dispersion was dependent on wetting and dryi ng, weathering and physical dispersion with seeding implements. Becaus e of the several factors that affect availability of S, general recomm endations for use of S on annual crops should be made on the basis of regional testing.