Optimizing yield and quality of canola seed with balanced fertilization in the Parkland Zone of western Canada
A number of field experiments were conducted from 1998 to 2001 (or are underway) in northeastern Saskatchewan to determine the effects of various rates (0 to 30 kg S/ha), sources (sulphate S – potassium sulphate and ammonium sulphate; and elemental S – ES 90 and ES 95), times (autumn, sowing, bolting and flowering) and methods (incorporation, sideband, seedrow, topdress and foliar) of S application, ratios of fertilizer N:S (0 to 150 kg N/ha and 0 to 30 kg S/ha) and cultivars (Quantum – Brassica napus, AC Excel – Brassica napus, Maverick – Brassica rapa and AC Parkland – Brassica rapa) on seed yield and quality of canola. The S deficiency on canola can be corrected and seed yields restored with application of sulphate-S fertilizer in the growing season, substantially until bolting growth stage and moderately at early flowering stage. There was no significant increase in seed yield from the elemental S fertilizers in the initial year of application. Even after three annual applications, the elemental S fertilizers had seed yields lower than the sulphate-S fertilizers in many cases particularly when the S fertilizers were applied in spring. Autumn-applied elemental S usually had greater seed yield than the spring-applied elemental S. Autumn-applied ammonium sulphate produced lower seed yield than spring-applied ammonium sulphate in some cases. For higher N application rates, there was a need of increased amount of fertilizer S to adequately meet the S requirements of canola. The severity of S deficiency, increase in seed yield of canola from applied S and seed quality varied with canola cultivars. In general, Quantum had the highest seed yield, followed by AC Excel, Maverick and AC Parkland. Application of S fertilizer also increased oil content in canola seed. In conclusion, seed yield and quality of canola can be optimized with proper S fertilizer management.
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