Sulphur fertilizer and tillage effects on canola seed quality in the Black soil zone of western Canada

Abstract

Field studies in Manitoba, Saskatchewan and Alberta over 3 yr evaluated immediate and residual effects of source, timing and placement of su lphur (S) fertilizers on canola quality under reduced (RT) and conventional tillage (CT). Oil concentration of canola seed increased and chlorophyll content decreased with application of plant-available forms of S fertilizer if soils were deficient in available sulphate-S. Therefore, canola seed quality was improved by correction of S deficiencies. The magnitude and consistency of fertilizer effects reflected the sulphate availability of the fertilizer source applied, with ammonium sulphate having a greater effect than the bentonite-elemental S product, Tiger 90®, in the year of application. Effects on seed N concentration were inconsistent, but decreases in seed N concentration occasionally occurred with correction of an S deficiency, reflecting an inverse relationship between seed yield or seed oil concentration and seed N concentration. Seed S concentration generally increased with increases in available sulphur. Application of ammonium sulphate in the preceding wheat crop provided residual sulphate-S for canola, leading to increased oil and seed S concentration, and decreased chlorophyll and seed N concentration. Tillage system had little influence on canola quality, with RT occasionally reducing oil concentration and increasing chlorophyll and seed N content. The response of seed quality to S fertilization was similar under CT and RT. Sulphate-S sources consistently improved canola quality on S-deficient fields. Key words: Bentonite S, chlorophyll, elemental S, green seed. zero oil, protein, zero tillage