Improving canola crop safety using phosphorus
and sulphur fertilizers in the seed row Canola seedlings are very sensitive to seed placed fertilizers; however phosphorus (P) fertilizers are most efficient if seed placed (MAFRI, 2007). Fertilizer rates applied with the seed are limited by crop safety, and blended P and sulphur (S) fertilizers could increase seedling toxicity. Enhanced efficiency fertilizers could increase crop safety. The objective of the study is to determine the safe rates of P and S fertilizer blends in the seed row and if enhanced efficiency fertilizers are less toxic than conventional fertilizers. P fertilizers used were 11-52-0 Monoammonium phosphate (MAP) and 11-51-0 coated Monoammonium phosphate (cMAP) at rates of 0, 20, and 40 kg P2O5/ha. S fertilizer used was 21-0-0-24 Ammonium sulphate (AS) at rates of 0, 9, and 18 kg S/ha. 13-33-0-15 Microessentials S15 (S15) was applied at 0, 20 kg P2O5 + 9kg S/ha and 40kg P2O5 + 18kg S/ha. Crop emergence counts were taken 2 and 4 weeks after the crop emerged. The preliminary results from Carman and Kelburn, MB sites are presented. Seed placed P and S fertilizers caused less seedling toxicity at Kelburn than at Carman, probably because the soil at Kelburn has higher clay content and moisture holding capacity; therefore, the salts from the fertilizers in the seed row are diluted. At Carman, blends of AS and MAP caused enough damage in the seed row to reduce the plant populations below the critical threshold of 40-50 plants/m² (Canola Council of Canada 2003). High rates of P added as MAP caused more seedling damage than cMAP. Adding AS with either MAP or cMAP increased seedling damage compared to either P or S product used alone. S15 caused less seedling toxicity than equivalent combinations of MAP + AS, probably because 50% of the sulphur in S15 is in the elemental form (non-toxic). References:
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