If you’re still seeding be careful not to apply too much fertilizer, says provincial crop specialist Mark Cutts. Seed-placed urea can reduce crop emergence through ammonia toxicity.
Factors that impact the amount of urea that can be seed placed include seedbed utilization (calculated as the spread of seed and fertilizer divided by the row spacing), soil conditions (soil texture, soil moisture), and seed size. The main phosphate fertilizer used in Alberta, monoammonium phosphate (11-52-0, 12-51-0), generally has low seedling toxicity.
But crop type is a factor — cereals are more tolerant, while oilseeds and pulses are more sensitive. For seed-placed potassium chloride (0-0-60), the salt effect can be an issue.