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With big crops in 2014, soil nutrient reserves could be lower than usual. This would mean higher fertilizer requirements — however lower crop prices come into play as growers calculate their return on investment for any incremental increase in applied fertilizer. A soil test will indicate soil nutrient reserves heading into 2014.
One blend, or many? Nutrient reserves vary from field to field, and from zone to zone within each field. This has encouraged some growers to create different blends for each field, and to use variable rate application to adjust rates based on management zones within a field. A soil testing program is essential to determine the right blend for each field.
The question, from an overall profit perspective, is what return can one expect from varying these rates, given the investment of time and money in soil tests, in variable rate equipment, and in handling and preparing all the different blends? For some growers, one blend might be the most practical option.
So what should that blend be? Canola needs sulphur, and given the variability of sulphur throughout a field, a blend should include at least 10-20 lb./ac. of sulphur, with ammonium sulphate being the most practical and plant available. Nitrogen rates will vary by grower and by region, reflecting the grower’s appetite for risk and the farm’s typical yield potential. The one point to make here is that canola yield potential may be untapped on some farms. Canola could provide a good return on investment from an incremental increase in nitrogen rates for many farms. Phosphorus is the only product that can safely go in the seed row, and probably at no more than 20 lb./ac. of phosphate. Any additional phosphorus applied for maintenance (which is something to consider, so as to avoid “hidden hunger”) should go with the blend applied outside the seed row. Potassium remains a question mark. Independent studies show little benefit for potassium in the canola blend. However, regional shortages could be showing up if soil potassium reserves are reaching critically low levels. Cereals tend to show potassium deficiencies well before they will show up in canola, so if you’re in an area where potassium is applied heavily for cereals, then potassium fertilizer may also benefit canola. Note that potassium should not go in the seed row.