Higher Yields Driving Nutrient Removal Budgets
Since 1990, canola yields have increased by 1.38 bu./ac./yr., corn yields by 1.8 bu./ac/yr. and soybeans by more than 0.45 bu./ac./yr. Producers in southern Alberta are reporting their highest canola average yields, as are Ontario soybean growers. Agronomists and the International Plant Institute (IPNI) have warned about seeing a steady decline in soil test nutrients, including phosphorus (P), potassium (K) and sulphur. A number of media articles recently have centered around whether farmers are adjusting their fertility plans to current realities of crop removal and declining soil test levels. The Farmtario article ‘High Yields Lead to greater Nutrient Removal’ makes a key point that in years of high yields, adjusting fertilizing plans to the 5-year average may not be enough. (https://bit.ly/33RNcni ). Our view is that growers can be surprised by the high removal rates associated with big yields. But this does not mean that fertilizer plans should target these big yields, just as fertilizing to the field average crop removal may not be enough. The impact high yields have on succeeding crops will depend on current state of soil test values, and the variability in test values across a field. Ontario Research and field trials show that the highest economic yields in a corn-soybean-wheat rotation are achieved with a build and maintain approach for all three crops compared to a sufficiency approach. Even where extra fertilizer was applied to lower testing fields, it still does not match the yield from build soils. What’s interesting about this approach is that it can be achieved using the 4R approach to sustainable fertility. Utilizing a 4R approach works for creating plans for next season, and a plan for the whole cropping cycle. To get there, requires having reliable site-specific soil test, yield and other data to properly address the in-field variability that inherently exists and drive profitability across the whole field.