Reducing Fertilizer Rates in a Drought
With the old ‘yield-goal’ mentality still alive and well unfortunately with many growers, there will be a tendency to greatly reduce fertilizer rates this spring.
With the old ‘yield-goal’ mentality still alive and well unfortunately with many growers, there will be a tendency to greatly reduce fertilizer rates this spring. This is a mistake. In dry conditions, crop nutrients are used much less efficiently than in a more ‘normal’ year. In 2012, efficiency of N applied to a dry soil was at least 1/3 less efficient than similar rates in a ‘normal’ year for corn in one of my experiments. It takes far more nutrient per bushel/pound/ton in a drought year compared to that in a normal year. That stated, being conservative on rates is not a bad strategy, within limits. In spring wheat, for example, if the rate from the NDSU N calculator is 150 pounds of N per acre, reducing it to 120 pounds N per acre would not be too extreme. If the weather turned around, the variety tended to be lower protein naturally, then supplementing the N early post-anthesis to regain some protein is a plan that conserves N early. If the weather remains dry, achieving high protein would happen without any extra N.
Extension Soil Specialist