Wheat yields pushing 150 bu/ac are very possible with good management and increased nitrogen (N) rates. Recent research clearly shows an interaction between fungicides and nitrogen. But high nitrogen rates immediately raises questions about lodging, nitrogen source, and application timing. Wheat’s nitrogen demand is much earlier than corn, so nitrogen management needs to be different. What is the right rate, and are there any strategies that might help get those monster yields, without breaking the bank?
Rate Without Fungicides
90 lbs N/acre and full stop! You will never achieve big wheat yields under Ontario weather conditions without fungicides, so you might as well pull in your horns and let the real wheat growers pass you by.
Rate With Fungicides
120 lbs N/acre is the base rate. In over 50% of our trials, the most economic rate of nitrogen (MER-N) pushed very close to 150 lbs N/acre. However, 150 lbs/ac N added only a small increase to the bottom line, so if you are afraid of lodging, go slowly. Try just 2 or 3 strips in the field at 150 lbs/ac, with the balance at 120 lbs/ac, until you learn how to keep rates high and that there is more yield there, without having flat wheat.
Rates and Rotation
Wheat after peas or very early planted wheat with high plant populations should have lower N rates. Pea nitrogen releases perfectly for wheat, meaning that 60-90 lbs N/ac acts like 120-150 lbs N/ac. Early planted, thick wheat has higher lodging potential, and 120 lbs N/ac may make it go flat. Proceed with caution.
Trials over the past several years have shown little impact of N source on yield. 28% or 32% liquid sources have consistently shown a small (2.5 bu/ac) yield advantage over dry, due mostly to more even distribution.
ESN, Agrotain Plus®
ESN has shown no yield advantage in winter wheat, but has provided a boost in protein. Agrotain Plus® actually decreased yields when nitrogen applications were delayed by weather into mid-May. Agrotain Plus® may have a fit with early nitrogen applications, but should not be used on later timings. ESN has a fit as part of the nitrogen blend on hard wheat, but only when protein brings added value. The jury is still out on whether to buy these “protected” N products, or just spend the extra dollars on more nitrogen.
The need for sulphur (S) has not been as consistent as expected when the deficiency first showed in 2011. , When it occurs, the response stops at 10 lbs S/acre. To date, the best general recommendation is to add 10 lbs S/ac (40 lbs/ac ammonium sulphate or 3 gal/ac ammonium thiosul) as an “insurance” policy, and do trials on each farm to find responsive and non-responsive fields. There is no slam dunk that added sulphur will pay.
Time single applications for late-April. This avoids significant N loss concerns from wet soil conditions that might occur earlier, while providing N when the crop demand goes high. However, large single N applications increase lodging concerns.
Yield increases with split N applications have been seen, but are not consistent. Other considerations drive split N applications more than yield. Reduced concerns over N loss, better weed control from crop competition, more uniform heading and less lodging all accrue from split applications. Apply 50-80 lbs N/ac as early as possible (on frost), with the balance at the first to second node (May 10th).
Wheat is the most responsive crop to management that we grow. Added attention to detail will give higher yields. With good management it is possible to eliminate lodging yet achieve very high yields. Whatever strategy you chose, you will be rewarded according to the amount of effort you put into the crop. Manage the crop, and be a REAL wheat grower!