Positive results for urea in ESN blendWhile nitrogen management is complex and varied, preliminary results of a new study show that the optimum rate of nitrogen may be higher than previously thought.
Between 2008 and 2012, Alberta Agri- culture and Rural Development (AARD), in collaboration with Agriculture and Agri-Food Canada (AAFC), investigated the effects of various nitrogen fertilizer management practices on barley, wheat and canola at nine sites in Alberta. Researchers applied three different products (urea, polymer coated urea, and a blend of the two), at four different rates (30, 60, 90 and 120 pounds), using three different application methods (fall and spring banded, spring seed placed fertilizer). The plots were analyzed for yield, plant population and various quality parameters, including protein and oil content, per cent plump kernels, and bushel and kernel weight.
“A blend of the two products often gave the best results,” said project lead Len Kryzanowski of AARD. For a coated product, Kryzanowski and his team used Environmentally Smart Nitrogen (ESN), which they valued at $0.20 per pound over the cost of urea. The same soil moisture and temperature conditions that promote crop growth are what controls nitrogen release from polymer-coated products like ESN, so theoretically the nitrogen should be available when the plants need it. Used alone or blended at a rate of 75 per cent ESN and 25 per cent urea, the various ESN treatments provided a positive economic response in 46.4 per cent of treatments on barley plots. Overall, a spring seed-placed blend of ESN and urea made the biggest financial sense when comparing the added yield to the added cost of coated urea.
“The initial release of good nitrogen in the spring, with slow release from coated nitrogen, would sustain the crop through the season,” said Kryzanowski. (See sidebar for regional variations in economic response.)
Placing ESN or a blend in the seed row produced healthier plant stand as the coated product mitigates seedling dam- age from urea. Seedling damage varied between the crops studied with more canola seedlings affected than wheat or barley. However, this does not mean that cereal crops are immune from too much seed-placed nitrogen.
“Canola is much more forgiving,” said Kryzanowski. “It can recover quite nicely even if you do get seedling damage from nitrogen replacement. Cereals are less affected, but there’s a greater yield reduction relationship.”
Dr. Elwin Smith, bioeconomist at AAFC in Lethbridge, is in the midst of analyzing the economics of nitrogen use.
“What we’ve found is that, in this study, the optimum rate of nitrogen tends to be higher than what I expected to see,” he said.
He added that his analysis is not complete and he will review the numbers to ensure accuracy. However, the preliminary results jive with articles he has read about producers who are seeing positive responses to higher-than- recommended nitrogen rates.
One of the main goals of this project is to update AARD’s Alberta Farm Fertilizer Information and Recommendation Manager (AFFIRM) software to bolster producers’ nitrogen use efficiency and take advantage of improvements in agriculture.
“With the advancement of plant genetics and higher yield potential, it sort of makes sense that [crops] need more nutrients,” said Smith, adding that farming practices like regular summerfallow have been replaced by continuous cropping since the AFFIRM software was last updated.
As well as assessing the yield and economic benefit of various nitrogen treatments, this study looked at the environ- mental impact of rate, timing and source of nitrogen. Losses from urea fertilizer include nitrous oxide (N2O), a gas with almost 300 times the global warming potential of carbon dioxide. While there seems to be some emission reduction by switching from urea to ESN, it appears that most of the reduction in N2O occurs when switching from fall to spring applications of fertilizer, as the spring thaw causes the most volatility. Any change from fall to spring application reduces N2O emissions by 16 to 25 per cent.
However, the use of ESN does not totally prevent N2O emissions. A change from spring applied urea to fall applied ESN results in a 20 to 40 per cent increase in emissions.
“From an environmental perspective, I think nitrogen management is well done in Alberta,” said Kryzanowski, while acknowledging that it is still challenging to make the best nitrogen recommendations.
The data will be included in the Nitrous Oxide Emission Reduction Protocol and could benefit farmers looking to take advantage of carbon off-set credits.
LOCATION PROPORTION OF ESN TIME AND PLACE TREATMENTS ON BARLEY PLOTS WITH A NET ECONOMIC BENEFIT
|SPRING SEED PLACED BLEND|
|Gibbons / St. Albert||50.0%||16.7%||33.3%||41.7%|
|Vegreville / Willingdon||31.3%||43.8%||43.8%||43.8%|
|Barrhead / Dapp||31.3%||31.3%||37.5%||25.0%|