Liquid N Broadcast on Fields Had Greater Loss

Iowa on-farm trials in 2006 showed more nitrogen was lost by applying liquid N on soil surface.

Cutting edge ideas on crop management and soil fertility were the focus of the annual On-Farm Network conference, sponsored by the Iowa Soybean Association, held in Des Moines February 21.

Tracy Blackmer, director of research for ISA, headed up the program. He told farmers attending the meeting that "There are a number of things you'll be interested in this year to help you improve corn and soybean yields."

The program explored those topics - as the 2007 meeting was a lot more than a "Nitrogen Conference," which is what the one-day meeting was called in recent years. "The economics of what we showed farmers this year was compelling as we looked at the results of our studies. Farmers need to do crop management practices that are more optimal and timely. That will allow them to either maintain or even increase their yield - without spending more money," says Blackmer.

Compare corn price vs. N rate

In the session that covered the results of corn nitrogen trials that the On-Farm Network conducted on farmers' farms around Iowa in 2006, farmers asked: How does the optimal nitrogen rate we should apply for corn change when prices jump from $2.50 corn to $4.00 corn? Does the higher price we see for corn this year influence the optimal N application rate?

"The answer is the higher corn price per bushel is less of a factor than the management practices we've seen in our on-farm trials," he says. "For example, the difference we saw in our preplant liquid nitrogen vs. preplant anhydrous trials is that farmers are losing more of the nitrogen and thus more yield potential with liquid N broadcast on the soil surface. That's much more of a profitability factor than the change in nitrogen rate with $4 corn.

"When we decide to conduct these trials, we don't start off by saying we already know the answers," says Blackmer. "Instead we go out and do the testing in farmers fields and evaluate the results. In 2006, we've had more clear-cut answers to our questions than we've ever had in previous years."

Greater loss from liquid N

ISA's on-farm trials across the state compared preplant liquid N vs. preplant anhydrous in 2006. "In the past several years we talked about how we suspected some loss with liquid nitrogen when it is spring applied on the soil surface. The spring of 2006 wasn't really a wet year in the early part of the season, but we did see some yield differences," he says. Yields were lower where the N wasn't worked into the soil or wasn't knifed into the soil.

At the same time, by comparing fall anhydrous application with spring or side-dress treatments in 2006, it was dry enough in spring 2006 that the side-dress treatments actually did slightly worse than the fall-applied anhydrous treatments.

"Farmers really don't think about this," he notes. "But it is possible, depending on the year. And by going out and looking at what happened we have enough sites replicated across the state that we can prove this statistically."

Fungicides are popular topic

At this year's conference, Blackmer and other researchers talked about more than just nitrogen. Farmers were very interested in the results of the on-farm manure trials. "Manure trials remain the category where we have the biggest yield losses from what people are expecting of any of our trials," says Blackmer. "Those manure trials cost me the most on the yield payouts in 2006."

What else were farmers interested in at this year's meeting? "Foliar fungicide application to corn plants has been the most popular topic farmers have talked about this year," he adds. "They keep asking us, did it pay to spray a foliar fungicide on cornfields? Looking at the results of our on-farm trials, we can indeed tell farmers on average how much it paid.

"We saw big differences in corn yield depending on how the fungicide was applied - aircraft vs. ground sprayer," says Blackmer. "With the aircraft applied fungicide treatments we got over a 10 bushel per acre yield increase compared to no fungicide being applied. With ground applications we only averaged around a 4-bushel yield increase on corn. Also, we noticed that the later in the season that we applied the fungicides to corn, the better our yields."

Higher prices for soybeans

On soybeans, the trials with foliar fungicide application showed that the results for 2006 weren't much different than those in the trials of past years. "But today, the difference of having a $7 per bushel price for beans vs. $4.50 per bushel beans means there's a different interpretation of the results in terms of profitability," says Blackmer. "You don't have to get as big of a yield increase with today's higher priced corn and beans. Higher priced grain makes it easier to justify paying for fungicide treatment."

The presentations at this year's ISA On-Farm Network Conference delivered a lot of information about various trials ISA sponsored in 2006 on farms across Iowa. Remote sensing, liming, government programs and the proposed 2007 Farm Bill were also discussed at the Feb. 21 On-Farm Conference.

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