The spike in fertilizer prices is making farmers and researchers alike take a closer look at the materials known as enhanced efficiency fertilizers.

“These materials will play a role,” says Glen Harris, University of Georgia Extension soil fertility specialist. “We'll keep looking at them, especially in different situations, to see which ones work.”

Before focusing on these new products, it's important not to forget the basics of soil fertility, the tried and true practices, says Harris. These begin with soil testing.

“We should also be comparing university and private lab recommendations, and even more so in asking where the research is coming from to back up those recommendations. This is a good question to be asked of private labs and universities,” he says.

Liming continues to be a critical factor in maintaining soil fertility, says Harris, in addition to the rate, timing, placement and source of fertilizer. Growers also need to give credit for legumes and animal manure, he adds.

“And something we really miss opportunities on is increasing our soil organic matter. Some of our growers in south Georgia have figured this out with strip-tillage. Even if you can build your organic matter by 1 to 2 percent, it'll help to build up your nitrogen,” he says.

Research is currently focusing on where enhanced efficiency fertilizers will fit best in helping growers deal with high fertilizer costs, says Harris.

“Enhanced efficiency fertilizer is a term coined by the Fertilizer Institute,” he says. “There's slow/controlled release which can be made in a number of ways. Examples would be ESN from Agrium — a polymer-coated urea — Agrotain and CoRon from Helena. There's also a lot of interest in stabilizers and additives. These are not fertilizers themselves, but a lot of them are additives that can be added to fertilizer. They include urease in inhibitors and nitrification inhibitors.”

The driving force behind the interest in these new materials is economics, contends Harris. Prior to 2005, nitrogen was 28 cents per pound, P205 was 22 cents, and K20 was 12 cents per pound in south Georgia, he says.

“When they peaked in October of last year, those prices were 85 cents per pound for nitrogen, 85 cents for P205, and 80 cents for K20 in Tifton, Ga. I know what the prices were because I called my dealer and asked him. What are prices going to do in 2009? Nitrogen and phosphorus already have come down in price. Potash hasn't come down yet, and it may be a few more months before we see a drop in price,” says Harris.

Growers shouldn't get the idea that enhanced efficiency fertilizers are a “silver bullet” or cure-all when it comes to soil fertility, he adds. “They might be just another tool in the tool box. I do think some will play a role. There are a lot of them out there and we're still trying to figure out which ones work and which ones don't work. More specifically, we need to know which ones work in different situations. It all depends on the product. Some sound similar but have different modes of action, and you have to look at each one individually, in my opinion, and you need to base their use on research,” he says.

Some of these products are designed just for nitrogen needs while others are designed for phosphorus. “Some might even cover nitrogen and phosphorus. The take-home message for the research data I compiled from this past year is that I didn't get a lot of response in my trials from these products. But I also didn't get a lot of response to just the fertilizer without the products. I've heard people who have experience with these materials say they'll work as long as you get a response to your regular added fertilizers.

“In my future research, I'll concentrate on trying to select better sites where I can guarantee some sort of response — a response that'll insure I see the effects of these products. We definitely need further testing.”

Harris says growers frequently ask him whether or not he can recommend any of these enhanced efficiency materials at the current time.

“I'm saying, based on my data, that the only one I can recommend now is Agrotain, because it is the only one for which I have enough consistent, positive results. This is not to say the others don't work — we just don't have enough data yet to be comfortable enough to make a recommendation.”

Agrotain, he says, is a known urease inhibitor. “There are different formulations of this product. There's also Agrotain Plus which has a known nitrification inhibitor in it. Nitrification inhibitors should limit nitrate leaching, which is a big issue around south Georgia, where we have a lot of irrigation on sandy soils.”

It's clear, says Harris, that researchers need to look at all of these materials in different situations because weather can influence the trials.

“It's not fair to say these products don't work. They'll probably work where you have a response.”

Looking at cost per acre, a product like Agrotain would be between $2 and $5 at the rate at which side-dress nitrogen is applied, says Harris. “You wouldn't have to save many pounds of nitrogen at 80 cents per pound to make it pay.”