Fertilizer prices clouding corn outlook

It’s one of the most asked questions among farmers this year: “How are we going to contend with high fertilizer prices?”

“Going back to 2004, fertilizer prices have just about doubled,” says Glen Harris, University of Georgia Extension soil scientist. “And it’s not the fault of your fertilizer dealer. There are a lot of reasons for increased fertilizer prices, and we just have to deal with them — you can’t make good corn without fertilizer.”

When nitrogen prices increased, it was blamed on natural gas, says Harris, and when lime prices increased, it was blamed on freight costs. “In general, everything is up because of supply and demand, and not just in the United States but worldwide. The global population is growing and the United States is a cheap market. If they can sell it somewhere else globally, they will. China has 1.3 billion people and 55 percent of them are farmers. There are 300 million people in the U.S. and about 2 percent of them are farmers,” he says.

With fertilizer prices being so high, farmers need to pay more attention to the details of selecting and applying fertilizer, says Harris.

“Soil testing is important — that’s how we find out what the crop needs, and that includes lime. It’s all about getting the most from fertilizer nutrients that you can use. With corn and cotton, we talk about nitrogen because it is the element we need in the largest amount,” he says.

Of course, he adds, growers don’t soil-test for corn, but those who are cutting back to the bare minimum on nitrogen can use tissue testing to insure they haven’t cut back too far.

Anytime fertilizer prices increase, Harris says he gets calls on fertilizer placement, including banding and timing. “In south Georgia, with our sandy soils and decent rainfall or rainfall plus irrigation, split applications for variable nutrients like nitrogen are critical,” he says.

Growers also are paying more attention to the form of nitrogen. “There are several forms out there, and they all work if we use them correctly. You can price them out to see which one is the cheapest. We’re taking a closer look at that and trying to figure out what will work the best for us and which form we can use,” he says.

Whenever you talk about doing different things with nutrients, it’s important to make a distinction between the nutrients, says Harris.

“We talked about split-applying nitrogen because it’s mobile. But phosphorus is not mobile. And you have to remember the nitrogen cycles because nitrogen is so complex. There are a lot of places where we can get nitrogen into system, but there also are a lot of places in the system where we can lose nitrogen. Phosphorus pretty much stays wherever we put it, and potassium is somewhat in between the two and is relatively mobile,” he says.

To combat high fertilizer prices, growers have to deal with several factors together, including soil testing and placement, says Harris.

“I’m getting a lot of questions on banding. We band our liquid nitrogen a lot, but we’re getting questions on whether or not you can also band P and K. It’s a longstanding Extension recommendation that we really don’t think you can gain a lot by banding P and K if your soil-test levels already are at medium or high levels. That means if you have a low soil-test P and K, you might actually get an advantage from banding.”

This isn’t the same, he says, as a starter fertilizer. “Starters are usually smaller amounts that are meant to get the crop started. Personally, I like starter fertilizer on corn. When we plant in Georgia, it’s still fairly cool, especially in you are strip-tilling and it’s a cool year. As long as you account for those nutrients into your program, things like 10-30-40 and some nitrogen solution is not a bad way to go.”

If something is limiting from a nutrient standpoint, it’s probably nitrogen, says Harris.

Several forms of nitrogen are available to growers, he says. “We start with ammonium and then we add things and do different things to it to come up with different forms of nitrogen.”

Up to now, whenever a grower takes a soil sample and sends it in for analysis, they get a recommendation for nitrogen. “But we never actually test that soil for any kind of nitrogen forms. The recommendation is based on field tests, yields goals and other factors. That might eventually change. There’s a lot of interest now in taking soil samples for nitrate as a gauge at planting, or, more likely, before you side-dress corn to find out if there’s enough there. They do this routinely in the Northwest and Midwest.”

Other factors that must be considered together include rate and timing. Timing, he says, is a key to successful corn production.

“We’ve always said to put out one-fourth to one-third of your corn nitrogen at planting and the remainder at side-dressing. That’s a minimum of two split applications.”

There’s interest among growers, he adds, in applying nitrogen through an irrigation pivot. “Research tells us the best system is 25 percent at planting and 22.5 percent at the six, 12 and 18-leaf stage and then the remaining 7.5 percent at tasseling. That’s a lot of splits in my opinion, and I’m not sure about it. We have a hard enough time keeping the pivots going, let alone injection pumps and everything else. It’s helpful whenever you can split applications when the crop really needs it, during the highest demand period. You can reduce your risk of loss, maybe reduce your total rate, and make a better crop.”

Turning to nitrogen sources, Harris says some growers are using granular — especially for side-dressing — and they’re probably using urea, which has resulted in some volatilization issues.

“We use a lot of nitrogen solution in Georgia — 32 percent is cut with some sulfur. Any time fertilizer prices go up, we start getting call about anhydrous. Anhydrous, per pound of N, is probably the cheapest, but dealers have gotten away from handling it because of cost, insurance and other factors. I know some growers are interested in taking another look at anhydrous. It’ll work on corn — we’ve just gotten away from using it.”

Harris reminds growers not to forget organic sources such as legume cover crops, including clovers and vetches.

“We also have a lot of poultry litter in Georgia. It’s decent fertilizer and good at pre-plant. Commonly, if you put out 2 tons, you get 60 pounds of available N and then you make up the difference with inorganic fertilizer at side-dress.”

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