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Mastering Early-Season Fertility

July 24, 2014 by Mosaic Agronomy Team

Whether you are growing wheat, canola or corn, you can set the stage for a healthy growing season and maximum yield with early-season treatments and starter fertilizer.

“Starter fertilizer means different things to different people,” says Dr. Kyle Freeman, Director, New Product Development for The Mosaic Company. “But one way to think about it is that starter is everything you do before and during planting to ensure healthy plants. One of the most effective programs can start with a foundation of dry nutrients either in the fall or earlier in the spring, and then complement that with a starter fertilizer you put down with the seed or close by, to give that young plant the boost it needs right out of the gate.”

When it comes to starter nitrogen applied at the time of planting, forget about broadcast surface application. Banding nitrogen, especially where residue is abundant, helps the plants get the best use of the nutrients the farmer is using, experts say.

“If the farmer has the ability to put down starter, injection is ideal, but a dribbled band can be fairly effective as well,” advises Dr. Jim Camberato, an Extension soil fertility specialist at Purdue who has done extensive research into starter fertilizers.

Dr. Camberato is currently conducting research that compares the effectiveness of pop-up in-furrow starter fertilizer versus a common practice known as two-by-two, in which the fertilizer is offset — 2 inches away from the seed row and 2 inches deep. One of the main differences is that more nitrogen can be used when the starter is offset.

“The standard recommendation is, the colder the soil, the greater the residue, the higher the yield potential, the more likely you are to see a yield benefit from using a starter,” Camberato says.

Farmers find starter fertilizer highly effective when they use no-till cultivation, especially in corn-after-corn rotations, in which there may be a lot of nitrogen tied up in the soil by the corn residues.

“The research has shown that most of the time, there are beneficial responses to the nitrogen component of the starter, but sometimes it’s the phosphorus content,” continues Camberato, referencing a consistent, but still unexplained finding. “You can get a response from phosphorus in the starter, even though soil tests indicate there’s an adequate level of phosphorus in the soil. There was a lot of work done in the good old days that showed that when you band nitrogen and phosphorus together, there was a synergistic effect on plant growth and uptake of the nutrients. They tried to localize the effect, to see if it was enhanced root proliferation or other factors, but they never could tie it to one thing. When the two are together, something happens that allows the plant to take up more of each, and to grow better.”

Camberato says that with today’s GPS-synced planters, producers can lay down a foundation of dry fertilizer and then lay the starter nitrogen right on top of it, even in a two-by-two arrangement, in order to get that synergistic effect from combining nitrogen and phosphorus fertilizers.

His current research project compares pop-up to two-by-two approaches with starter. It also looks at the combination of pop-up and two-by-two, and then compares this with a higher rate of two-by-two.

“We are moving into the second year of that project,” Camberato says. “In the first year, we had a pretty substantial yield response to the two-by-two placements, and it was even greater at the high rate. We were comparing 25 and 50 pounds of nitrogen per acre; then two-by-two and comparing that to zero, of course. Both the 25 and the 50 were beneficial, and the 50 was more beneficial than the 25. It was in no-till continuous corn.

“That is a situation in which we might expect to see a good response; yet, there was no effect using the pop-up in that experiment.”

The difficulty with using pop-up alone as a starter is the limited amount of nitrogen that can be used, since it is placed so close to the seed.

“If the benefit to the starter is getting a corn-after-corn crop off to a good start because of nitrogen tie-up by residues, then we can’t effect much of a change with 10 pounds of nitrogen in-furrow,” Camberato says.

Salt and ammonia in the nitrogen fertilizer can ‘burn’ the seedling.

“The fertilizer you put with the seed has the potential to reduce germination and damage young seedlings,” Camberato says. “You have to be careful with the form that you choose, as well as the amount. Some fertilizers are more toxic because they generate more ammonia and have more salt, so that in-furrow placement limits how much nutrient you can apply.”

MicroEssentials ® SZ TM from The Mosaic Company combines the proper nutrient ratio of nitrogen, phosphorus, sulfur and zinc into one granule, making it easy to apply and ensuring uniform distribution of the four nutrients across an entire field.

“From a seed safety standpoint, MicroEssentials is as safe as MAP [monoammonium phosphate] and safer than DAP [diammonium phosphate],” says Dr. Freeman. “It can be used in the same way that we see these traditional phosphate sources. Using MicroEssentials not only gives you phosphorus, but you are also applying other nutrients like sulfur and zinc.”

For two-by-two, you can use a coulter or a knife to open up a slit; and either dribble the fertilizer into that open slit, or feed a line of fertilizer into the soil from the base of the knife.

“When it comes to nitrogen, banding is essential, both from the standpoint of putting a high concentration of nutrient near the plant that has a limited root system, as well as getting more of that nitrogen to move into the soil and result in less volatilization,” Camberato says.

In contrast, with broadcasting, the operator can experience an increased loss of nitrogen due to volatilization.

“If you think about starter fertilizer in the Corn Belt, it’s usually part of a crop nutrition plan that involves dry or liquid fertilizer applied either in the fall or early in the spring,” Freeman says. “That is followed by an application of liquid fertilizer that goes on at planting with the seed. Starter fertilizer helps the seed get off to a good start by supplying available nutrients in close proximity to the seed.

“We have seen early-season growth benefits from starter fertilizer,” Freeman explains. “When you have wet conditions early, especially in no-till situations, or with corn-on-corn, there are advantages to using starter fertilizer. However, that early-season vegetative difference doesn’t always translate into a yield benefit at the end of the year.”

Some past research hints at ways of thinking about starter and when it might be an essential part of the crop nutrient plan.

“One of our students read through some of the older research and found a couple of experiments in which they tried to identify hybrids that would be more responsive to starter,” Camberato says. “The suggestion from the results was that hybrids that might have a smaller or slower-to-establish root system, early in the season, were more influenced by starter fertilizer. We are going to take a look at some of the popular hybrids and their early season, and look at whether those with lower early-season vigor would be more likely to respond to this sort of approach.”