Farm Journal Test Plots examine starter attachments that bridge the nutrient gap and get corn off to a strong start

For two decades, the Farm Journal Test Plots have studied nearly every aspect of starter fertilizer: attachments, placement and rates. This ever popular topic continues to generate more questions than any other topic from farmers.

"The key to fertilizer is to know the three R’s," says Farm Journal Field Agronomist Ken Ferrie. "Right time, right place, right rate."

Ferrie, along with Farm Journal Associate Field Agronomist Missy Bauer, organized more than a dozen plots to look at attachments, rates and blends for starter. This article discusses the test plot results relating to attachments. (Watch future issues for continued coverage.)

Dialing in on attachments involves two of the R’s: right timing and placement.

There are a wide variety of starter attachments available to apply in the furrow, above the seed, below the seed and to the side of the seed. Each placement is a source of nutrients for the two types of roots that starter fertilizer targets: the seed root and the crown root.

The first roots to emerge are the seed roots. Once they emerge from the seed, they grow downward in the soil to establish the plant.

"While seed roots only pick up small amounts of nutrients, for a tiny plant those nutrients are important in the early days," Ferrie explains.

When starter is placed so the seed roots can pick it up, you see a quick visual response at the two-leaf stage. When fertilizer is placed farther away or above the seed roots, the crown roots come into contact with it. The response from that can be seen in five-leaf corn.

"Placing starter in the furrow gives quicker response early in the season, and that usually translates to a 3 bu. to 5 bu. increase," Ferrie says. "Placing a higher rate of fert-ilizer away from the seed root avoids the risk of starter burn and tends to get a higher response overall of 7 bu. to 10 bu., but it is a somewhat delayed visual response compared with in-furrow."

In considering the options for applying starter fertilizer, there are positives and limitations to only applying either in the furrow or outside the furrow. Applying starter in the furrow always carries some risk of starter burn regardless of the rate or salt load.

But going the in-furrow starter route also adds less weight to the planter and makes it easy to run in the field.

Some farmers, due to soil fertility and phosphorus needs or crop rotation and nitrogen needs, go outside the furrow to be able to apply a higher rate.

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