Minnesota Corn: Should You Use an In-Furrow Starter This Year?

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Low corn prices will often mean some evaluation of management costs for growers across Minnesota.

Looking ahead, should you consider using an in-furrow starter fertilizer? It can present additional costs, which may or may not be worth it, depending on the soil and the operation.

New research from the University of Minnesota evaluates sources and rate of fluid starter fertilizers.

Soil scientist Jeff Vetsch and Dan Kaiser, Extension nutrient management specialist, are leading this research. They say that crop rotation, soil type, tillage and application practices all play important roles in your decision to use an in-furrow starter this year.

Evaluating source and rate

A recent U-M study conducted in Waseca, Minn., and Rochester, Minn., evaluated sources and rates of three fluid starter fertilizers: ammonium polyphosphate (APP), urea ammonium nitrate (UAN) and ammonium thiosulfate (ATS).

These applications generally increased early growth while reducing plant variability of corn after corn in reduced tillage. Applying APP, UAN and ATS either independently or in combination often reduced grain moisture at harvest, and occasionally increased grain yield.

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“A surface dribble band of liquid starter fertilizer applied a few inches off the corn row is an effective way to apply N and S as ATS, or N as UAN,” says Vetsch. “It will be most beneficial in corn after corn on poorly drained glacial till soils. You’ll see enhanced early growth and development with near-row placement of liquids, but yields will likely be the same as when these nutrients are applied in a broadcast application.”

For sulfur, starter fertilizers’ advantage over broadcast is reduced application rates. This research showed 6 to 10 pounds of S per acre as ATS was sufficient. Additional research at Waseca showed 10 pounds of S per acre as ATS produced the same yields as 20 pounds of S broadcast as dry fertilizer sources (ammonium sulfate and elemental sulfur).

Phosphorus starters

In Minnesota, phosphorus is the most limited nutrient early in the season, but not all fields will benefit from a phosphorus-based, in-furrow starter fertilizer program. When evaluating which source of fertilizer to use and at what rate, Kaiser says to think about your overall fertility program and evaluate the cost per unit nutrient applied.

“While placement of phosphorus near the corn seed can have profound impacts on corn early growth, in the end, the impact on grain yield is related to the total rate of a nutrient applied relative to the capacity of the soil, to supply all of a crop’s nutrient needs within a given season,” says Kaiser. “Starter fertilizers are just like any other nutrient source, so think about them accordingly.”

Deciding on starter fertilizer

Once you’ve considered your economic and agronomic factors and are ready to decide on a starter fertilizer, Vetsch says to answer the following questions first:

  • Do you farm on poorly drained fine-texture soil?
  • Is corn after corn a significant portion of your corn acres?
  • Do you use conservation tillage, like chisel plow or disk ripper, for corn after corn?
  • Do you have time to apply starter fertilizer at planting vs. broadcast applications that save time?

If you answered yes at least two of these questions, you should consider adding liquid starter fertilizer equipment to your corn planter.

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