By Hans Schmitz, Technical Assistance Specialist
Indiana Ag Nutrient Alliance
Why starter?
Planting corn with starter fertilizer is a very common practice in Indiana and counts in many cases as a 4R Nutrient Management technique. Whether applying nutrients in furrow or banding at 2 inches by 2 inches off the seed bed, here are some considerations for efficient and effective application.
Right rate:
- In-furrow application rates should have low levels of nitrogen and avoid salts where possible.
- Applications 2×2 can have much greater rates.
- A balance should occur with other fertilizers to avoid overapplication.
Right source:
- In-furrow applications should focus on ammonium or nitrate forms of N, avoiding urea or ammonia.
- Note that the salt index of ammonium products is higher, which still requires limiting use.
- Banded applications have fewer restrictions, although the University of Minnesota recommends UAN if focused on getting nitrogen to the corn plant.
- For phosphorus, DAP, APP, and MAP can certainly be banded with little use.
- Avoid thiosulfates in furrow if possible.
Right time:
- We’re applying with the planter here.
Right place:
- If focused on optimizing yield, starter is a non-issue. According to “Corn Response to Starter Fertilizer in Indiana,” having starter boosted yield above not having starter in less than 50% of the experiments, regardless of in-furrow or 2×2 placement.
- Of those that did affect yield, the ability to put larger amounts of fertilizer in 2×2 placement makes a difference.
- Either placement should result in an early season vegetative plant health response that allows roots time to grow into larger sources of preplant or sidedress fertility.
- Plants will also mature faster with starter, with an average of one percentage point drier corn at harvest across the publication’s trials mentioned below.
https://www.agry.purdue.edu/ext/corn/research/updates/CornRespStarter.pdf
https://extension.umn.edu/crop-specific-needs/banding-fertilizer-corn-seed#ammonia-damage-3413611