Do starter fertilizers and additives boost corn yields? Recent research has shown that by combining a starter fertilizer with management practices that increase early root growth, a larger root system can be developed. Larger root systems enhance early plant growth, resulting in larger ear size, better stress tolerance, less lodging and greater yield. New fertilizer additives, such as Avail, claim to further increase root growth and boost yield.

Replicated research trials in 2007 and 2008 at 10 North Carolina locations were designed to test these claims. At most locations, starter fertilizer increased corn grain yield, moisture and test weight significantly when compared to the untreated check. Avail increased yield at some locations, but an analysis across all locations did not find a significant yield improvement from its use.

The trials compared no starter fertilizer treatment with several different starter treatment rates — with and without Avail. Starter treatments consisted of 10-27-0, 12-12-4 or 17-17-0 with Avail, and the same treatments without Avail. Treatments were applied in a 2 × 2-in. band or in a deep band 8 in. below and 2 in. to the side of the seed.

Trials were carried out on a wide range of soil types in eight counties. The seeding rate for most of the trials was 33,000 seeds/acre on 30-in. rows. Data was collected on root mass, stalk diameter, yield, moisture and test weight.

This research helps answer several corn management questions:

  • Is there a benefit to using starter fertilizer on corn?

    These tests support previous work that shows a benefit to using starter fertilizer on corn. In most of these trials there was a significant yield increase from at least one of the starter materials compared with the no-starter check.

  • What blend of starter fertilizer results in the best yield?

    No starter material resulted in a consistent advantage across all locations in both years. At some locations an equal blend of N and P resulted in the best yield (17-17-0 or 12-12-4 being good examples). At others the use of 30% UAN as a starter material improved yield.

  • Did the addition of Avail to starter fertilizer improve plant properties and yield?

    Avail did improve stalk diameter and root mass. But when all 10 site-years were considered together, there was no significant yield advantage to using Avail as a fertilizer additive.

However, there were locations where Avail added to starter fertilizer did increase yield by as much as 14 bu./acre. It appears that Avail was effective under certain conditions such as wet, cool soils, low soil P levels or high pH.

When deciding whether or not to apply Avail, growers should consider their soil and environmental conditions.


Ron Heiniger has focused primarily on precision research, with recent emphasis on multiband images to determine N fertilizer requirements for corn.