Starter Fertilizer in Corn: Current Research and Recommendations

Even with softening of some fertilizer prices, fertilizer use in 2009 remains a very hot topic. And one of the most discussed areas is the use of starter fertilizer. First, let me preface the conversation by stating up front that there is no proven difference between liquid and dry starter fertilizers when considering equivalent fertilizer rate and placement. In fact, research conducted at Farm Focus in 2008 evaluated the use of liquid and granular starter fertilizers and found no differences with respect to corn yield in Hoytville soils.

Next, you’ll need your most recent soil test results in front of you to answer the question of whether or not to include phosphorus and potassium in your starter. Research from Ohio State University and at our own Farm Focus plots clearly indicates that soils that have a history of adequate phosphorus and potassium fertilization and resulting in soil test above the critical levels are unlikely to see a yield benefit from the inclusion of phosphorus and potassium in the starter. Soils that are below the critical level for phosphorus and potassium can benefit from starter, especially if broadcast applications were not made the previous fall. Soils that have been in continuous no-till may benefit from starter phosphorus, regardless of soil test level. Also, keep in mind that the efficiency of phosphorus will be the same if applied broadcast in the fall (or even now), as compared to applying that phosphorus as a starter.

Below are two starter fertilizer trials conducted at Farm Focus in Van Wert County:

2007– Four liquid starter fertilizers compared to untreated check.  Fertilizers included 2-20-18, 6-24-6, 8-19-3, and 10-34-0.  These four liquid starter fertilizers were applied in-furrow directly behind the seed at 5.0 gallons per acre. Results did not show any statistically significant yield differences among the treatments.  Soil test taken from this research field in 2005 show phosphorus at 69 ppm and potassium at 160 ppm (CEC = 12 meq/100g).  Full research report is available at  http://farmfocus.osu.edu/corn_pop-up_fertilizer-07.pdf

2008– Three liquid starter fertilizers and one dry starter fertilizer were compared to an untreated check.  The liquid starter fertilizers included 2-20-18, 2-20-18 with Avail (blended to 0.5%), and 2-20-18 with organic additives; the liquid starter fertilizers were applied in-furrow directly behind the seed at a rate of 5.5 gallons per acre. The dry starter consisted of 32-9-8 2×2 banded at 136 lb/acre.   Results did not show any statistically significant yield differences among the treatments.  Soil test taken from this research field in 2007 show phosphorus at 40 ppm and potassium at 182 ppm (CEC = 19 meq/100g).  Full research report is available at  http://farmfocus.osu.edu/corn_starter_fertilizer-08.pdf

In summary, for starter applications Ohio State University recommends a 2×2 placement for optimum application of nitrogen, which is normally the most limiting nutrient for corn production. Inclusion of phosphorus and potassium in a starter blend is necessary if soil test levels for those two nutrients are at or below the established critical values based on the Tri-State Fertilizer Recommendations.

ADDENDUM: Larger planting equipment may not be able to support 2×2 attachments; as such, pop-up or in-seed furrow applications of fertilizers might be used. The same rule of determining whether to include potassium and phosphorus still applies. That is, you should look at your soil test to determine whether you are near or above the critical level.