Corn Research

Starter fertilizers for corn
Greg Stewart, OMAFRA Corn Specialist

It has been long recognized that proper use of starter fertilizers can increase corn yields and net profits. A three year study was initiated in 2008 designed to evaluate yield and economic response of corn to various starter fertilizer products, placement options and rates when bulk nitrogen (N) fertilizer was either applied pre-plant or side-dress.

In 2008, two field sites were selected on silt loam soils located near Elora and Hamilton.

There was no consistent effect of timing of bulk N fertilizer application on corn yield response to starter fertilizer across the two sites. Furthermore, the same general corn yield response to the various starter options occurred across sites. Therefore, the yield results presented in Table 1 are averaged across sites and bulk N application treatments.

Generally, the in-furrow fertilizers increased yield by 12 to 15 bushels per acre, 75 to 150 pounds per acre of Mono-Ammonium Phosphate (MAP) increased yield by 16 to 18 bushels per acre and dry fertilizer blends that contained N, phosphorous (P) and potassium (K) increased yield by 24 to 27 bushels per acre (see Table 1).

In these trials applying 10 gallons per acre of 28 percent as a starter, or in combination with another starter fertilizer did not increase yield by more than four bushels per acre compared to the treatments where the other starter fertilizer was applied alone. Grain harvest moisture was not affected by more than one percent by starter fertilizer (Table 1).

Net returns were increased by approximately $15 to $21 per acre using just in-furrow fluid starters, $30 per acre using just 75 pounds per acre of MAP and $43 using custom blend starters that contained N, P and K. Net returns were not increased by applying 150 pounds per acre of MAP over the 75 pounds per acre rate.

Use of 28 percent, either as a stand alone or in combination with other fertilizers, did not increase profits over what could be obtained if it was not applied. Also, combining a five gallon per acre 10-34-0 in-furrow application in combination with 75 pounds per acre of MAP did not increase net returns over what could be obtained using these products separately. It should be noted that time and equipment costs were not included in these preliminary net return calculations. Some caution should be taken in interpreting these results as these sites were quite responsive to starter fertilizers and yields were quite high in 2008.

The first year of this three year study demonstrated that a wide range in yield responses and profits can be obtained based on choice and rate of starter fertilizers applied. The study to date has shown that on fields with medium to medium low soil P and K tests that profitable yield responses will occur when P and K based starters are applied. The profitability of the starter options (just considering cost of products) ranked as follows: