Field testing T-22™ Planter Box for corn in Iowa

Several corn producers used precision farming technologies to evaluate a new product that is reported to enhance nitrogen (N) use by plants. The studies demonstrate that precision farming technologies make it possible for groups of producers to objectively assess the value of new products as soon as they appear on the market.

They tested T-22TM Planter Box, which is an EPA-registered biofungicide seed treatment produced by Bioworks, Inc. (Geneva, New York). Studies at Cornell University in New York indicate that this product promotes root growth, enhances N use, and increases yields of corn.

Each corn producer added T-22TM Planter Box to the seed in one-half of their planter and planted 10 to 30 acres in a serpentine pattern. The resulting strips with and without the treatment were marked at planting. Effects of the treatment on end-of-season cornstalk nitrate concentrations were assessed by collecting pairs of stalk samples from adjacent strips at four places in each field. Producers harvested the strips by using combines equipped with yield monitors and global positioning system. The treatment had no effect on mean yields of grain measured across all sites (Table 1). Mean concentrations of cornstalk nitrate were higher with than without the treatment, but the increase was not statistically significant.

The cornstalk nitrate concentrations revealed that all fields had adequate N without the addition of T-22TM Planter Box. Previous studies have shown that yield increases in response to added N are seldom observed in situations where cornstalk nitrate-N concentrations without the extra N exceed 250 ppm. Information concerning the interpretations of this test is given in ISU Extension publication PM 1584 (August 1997), Cornstalk testing to evaluate nitrogen management.

The stalk nitrate concentrations are important because they indicate that the product did not have opportunity to increase yields by increasing N uptake by the crop at the sites studied. A noteworthy point illustrated, therefore, is that products designed to enhance N uptake should not be expected to increase corn yields unless rates of N fertilization are substantially lower than used by most corn producers today.

Table 1. Effects of T-22TM Planter Box on corn yields and stalk nitrate concentrations.

Grain Yields Stalk Nitrate
County Fertilizera

N Rate
With T-22 Without T-22 With T-22 Without T-22
lb/acre bu/acre ppm-N
Greene 110 174 171 1236 1163
Greene 120 169 164 3086 2738
Buchanan 130 201 202 1722 735
Palo Alto 130 151 154 905 321
Greene 140 179 179 832 1317
Hamilton 140 135 136 2538 1947
Woodbury 145 185 185 2496 3563
Cherokee 160 141 148 1191 1065
Mean 134 167 167 1751 1606

aThe values shown do not include any N applied as diammonium phosphate.

This article originally appeared on pages 44-45 of the IC-488 (5) -- April 15, 2002 issue.

Updated 04/14/2002 - 1:00pm