|February 10, 2015
||Field Crops 28.33
How Much Yield Loss Occurs with Corn Hybrids Sold as "Organic"?
Joe Lauer, Corn Agronomist
Farmers growing corn for the organic
market often get a premium and rightly so. Organic farmers are required to
go through a certification process that requires a fee and extra effort and
time for paperwork. They have more expenses due to increased pest control,
especially weeds. Organic farmers have also expressed some concern about the
genetic yield potential of the commercial hybrids used in organic corn
Since 2004, the UW Corn Hybrid Evaluation program has been testing corn
hybrids sold for the organic market. A total of 55 organic hybrid trials have been conducted at 10 locations
in Wisconsin (see http://corn.agronomy.wisc.edu/HT/).
The average yield of the commercial organic hybrids in these trials was 174 bu/A. The average range between the top- and bottom-ranked hybrids
was 73 bu/A. These
trials are planted early and managed aggressively for pests. All pests are
controlled to the best of our ability. Differences among hybrids are likely
due to genetic
differences, rather than management interaction differences.
In 53 of the trials, a high-performing conventional hybrid check (nontransgenic)
was included. Two treatments were applied to the check conventional hybrid.
In one treatment the check hybrid was treated exactly the same as the other
organic commercial hybrids in the trial. In the other treatment the check
hybrid was hand weeded up to 3x during the growing season. No difference was found
between the control and hand weeded conventional check hybrids, so data from these
pooled together. Organic hybrids yielded 7% (14 bu/A) less than the
conventional hybrids in these trials (Table 1).
Table 1. Yield of commercial organic and conventional hybrids in the
UW Corn Hybrid Evaluation program. Data are derived from 53 organic trials conducted
||Grain yield (bu/A)
The organic trials are almost always planted adjacent to the public
trials. An estimate of relative performance can be made between these
adjacent trials by calculating an average for each trial and treating
each environment as a replication. In this analysis, the conventional
check hybrid included in the commercial organic trial was dropped so
that the mean from the organic trials only represent commercial organic
hybrids. Hybrids in the public trials include both conventional and
A total of 48 environments had both organic and public trials planted
adjacent to each other. The hybrids in the organic trials yielded 12%
(24 bu/A) less than hybrids in the public trials (Table 2).
Table 2. Analysis of average yield for organic and public hybrid
trials in the
UW Corn Hybrid Evaluation program. Data are derived from 48 environments
where both trials were grown.
||Grain yield (bu/A)
In both analyses, organic hybrids yielded less than modern hybrids. In
the organic trials, the conventional check hybrid was consistently the top
performing hybrid in the trial. However, the commercial organic hybrids were
not far behind (7-12% on average). Again, in these trials, all interactions
are minimized to the best of our ability, so the trials represent potential
genetic differences. As plant stresses increase in organic systems due to
management constraints for certification and pest pressure versus the
relative ease of controlling some of those same pests in conventional
systems, the relative
differences between modern organic and conventional systems would also