Page 14-Com Talk, Lancaster Farming, Saturday, October 9,1993
Voluntary Programs, Funding
(Conllniwd from Pago 10)
Clinton Administration’s fiscal
1994 budget proposal to
ALTERNATIVE DESIGNS
FOR HYBRID
STRIP TESTS
Greg Roth
Hybrid strip trials are usually con
ducted in one of two designs. One is a
nonreplicated strip with individual
hybrids laid out in adjacent strips.
Another method is a tester design that
involves a tester hybrid to be placed
between every second or third hybrid in
the trial.
In this design, hybrid yields are
adjusted based on the yields of the adja
cent tester strips. Comparisons between
hybrids are then made on the basis of
adjusted yields. The puipose of this pro
cedure is to adjust for variation that might
be encountered across the Held.
A recent article published in the July
1992 issue of the Journal of Production
Agriculture by M. A. Schmitt of the Uni
versity of Minnesota and S. J. Openshaw
and M. W. Davis of Pioneer Hi-Bred
International examined the relative bene
fits of the two designs. In the study, 19
large plot yield trials were conducted in
Minnesota using live hybrids each. The
authors used statistical techniques to esti
mate the variation encountered with each
design.
The authors found that in 14 of 19
trials, the use of the tester system actually
increased the variation encountered in the
test. In most cases, the adjustment using
the testers did not increase the precision
of the test. As a result, the use of testers to
increase the confidence of performance
data is usually unwarranted.
The authors suggest that to increase the
precision of on-farm testing, instead, of
going to a tester system, a second replica
tion should be considered. Replication
could reduce the variation by one half and
could be accomplished with little extra
work compared to the tester system.
The failure of the tester system to
adjust yields may be due to several rea
sons. First, the variations in fields arc not
always consistent in one direction. This is
obvious to anyone who has flown over
Pennsylvania farmland. Secondly,
hybrids may not react the same way to
gradients in productivity. We know that
some hybrids are more sensitive to
drought stress, for example, than others.
And finally, the tester system spreads the
test out over more land and there is a grea
ter chance to encounter more variation.
This study shows that we should recon
sider how we design hybrid strip trials.
Some good basic rules to follow on
designing strip trials include:
• Keep the number of entries as low as
possible
• Replicate if possible
• Limit the test to hybrids of a similar
maturity (or group the hybrids by maturi
ty in the test)
• Don’t rely only on the' results of a
single trial.
increase funding for Section
319 to $BO million, Wenms
trand expressed disappoint-
ment that no 1994 funds were
specified for USDA’s Water
Quality Incentives Program.
“There is ample evidence that
when farmers are provided
with information on manage
ment practices which minimize
erosion and runoff and enhance
their economic viability, they
are quick to adapt without fac
ing any government mandate,”
he said. Wenstrand used as an
example his experience with
no-till farming, which he first
experimented with a decade
ago. He now uses a no-till sys
tem to farm about 1,500 acres
of com, soybeans and wheat.
For more information on
how to protect water quality,
contact the Alliance for a Clean
Rural Environment at (800)
545-5410.
For the name of your nearest dealer, contact:
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