Agriculture Reference
In-Depth Information
6
Within each location there can be multiple sites or fields where the trial will be carried out
(Information Systems for Biotechnology, 2013).
7
A petition (as well as an approval) may include more than one trait or phenotype category. For
example, a petition for corn may include one or more HT traits and one or more Bt traits.
8
Pharmaceutical plant compounds produced are intended for pharmaceutical use and would need
to be approved from at least one of the following agencies prior to commercialization: U.S.
Food and Drug Administration (FDA) Center for Biologics Evaluation and Research
(human biologics), FDA Center for Drug Evaluation and Research (human drugs), FDA
Center for Veterinary Medicine (animal drugs), and USDA Center for Veterinary Biologics
(animal biologics). None of the plants currently under permit produce pharmacologically
active compounds.
9
Over 90 percent of U.S. acreage devoted to major crops has been treated with herbicides in
recent decades (Osteen and Fernandez-Cornejo, 2012).
10
Some other GE crops were only on the market for a limited amount of time. Bt potato varieties
were introduced in 1996, but withdrawn from the market after the 2001 season. FlavrSavr
tomatoes, which were genetically engineered to remain on the vine longer and ripen to full
flavor after harvest, were introduced in 1994, but withdrawn from the market after several
years.
11
Drought-tolerant corn was approved for commercial use in 2011 (
Federal Register
, 2011;
Monsanto, 2012) and commercially introduced in 2012.
12
USDA's National Agricultural Statistics Service (NASS) and Economic Research Service
(ERS) sponsor the Agricultural Resource Management Survey (ARMS). This survey
includes a crop-specific survey of production practices (called ARMS Phase 2) for selected
major corps each once every 5 years on a rotating basis. This survey was conducted in 2006
for soybeans, 2007 for cotton, and 2010 for corn.
13
Potential yield is defined as “the yield of an adapted cultivar when grown with the best
management and without natural hazards such as hail, frost, or lodging, and without water,
nutrient, or biotic stress limitations (water stress being eliminated by full irrigation or ample
rainfall)” (Fischer and Edmeades, 2010). Farm level (actual or effective) yield is equal to
potential yield minus the yield lost to pests or to other stresses.
14
Since Bt and HT traits protect yield rather than increase potential yield, it is possible that in
some cases the Bt and HT traits are not introduced in the highest yielding germplasm. Over
time, this so-called “yield drag” usually disappears (NRC, 2010, Ch 3). On the other hand,
Shi et al. (2013) show that the opposite situation may arise if GE genes are added more
frequently to “high quality” germplasm. They call this situation genetic selectivity bias.
15
In this report, net returns are defined as per-acre revenues minus per-acre variable costs.
Revenues per acre are equal to crop yields times crop price. Per-acre variable input costs
include pesticide, seed and labor costs. Seed costs paid by adopters of GE varieties include
a technology fee. This measure of net returns is used because most of the financial impacts
of adopting GE crops result from changes in crop yields, chemical costs, and increased seed
costs. This measure is estimated using field-level data and captures the greatest influence
that GE crop adoption would have on farm financial performance as it also filters out the
impact of other farm activities—such as livestock production (Fernandez-Cornejo and
McBride, 2002). The econometric estimation involves estimating a restricted profit function
(Fernandez-Cornejo and Wechsler, 2012) together with the associated supply function and
input demand functions (hired labor is also included and wages are used as the
numeraire
).
16
The difference in means of corn yields between adopters and nonadopters is statistically
significant for 2005 and 2010 using either the delete-a-group jackknife procedure (Kott,
1998) or the standard statistical test.
17
The panel members who wrote the NRC report were Y. Carriere, W. Cox, D. Ervin, J.
Fernandez-Cornejo, R. Jussaume Jr., M. Marra, M. Owen, P. Raven, L. Wolfenbarger and
D. Zilberman.
