As shown in Chapter 1, farmers growing soybean, cotton, and corn adopted genetically engineered (GE) varieties over the last decade on the majority of acres planted to these crops in the United States. Much smaller acreages were planted in 2009 to a few other GE crops, such as canola, sugar beet, squash, and papaya. The decision to plant GE crops has affected the economic circumstances not only of the adopting farmers but in some cases of farmers who chose not to adopt them. The economic effects on farmers who adopt GE crops span their production systems and marketing decisions. In this chapter, we discuss the potential yield effects, changes in overhead expenses and management requirements, and shifts in market access and value of sales. A wide array of studies conducted mostly during the first 5 years of adoption has provided evidence for assessing the overall economic implications for farmers (see Box 3-1). We also discuss here the economic effects of GE-crop use on livestock producers who use the crops for feed and on farmers who do not elect to use the technology. The chapter concludes by examining the economic implications of gene flow from GE crops to non-GE crops and weedy relatives.
GE crops have affected the economic status of adopters in several ways. The use of GE crops has had an effect on yields and their risk-management decisions. Genetic-engineering technology has also changed
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3
Farm-Level Economic Impacts
A
s shown in Chapter 1, farmers growing soybean, cotton, and corn
adopted genetically engineered (GE) varieties over the last decade
on the majority of acres planted to these crops in the United States.
Much smaller acreages were planted in 2009 to a few other GE crops, such
as canola, sugar beet, squash, and papaya. The decision to plant GE crops
has affected the economic circumstances not only of the adopting farmers
but in some cases of farmers who chose not to adopt them. The economic
effects on farmers who adopt GE crops span their production systems and
marketing decisions. In this chapter, we discuss the potential yield effects,
changes in overhead expenses and management requirements, and shifts
in market access and value of sales. A wide array of studies conducted
mostly during the first 5 years of adoption has provided evidence for
assessing the overall economic implications for farmers (see Box 3-1). We
also discuss here the economic effects of GE-crop use on livestock produc-
ers who use the crops for feed and on farmers who do not elect to use the
technology. The chapter concludes by examining the economic implica -
tions of gene flow from GE crops to non-GE crops and weedy relatives.
ECONOMIC IMPACTS ON ADOPTERS OF
GENETICALLY ENGINEERED CROPS
GE crops have affected the economic status of adopters in several
ways. The use of GE crops has had an effect on yields and their risk-
management decisions. Genetic-engineering technology has also changed
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THE IMPACT OF GE CROPS ON FARM SUSTAINABILITY
BOX 3-1
Measuring Impacts
To evaluate the economic impacts of GE crops on adopters and non-
adopters, the committee relied on the results of empirical analyses of farmer
surveys and market data. Studies were peer reviewed, but the research
approach and methods varied considerably with each study’s purposes
and data. Each study has its own strengths and limitations. For example,
some studies may use a different guideline in judging the significance (i.e.,
confidence level) of factors affecting the adoption of GE crops compared to
other studies. The committee could not make the various studies comparable
and accepted each set of findings as valid evidence. Some of the general
approaches used to estimate economic impacts are explained here.
Empirical data. A comparison of means or averages is sometimes used
to analyze results from experiments in which factors other than the item of
interest are “controlled” by making them as similar as possible. For example,
means of yield or pesticide use can be compared for two groups of soybean
plots that are similar in soil type, rainfall, sunlight, and all other respects. One
of the two groups is considered to have a treatment (e.g., soybean with a
genetically engineered trait), and the other does not (e.g., conventional soy-
bean). As an alternative to controlled experiments, the subjects that receive
treatment and those that do not can be selected randomly with data collected
through mail, phone, Internet, or personal surveys.
Survey data. Caution must be exercised in interpreting the results
obtained by analyzing the differences in means from data from “uncontrolled
experiments,” such as farm surveys. Conditions other than the “treatment” are
not equal across the farms surveyed. For example, differences between mean
estimates for yield and pesticide use from survey results cannot necessarily be
attributed to the use of GE seeds because the different results are influenced
by many other factors which are not controlled, including irrigation, weather,
soil, nutrient and pest-management practices, other cropping practices, opera-
tor characteristics, and pest pressures.
Moreover, farmers are not assigned randomly to the two groups (adopters
and nonadopters) but make the adoption choices themselves. Therefore,
adopters and nonadopters may be systematically different as groups, and
these differences may manifest themselves in farm performance. They could
be confounded with differences due to the adoption of GE crops (i.e., the treat-
ment). This situation, called self-selection, would bias the statistical results
unless it is recognized and corrected.
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FARM-LEVEL ECONOMIC IMPACTS
However, farmer surveys give a more accurate picture of the total farm-
level economic effects of GE-crop adoption in terms of the secondary behav-
ioral changes resulting from adoption (e.g., adoption of conservation tillage
and changes in the timing of pesticide application). Moreover, it is rarely the
case that a farmer would or could choose to adopt a GE cultivar to replace
a non-GE cultivar that is an isoline or near-isoline, so relying on agronomic
experimental data to measure the economic differences can be biased. Also,
only farmer surveys can reveal the value of the changes in nonpecuniary
characteristics that can occur with the adoption of GE cultivars.
Social scientists often are able to statistically control for certain influencing
factors for which there are data (apart from the GE-crop treatment) by using
multiple regression techniques in econometric models. That is, differences in
economic conditions and crop or management practices that also influence
yield or other outcomes are held constant so that the effect of adoption can be
isolated. For example, in research on GE crops, economists control for many
factors, including output and input prices, pest infestation levels, farm size,
operator characteristics, and management practices such as crop rotation and
tillage. In addition, economists control for self-selection and simultaneity (of GE
adoption and pesticide use decisions) using particular types of econometric
models. To account for simultaneity of decisions and self-selectivity, a two-stage
model may be used. The first stage consists of the adoption-decision model
for GE crops. The second stage then uses the findings from the first stage to
examine the impact of using GE crops on yield, farm profit, and pesticide use.
The Counterfactual. Ideally, measuring the impact of a treatment requires
the observation of the results that would emerge in the absence of the treat-
ment: a counterfactual. Aside from controlled experiments, it is not possible to
observe this counterfactual outcome. Rather, the counterfactual is inferred by
methods such as those summarized above (e.g., controlling for all other influ-
encing factors). Moreover, regarding environmental impacts, Ferraro (2009)
argues that “elucidating casual relationships through counterfactual thinking
and experimental or quasi-experimental designs is absolutely critical in envi-
ronmental policy and that many opportunities for doing so exist.” The use of
the two-stage estimation procedure to correct for selection bias exemplifies
such a quasi-experimental design. However, Ferraro also admits that “not all
environmental programs are amenable to experimental or quasi-experimental
design.” In those cases, firm conclusions cannot be drawn about the causative
factors inducing GE-crop adoption or other outcomes of interest.
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THE IMPACT OF GE CROPS ON FARM SUSTAINABILITY
farmers’ production expenses and altered their decisions related to time
management. Furthermore, because of the widespread adoption of GE
crops and their subsequent impact on yields, genetic-engineering technol-
ogy has influenced the prices received by U.S. farmers.
Yield Effects
The first generation of GE varieties contains traits that control or facil-
itate the control of pest damage. A starting point for analyzing the produc-
tivity effect of such control is the damage-control framework (Lichtenberg
and Zilberman, 1986) that was developed to estimate the effectiveness
of the use of chemical pesticides and other pest-control activities. The
framework recognizes that damage-control agents, like pesticides and GE
traits for pest management, have an indirect effect on yield by reducing
or facilitating the reduction of crop losses, in contrast with such inputs as
fertilizers, capital, and labor, which affect yields directly. In particular, the
framework assumes that
effective yield = (potential yield)(1 – damage).
Potential yield is defined as the yield that would be realized in the
absence of damage caused by pests (i.e., weeds, insects).1 It is a function of
production inputs, such as water and fertilizer, and of agroecological con-
ditions and seed varieties. The yield actually observed is called effective
yield and is equal to potential yield minus damage. Damage is affected by
the pervasiveness of pests, which may be controlled with pesticides, the
adoption of GE varieties, or other control activities. With that framework,
the yield effects of GE varieties can be analyzed, but spatial, temporal, and
varietal factors must be taken into consideration.
Indirect Yield Effects
The indirect yield effects of the use of insect-resistant (IR) crops are
most pronounced in locations and years in which insect-pest pressures
are high. For example, it is generally recognized that the adoption of Bt
corn for European corn borer (Ostrinia nubilalis) control resulted in annual
average yield gains across the United States of 5–10 percent (Falck-Zepeda
et al., 2000b; Carpenter et al., 2002; Fernandez-Cornejo and McBride,
2002; Naseem and Pray, 2004; Fernandez-Cornejo and Li, 2005). Empirical
1 Damage may also be caused by weather conditions, such as wind, rain, drought, and
frost. For succinctness and convenience here, the definition of damage is restricted to pest
problems.
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FARM-LEVEL ECONOMIC IMPACTS
studies, however, have clearly indicated that the indirect yield effects of
Bt corn hybrids for European corn borer control vary temporally and
spatially. In years with high pressure—corn borer damage of more than
one tunnel per plant that exceeds 2 inches in length (Baute et al., 2002;
Dillehay et al., 2004)—the yield advantage for Bt hybrids relative to near-
isolines2 was 5.5 percent in Pennsylvania and Maryland (Dillehay et al.,
2004), 6.6 percent in Wisconsin (Stanger and Lauer, 2006), 8 percent in
New Jersey and Delaware (Singer et al., 2003), 9.4 percent in Iowa (Traore
et al., 2000), and 9.5 percent in South Dakota (Catangui and Berg, 2002).
The yield advantage for Bt corn was negligible in those regions during
years with low pest pressure (Traore et al., 2000; Catangui and Berg, 2002;
Singer et al., 2003; Dillehay et al., 2004; Stanger and Lauer, 2006). Likewise,
in regions where European corn borer is an occasional pest, there was no
indirect yield advantage from the use of Bt hybrids in comparison to near-
isolines (Cox and Cherney, 2001; Baute et al., 2002; Ma and Subedi, 2005;
Cox et al., 2009). Most of the early empirical studies, however, included
some Bt events3 that did not have season-long control of corn borer, and
this may have muted the yield advantage of Bt hybrids (Traore et al., 2000;
Catangui and Berg, 2002; Pilcher and Rice, 2003).
There have been fewer empirical studies of the yield effects of Bt
corn for control of corn rootworm (Diabrotica spp.) than of the effects of
Bt corn for control of European corn borer. Rice (2004) estimated potential
annual benefits if 10 million acres of Bt corn for corn rootworm control
were planted. They included
• Intangible benefits to farmers (safety because of reduced exposure
to insecticides, ease and use of handling, and better pest control).
• Tangible economic benefits to farmers ($231 million from yield
gains).
• Improved harvesting efficiency due to reduced stalk lodging.
• Increased yield protection (9 to 28 percent relative to that in the
absence of insecticide use and 1.5 to 4.5 percent relative to that with insec -
ticide use).
• Reduction in insecticide use (a decrease of about 5.5 million pounds
of active ingredient per 10 million acres).
2 Near-isolines are cultivars that have the same or near genetic constitution (except for
alleles at one or a few loci) as the original cultivar from which they were developed. Near-
transgenic isolines that have similar genetic makeup except for the transgenic trait allow
a comparison of the cultivar with or without the transgene for its agronomic, quality, or
nutritional aspects.
3 Each seed company has different events associated with different insertion places of the
Bt gene and different promoter genes that allow a Bt toxin to be produced at different times
of the season or in different plant parts.
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0 THE IMPACT OF GE CROPS ON FARM SUSTAINABILITY
• Increased resource conservation (about 5.5 million gallons of water
not used in insecticide application).
• Conservation of aviation fuel (about 70,000 gallons not used in
insecticide application).
• Reduced farm waste (about 1 million fewer insecticide containers
used).
• Increased planting efficiency.
• Improved safety of wildlife and other nontarget organisms.
A recent study by Ma et al. (2009) indicated spatial and temporal vari-
ability in indirect yield responses. Bt corn rootworm hybrids produced
yields 11–66 percent larger than untreated near-isoline hybrids. Bt yields
were also larger than yields of the non-Bt hybrid variety planted on clay
soils and treated with insecticide in 1 of 3 years that had high infestations
of western corn rootworm (Diabrotica irgifera irgifera). On sandy soils,
where corn rootworm infestations are typically much lower than on clay
soils, yield differences also occurred between Bt corn rootworm hybrids
and their near-isolines with or without the standard soil-applied insecti -
cide treatment in 1 of 2 years. The study reported low levels of western
corn rootworm on droughty sandy soil, however, and attributed yield
increase to improved drought tolerance from the finer, longer fibrous
roots of the Bt hybrid corn. Cox et al. (2009) found no yield advantage for
corn hybrids with Bt rootworm control compared with near-isolines in a
dry year when rootworm damage did not occur.4
Gray et al. (2007) expressed concern that one of the Bt corn rootworm
events was somewhat susceptible to injury by a variant of western corn
rootworm in Illinois. Another Bt corn rootworm event, however, had
superior control of western corn rootworm larvae in Iowa, Illinois, and
Indiana (Harrington, 2006); this suggests that distinct Bt events from dif -
ferent seed companies may differ somewhat in corn rootworm control as
they did initially in corn borer control. Cox et al. (2009) evaluated both Bt
rootworm events on second-year corn in field-scale studies on four farms
4 As discussed in Chapter 1, all Bt rootworm corn hybrids are treated with a low level
of insecticide and fungicide (typically a neonicotinoid). The low level (0.25 mg of active
ingredient per seed) targets secondary pests but does not affect corn rootworm. In fields
planted continuously with corn, the low level used with a soil-applied insecticide resulted
in lower corn yields compared to a high level (1.25 mg of active ingredient per seed) with
a soil-applied insecticide (Cox et al., 2007c). That is indirect evidence that the high level of
seed-applied insecticide increases control of corn rootworm, but the low level does not.
In addition, the low and high levels of seed-applied insecticides had no positive effects
on corn grain (Cox et al., 2007b) or corn silage yields (Cox et al., 2007a) when following
soybean, which suggests there is no yield enhancement of these seed-applied insecticides
in the absence of pests.
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FARM-LEVEL ECONOMIC IMPACTS
in New York and found that neither rootworm event provided a yield
advantage because rootworm occurrence was low in all fields. As with
Bt corn for corn borer, Bt corn for rootworm control did not provide an
indirect yield benefit in the absence of pest pressure.
Piggott and Marra (2007), relying on 1999–2005 university field-trial
data from North Carolina, found that Bt cotton with two endotoxins
out-yielded conventional cotton by 128 more lbs of lint per acre (14 per-
cent of average yield in the region) and out-yielded Bt cotton with one
endotoxin by 80 lb/acre (8 percent of average regional yield). A study
of Bt cotton varieties with two endotoxins in 13 southern locations that
had mostly moderate to high infestations of cotton bollworm (Helicoerpa
zea), with or without foliar-applied insecticides, showed that indirect
yield effects had spatial variability. The Bt cotton cultivars without insec -
ticide use provided consistent control of the Heliothines (cotton bollworm
and tobacco budworm, Heliothis irescens), regardless of the magnitude
of infestation (Siebert et al., 2008). Furthermore, supplemental insecti -
cide applications to the Bt cotton cultivars rarely improved control of
budworm and bollworm. In the low-infestation environments, however,
the use of Bt cultivars with or without insecticides provided no yield
improvement relative to the control of the non-Bt cultivar without insec -
ticide application. In the moderate- to high-infestation environments, the
Bt cultivars provided the same 30-percent yield increase in lint yield with
or without insecticides compared with the control (Siebert et al., 2008). In
a large-scale study of 81 commercial cotton fields conducted in 2002 and
2003, average yield did not differ among Bt cotton, Bt cotton resistant to
glyphosate, and non-GE cotton (Cattaneo et al., 2006). However, after
statistical control for variation in two factors significantly associated with
yield (number of applications of synthetic insecticide and seeding rate),
the yield of Bt cotton and Bt cotton with herbicide resistance was signifi-
cantly larger (by 8.6 percent) than the yield of non-GE cotton. A total of
eight GE cotton cultivars and 14 non-GE cultivars were included in the
study. For those cultivars, it appears that Bt cotton (herbicide-resistant or
not) would generally out-yield non-Bt cotton given similar production
inputs and agronomic conditions.
The indirect yield effects of herbicide-resistant (HR) crops generally
may have less spatial and temporal variability because weeds are ubiq -
uitous and cause yield losses in most situations. For example, the use of
HR soybean with timely glyphosate application almost always achieves
yield gains relative to production without weed control (Tharp and
Kells, 1999; Corrigan and Harvey, 2000; Mulugeta and Boerboom, 2000;
Wiesbrook et al., 2001; Knežević et al., 2003a, 2003b; Dalley et al., 2004;
Scursoni et al., 2006; Bradley et al., 2007; Bradley and Sweets, 2008).
Likewise, the use of HR corn and cotton varieties with timely glyphosate
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THE IMPACT OF GE CROPS ON FARM SUSTAINABILITY
application almost always results in yield increases (Culpepper and
York, 1999; Johnson et al., 2000; Gower et al., 2002; Dalley et al., 2004;
Richardson et al., 2004; Sikkema et al., 2004; Thomas et al., 2004; Cox et
al., 2005; Myers et al., 2005; Sikkema et al., 2005; Cox et al., 2006; Thomas
et al., 2007).
Yield Lag and Yield Drag
Despite properties that result in indirect yield benefits, some farmers
observed a yield reduction when they first adopted HR varieties (Raymer
and Grey, 2003). Indeed, shortly after the adoption of glyphosate-resistant
soybean, university soybean trials reported lower yields of HR varieties
(Oplinger et al., 1998; Nielsen, 2000). In a study that compared five HR
varieties with five non-HR varieties in four locations in Nebraska, evi-
dence of “yield lag” and “yield drag” was found (Elmore et al., 2001a,
2001b).5 A 5-percent yield lag was due to the difference in productivity
potential between the older germplasm used to develop the HR varieties
and the newer, higher yielding germplasm of the non-HR varieties. 6 A
5-percent yield drag resulted from the reduced production capacity of the
soybean plant following the presence or insertion process of the HR gene
(Elmore et al., 2001b). Although not as pronounced as in the Nebraska
study, Bertram and Petersen (2004) also presented data that indicated a
potential yield lag at one location in Wisconsin with the early HR soybean
varieties.
Fernandez-Cornejo et al. (2002b) reported that a national farm-level
survey indicated that HR soybean showed a small advantage in yield
over conventional soybean, probably because of better weed control.
5Yield lag is a reduction in yield resulting from the development time of cultivars with
novel traits (in this case, glyphosate resistance and Bt). Because of the delay between the
beginning of the development of a cultivar with a novel trait and its commercialization,
the germplasm that is used has lower yield potential than the newer germplasm used in
cultivars and hybrids developed in the interim. Consequently, the cultivars with novel traits
have a tendency to initially yield lower than new elite cultivars without the novel traits.
Over time, the yield lag usually disappears.
Yield drag is a reduction in yield potential owing to the insertion or positional effect of a
gene (along with cluster genes or promoters). This has been a common occurrence through -
out the history of plant breeding when inserting different traits (e.g., quality, pest resistance,
and quality characteristics). Frequently, the yield drag is eliminated over time as further
cultivar development with the trait occurs.
6 During selection for a particular trait in a plant-breeding program, many other traits
may also change. Such “correlated” changes may occur because a gene controls more than
one trait (pleiotropy), because genes controlling two traits are in physical proximity on a
chromosome (linkage), or because of random segregation (drift). The distinctions among the
three causes are important because the solutions to them differ. Solutions may be necessary
because some correlated changes are undesirable.
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FARM-LEVEL ECONOMIC IMPACTS
A national survey of soybean producers in 2002 found that there was
no statistical difference in yield between conventional soybean and HR
soybean (Marra et al., 2004). A mail survey of Delaware farmers in 2001
found that HR soybean had a 3-bushel/acre yield advantage (Bernard et
al., 2004). The survey data and results of empirical studies in Wisconsin
indicate that the use of more elite germplasm in variety development has
probably eliminated the yield lag or yield drag associated with the use of
HR varieties (Lauer, 2006).
Similarly, early empirical studies of Bt corn hybrids indicated a poten-
tial yield lag, as indicated by the lower yield of Bt hybrids than of new
elite hybrids (Lauer and Wedberg, 1999; Cox and Cherney, 2001). How-
ever, Bt hybrids yielded as well as or better than near-isolines (Lauer and
Wedberg, 1999; Traore et al., 2000; Cox and Cherney, 2001; Baute et al.,
2002; Dillehay et al., 2004), and this suggests that there was no yield drag
or loss of yield because of the insertion of the Bt gene with the early Bt
corn hybrids.
Furthermore, whether a yield loss or a yield increase materializes
for a GE crop depends on the particular farming situation. For exam -
ple, in their comparison of HR corn hybrids with non-HR varieties,
Thelan and Penner (2007) reported that in low-yield environments HR
hybrids yielded 5 percent more than non-HR hybrids and in high-yield
environments non-HR hybrids yielded about 2 percent more than HR
hybrids. An early study of cotton (May and Murdock, 2002) that com -
pared first-generation glyphosate-resistant cultivars with nonresistant
cultivars showed no yield lag in glyphosate-resistant cultivars and a
yield advantage of using glyphosate instead of the standard conven -
tional soil-applied herbicides. The results of the study suggested that the
use of soil-applied herbicides resulted in some type of injury to cotton,
whereas glyphosate application before the fourth leaf stage did not. A
study at nine locations across the United States (May et al., 2004) showed
that one of Monsanto’s later glyphosate-resistant cotton lines provided
even greater yield than the first-generation glyphosate-resistant cotton
when glyphosate was applied from the fourth to the 14th leaf stage; this
resulted in an agronomic advantage of the later technology.
A 2002 U.S. Department of Agriculture (USDA) survey found that
increases in cotton yields in the Southeast were associated with the adop -
tion of HR cotton and Bt cotton in 1997: A 10-percent increase in HR-
cotton acreage led to a 1.7-percent increase in yield and a 10-percent
increase in Bt cotton acreage led to a 2.1-percent increase in yield if other
productivity-influencing factors were constant (Fernandez-Cornejo and
Caswell, 2006).
It was noted above that most of the yield studies of GE versus non-
GE crops conducted in the United States used data from the late 1990s
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THE IMPACT OF GE CROPS ON FARM SUSTAINABILITY
and early 2000s.7 Any yield differences between GE and non-GE varieties
found during the first 5 years of adoption could have diminished as seed
companies developed new IR and HR events. One reason for the lack of
recent studies on yields may be that it is increasingly difficult to find suffi-
cient data on non-GE varieties owing to the predominance of GE varieties
in major crops (see Chapter 4).
Improved Crop Quality and Risk Management
Bt corn has been found to decrease concentration of the toxic chemi -
cal aflatoxin (Wiatrak et al., 2005; Williams et al., 2005) and some other
mycotoxins produced by fungi (fumonisins in particular) in the grain
(Clements et al., 2003). In doing so, it decreases the risk of price dock -
age to farmers because of poor crop quality and increases food safety
for consumers. Bt crops also have reduced stalk lodging at harvest (Rice,
2004; Wu et al., 2005; Stanger and Lauer, 2006; Wu, 2006);8 this improves
crop quality and increases harvest efficiency, thus reducing the farmers’
fuel and labor costs. A benefit of the use of HR soybean is that the pres -
ence of foreign matter (such as weed seeds) in the harvested crop has
greatly decreased (from 5-25 percent to 1-2 percent in the southeastern
states) (Shaw and Bray, 2003), reducing the need for handlers to blend
soybean with high foreign matter with soybean with lower foreign matter
to improve the overall quality of the crop.
The use of GE crops can also reduce agronomic risks for farmers.
For example, in the case of HR crops, glyphosate breaks down quickly in
the soil, removing the potential for the residual herbicide to injure a suc -
ceeding crop (Scursoni et al., 2006). Additionally, some Bt varieties may
improve drought tolerance (Wilson et al., 2005). Empirical studies have
not documented that the use of Bt corn for corn borer provides a yield
benefit in the presence of drought (Traore et al., 2000; Dillehay et al., 2004;
Ma et al., 2005), but Ma et al. (2009) found in an empirical study on Bt
corn for corn rootworm that in a drought year on sandy soil, the Bt corn
rootworm hybrid yielded 10 percent more than the near-isoline. The roots
of the Bt corn rootworm hybrids were longer and more dense than those
of the non-GE hybrid because the Bt trait kills the below-ground larvae
that feed on the roots of the corn plant. Ma et al. (2009) speculated that Bt
7 More recent data from field trials are available but have not been published in peer-
reviewed literature.
8 Stalk lodging is the permanent displacement of the stems of crops from their upright
position, resulting in a crop that either leans or can be prostrate. A mildly lodged crop results
in only a slight slowdown of harvest, whereas a severely lodged crop greatly slows down
harvest (in some instances the crop can only be harvested in one direction, further reducing
harvesting efficiency).
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FARM-LEVEL ECONOMIC IMPACTS
corn rootworm hybrids may have more drought tolerance than standard
hybrids in drought years because the root system is more intact and there-
fore capable of taking up more water. Such risk reduction may explain in
part farmers’ motivation to adopt these GE crops. A related risk posed
by adoption of Bt corn in northern latitudes, however, is the potential for
higher grain moisture at harvest because of improved plant health, which
increases drying costs or delays harvest (Pilcher and Rice, 2003; Dillehay
et al., 2004; Ma and Subedi, 2005; Cox et al., 2009).
Because GE crops have the ability to reduce yield loss, adopting farmers
also have different insurance options for managing risk. In 2007, Monsanto
developed a submission to the USDA Federal Crop Insurance Corporation
for a new crop-insurance endorsement for corn that contains three traits:
a Bt toxin that controls corn borer, one that controls corn rootworm, and
herbicide resistance.9 The submission proposed a premium-rate discount
for those hybrids based on several thousand on-farm field trials conducted
over several years in the Corn Belt states of Illinois, Indiana, Iowa, and
Minnesota. The trials demonstrated the yield and yield-risk reduction
advantages of the hybrids compared with conventional or single-trait
HR hybrids and showed that the current premium rates were no longer
actuarially appropriate. A lower insurance premium became available in
the 2008 crop year to farmers who adopted the triple-stacked hybrids. The
rate discount was applied to the yield portion of the premium for actual
production history of the field and based policies on crop-insurance units
in which at least 75 percent of the acreage was planted to qualifying corn
hybrids. The average premium-rate discount was 13 percent in 2008, or
about $3.00/acre.
Comparable triple-stacked hybrids from seed companies Dupont/
Pioneer and Syngenta were approved for inclusion in the program for
the 2009 crop year, and the premium-rate discount applies to all three
companies’ and licensees’ seed brands that contain at least the above-
mentioned traits for dryland corn in at least a subset of 13 Midwest states
and irrigated corn in Kansas and Nebraska. This is the first approved
crop-insurance innovation that has resulted in reduced premium rates,
and it provides a saving for farmers and reduces the need for premium
subsidies by the federal government. Cox et al. (2009), however, found
no consistent yield or economic advantage for triple-stacked hybrids
compared to double-stacked hybrids from both companies in second-
year corn in New York, despite one of the years being dry and warm. In
both years, corn rootworm damage was low, and corn borer damage was
sporadic across locations.
9 These products are marketed by Monsanto as YieldGard® Plus, Roundup Ready 2®, and
YieldGard VT Triple® hybrids.
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THE IMPACT OF GE CROPS ON FARM SUSTAINABILITY
Baute, T.S., M.K. Sears, and A.W. Schaafsma. 2002. Use of transgenic Bacillus thuringiensis
Berliner corn hybrids to determine the direct economic impact of the European corn
borer (Lepidoptera: Crambidae) on field corn in eastern Canada. Journal of Economic
Entomology 95(1):57–64.
Baylis, A.D. 2000. Why glyphosate is a global herbicide: Strengths, weaknesses and pros -
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