Facilitating Conservation Farming Practices and Enhancing Environmental Sustainability with Agricultural Biotechnology

Conservation Technology Information Centerwww.ctic.org

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Demands to Feed a Growing World . . . . . . . . . 2

Breakthroughs in Agricultural Biotechnology . . 4

Biotechnology Enhances Stewardship of Soil, Air and Water Resources . . . . . . . . . . . 8

Biotech Crops Reduce Pesticide Use . . . . . . 18

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

RevieweRsDr . Shaun Casteel Purdue UniversityDr . Jerry Hatfield National Laboratory for Agriculture and the EnvironmentDr . Richard Joost United Soybean BoardDr . Hans Kok Conservation Cropping Systems InitiativeJames W . Pollack Environmental consultant, Omni Tech Int'l., Ltd.

Facilitating Conservation Farming Practices and Enhancing Environmental Sustainability with Agricultural Biotechnologyby

Dan Towery Ag Conservation Solutions, LLC Steve Werblow Conservation Technology Information Center

© 2010 Published by the ConseRvation teChnology infoRmation CenteR The Conservation Technology Information Center (CTIC) is a national, nonprofit 501(c)(3) organization . CTIC champions, promotes and provides information about comprehensive conservation and sustainable agricultural systems that are beneficial for soil, water, air and wildlife resources and are productive and profitable for agriculture .

This publication was made possible through funding provided by the United Soybean Board (USB) Sustainability Initiative . USB is made up of 68 farmer-directors who oversee the investments of the soybean checkoff on behalf of all U .S . soybean farmers . Checkoff funds are invested in the areas of animal utilization, human utilization, industrial utilization, industry relations, market access and supply . As stipulated in the Soybean Promotion, Research and Consumer Information Act, USDA’s Agricultural Marketing Service has oversight responsibilities for USB and the soybean checkoff . The opinions expressed are those of the authors based on a comprehensive review of the published literature .

Roundup,® Roundup Ready,® Roundup Ready 2 Yield,® Roundup Ready Flex,® Bollgard,® YieldGard,® SmartStaxTM and Genuity,® are registered trademarks of Monsanto Technology LLC. Herculex® is a registered trademark of Dow AgroSciences LLC. Liberty Link® is a registered trademark of Bayer Crop Science. Flavr Savr® is a registered trademark of Calgene.

ISBN 978-0-9822440-1-2

Today’s farmers are under unprecedented pressure. The world’s

population is closing in on seven billion, and it is projected to reach

nine billion by 2050. Billions of those people will be enjoying an improv-

ing standard of living, including increased consumption of more nutri-

tious food, milk, meat and energy.

A crowded planet adds to the environmental challenges of feeding,

clothing and powering the world. Water supplies will be increasingly

scarce, threatened by pollution, and diverted to population centers.

We can no longer set out to farm new frontiers – we must make every

acre already being farmed even more productive and prevent environ-

mental degradation.

With shrinking resources and little margin for expansion, the stakes

of environmental degradation are too high. Protecting our soils, air and

water – and our forests, wetlands and grasslands – is vital to all of us in

the long term. Environmental and economic sustainability are essential

on every farm.

Norman Borlaug, the legendary plant breeder and Nobel laure-

ate who was the driving force behind the Green Revolution of the

1960s and 1970s, summed up the task when he wrote, “Over the

next 50 years, the world’s farmers and ranchers will be called upon to

produce more food than has been produced in the past 10,000

years combined, and to do so in environmentally sustainable ways”

(Matz, 2009).

Introduction

The American farmer is uniquely prepared to meet the challenge of

feeding a growing world. Pioneer spirit, hard work and grit are comple-

mented by tools, technology and management. Together, they allow

U.S. farmers to feed more people with every acre. Among those tools

is plant biotechnology, which is already enabling growers to feed more

people, with less land and chemicals, than ever before. As the pressure

on farmers grows, agricultural biotechnology is on its way to becoming

the most revolutionary life-saving technology the world has ever seen.

Soybeans have already enriched countless lives around the world

through the protein and oils they provide directly to human diets, as

well as nutrition for livestock and a sustainable biofuel feedstock.

Soybeans have been among the first crops targeted for many advances

in biotechnology. In addition to direct production improvements includ-

ing improved pest control options, biotech soybeans have facilitated

farmers’ adoption of a variety of sustainable farming practices, includ-

ing conservation tillage – in which high-disturbance tools are replaced

by tillage tools that cause less soil disturbance and leave more crop

residue on the soil surface – or no-till farming, in which the soil is undis-

turbed except for placing the seed into a narrow seedbed.

In this document, we will explore how plant biotechnology and the

sustainable farming systems it helps facilitate – in soybeans as well as

in other crops – are helping farmers grow more food, feed, fiber and fuel

while protecting the environment.

1

109876543210

1950

1960

1970

1980

1990

2000

2010

2020

2030

2040

2050

Year

Popu

latio

n (b

illio

ns)

3 Billion

4 Billion5 Billion

6 Billion

7 Billion

8 Billion

9 Billion

World Population: 1950 - 2050

Source: U.S. Census Bureau, International Data Base, June 2009 Update.

The earth’s population is growing at a steadily increasing rate. It took

the human race until the turn of the 19th century to reach a population

of 1 billion, and the 20th century dawned on a population of 1.65 billion

(Daigger, 2009). By 2000, the global population was roughly 6 billion,

and the U.S. Census Bureau projects that it will top more than 9 billion

by about 2050. That increase alone is equal to the entire world popula-

tion in 1950 (UN Population Fund, 2008).Demands to Feed a Growing World

Rapid population growth is the result of a variety of factors. High fertil-

ity is, of course, a primary one. But so are lower mortality, greater life

expectancy and an age curve that skews increasingly toward a younger

population – billions of people of childbearing age (UN Population

Fund, 2008).

As the population increases by 50 percent in less than a half-century,

the standard of living in many areas of the globe is also expected to

steadily increase. In fact, Daigger (2009) estimates that if current con-

sumption trends do not change in the 21st century, growing demand

for improved diets, combined with the increasing population, will create

three times the current pressure on the earth’s resources.

2

As living standards rise for many people in the developing world,

others remain mired in poverty. According to the Food and Agriculture

Organization of the United Nations (FAO), 854 million people, or 12.6

percent of the global population, were malnourished in 2006 (FAO,

2006). Malnutrition, also called undernourished, plays a role in at least

half of the 10.9 million child deaths each year, exacerbating the effects

of diseases ranging from malaria to measles, according to the World

Hunger Education Service (2009).

Room for New Farms?Expanding the global cropland base could increase world food pro-

duction, but even an expansion in acreage must be accompanied

by steady improvements in yields to keep pace with the growing

population. Peter Goldsmith, executive director of the National Soybean

Research Laboratory at the University of Illinois, estimates that to meet

the food and feed demands of the projected human population in 2030,

growers would have to add 168 million acres of soybeans to existing

production levels if world yields remained at the current average of

34.2 bushels per acre, or plant an additional 118 million acres if yield

increases continued along their current trend and reached 38.6 bushels

per acre. To supply enough soybeans projected under the scenario

without increasing acreage, yields would have to nearly double to 59.5

bushels per acre (Goldsmith, 2009).

Meanwhile, the environmental costs of bringing new land into crop

production are under increasing scrutiny. Most of the world’s remaining

arable land is in South America and Africa. On a significant amount of

that land, soils and climate may be considered marginal for sustainable

farming. Clearing new land for agriculture could also lead to the loss of

valuable forests and other ecosystems, which could impact the global

climate system (Costa and Foley, 2000) or contribute to desertification

(Reich et al., 2001).

Global climate change is predicted to result in more extreme weather

events – instead of a relatively steady cycle of moderate rain and dry

periods, many areas of the world are expected to experience drier

droughts punctuated by more severe storms. That variability from year

to year would add uncertainty to global food supplies, world econom-

ics, farmer profitability around the world and future land-use decision

making. Those effects would be felt first, and most dramatically, where

farmers bring marginal land into production or farm in regions already

prone to extensive droughts or storm damage.

U.S. Trends Track Global OnesTrends in the U.S. are expected to parallel the world population curve –

demographers expect a 50-percent increase in the U.S. population by

2050, a total of 450 million people (Daigger, 2009). Meanwhile, cropland

acreage in the U.S. has decreased slightly over the past 60 years, and

pasture/grassland acreage has also been declining (Lubowski et al.,

2006). Today, American farmers produce annual crops on about 20

percent of the nation’s land area, and raise forage or grazing livestock

on another 26 percent (Lubowski et al., 2006).

Among the most versatile and nutritious crops produced by U.S.

growers are soybeans. High in protein, rich in oil, and versatile enough

to be consumed directly or fed to livestock, soybeans are a key com-

ponent in diets around the world. With improvements in productivity

and crop characteristics – many made possible through agricultural

biotechnology – soybeans will remain a mainstay of diets in both devel-

oped and developing countries as the population continues to grow.

3

The term “biotechnology” was coined early in the 20th century,

but the practice – using living organisms to produce other materials

or perform specific industrial tasks – dates back thousands of years.

Harnessing yeast to make bread and wine, or using rennet to turn milk

into cheese, are ancient examples of biotechnology. That basic prin-

ciple endures today: pharmaceutical companies use microorganisms

to create antibiotics and a host of other important medicines.

Biotechnology has also modernized. It is at the heart of processes

like DNA fingerprinting, which uses enzymes to reveal patterns in

genetic material. Biosensors can instantly detect E. coli bacteria in

food samples. Biotechnology also permits marker-assisted breeding,

which allows breeders to “peek” into the genetic material of their crosses

to quickly determine whether plants contain key traits – an advance

that speeds the breeding process dramatically and has nearly doubled

the rate of yield gain compared to conventional breeding techniques

(Monsanto, 2009).

In this paper, the terms “biotech crops” and “biotechnology-derived”

crops refer to plant cultivars that have been modified using biotechnol-

ogy tools such as genetic transformation – the movement of specific

genes from one source to another.

Commercial IntroductionIn 1996, Monsanto introduced two biotechnology breakthroughs in the

U.S. – Roundup Ready® soybeans and Bollgard® cotton, the first com-

mercially released biotech-derived row crops.

Roundup Ready soybeans are elite lines of soybeans that have been

transformed to include a gene that allows them to produce an enzyme

system in their growing points that is not susceptible to disruption by

glyphosate, the active ingredient in Roundup® herbicide. Planting a

soybean variety tolerant to glyphosate allows growers to apply the

herbicide – which is relatively inexpensive, extremely low in toxicity to

humans and animals, environmentally benign and extremely effective

at controlling more than a hundred species of weeds – without risk of

killing their crop (Monsanto, 2007).

Breakthroughs in Agricultural Biotechnology

4

Photo courtesy of Mark Leigh, Monsanto

Bollgard cotton varieties and Bt corn hybrids include a gene from

a bacterium called Bacillus thuringiensis, or Bt, that causes the plant

to produce an insecticidal protein. B. thuringiensis can produce dif-

ferent crystalline proteins that vary in their efficacy on specific insect

species. Ingested by a susceptible insect pest, the crystal dissolves,

releasing its endotoxins, which are in turn activated by enzymes in the

insect’s digestive system. The activated toxin perforates the insect’s gut

wall, killing the target pest through starvation or a secondary infection

(Witkowski, 2002). By harnessing Bt, which can also be sprayed onto

crops as an organic insecticide, growers who planted the modified

crops immediately reduced their use of insecticide sprays dramatically.

Subsequent commercial releases built on early successes. Roundup

Ready canola, which was released in Canada in 1996, entered the

U.S. in 2000. In 2008, Roundup Ready sugar beets were introduced

in the U.S. The following year, Monsanto released Roundup Ready 2

Yield varieties of soybeans, which contain a second-generation trait for

glyphosate tolerance. The company says the new varieties have the

potential to deliver yields 7 to 11 percent higher than first-generation

Roundup Ready soybeans, and are a stepping stone to achieving

Monsanto’s goal of doubling yields in soybeans, corn and cotton by

2030 (Monsanto, 2008).

U.S. growers also had their first opportunity to grow Liberty Link®

soybean varieties in 2009, which contain a gene that conveys

tolerance to glufosinate, the active ingredient in Bayer’s Liberty® and

Ignite® herbicides, broad-spectrum alternatives to glyphosate.

Stacked Varieties Combine BenefitsImprovements in genetic engineering capabilities have also allowed

breeders to combine traits in elite crop varieties, “stacking” genes for

both insect and herbicide tolerance in the same plants. Stacked variet-

ies simplify management and reduce risk on several fronts at once.

Three-way stacks in corn – for instance, hybrid packages that com-

bine a gene for a Bt protein aimed at European corn borer, a gene

for another Bt protein geared toward protection from corn rootworm

and herbicide tolerance in the same hybrids – are not uncommon. A

partnership between Monsanto and Dow AgroSciences has developed

a remarkable eight-way stack that delivers multiple modes of action

against several insect pests as well as the opportunity for growers to

choose among key herbicides for efficient weed control.

Huffman (2009) points out that stacked hybrids are likely to double

or triple the rate of yield increase in corn. Rather than the two-bushel-

per-acre average annual increase that has been achieved since 1955,

breeders have targeted a rate of increase of four to six bushels per

acre per year between now and 2019. Over the past 50 years, soybean

productivity has improved by an average of 0.5 bushels per acre per

year; Huffman predicts biotechnology will match or exceed that rate

of improvement (Huffman, 2009). Monsanto and Syngenta project

drought-tolerant hybrids in development will add 8 to 10 percent yield

in corn.

5

10

9

8

7

6

5

4

3

2

1

0

Year

Corn

Yie

ld (m

etric

tons

/hec

tare

)

Trend Line

19001880 1920 1940 1960 1980 20001860

Source: International Service for the Acquisition of Agri-Biotech Applications (James, 2008)

Corn Yield Trend Line

The Next Generation of Biotech Crops

The direct benefits of the first generation of biotechnology-derived

crops lay largely in production efficiencies – easier, more effective pest

control. Part of the reason is that introducing a gene that produces a

single protein is much simpler than transforming a crop with multiple

genes to address more complex challenges such as nutrient content

or stress tolerance.

Ironically, the success of the first generation of biotech crops fueled

some opposition to plant biotechnology. Though the rapid embrace

of biotechnology by the pharmaceutical industry – where it was har-

nessed to design, improve and produce a variety of medicines, includ-

ing insulin – raised little or no consumer suspicion, biotech crops have

stimulated heated public debate in many areas.

As a result, the commercial release of some biotech crops has been

challenged, and sometimes delayed. In some cases, the impetus came

from consumers, such as the 2009 lawsuit – the second year Roundup

Ready sugar beets were planted commercially – in which a U.S. District

Court judge ruled that Monsanto had to complete an environmental

impact statement on the crop (Pollack, 2009). In other cases, such as

with bioengineered wheat and potatoes, many farmers and large food

retailers resisted the commercialization of the crops, afraid that fright-

ened consumers, especially in export markets, would close their doors

on biotech staples.

Much of the anti-biotech debate highlights the fact that some shop-

pers are wary of input traits that benefit farmers without a direct payoff

for consumers. Also, they may not consider indirect benefits such as

lower food prices, less use of crop protection products and better con-

servation practices that protect soil, water and air resources. However,

a new wave of biotech crops may offer consumers more benefits to

which they can relate directly.

The next generation of biotechnology will be focused

on output traits, or consumer attributes, including:

• Soybeans whose oil contains less linolenic

acid and more oleic acid, which improves

heat stability without producing trans fats

that have been implicated in coronary disease;

• Soybeans with lower levels of saturated fat

and high levels of unsaturated oleic acid, for

a health profile akin to olive oil;

• Soybeans high in heart-healthy Omega 3 fatty

acids, such as stearidonic acid;

• Food ingredients in which the major allergens

are modified or eliminated;

• “Golden rice,” which produces beta-carotene in its endosperm.

Beta-carotene, the carotenoid that stimulates the production

of Vitamin A, is typically produced in the green tissues of riceplants,

but is ordinarily not consumed (Golden Rice Humanitarian Board,

2009). Vitamin A deficiency blinds more than 500,000 children and

kills more than 2 million people per year, according to the World

Health Organization (Dobson, 2000);

• Crops that can be converted more efficiently into biofuels, such as

readily fermentable corn.

Additional input traits are also being developed or commercially intro-

duced, including:

• High-yielding soybeans capable of 7-to-11-percent increases in

yield potential;

6

Source: USDA Agricultural Baseline Projections to 2016 (USDA ERS, 2007). USDA, Economic Research Service.

1980 1985 1990 1995 2000 2005 2010 2015

80

70

60

50

40

30

20

10

0

50

45

40

35

30

25

20

U.S. Soybean Acres and Yield

Acres (millions) Bushel per acre

Year

Planted Yield

• Resistance to a wider range of herbicides;

• Bt soybeans with built-in protection against caterpillars such as

soybean loopers, an innovation most likely to be introduced in

South America, where caterpillar pests are a more significant

problem than they are in the U.S.;

• Soybeans with built-in resistance to soybean cyst nematode, the

most economically damaging disease in U.S. soybean production,

estimated to have reduced the U.S. soybean crop by nearly 2 million

metric tons in 2005 (Wrather and Koenning, 2009);

• Crops that utilize nitrogen or water more efficiently, which allows

them to produce food and fiber with less applied fertilizer and

irrigation – an advance that could not only reduce production costs,

but could also improve water quality;

• Wheat tolerant to the devastating Fusarium fungus;

• Rice tolerant to herbicides and insects;

• Plants that tolerate poor soils, such as saline soils or those with low

fertility or high levels of phytotoxic elements.

Many of these second-generation traits reflect huge advances in

scientists’ ability to unlock the genetic code and identify the genes –

often several genes scattered about the DNA of donor plants – that

can confer these important abilities. Moving bigger parcels of genetic

material and screening offspring for commercial performance represent

remarkable achievements in the science and art of breeding.

With the advent of more biotech-derived varieties featuring output

traits, the benefits of agricultural biotechnology will be even more directly

appealing to consumers around the world, and even more important tools

for improving crop quality, human health and food security.

High Adoption of Biotechnology

Growers immediately recognized the benefits of biotech crops. The new

genes offered the opportunity to fight pests with safer tools, make crop

management simpler, and apply less pesticide. As a result, farmers

enthusiastically planted biotech seed in the mid ‘90s.

Worldwide, biotech crop acreage has been increasing at a steady

rate of more than 10 percent each year since the turn of the 21st

century; today, more than 13 million farmers in 25 countries plant

biotechnology-derived crops (James, 2008). James estimates the

economic benefits of biotech totaled more than $44 billion between

1996 and 2007, the result of both yield gains and reduced production

costs attributed to biotech varieties (James, 2008). Abdalla et al. (2003)

predict the full global adoption of biotech crops would result in income

gains of $210 billion per year for farmers – and that some of the greatest

gains are expected to occur in developing countries.

Biotech crops already dominate key U.S. crops. By 2009, 91.5 per-

cent of the U.S. soybean crop, 85 percent of the nation’s corn crop

and 88 percent of the country’s cotton acreage were planted to biotech

varieties (Fernandez-Cornejo, 2009).

Of the 88 percent of the U.S. cotton crop planted to biotech varieties

in 2009, 17 percent was planted to Bt cotton, 23 percent to herbicide-

tolerant varieties and 48 percent planted to stacked varieties that com-

bine Bt and herbicide tolerance (Fernandez-Cornejo, 2009).

Similarly, corn growers planted 85 percent of their acreage, or 74 mil-

lion acres, to biotech-derived corn in 2009. Seventeen percent of the

corn acres were planted to Bt corn, 22 percent was herbicide-tolerant

only, and 46 percent contained stacked traits (Fernandez-Cornejo, 2009).

7

Data for each crop category include stacked varieties with both HT (herbicide-tolerant) and Bt (insecticide-producing) traits. Source: USDA NASS (2009).

100

80

60

40

20

01997 1997 19991998 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

HT Soybeans

HT CottonBt CottonBt CornHT Corn

Year

Rapid Growth in Adoption of Genetically Engineered Crops Continues in the U.S.

Percent of acres

HT (herbicide-

tolerant)

Sustainability is a key concept in agriculture. It is a multi-faceted

term that refers not just to the ability of a field to produce crops, but

to maintain productivity while accomplishing a variety of ecological,

economic and social goals as well. Building on the definition of sustain-

ability used in the 1990 Farm Bill, and according to Gold (1999), those

goals include:

• Satisfying human food and fiber needs;

• Increasing the resource use efficiency of energy, water, fertilizer,

soil and other natural resources;

• Enhancing environmental quality and the natural resource base

upon which the agricultural economy depends;

• Reducing pressure on habitat, forests and other land uses by

increasing the productivity of farmland;

• Making the most efficient use of nonrenewable resources and on-

farm resources;

• Integrating, where appropriate, natural biological systems and

control mechanisms;

• Sustaining the economic viability of farm operations, and

• Enhancing the quality of life for farmers and society as a whole.

Ultimately, sustainability is achieved when farmers make choices that

are beneficial both ecologically and economically, and increase the

long-term efficiency of their operations. By increasing yields, making

pest control simpler and more effective, and facilitating the adoption

of no-till or conservation tillage, biotech crops contribute significantly

to agricultural sustainability. The benefits accrue in the improvement of

soil, air and water resources.

Biotechnology Enhances Stewardship of Soil, Air and Water8

As society creates incentives for sustainability, farmers’ ability to

reduce erosion and build soil organic matter through conservation

tillage also opens new economic opportunities. U.S. Department

of Agriculture funding for environmental cost-share programs has

increased steadily – from roughly $3 billion in 1990 to $5.6 billion in 2005

– directing billions of dollars annually to conservation-oriented members

of the farm community (U.S. EPA, 2008). Emerging markets for carbon

offsets and water quality trading credits show great promise to create

new revenue streams for producers with the interest, skills and tools to

adopt best management practices (BMPs) such as no-till farming.

Biotechnology Facilitates Conservation Tillage

For millennia, farmers have tilled the soil to prepare seedbeds and con-

trol weeds, which compete with crops for nutrients, water and light, and

can interfere with harvest. The advent of herbicides in the latter half of

the 20th century allowed growers to combat weeds by chemical means,

though pre-plant tillage and the use of post-emergence cultivation are

still quite common.

The use of biotechnology to develop herbicide-tolerant crops was a

breakthrough. Not only did it allow growers to simplify their weed control

practices by using nonselective herbicides after crop emergence, but

also those herbicides were so broad in their weed control spectrum

and so reliable that pre-plant tillage was no longer necessary. The

herbicide-tolerant crops made it far easier and less risky to adopt con-

servation tillage and no-till.

In 1995, the year before glyphosate-tolerant soybeans were intro-

duced to the market, approximately 27 percent of the nation’s full-

season soybeans were no-tilled, according to the Conservation

Technology Information Center (CTIC, 1995). The latest surveys by

CTIC indicate that 39 percent of U.S. full-season soybean acres are

no-tilled today, a phenomenon that closely tracked the adoption of

herbicide-tolerant soybeans.

9

In some states, no-till acres dominate the soybean landscape. For

example, 69 percent of Indiana’s soybeans were no-tilled in 2007 as

well as 72 percent of Maryland’s and 63 percent of Ohio’s. Fifty percent

of the soybeans in Illinois, 43 percent in South Dakota and 40 percent

in Iowa were also no-tilled (CTIC, 2008).

Fighting Erosion

The growth of conservation tillage and no-till acreage has a significant

impact on soil, water and air quality, which trace back to dramatic

reductions in soil erosion. No-till farming can reduce soil erosion by 90

to 95 percent or more compared to conventional tillage practices, and

continuous no-till can make the soil more resistant to erosion over time.

In fact, Baker and Laflen (1983) documented a 97-percent reduction in

sediment loss in a no-till system. Fawcett et al. (1994) summarized natu-

ral rainfall studies covering more than 32 site-years of data and found

that, on average, no-till resulted in 70 percent less herbicide runoff, 93

percent less erosion and 69 percent less water runoff than moldboard

plowing, in which the soil is completely inverted.

Source: Conservation Technology Information Center (adapted from Johnson et al., 2007)*Partially updated data: 2008 data from 2/3 of the counties in Iowa; 2007 data for Indiana and some counties in Virginia and Minnesota; 2006 data for Illinois, some counties in Missouri and Nebraska; 2004 data for the rest.**Relative to 1995

1995 1996 1997 1998 2000 2002 2004 2008

80

70

60

50

40

30

20

10

0

No-Till in U.S. Full-Season Soybeans*

U.S.

Soy

bean

Acr

eage

(mill

ions

)

Year

Total acreage No-till acreage

2%** increase

13% increase

69% increase

64% increase45%

increase35% increase20%

increase

Erosion on Cropland by Year

Cropland includes cultivated and non-cultivated cropland. Source: USDA NRCS Natural Resources Inventory, 2010.

3.50

3.00

2.50

2.00

1.50

1.00

0.50

0.001982 1987 1992 1997 2002 2007

total3.06 total

2.79

total2.17

total1.89 total

1.81 total1.72

Billi

ons

of T

ons

1.39

1.67

1.30

1.49

0.99

1.18

0.85

1.04

0.80

1.01

0.76

0.96

Water (Sheet & Rill) Erosion Wind Erosion

Despite the significant expansion of conservation tillage to date,

erosion remains a tremendous threat to the productivity of the world’s

soils, as well as to the quality of water and air. Clearly, the opportunity

to take highly erodible fields out of crop production and farm other soils

more productively and with less soil loss will continue to be important

sustainability goals.

When topsoil erodes – swept away by water or wind – it removes

nutrients and well-structured soil from the field. That depletes the very

layer of soil that is most hospitable to seeds and plants and sweeps

away organic matter so valuable to soil health. It also results in the

transport of sediment, pesticides and excess nutrients – especially

phosphorus, which tends to be bound to the soil particles – to rivers,

lakes and oceans, where they can disrupt natural ecological cycles.

According to the U.S. Department of Agriculture Natural Resources

Conservation Service (NRCS), an estimated 60 percent of the nation’s

total river-borne sediment is the product of erosion from agricultural

fields (USDA NRCS, 1997).

Sediment clouds the water, reducing light penetration and reducing

photosynthesis of submerged plants and algae. It can also clog the gills

of aquatic organisms. Pesticides in streams and rivers can disrupt local

plants, fish, macro invertebrates and other organisms.

Excess nutrients can cause algal blooms that in turn disrupt natural

vegetation or even deplete the water of the oxygen needed by local

aquatic communities to survive. In its 2004 National Water Quality

10

Conservation Tillage DefinitionsThe Conservation Technology Information Center (CTIC) has defined tillage systems according to the amount of crop residue left on the soil surface after planting and the type of tillage tools used. Reductions in erosion are proportional to the presence of crop residue on the soil surface (Shelton, 2000).

CTIC’s definitions include:

Conservation tillage: Any tillage and planting system that covers more than 30 percent of the soil surface with crop residue, after planting, to reduce soil erosion by water. No-till, ridge-till and mulch-till are types of conservation tillage.

No-till: The soil is left undisturbed from harvest to plant-ing except for planting and nutrient injection. Planting or drilling is accomplished in a narrow seedbed or slots cre-ated by coulters, row cleaners, disk openers, in-row chisels or rotary tillers. Weed control is accomplished primarily by herbicides.

Ridge-till: The soil is left undisturbed from harvest to planting except for nutrient injection. Planting is com-pleted on a seedbed prepared on ridges with sweeps, disk openers, coulters or row cleaners. Residue is left on the surface between the ridges. Weed control is accomplished with herbicides and/or mechanical cultivation. Ridges are rebuilt during cultivation.

Mulch-till: The soil is disturbed prior to planting. Tillage tools such as chisels, field cultivators, disks, sweeps and blades are used. Weed control is accomplished with herbi-cides and/or mechanical cultivation.

Conventional tillage leaves less than 15 percent residue cover after planting. It typically involves plowing or intensive tillage. Tillage types that leave 15-to-30-percent residue cover after planting sometimes are referred to as reduced tillage, but they do not qualify as conservation tillage.

Continuous no-till: Maintaining no-till practices throughout the crop rotation cycle – avoiding the regular or periodic use of tillage – is called continuous no-till. The benefits of improved soil structure and carbon sequestration result from continuous no-till.

Inventory, a report to Congress, the U.S. Environmental Protection

Agency (EPA) stated that sediment was the number-one pollutant in

American rivers and streams, followed by bacteria, then organic enrich-

ment/oxygen depletion (U.S. EPA, 2004).

Andraski et al. (1985) compared losses of three forms of phosphorus

in runoff from four tillage systems – no-till, chisel plowing, strip-till and

moldboard plowing. No-till reduced losses of total phosphorus by 81

percent; conservation tillage with a chisel reduced total phosphorus

run-off by 70 percent and strip-till reduced it by 59 percent compared

to moldboard plowing. Baker and Laflen’s (1983) study compared total

phosphorus losses between no-till and conventional tillage and found

that no-tilling soybeans following corn reduced phosphorus loss in the

soybeans by 80 to 91 percent compared to conventional tillage. They

also found that no-till corn following soybeans resulted in an 86-percent

reduction in soil loss, which in turn led to a 66-to-77-percent reduction

in the loss of phosphorus.

Results of this type illustrate conservation tillage and no-till are

extremely useful practices for reducing nutrient loads in surface waters

– a fact being employed in water quality trading programs discussed

later in this document.

Crop residue left on the soil surface by no-till or conservation tillage

practices can significantly reduce topsoil erosion by wind. Crop resi-

dues reduce wind velocity at the soil surface, and trap soil particles to

stop their movement (Lyon and Smith, 2004). Covering 30 percent of the

soil surface reduces soil loss to wind erosion by 70 percent compared

to bare soil, and 60-percent residue cover reduces wind erosion by 90

percent, according to Lyon and Smith (2004). Increasing the size of

soil aggregates – one of the benefits of conservation tillage and no-till

– also limits the ability of wind currents to lift soil and begin the cascad-

ing effect of erosion (Lyon and Smith, 2004). Compared to cereals,

soybeans are not a high-residue-producing crop, but their residue can

contribute to soil protection, and they play a major role in the agronomic

and economic viability of crop rotations that include conservation till-

age, the planting of higher-residue crops, and cover crops.

The airborne dust caused by wind erosion is a public health hazard

as well as a highly destructive force. As it depletes cropland of its

most precious resource, wind erosion can also cause other economic

damage, such as sediment deposits in ditches and soil drifts across

roads and railroad tracks, which are costly to remove.

The economic costs associated with wind erosion have not been as

well-quantified as those of water erosion (Tegtmeier and Duffy, 2004).

However, calculations by Tegtmeier and Duffy of the maintenance and

infrastructure costs incurred in the U.S. to deal with water-borne sediment

from cropland reveal a significant economic burden caused by erosion.

Iowa State University researchers determined that clearing roadside

ditches and irrigation canals of sediment from cropland costs $268 mil-

lion to $798 million per year; the total annual costs to the nation’s reservoir

system from reduced capacity and dredging range from $241.8 million

to $6.0 billion (Tegtmeier and Duffy, 2004). Reducing soil erosion through

conservation farming practices, with risks and costs borne largely by

farmers themselves, thus has clear impact on the nation’s economy that

extends beyond the loss of capacity on individual fields.

Rebuilding SoilsTopsoil is formed in a very slow process of physiochemical transforma-

tion of parent material and organic matter. Topsoil is the most fertile

layer of soil, and can range from mere inches to many feet deep. Within

the topsoil is a complex ecosystem of uncounted species of arthropods,

nematodes, fungi, bacteria, actinomycetes and other microbes, as well

as the compounds on which they feed.

Soil organic matter is the principal measure of the living portion of

topsoil. Scientists categorize soil organic matter in three fractions:

• The living fraction, which includes the microbes, insects, microath-

ropods, animals, and plants. Many of these organisms are beneficial,

and may play a role in suppressing pathogens or enhancing plant

health, resulting in a hardier, more pest-resistant crop (Gugino et

al., 2009).

11

• Active organic matter, which includes the sugars, proteins and

cellulose from dead plant, arthropod and microbial tissue that

nurture the living fraction. It also includes sticky exudates from

microbes and roots that bind soil particles together in aggregates

that typify healthy soil.

• Humus, the dead, stable fraction of soil organic matter. Humus

aids in the storage of nutrients and water, the deactivation of toxic

chemicals, and stabilizing soil aggregates, but it is not a food

source for microbes.

Soil flora and fauna thrive in conservation tillage conditions, gener-

ally increasing the level of soil organic matter and encouraging greater

aggregation of soil particles. Between the small clumps of agglomer-

ated soil are macro pores, or relatively large spaces, that aerate the soil,

stimulating microbial-mediated mineralization of nutrients and allowing

moisture to enter the soil through capillary flow. Cracks formed during

weather changes, root channels and earthworm burrows provide con-

duits for water to enter the soil quickly.

Healthy, living soil with good structure can repair compacted layers

formed by traffic or tillage over time. By contrast, soils with plow pans

or other man-made compacted layers, or soils

made shallow by erosion, leave crops more sus-

ceptible to fluctuations in the weather, such as

drought or flooding (Gugino et al., 2009).

Years of conservation tillage rebuild soil organic

matter as crop residues are steadily broken

down in the upper inches of the soil by a healthy

community of soil microbes, as well as macro

invertebrates such as earthworms and insects.

Reicosky and Lindstrom (1995) found that organ-

ic matter increased by as much as 1,800 pounds

per acre per year in long-term no-till studies. In

fact, a combination of no-till and cover crop management in corn fields

derived from former grasslands or forests can yield higher levels of soil

organic matter than the original grasslands or forests would have had

they been left undisturbed (Kim et al., 2009).

Blanco-Canqui and Lal (2007) examined the impact of removing

various amounts of corn stover on soil organic carbon in three different

Ohio soils. They found that in two silt loam soils, the amount of stover

removed from the soil surface was inversely proportional to the amount

of new soil organic carbon that was produced during the 2.5-year study

period. Complete removal of stover resulted in a 1.95 mt/ha (0.87 ton/

acre) reduction in soil organic matter (Blanco-Canqui and Lal, 2007).

They suggest that the study’s clay soil, in which the organic matter did

not respond significantly to the removal of stover, may offer a challeng-

ing environment to microbes, and be at or close to its saturation level

for soil organic carbon, a stable state slow to react to stover removal.

Reducing Agriculture’s Carbon FootprintConservation tillage and no-till can reduce greenhouse gas emissions

in a number of important ways, including:

• Capturing atmospheric carbon in healthy, no-tilled soils and

converting it into soil organic matter, a process called carbon

sequestration. If the process is continued for years, that organic

matter becomes a stable sink for carbon.

• Lowering fuel consumption and the emissions from it.

• Reducing the application of nitrogen, much of which is made

from fossil fuels (and applied with fossil-fuel-burning equipment),

improving the carbon footprint of agriculture and the nation as

a whole.

Viewing those reductions individually and together shed light on oppor-

tunities to contribute to a reduced carbon footprint through conservation

tillage, an ecologically sustainable practice made more economically

viable with the help of agricultural biotechnology.

Carbon sequestration . Sequestering carbon on cropland is one of

the most attractive carbon offsets in agriculture’s portfolio. In fact, Lal

et al. (1998) estimate the capacity of U.S. cropland soils to sequester

carbon at 75 to 208 million metric tons (83 to 229 short tons) of carbon

equivalent per year – 24 percent of the emissions reduction assigned

to the U.S. in the Kyoto Agreement.

12

U.S. cropland soils have the potential to sequester 75 to 208 million metric tons of carbon equiva-lent per year.

Lal et al. (1998)

Conservation tillage has a very direct effect on the rate at which

atmospheric carbon is sequestered in cropland soils. In an Indiana

study, intensive tillage stored 0.042 tons (84 pounds) of carbon per

acre, moderate tillage sequestered 0.169 tons (338 pounds) per acre,

and no-till stored 0.223 tons (446 pounds) of carbon per acre annually

(Smith et al., 2002). According to Feng et al. (2000), conservation tillage

and residue management could account for 49 percent of the carbon

sequestration potential of U.S. cropland. Switching from conventional

tillage to no-till in a corn-soybean rotation in Iowa has been estimated to

increase carbon sequestration by 550 kg/ha (485 lb/a) per year (Paustian

et al., 2000).

The power of no-till to build soil organic matter and sequester carbon

was documented by Reicosky and Lindstrom (1995), who measured

that a single pass with a moldboard plow in a field of wheat stubble

released five times as much carbon dioxide over 19 days as was

released from untilled plots.

Because even a single tillage pass can aerate the soil and stimulate

microbial activity that returns a significant amount of the soil organic

carbon to the atmosphere as CO2, continuous no-till – maintaining no-

till practices throughout the crop rotation – is the most effective way

to maximizing the carbon sequestration potential of the soil. Using a

conservative assumption that an acre of continuously no-tilled cropland

sequesters 0.6 metric tons of carbon dioxide equivalent (the standard

measure of carbon sequestration) per acre per year, it is estimated the

16.3 million acres of continuously no-tilled cropland in the U.S. is cur-

rently sequestering 9.7 million tons of carbon dioxide equivalent each

year (CTIC, 2009).

Reduced emissions . Conservation tillage has an even more direct

impact on greenhouse gas levels. It can reduce the number of trips

needed to produce a crop and lowering the horsepower requirement for

crop production, it reduces the amount of fuel used in farming. Mulch

tillage – light to moderate tillage passes that leave more than 30 percent

residue cover after planting – saves approximately 2.0 gallons per acre

(Jasa et al., 2000). Across the 46.7 million acres of mulch-tilled crop-

land, that represents a savings of 93.4 million gallons of diesel. Jasa

et al. (1991) figured the advantage of no-till over moldboard plowing

Soybeans: Valuable Rotation Crop

Technology that encourages the use of soybeans in a crop rotation provides growers with a powerful tool for improving yields and man-aging pests. Beyond their ability to fix atmospheric nitrogen in the soil, soybeans can also enhance the yield of subsequent crops by leaving soil moisture in place for the fol-lowing crop, interrupting pest and disease cycles, supplying chemical compounds that may enhance the health or growth of other crops, and improving the microbial community in the soil (Swink et al., 2007).

13

to be a fuel savings of 3.9 gallons per acre. Extrapolating that out over

the nation’s 65 million acres of no-till crops, a savings of 253.5 million

gallons of diesel is realized. Combining those two figures, conservation

tillage saves 353.8 million gallons of diesel per year.

Kern and Johnson (1993) determined no-till could reduce fuel con-

sumption by 3.5 to 5.7 gallons per acre, depending on the number and

type of tillage trips eliminated, the soil type and moisture content.

Calculations by the Western Environmental Law Center estimate die-

sel agricultural tractors contribute 17.11 percent of the CO2 emissions

from nonroad vehicles and engines in the U.S., so reducing tractor

passes has a direct effect on national greenhouse gas output (Western

Environmental Law Center, 2007).

According to the U.S. EPA, every gallon of diesel represents 22.2

pounds of carbon dioxide emissions (U.S. EPA, 2005). Applying that

figure to the 353.8 million gallons of diesel saved by reducing or elimi-

nating tillage, conservation farmers lower carbon dioxide emissions

by 3.92 million tons per year through fuel savings alone. If, in the year

2020, 90 percent of the nation’s soybeans were herbicide-tolerant vari-

eties and 80 percent of the crop was planted no-till, the combination

of biotechnology and no-till farming would reduce soybean farmers’

carbon dioxide emissions by 2.3 million tons.

Reducing tillage passes also saves farmers time and money.

Eliminating an average of 2.5 tillage trips per year in a corn/soybean

rotation on a 2,000-acre operation would reduce on-farm labor by 600

hours each year. Tractors would last longer because they were not

being used for the hard duty of pulling heavy tillage implements through

the soil, and equipment costs could be lowered because the number,

horsepower requirements and annual hours of service of tractors can

be reduced.

Less fertilizer . Soybeans play an important role in reducing the need

for nitrogen fertilizer, which is typically manufactured from fossil fuel,

and can release nitrogen oxides under certain conditions after applica-

tion. Soybean plants fix atmospheric nitrogen in the soil through their

relationship with bacteria that live in nodules on their roots.

The amount of nitrogen captured from the air and fixed in the soil by

soybean crops can be substantial. Varvel and Wilhelm (2003) deter-

mined that corn planted after soybeans obtained 65 kg/ha (58 lb/a) of

14

Making a Great Biofuel Source Even BetterSoybeans are an important source of biofuel feedstock. Producing soybeans in conservation tillage systems improves the carbon footprint of the process significantly; future biotech varieties may also contribute further. An important and controversial metric in assessing the envi-ronmental impacts of biofuels vs. fossil fuels is the “payback period,” the length of time required for biofuels to overcome the “carbon debt” of greenhouse gases released due to changes in land use related to producing the biofuel feedstock. The normal payback period for biofuels has been estimated at 100 to 1,000 years, depending on the ecosystem affected by the land use change; however, no-till or no-till/cover crop systems can reduce the payback period to three years in the case of payback for grassland conversion or 14 years if called upon to pay back for the conversion of forest (Kim et al., 2009).

nitrogen from the soybean crop, and sorghum in a sorghum-soybean

rotation received an 80 kg/ha (71 lb/a) nitrogen fertilizer replacement

value from the prior year’s soybeans. Swink et al. (2007) conducted an

extensive literature review, finding nitrogen fertilizer replacement values

(NFRVs) from soybeans ranging from 0 to 188 lb/a. They also found

evidence that nitrogen mineralization rates in corn peaked both higher

and earlier after soybeans than after corn (Swink et al., 2007).

The University of Nebraska recommends allowing a 45-pound-per-

acre nitrogen credit in corn following soybeans; the University of Illinois

calculates a nitrogen fertilizer replacement value of 40 pounds per acre

after a soybean crop. Using a conservative NFRV of 20 to 30 pounds of

nitrogen following soybeans – to recognize the variation in effect across

climates and soil types – soybeans on 73 million acres of U.S. cropland

in 2008 supplied 2.9 to 3.7 million pounds of nitrogen for possible use

by subsequent crops.

The use of soybeans in rotation, more precise rates and application

of fertilizer, and other agronomic practices that minimize the rates and

loss of nutrients can be a highly cost-effective approach to reducing

greenhouse gases.

Evolving Incentives for Reducing Greenhouse GasesSociety has expressed a growing interest in reducing levels of atmo-

spheric carbon and other greenhouse gases. Costs or benefits to

society that do not accrue to parties engaged in a market transaction

are called externalities. In the case of soil carbon sequestration, exter-

nalities may include the conservation of soil nutrients, fossil fuels, water

quality, wildlife habitat and biodiversity. In fact, carbon sequestration is

best viewed as part of a package of environmental benefits, according

to Tweeten et al. (2000). Researchers have calculated a wide range of

values for the externality costs of soil erosion, a spectrum that extends

from $500 million to $7 billion per year (Tweeten et al., 2000).

The value of the externalities associated with carbon sequestration

and conservation tillage can help society set a price on the greenhouse

gas-reducing services agriculture can provide.

As society seeks solutions to elevated levels of greenhouse gases in

the atmosphere, lawmakers may create larger incentives for adopting

conservation farming practices. Greater funding for cost-share pro-

grams that help make BMPs, such as conservation tillage, more attrac-

tive can have a large impact on the adoption of conservation practices.

So can a strong market for carbon credits, which allow emitters of

greenhouse gases to pay farmers to offset those emissions through

the use of BMPs such as those mentioned above. Selling carbon

credits for their sequestration services could provide U.S. farmers with

a steady, long-lasting revenue stream and could provide the country

with inexpensive, easily enabled tools to begin lowering greenhouse

gas emissions.

In either case, biotech crops will play a significant role in reducing

agriculture’s carbon footprint – and America as a whole – by facilitating

the adoption of conservation farming practices.

Conserving Water

Conservation tillage and no-till conserve water in several ways, primarily

by minimizing evaporation and improving infiltration. Soils improved by

years of conservation tillage also have greater water retention capacity

due to their increased levels of soil organic matter.

Tillage exposes moist soil to the atmosphere, releasing moisture

through evaporation. Each tillage pass reduces soil moisture by the

equivalent of 0.5 inches to 1.0 inch of rainfall. In Kentucky, annual evap-

oration was reduced by 5.9 inches in a no-till system (Siemans, 1998).

15

Several South American studies have indicated

that crop residue left on the soil surface in no-till

systems results in a reduction in surface soil water loss

due to evaporation of up to 30 percent (Damalgo et al., 2004).

As noted previously, the formation of healthier soil structure,

macro pores, cracks and earthworm burrows through long-

term no-till improves infiltration of water into the soil.

Blanco-Canqui and Lal (2007) observed that removing more

than 50 percent of the corn stover from the soil surface reduced ini-

tial water infiltration rates – measured for the first hour – by a

factor of four in a hilly Rayne silt loam and by a factor of two on

a rolling Celina silt loam soil, noting the unprotected soil was

more prone to crusting and had fewer surface-connected earthworm

burrows than residue-protected soils.

Water that infiltrates into the soil rather than running off into ditches

and streams is more likely to be available to the crop later in the season.

That can be important in dry years or semi-arid areas, and will grow

ever more critical as pressure mounts to manage every acre to produce

its maximum potential yield.

When water follows its natural pathway of infiltrating into healthy soil

rather than flowing across the soil surface in gully-like rills or broad sheets,

it flows to the water table and feeds rivers and streams through subsur-

face flow. That water is filtered by the soil through which it passes, and the

rate of its introduction to the stream is moderated by hydraulic pressure in

the ground. If the adoption rate of conservation tillage and other BMPs is

high enough, the result can be cleaner water and potentially less dramatic

flood events compared to replenishment by surface flow.

An Ohio study compared the total water runoff from a 1.2 acre area

with a 9-percent slope that had been continuously no-tilled with a similar

test area that had been conventionally tilled. Over four years, runoff was

99 percent less where long-term no-till had been practiced (Edwards et

al., 1989). The authors attributed the vast difference in infiltration to the

development of macro pores in the no-tilled soils.

In a study of the Pecatonica River in Wisconsin, Potter (1991) docu-

mented a decrease in winter/spring flood peaks and volumes, as well

as an increase in base flow from infiltration of water into the river. He

attributed the reduced flooding to the adoption of conservation tillage

in the area, noting that there were no major land-use changes, new

reservoirs or weather events to correlate with the observation.

16

U.S. Conservation Tillage by Crop*

Source: 2008 National Crop Residue Management Survey, Conservation Technology Information Center 2004 data for most states/counties (2006 for Illinois, some counties in Missouri and Nebraska; 2007 for Indiana and some counties in Virginia and Minnesota, 2008 Iowa (2/3 of counties).*Conservation tillage has more than 30% residue left on the soil’s surface after planting and is the sum of no-till, much-till and ridge-till acres. Ridge-till acres are less than 1% of all cropland and are not listed individually but are included in conservation tillage acres. Number may not total 100% due to rounding.

Crop Total Acres No-till Mulch-till Conservation tillage total Million Million acres Million acres

Corn 83.1 17.4 (21%) 14.8 (18%) 33.4 (40%)

Soybeans 72.9 30.1 (41%) 15.3 (21%) 46.0 (63%)

Winter Wheat 44.0 6.4 (15%) 6.1 (14%) 12.5 (29%)

Grain Sorghum 8.5 1.7 (20%) 0.95 (11%) 2.7 (32%)

Cotton 13.5 2.4 (18%) 0.25 (22%) 2.9 (21%)

Spring Grains 27.1 4.5 (17%) 6.1 (27%) 10.7 (39%)

Forages 7.4 1.0 (14%) 0.84 (11%) 1.9 (25%)

Other Crops 17.6 1.5 ( 8%) 2.1 (12%) 3.7 (21%) TOTAL 274.2 65.0 (24%) 46.5 (17%) 113.8 (42%)

Water Quality Trading Opportunities

As with carbon credits, water quality credits could become a market-

able commodity for many U.S. farmers. In an effort to reduce nutrient

loading in rivers and lakes, many states allow municipal and industrial

dischargers to offset their emissions with purchased water quality cred-

its. Erosion-reducing BMPs such as conservation tillage allow farmers

to provide effective water quality services at a fraction of the cost of

facility upgrades or other options.

For instance, the Miami Conservancy District in Dayton, Ohio, esti-

mated water quality treatment plant upgrades needed to bring a local

watershed into compliance with water quality regulations would cost

$23 per pound of phosphorus. By contrast, the average unit cost of

phosphorus reduction by converting farmland to no-till was estimated at

$1.08 – and even though costs of agricultural BMPs rose to $1.29 dur-

ing the district’s pilot trading project, they still represent a significantly

more cost-effective approach to removing phosphorus from the system

(U.S. EPA, 2008). During the course of the pilot program, farmers in the

Great Miami watershed reduced waterborne nitrogen and phosphorus

by 434,000 pounds (U.S. EPA, 2008).

Similarly, the city of Cumberland, Wis., contracted to pay area grow-

ers $18.50 per acre to convert to no-till farming as part of its water

quality trading program to reduce phosphorus in the Red Cedar River

(CTIC, 2006), and removed 31,500 pounds of phosphorus under the

program by 2004 (U.S. EPA, 2008).

Like the market for carbon credits, water quality trading programs

remain a work in progress, subject to the evolution of frameworks that

create fungible instruments, verifiable results, and viable marketing sys-

tems, as well as regulations that could strengthen demand and prices

for the services farmers provide. As society continues to demand effec-

tive solutions to air and water pollution, these mechanisms are likely to

mature, with farmers likely to be paid for their environmental services as

well as the food and fiber they produce.

Improving Wildlife Habitat Conservation tillage and no-till provide far superior habitat for an array of animals, including insects and the birds that feed on them. Reducing the disturbance of residue in the top few inches of the soil favors the survival of ants, spiders, ground beetles and rove beetles that often feed on other insects, including pests (Barnes, 2006). In turn, the insects provide sustenance for an array of birds and other animals that thrive in the low-disturbance environment of a no-till field. Palmer (1995) found that bobwhite quail chicks in North Carolina needed 22 hours to obtain their minimum daily requirement of insects in conventional soybean fields. In no-till soybean fields, the chicks needed just 4.2 hours to obtain their minimum requirement. That was roughly the same amount of time the chicks needed to sustain themselves in natural fallow areas believed to be ideal quail habitat, where it took 4.3 hours.

17

Among the most attractive benefits of many early biotech crops –

from a grower perspective as well as an environmental one – is their

built-in ability to combat pests such as insects or pathogens, or to

allow producers to use highly effective products to fight weeds. The net

result is not just more grower-friendly crops, but also a reduction in the

cost of production and the use of crop protection chemicals.

Combating Weeds

Weeds are the leading challenge for soybean growers worldwide,

causing more yield loss than either insects or diseases (Heatherly et

al., 2009; Oerke, 2006). Oerke (2006) estimates global yield loss to

weeds at 37 percent. The development of herbicides in the latter half of

the 20th century replaced time- and tillage-intensive mechanical weed

control with management-intensive chemical control.

Herbicides brought challenges of their own. The efficacy of available

herbicides on specific weed species caused shifts in the population

dynamics of weeds, with less-adequately-controlled species increas-

ing in dominance until other herbicides or mechanical weed control

were introduced. Many persistent soil herbicides, used for decades on

millions of acres of cropland each year, found their way into streams

and groundwater.

Targeting, timing and application also require knowledge and skill.

By 1996, the year glyphosate-tolerant soybeans were introduced to the

marketplace, 27 different herbicidal active ingredients representing

nine distinct modes of action, each with its own strengths and weak-

nesses, were registered for use in U.S. soybeans (Heatherly et al.,

2009). By contrast, planting Roundup Ready soybeans allowed grow-

ers to apply glyphosate, the active ingredient in Roundup and several

other herbicides, as a broadcast post-emergence spray to control a

broad spectrum of weeds in one or two applications.

Glyphosate is a remarkable herbicide, both in its efficacy and its

environmental profile. When it comes in contact with plant tissue,

glyphosate translocates quickly through the plant to accumulate in the

Biotech Crops Reduce Pesticide Use18

growing point. There, it inhibits the action of the 5-enolpuruvylshikimate-

3-phosphate synthase (EPSPS) enzyme, which plays a vital role in

the growth of plants, fungi and bacteria. Inhibited by glyphosate, the

EPSPS system fails and the plants die – even perennial weeds that were

extremely difficult to control with other herbicides. In fact, glyphosate

is labeled for control or suppression of well over 100 weed species

(Monsanto, 2007).

Ordinarily, glyphosate would also kill the crop. However, there are two

EPSPS enzyme systems in nature – EPSPS 1, found in plants, fungi and

some bacteria, which is susceptible to glyphosate, and EPSPS 2, a ver-

sion found in some bacteria that is not inhibited by glyphosate (Shaner,

2006). To create glyphosate-tolerant soybeans, breeders used genetic

transformation technology to move a gene for the EPSPS 2 system

from a soil bacterium to a soybean plant. The transformed soybean

line was then crossed with elite germplasm to create high-performing

soybean varieties that rely on the EPSPS 2 enzyme system rather than

the glyphosate-susceptible EPSPS 1 pathway.

Better Environmental ProfileAccording to the Extension Toxicology Network (Extoxnet, 1996), a

multi-university clearinghouse for information on crop protection prod-

ucts, glyphosate is “practically non-toxic by ingestion,” “practically non-

toxic to fish,” and long-term feeding studies have consistently shown no

adverse effects even after two years of high-rate exposure in the diets

of several animal species. The molecule is also tightly bound to soil

particles almost immediately, which renders glyphosate unlikely to leach

into the soil or run off in the event of rain (Extoxnet, 1996). Glyphosate

also has a half-life in the environment of 47 days, compared with half-lives

of 60 to 90 days for the herbicides it replaces (Heimlich et al., 2000).

Using the U.S. EPA’s reference dose for humans to create a chronic

risk indicator, USDA calculates that glyphosate replaces herbicides that

have toxicity ratings 3.4 to 16.8 times higher (Shutske, 2005).

In addition to permitting a shift to a more environmentally benign

herbicide, glyphosate-tolerant soybeans led to a significant decrease

in production costs. The herbicide cost for the biotech soybean crop

represented an annual savings of $1.56 billion in production costs in

spite of the additional investment in technology fees for biotech seed

(Johnson et al., 2007).

Weed Resistance Requires Management

Glyphosate-tolerant crops – notably soybeans

and corn, which are commonly rotated

with each other in the Midwest, and

glyphosate-tolerant cotton in the

South – are increasingly being

challenged by weeds resistant

to glyphosate. Once considered

a remote possibility, the specter

of glyphosate-resistant weeds

has become a harsh reality.

Horseweed (marestail) exhibiting

8-to-13-fold resistance to glypho-

sate emerged in a Delaware

soybean field in 2000 after

three years of glyphosate-

only weed management

(VanGessel, 2001).

19

Since then, certain populations of an array of weeds have exhib-

ited resistance, including giant ragweed, common ragweed, common

waterhemp, Palmer amaranth, Italian ryegrass and Johnsongrass.

Resistant weeds are not a new phenomenon, and though disappoint-

ing, resistance to glyphosate does not eclipse the cost, management

and environmental benefits of glyphosate-tolerant crops. However, it

does require growers to employ other weed control tools where resistant

populations are present or expected. They may need to draw from the

arsenal of older herbicides that are effective against the resistant weed

species, or consider adding glufosinate-tolerant crops (biotech variet-

ies marketed as Liberty Link®), or forthcoming biotech crops tolerant

to such classic herbicides as dicamba or 2,4-D to their crop rotation in

order to bring another mode of action into their program.

Regardless of the development of weed resistance to herbicides, the

net benefits of biotech herbicide-resistant crops remain positive.

Fewer Pounds of Active IngredientAmong the most dramatic and immediate benefits of biotech input traits

was a significant reduction in the use of herbicides and insecticides.

By 2006, 90 percent of the U.S. soybean crop was planted to herbi-

cide-tolerant soybeans. That year, soybean growers reduced their her-

bicide usage by an average of 0.5 pounds of active ingredient per acre,

or a total of 23 million pounds nationwide, compared to conventional

herbicide programs (Johnson et al., 2007). That

represents a reduction of nearly one-third of the

average of 1.53 pounds per acre of herbicide

active ingredient applied that year in conventional

soybean programs.

Herbicide-tolerant cotton varieties reduced the amount of herbicide

active ingredient applied to the cotton crop by 24.4 million pounds and

saved cotton growers an estimated $230 million in weed control costs

(Johnson et al., 2007).

Similarly, the adoption of Bt varieties of corn and cotton led to wide-

scale reductions in insecticide use. For instance, Johnson et al. (2007)

calculated that YieldGard® Bt corn planted on 16.6 million acres in

2006 to combat corn borer resulted in a nationwide increase in corn

production of 65.1 million bushels, for a net return of $185 million – while

reducing insecticide applications by a staggering 2.87 million pounds

of active ingredient. The same year, cotton growers who planted Bt

cotton varieties reduced insecticide use by 1.9 million pounds of active

ingredient (Johnson et al., 2007).

Following the successful introductions of cotton Bt varieties targeted

at the cotton bollworm complex and corn that expressed Bt crystals

toxic to several species of corn borers, other Bt proteins, or events,

were introduced. Events targeted at corn rootworm – a pest that forces

growers to apply millions of pounds of soil insecticides and seed treat-

ments per year in prophylactic applications – are among the most

important new Bt genes. So are Bt events designed to minimize the risk

of insect resistance among target Lepidoptera, as well as stacks of corn

borer, cutworm and rootworm Bt events such as Dow AgroSciences’

Herculex® XTRA.

Johnson and his team (2007) estimated that YieldGard RW corn, a

family of Bt hybrids targeted at rootworm control, delivers a 5-percent

improvement in yields over conventional insecticide treatments. In 2006,

they calculated the 5-percent yield improvement totaled 3.3 million

pounds (58,000 bushels) of corn on 7.7 million acres planted to the

YieldGard RW hybrids. On that acreage, growers would have otherwise

applied 3.9 million pounds of insecticide active ingredient to control

rootworms, according to the researchers.

20

The Role of Conservation Tillage in Reducing Pesticide Movement

Conservation tillage plays an interesting role in reducing the chances

of off-target movement of crop protection products. Because of their

spectrum of control and the fact that they do not require incorporation

into the soil, glyphosate and other postemergence herbicides are an

excellent fit in conservation tillage and no-till systems. Glyphosate also

rapidly becomes deactivated by quickly and tightly binding to soil

particles, which reduces leaching. Conservation tillage systems signifi-

cantly reduce soil erosion, so runoff of the herbicide molecules that are

tightly bound to the soil is minimized.

Conservation tillage also tends to foster high populations of earth-

worms (Stinner and House, 1990). Earthworm burrows are lined with

mucous that has been shown to adsorb pesticides. When the herbicide

atrazine was poured down nightcrawler burrows, concentrations exiting

at the bottom were reduced ten-fold (Stehouwer et al., 1994). Though

not all studies demonstrate that no-till reduces pesticide leaching, the

practice is widely recommended by water quality specialists because

many studies have shown reductions in the movement of crop protec-

tion products through the soil where no-till is used (Gish et al., 1995;

Novak, 1997).

21

It has been nearly two decades since agricultural biotechnology

put the ancient art of employing living organisms to produce specific

products to the modern task of creating crops with novel properties –

including tolerance to environmentally friendly herbicides and built-in

protection from pests and diseases. In that short time, plant breeders

have equipped farmers with crops that can be grown more produc-

tively and more cost-effectively to supply a growing population. No

other options have been identified that offer potential benefits as great

as biotech crops farmed with sustainable agricultural practices.

The first generation of those engineered crops have boosted produc-

tion, reduced pesticide applications by millions of pounds of active

ingredients every year, and made it more attractive for growers to

adopt no-till and other conservation farming practices that improve soil,

water and air quality.

The next generations of bioengineered crops will include produc-

tion-oriented traits such as improved tolerance to stresses including

drought and salinity – vital to growers here and in the developing

Conclusion

world – as well as output-oriented traits including better oil and dietary

nutrient profiles, and starches suited for high yields of biofuel production.

In all, biotechnology has played a significant role in influencing

the shift of millions of acres of U.S. cropland to conservation tillage

systems, which in turn has reduced topsoil loss, energy consumption,

pesticide use, labor, water pollution and air pollution. Conservation

farming systems facilitated by biotech crops also may create opportu-

nities for farmers to generate revenue by providing ecological services

to society, sequestering carbon and improving water quality in quickly

adoptable and highly cost-effective ways.

The result is improved sustainability, both ecologically and economi-

cally, as well as increased production.

Every ton of soil saved on the field, every pound of pesticide that

doesn’t have to be applied, every extra dollar to help a farmer stay

financially viable and – most important – every bushel of yield produced

is a milestone in the effort to provide for a global population that steadily

continues to increase.

22

23

Photo courtesy of harlen Persinger

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