Facilitating Conservation Farming Practices and Enhancing ...

Facilitating Conservation Farming Practices 

and Enhancing Environmental Sustainability 

with Agricultural Biotechnology 

Conservation Technology Information Center 

www.ctic.org

Facilitating Conservation Farming Practices 

and Enhancing Environmental Sustainability 

with Agricultural Biotechnology 

by 

Dan Towery Ag Conservation Solutions, LLC 

Steve Werblow Conservation Technology Information Center 

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 

ISBN 978-0-9822440-1-2 

© 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, ® SmartStax TM 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. 

Reviewers 

Dr. Shaun Casteel Purdue University 

Dr. Jerry Hatfield National Laboratory for Agriculture and the Environment 

Dr. Richard Joost United Soybean Board 

Dr. Hans Kok Conservation Cropping Systems Initiative 

James W. Pollack Environmental consultant, Omni Tech Int'l., Ltd.

Introduction 

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 improving 

standard of living, including increased consumption of more nutritious 

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 environmental 

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 laureate 

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). 

The American farmer is uniquely prepared to meet the challenge of 

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

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 including 

improved pest control options, biotech soybeans have facilitated 

farmers’ adoption of a variety of sustainable farming practices, including 

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 undisturbed 

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

2 

Demands 

to Feed a 

Growing 

World 

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 population 

in 1950 (UN Population Fund, 2008). 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

1950 

1960 

1970 

1980 

1990 

2000 

2010 

2020 

2030 

2040 

2050 

Population (billions) 

World Population: 1950 - 2050 

9 Billion 

8 Billion 

7 Billion 

6 Billion 

5 Billion 

4 Billion 

3 Billion 

Year 

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

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

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 consumption 

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.

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 production, 

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 economics, 

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 Ones 

Trends 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 component 

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 developed 

and developing countries as the population continues to grow. 

3

4 

Breakthroughs 

in Agricultural 

Biotechnology 

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 principle 

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 biotechnology 

tools such as genetic transformation – the movement of specific 

genes from one source to another. 

Commercial Introduction 

In 1996, Monsanto introduced two biotechnology breakthroughs in the 

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

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). 

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 different 

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 Benefits 

Improvements 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 varieties 

simplify management and reduce risk on several fronts at once. 

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

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-bushelper-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. 

Corn Yield (metric tons/hectare) 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

1860 

Corn Yield Trend Line 

Trend Line 

1880 1900 1920 1940 1960 1980 2000 

Year 

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

5

6 

U.S. Soybean Acres and Yield 

Acres (millions) 

Bushel per acre 

80 

70 

60 

50 

40 

30 

20 

10 

0 

Planted Yield 

50 

45 

40 

35 

30 

25 

20 

1980 1985 1990 1995 2000 2005 2010 2015 

Year 

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

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 harnessed 

to design, improve and produce a variety of medicines, including 

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 frightened 

consumers, especially in export markets, would close their doors 

on biotech staples. 

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

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 conservation 

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 introduced, 

including: 

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

yield potential;

• 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 percent 

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 herbicidetolerant 

varieties and 48 percent planted to stacked varieties that combine 

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

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

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). 

Percent of acres 

100 

80 

60 

40 

20 

Rapid Growth in Adoption of 

Genetically Engineered Crops Continues in the U.S. 

0 

1997 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Data for each crop category include stacked varieties with both HT (herbicide-tolerant) 

and Bt (insecticide-producing) traits. Source: USDA NASS (2009). 

HT 

Soybeans 

HT Cotton 

Bt Cotton 

Bt Corn 

HT Corn 

HT 

(herbicidetolerant) 

Year 

7

8 

Biotechnology 

Enhances 

Stewardship 

of Soil, Air 

and Water 

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 sustainability 

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 onfarm 

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.

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

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. 

U.S. Soybean Acreage (millions) 

80 

70 

60 

50 

40 

30 

20 

10 

0 

2%** 

increase 

Total acreage 

13% 

increase 

20% 

increase 

No-till acreage 

35% 

increase 

45% 

increase 

64% 

increase 

1995 1996 1997 1998 2000 2002 2004 2008 

Year 

69% 

increase 

Biotechnology Facilitates 

Conservation Tillage 

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

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 conservation 

tillage and no-till. 

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

to the market, approximately 27 percent of the nation’s fullseason 

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. 

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 

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 natural 

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. 

9

10 

Conservation Tillage Definitions 

The 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 planting 

except for planting and nutrient injection. Planting or 

drilling is accomplished in a narrow seedbed or slots created 

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 completed 

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 herbicides 

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. 

Billions of Tons 

3.50 

3.00 

2.50 

2.00 

1.50 

1.00 

0.50 

0.00 

Erosion on Cropland by Year 

Water (Sheet & Rill) Erosion 

total 

3.06 total 

2.79 

1.39 

1.67 

1.30 

1.49 

total 

2.17 

0.99 

1.18 

total 

1.89 

0.85 

1.04 

Wind Erosion 

total 

1.81 

0.80 

1.01 

1982 1987 1992 1997 2002 2007 

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

total 

1.72 

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 

0.76 

0.96

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 enrichment/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 residues 

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 cascading 

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 tillage, 

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 million 

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 Soils 

Topsoil is formed in a very slow process of physiochemical transformation 

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, microathropods, 

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

12 

• 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, generally 

increasing the level of soil organic matter and encouraging greater 

aggregation of soil particles. Between the small clumps of agglomerated 

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 conduits 

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 susceptible 

to fluctuations in the weather, such as 

U.S. cropland 

soils have the 

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

potential to 

sequester 75 

Years of conservation tillage rebuild soil organic 

to 208 million 

matter as crop residues are steadily broken 

metric tons of 

down in the upper inches of the soil by a healthy 

carbon equivalent 

per year. 

invertebrates such as earthworms and insects. 

community of soil microbes, as well as macro 

Reicosky and Lindstrom (1995) found that organic 

matter increased by as much as 1,800 pounds 

Lal et al. (1998) 

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 challenging 

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 Footprint 

Conservation 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 opportunities 

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.

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 CO 2 , continuous no-till – maintaining notill 

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 currently 

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 cropland, 

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 managing 

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 following 

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

14 

Making a Great Biofuel Source Even Better 

Soybeans 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 environmental 

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). 

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 consumption 

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 diesel 

agricultural tractors contribute 17.11 percent of the CO 2 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 eliminating 

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 varieties 

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 application. 

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) determined 

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

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-peracre 

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 Gases 

Society has expressed a growing interest in reducing levels of atmospheric 

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, externalities 

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 programs 

that help make BMPs, such as conservation tillage, more attractive 

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 evaporation 

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

15

16 

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 longterm 

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 initial 

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 subsurface 

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) documented 

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. 

U.S. Conservation Tillage by Crop* 

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%) 

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.

Water Quality 

Trading Opportunities 

As with carbon credits, water quality credits could become a marketable 

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 credits. 

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, estimated 

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 during 

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 growers 

$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 systems, 

as well as regulations that could strengthen demand and prices 

for the services farmers provide. As society continues to demand effective 

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

18 

Biotech 

Crops 

Reduce 

Pesticide 

Use 

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 increasing 

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 weaknesses, 

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

2009). By contrast, planting Roundup Ready soybeans allowed growers 

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

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 version 

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 Profile 

According to the Extension Toxicology Network (Extoxnet, 1996), a 

multi-university clearinghouse for information on crop protection products, 

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

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 glyphosate 

emerged in a Delaware 

soybean field in 2000 after 

three years of glyphosateonly 

weed management 

(VanGessel, 2001). 

19

20 

Since then, certain populations of an array of weeds have exhibited 

resistance, including giant ragweed, common ragweed, common 

waterhemp, Palmer amaranth, Italian ryegrass and Johnsongrass. 

Resistant weeds are not a new phenomenon, and though disappointing, 

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 varieties 

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 Ingredient 

Among 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 herbicide-tolerant 

soybeans. That year, soybean growers reduced their herbicide 

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 widescale 

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 treatments 

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.

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 significantly 

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 earthworms 

(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 protection 

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

Novak, 1997). 

21

Conclusion 

22 

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 productively 

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 production, 

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 production-oriented 

traits such as improved tolerance to stresses including 

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

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 opportunities 

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 economically, 

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.

Photo courtesy of Harlen Persinger 

23

References 

24 

Abdalla, A., P. Berry, P. Connell, Q.T. 

Tran and B. Buetre (2003). Agricultural 

biotechnology: Potential for use in developing 

countries. Australian Bureau of 

Agricultural and Resource Economics. 

ABARE Project 2772. Retrieved from 

http://croplife.intraspin.com/Biotech/ 

agricultural-biotechnology-potentialfor-use-in-developing-countries/ 

Andraski, B.J., D.H. Mueller, and 

T.C. Daniel, (1985). Phosphorus 

losses in runoff as affected by tillage. 

Soil Sci. Soc. Am. J. 49:1523-1527. 

Baker, J.L. and J.M. Laflen. (1983). 

Water quality consequences of 

conservation tillage. J. Soil and 

Water Cons. 38:186-193 

Barnes, J. (2006). Soil and water 

conservation practices also benefit 

wildlife. In South Carolina Department 

of Natural Resources NewsCenter. 

Retrieved from http://sc.gov/ 

NewsCenter/DNR/SoilandWater.htm 

Blanco-Canqui, H. and R. Lal. (2007). 

Soil and crop response to harvesting 

corn residues for biofuel production. 

Geoderma 141(3-4): 355-362. 

CTIC. (1995). National Crop Residue 

Management Survey. Retrieved from 

http://www.ctic.org/CRM 


Management Survey. Retrieved from 

http://www.ctic.org/CRM 

CTIC. (2006). Getting Paid for 

Stewardship: An Agricultural 

Community Water Quality Trading 

Guide. Conservation Technology 

Information Center. July 2006. 


Management Survey. Retrieved 

from http://www.ctic.org/CRM 

CTIC. (2009). Cropland’s potential 

role to sequester carbon. Conservation 

Technology Information Center. 

Costa, M.H. and J.A. Foley. (2000). 

Combined effects of deforestation 

and doubled atmospheric CO2 

concentrations on the climate of 

Amazonia. J. Climate. 13: 18-34 

Daigger, G.T. (2009). Evolving urban 

water and residuals management 

paradigms: Water reclamation and 

reuse, decentralization, and resource 

recovery. Association of Environmental 

Engineering and Science Professors 

Lecture 81st Annual Water Environment 

Federation Technical Exhibition and 

Conference. Chicago, IL. Oct. 18-22, 2008. 

Dalmago, G.A., H. Bergamaschi, J.I. 

Bergonci, C.M. Bianchi, F. Comiran, and 

B.M. Heckler. (2004). Evapotranspiration 

in maize crops as function of soil tillage 

systems 2004. http://www.tucson.ars. 

ag.gov/isco/isco13/PAPERS%20A-E/ 

DALMAGO%201.pdf 

Dobson, R. (2000). Royalty-free licenses 

for genetically modified rice made available 

to developing countries. Bulletin of 

the World Health Organization. 78(10) 

Edwards, W.M., M.J. Shipitalo, L.B. Owens, 

and L.D. Norton. (1989). Water and nitrate 

movement in earthworm burrows within 

long-term no-till cornfields. J. Soil and 

Water Cons. 44:240-243. 

Extoxnet. (1996). Glyphosate. 

Pesticide Information Profiles. 

Retrieved from http://extoxnet.orst. 

edu/pips/glyphosa.htm 

Fawcett, R.S., B.R. Christensen, and 

D.P. Tierney. (1994). The impact of conservation 

tillage on pesticide runoff into 

surface water: a review and analysis. 

J. Soil and Water Cons. 49(2):126-135. 

Feng, H., J. Zhao, and C.L. Kling. (2000). 

Carbon sequestration in agriculture: 

Value and implementation. Center for 

Agriculture and Rural Development 

(CARD) Publications. 00-wp256. 

Iowa State University. 

Fernandez-Cornejo, J. (2009). Adoption of 

genetically engineered crops on yields, 

pesticide use and economic returns 

in the USA. USDA-ERS. July 1, 2009. 

Retrieved from www.ers.usda.gov/Data/ 

BiotechCrops/ 

Food and Agriculture Organization of the 

United Nations. (2006). The state of food 

insecurity in the world 2006: Eradicating 

world hunger – taking stock ten years 

after the World Food Summit. Retrieved 

from http://www.fao.org/docrep/009/ 

a0750e/a0750e00.htm 

Gish, T.J., A. Shirmohammadi, R. 

Vyrahpillai, and B.J. Weinhold. (1995). 

Herbicide leaching under tilled and 

no-tillage fields. Soil Sci. Soc. Am. J. 

59:895-901. 

Gold, M. (1999). Sustainable agriculture: 

Definitions and terms. U.S. Department 

of Agriculture. Special Reference Briefs 

Series N. SRB 99-02. September 1999. 

Retrieved from www.nal.usda.gov/afsic/ 

pubs/terms/srb9902.shtml#toc2 

Golden Rice Humanitarian Board. (2009). 

Golden rice is part of the solution. 

Retrieved from www.goldenrice.org 

Goldsmith, P. (2009). The 21st century 

and the post modern challenges for the 

global soybean industry. World Soybean 

Research Conference VIII. Beijing, 

China. August 15, 2009. 

Gugino, B.K., O.J. Idowu, 

R.R. Schindelbeck, H.M. va Es, 

D.W. Wolfe, B.N. Moebius, J.E. Thies, 

and G.S. Abawi. (2009). Cornell Soil 

Health Assessment Manual, Second 

Edition. Cornell University. 

Heatherly, L., A. Dorrance, R. Hoeft, 

D. Onstad, J. Orf, P. Porter, S. Spurlock, 

and B. Young. (2009). Sustainability of 

U.S. soybean production: Conventional, 

transgenic, and organic production 

systems. Council for Agricultural 

Science and Technology. Ames, IA. 

Special Publication No. 30. 

Heimlich, R.E., J. Fernandez-Cornejo, 

W. McBride, C. Klotz-Ingram, S. Jans 

and N. Brooks. (2000). Genetically 

engineered crops: Has adoption 

reduced pesticide use? Agricultural 

Outlook. USDA-ERS. August 2000. 

Huffman, W. (2009). Technology and 

innovation in world agriculture: 

Prospects for 2010-2019. In Iowa 

State University Department of 

Economics Staff General Research 

Papers. Retrieved from http://ideas. 

repec.org/p/isu/genres/13060.html 

James, C. (2008). Brief 39: Global 

status of commercialized biotech/GM 

crops. In International Service for the 

Acquisition of Agri-Biotech Applications 

Briefs. Retrieved from http://www.isaaa. 

org/resources/Publications/briefs/39/ 

default.html 

Jasa, P.A., D. Shelton, A. Jones, and E. 

Dickey. (1991). Conservation tillage and 

planting systems. Cooperative Extension 

Service, University of Nebraska-Lincoln. 

Jasa, P., D. Shelton, and J. Siemens. 

(2000). Tillage system selection and 

equipment considerations. Conservation 

Tillage Systems and Management. 

Midwest Plan Service. 2000. 

Johnson, S.R., S. Strom, and K. Grillo. 

(2007). Quantification of the impacts 

on U.S. agriculture of biotechnologyderived 

crops planted in 2006. National 

Center for Food and Agricultural Policy. 

Washington, DC. 

Kern, J.S. and M.G. Johnson. (1993). 

Conservation tillage impacts on national 

soil and atmospheric carbon levels. 

Soil Sci. Soc. Amer. J. 57:200-210. 

Kim, H., S. Kim, and B.E. Dale. (2009). 

Biofuels, land use change, and greenhouse 

gas emissions: Some unexplored 

variables. Environ. Sci. Technol. 43(3): 

961-967.

Lal, R., J.M. Kimble, R.F. Follet, and 

C.V. Cole. (1998). The potential of 

U.S. cropland to sequester carbon 

and mitigate the greenhouse effect. 

Ann Arbor Press, Chelsea, MI. 

Lubowski, R., M. Vesterby, S. Bucholtz, 

A. Baez, & M.J. Roberts. (2006). Major 

uses of land in the United States, 2002. 

USDA Economic Research Service. 

May 2006. EIB-14. Retrieved from http:// 

www.ers.usda.gov/publications/eib14/ 

Lyon, D.J., and J.A. Smith. (2004). Wind 

erosion and its control. NebGuide File 

G1537. University of Nebraska. May 2004. 

Matz, M. (2009). U.S. farmers feed the 

planet. In Milwaukee Journal Sentinel. 

Retrieved from http://www.jsonline.com/ 

news/opinion/61525637.html 

Monsanto. (2007). Roundup Original 

Max Herbicide. Specimen label. Retrieved 

from www.monsanto.com/monsanto/ 

ag_products/pdf/labels_msds/roundup_ 

orig_max_label.pdf 

Pollack, A. (2009). Judge rejects approval 

of biotech sugar beets. The New York 

Times. September 23, 2009. 

Potter, K. (1991). Hydrological impacts of 

changing land management practices in 

a moderate-sized agricultural catchment 

water resources research 27(5), 845–855. 

http://www.agu.org/pubs/crossref/1991/ 

91WR00076.shtml 

Reich, P.F., S.T. Nubem, R.A. Almaraz and 

H. Eswaran (2001). Land resource stresses 

and desertification in Africa. In: Bridges, 

I.D. Hannam, L.R. Oldeman, F.W.T. Pening 

de Vries, S.J. Scherr and S. Sompatpanit 

(eds.). Responses on land degradation. 

Proc. 2nd. International Conference on Land 

Degradation and Desertification, Khon Kaen, 

Thailand. Oxford Press, New Delhi, India. 

Reicosky, D.C. and M.J. Lindstrom (1995). 

Impact of fall tillage on short-term carbon 

dioxide flux. In Soils and Global Change. 

R. Lal, J. Kimble, E. Levine, and B.A. 

Steward, eds. CRC Press. Boca Raton, 

FL. 177-187. 

Stehouwer, R.C., W.A. Dick, and S.J. Traina 

(1994). Sorption and retention of herbicides 

in vertically oriented earthworm and artificial 

burrows. J. Environ. Qual. 22: 286-292. 

Stinner, B.R. and G.J. House. (1990). 

Arthropods and other invertebrates in 

conservation-tillage agriculture. Annual 

Reviews of Entomology 35: 299-318. 

Sundermeier, A., R. Reeder and R. Lal. (2005). 

Soil carbon sequestration – Fundamentals, 

Ohio State University Fact Sheet, AEX 

510-05. http://ohioline.osu.edu/aex-fact/ 

0510.html 

Swink, S.N., Q.M. Ketterings and J.W. Cox. 

(2007). Nitrogen fertilizer replacement 

value of soybean for corn. Crop Mgmt. doi: 

10.1094/CM-2007-1005-01-RV. Retrieved 

from http://www.plantmanagementnetwork. 

org/pub/cm/review/2007/replace/ 

Tegtmeier, E.M. and M.D. Duffy. (2004). 

External costs of agricultural production 

in the United States. Intl. J. of Agricultural 

Sustainability. 2(1): 1-20. 

USDA NRCS. (1997). Water quality and 

agriculture status, conditions, and trends. 

Working Paper #16. http://www.nrcs.usda. 

gov/technical/NRI/pubs/WP16.pdf 

USDA NASS. (2009). National Agricultural 

Statistics Service Acreage Estimates. 

June 30, 2009. 

U.S. EPA. (2004). U.S. EPA national water 

quality inventory: Report to congress, 2004 

reporting cycle. Retrieved from http://www. 

epa.gov/owow/305b/2004report/ 

U.S. EPA. (2005). Emission facts: Average 

carbon dioxide emissions resulting from 

gasoline and diesel fuel. EPA420-F-05-001. 

February 2005. Retrieved from www.epa. 

gov/oms/climate/420f05001.htm#calculating 

U.S. EPA. (2008). EPA water quality trading 

evaluation: Final report. October 2007. 

Retrieved from www.epa.gov/evaluate/wqt.pdf 

VanGessel, M.J. (2001). Glyphosate-resistant 

horseweed from Delaware. Weed Science. 

49(6): 703-705. 

25 

Monsanto. (2008). Growers excited about 

Roundup Ready 2 Yield. Retrieved from 

www.monsanto.com/rr2y/ 

Monsanto. (2009). Do GM crops increase 

yield? MonsantoToday.com. Retrieved 

from http://www.monsanto.com/monsanto_ 

today/2009/gm_crops_increase_yields.asp 

Novak, I.M. (1997). Conservation tillage 

reduces pesticide leaching. CTIC Partners. 

15:12. 

Oerke, E.C. (2006). Crop losses to pests. 

J. Agric. Sci. 144:31-43. 

Palmer, W. (1995). Effects of modern 

pesticides and farming systems on northern 

bobwhite quail brood ecology. Ph.D. 

Dissertation, North Carolina State University. 

Paustian, K., J. Brenner, J. Cipra, M. Easter, 

K. Killian, S. Williams, L. Asell, G. Bluhm, 

and T. Kautza. (2000). Findings of the Iowa 

carbon storage project. Presentation at the 

Iowa Carbon Conference, Exploring the 

benefits to farmers and society. August 

29-31, 2000, Des Moines, Iowa. 

Shaner, D.L. (2006). An overview of glyphosate 

mode of action: Why is it such a great 

herbicide? North Central Weed Science 

Society Annual Meeting. Milwaukee, WI. 

December 12, 2006. Retrieved from http:// 

www.ars.usda.gov/research/publications/ 

publications.htm?SEQ_NO_115=204435 

Shutske, J.M. (2005). The impact of 

biotechnology and information technology 

on agricultural worker safety. University 

of Minnesota Extension. January 2005. 

Siemans, J.C. (1998). Water quality. 

In Picklesmer, P. (ed.) Illinois Agronomy 

Handbook 1999-2000. University of Illinois 

Extension. 117-128. 

Smith, P., J. Brenner, K. Paustian, G. Bluhm, 

J. Cipra, M. Easter, E.T. Elliott, K. Killian, 

D. Lamm, J. Schuler and S. Williams. (2002). 

Quantifying the change in greenhouse gas 

emissions due to natural resource conservation 

practice application in Indiana. 

Final Report to the Indiana Conservation 

Partnership. Colorado State University 

Natural Resource Ecology Laboratory and 

USDA Natural Resources Conservation 

Service, Fort Collins, CO, USA. 

Tweeten, L, B. Sohngen, and J. Hopkins. 

(2000). Assessing the economics of carbon 

sequestration in agriculture. In R. Lal, J.M. 

Kimble, R.F. Follett, and B.A. Stewart (eds) 

Assessment Methods for Soil Carbon Pools. 

CRC/Lewis Publishers, Boca Raton, FL. 

Retrieved from www.cnr.berkeley.edu/ 

csrd/global/dcconf/pdf/tweeten_co2.pdf 

United Nations Population Fund (2008). 

Linking population, poverty and development: 

Rapid growth in less developed 

regions (n.d.). Retrieved from http://www. 

unfpa.org/pds/trends.htm 

U.S. Census Bureau. (2009). International 

data base. June 2009 update. Retrieved 

from www.census.gov/ipc/www/idb/ 

worldpopgraph.php 

USDA ERS. (2007). Agricultural baseline 

projections to 2016. February 2007. 

Retrieved from www.ers.usda.gov/briefing/ 

soybeansoilcrops/2007baseline.htm 

USDA NRCS. (2010). Natural resources 

inventory – Soil erosion http://www.nrcs. 

usda.gov/technical/nri/2007/2007_NRI_ 

Soil_Erosion.pdf 

Varvel, G.E., and W.W. Wilhelm. (2003). 

Soybean nitrogen contribution to corn 

and sorghum in western Corn Belt 

rotations. Agron. J. 95:1220-1225. 

Western Environmental Law Center. (2007). 

CO2 emissions from nonroad vehicles 

and engines. Retrieved from http://www. 

westernlaw.org/pressroom/press-releases/ 

environmental-groups-petition-epa-to-limitgreenhouse-gas-emissions-generated-bynon-road-vehicles-and-engines 

Witkowski, J.F., et al. (2002). Bt corn 

& European corn borer: long-term 

success through resistance management. 

Regents of the University of Minnesota. 

http://www.extension.umn.edu/distribution/ 

cropsystems/DC7055.html 

World Hunger Education Service (2009). 

World hunger facts 2009. Retrieved from 

http://www.worldhunger.org/articles/Learn/ 

world%20hunger%20facts%202002.htm 

Wrather, A. and S. Koenning. (2009). Effects 

of diseases on soybean yields in the United 

States 1996 to 2007. Plant Health Progress 

doi: 10.1094/PHP-2009-0401-01-RS.

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