Assessment of Emissions Risk on Chinese and American Farms:
Erosion, Pesticides, and Fertilizers
By: Amelia Harris, Pete Kerns, and Libby Nachman
ENTS 261: Hougen-Eitzman
01/28/10
1
Introduction
A farmer knows that his or her farm is not simply a contained entity, separate from the rest of
the world. As the farmer makes decisions on how to run the farm, he or she must also be aware
of how these decisions increase or decrease emissions from the farm into other ecosystems. In
the context of this paper, "emissions" are defined as everything that leaves a farm, including all
solids, liquids and gases. This category is not restricted to simply gas emissions, which is the
definition commonly associated with the term "emissions." We define the boundaries of "the
farm" as both the linear edges of the property and the horizontal plane above the soil of the farm.
Therefore, anything that crosses these boundaries through run-off, leaching or volatilization is
considered an emission. There are, though, a few exceptions. Emissions not counted in this
category include all GHG emissions from energy use and transport of final product; these will be
accounted for in the "energy-use sustainability" category.
The sustainability of farms due to emissions varied dramatically among farms and in the
United States and China. Farms with flat land had significant advantages to those with sloping
land because soil erosion and run off of pesticides and fertilizers cannot take place as easily on
flat land. Despite this difference, we found a number of farms with sloping land that successfully
prevented erosion by implementing a number of erosion prevention techniques. Thus, some
farms with unfavorable land situations received the same ecological sustainability score as those
with natural advantages.
Pesticide use was not markedly different in the U.S. and China. The only major difference was
the decision on many Chinese farms to abstain completely from pesticide use, while some U.S.
farms that similarly self-identified as organic did use some pesticides that were deemed "natural"
or "organic." It is interesting to note that the organic farms in both countries that did use
pesticides scored significantly less on their emissions score than farms in both countries that
didn't use pesticide. Furthermore, the pesticide-using organic farms scored only slightly better or
even similarly to non-organic farms that used non-natural pesticides.
Fertilization is also different in China. We found some examples of "conventional"
fertilization techniques, but in general the size of the farm and the availability of technology is a
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significant factor in the sustainable use of fertilizer. Both small and large farms in China did not
uses large-scale manure spreaders or liquid fertilizer injectors. The methods were different along
with the fertilizers and fertilization schedules. In and around the Sichuan province, farms had
multiple harvests and farmers did not utilize the concept of cover crops and fallow periods.
Sometimes, with crops like tea and oranges, which are perennials, farmers only fertilized by
sidedressing because they were fertilizing a mature plant. In addition to synthetic fertilizers,
farmers in China used rapeseed pomace and numerous kinds of manure. However, there wasn't
any fish emulsion or alternative fertilizers like there are on some farms in the United States.
Methodology
The first indicator of farm sustainability of due to emissions is soil erosion. Soil provides the
nutrients by which a farm is maintained. Without soil, the farm could not survive. In every
ecosystem, there is inevitable soil loss, the amount of which is contingent on a number of factors
including ones controlled by the environment and ones determined by farmer choice. Using the
answers farmers provide to the aforementioned questions, the flow chart provides a score of soil
sustainability. The more sustainable a farm is, the higher the score will be.
The second ecological indicator of farm sustainability is the effect of pesticides emitted from
the farm. Though a farm most mimics a natural system when no pesticides are used, pesticides
that don't leave a farm are least likely to enter other ecosystems and cause damage. Therefore, we
first examined the likelihood of a pesticide to be emitted from a farm. Pesticides can leave farms
in four ways: volatilized in gas form, attached to soil particulates during erosion, dissolved in
water as runoff and dissolved in water leaching through the soil (Kerle, Jenkins and Vogue
2007). For the purposes of this project, we looked at pesticide emissions in water only in terms
of leaching, not runoff. This is because we assume that any pesticides likely to leave a farm in
runoff are just as likely to leave a farm by leaching as judged by their mobility. Pesticide
emissions through runoff, then, were restricted to pesticide emissions through attachment to
particulate matter. If erosion is zero, we assumed that runoff is also zero and no pesticides are
being emitted from the farm in this capacity.
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The third ecological indicator of farm sustainability is the effect of fertilizers emitted from
the farm. In our evaluation we consider the two macronutrients as the primary emissions due to
fertilizer use and nutrient management. Nitrogen can be emitted from the farm in three ways:
leached through groundwater, runoff through surface water, and volatilized in gaseous form.
Nitrogen leaching and runoff both occur in nitrogen’s primary dissolved form, NO3- (nitrate)
(Randall, Rehm, and Lamb). Nitrogen volatilizes in gaseous form, NH3 (Nielsen). Phosphorus
can be emitted from the farm in two ways: leached through groundwater and runoff through
surface water. Phosphorus leaches and runs-off in two forms: bound to soil particles through
adsorption (70% of P loss) and dissolved as an orthophosphate, H2PO4- or HPO42- (Rehm,
Schmitt, Lamb, Randall, and Busman).
The methods used to collect data were based mostly in interviews. Student researchers
interviewed farmers on each farm in individual sessions. The questions were predetermined and
asked to each farmer as applicable. In most cases, more information from the farmer was
favorable because it was difficult for students to ask follow up questions as a later date
(especially in China).
Chinese student translators aided research in China. At these farms, the student translators
either had backgrounds in English rather than farming or backgrounds in farming, but not
English. Therefore, some of the information may have been lost in translation. (This confound
should be taken into account in follow-up studies.)
Pesticide appendix:
After fieldwork was completed, a variety of online databases (such as the Pesticide Action
Network database and the Extension Toxicology Network) were used to determine physical
properties of the active ingredients in the pesticides. However, due to the limitations of
knowledge available in these databases, not all factors were able to be accurately assessed.
Though the majority of the scores were calculated using the correct numbers, the emissions score
of a small number of the pesticides were estimated using the qualitative information associated
with the pesticide. This data mostly dealt with toxicology information regarding the pesticide.
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Fertilizer appendix:
On some smaller scale farms, (especially in China) sidedressing consists of a farm worker
actually digging a small hole next to each plant or bunch of plants and placing some fertilizer in
the whole, than covering it from air exposure. This procedure which is comparable to the sweep
knife method of fertilizer application because it decreases the time the fertilizer is exposed to the
air and it involves immediate incorporation into the soil. This procedure, so as to distinguish it
from the sweep knife method, will be called the Chinese sidedress for the purposes of this
assessment.
Results and Analysis
Gardens of Eagan (Linda Halley)- Emissions Score: 6.94
The farm is sloping and implements a number of erosion prevention techniques. The farm
cannot receive the highest sustainability score because it does not have terraces and the crops are
not contour tilled into the fields. The farm uses pyrethrins, copper and All-Down. Pyrethrins are
likely to attach to soil particles and not move into groundwater. Furthermore, they are only
moderately toxic. Sufficient data was unable to be collected about copper and All-Down to
accurately assess them. This farm uses sustainable fertilizer sources. They use composted
turkey and cow manure. Also, they use cover crops to add nutrients to their soil. They also use a
"sweep knife"-type method to add the fertilizers to their soil. This method decreases the time
where the fertilizer is exposed to air, and thus, exposed to volatilization. Also, this method
immediately incorporates the fertilizer directly next to the developing seed. However, this farm
fertilizes in the late fall which decreases the amount of time when the fertilizer is being used by a
mature developing plant. Also, this farm has some erosion which promotes the loss of
particulate phosphorous.
Pahl's (Gary Pahl)- Emissions Score: 6.61
The farm land is 90% flat and 10% sloping. Therefore, 90% of the land has a erosion
sustainability of 10 because flat land cannot emit soil. We then evaluated the erosion
sustainability of the other 10% of Pahl's land. The only erosion prevention techniques that
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effected erosion were that the weather is relatively mild and that they leave 20-50% of their
fields covered in residue. This sloping land thus receives a score of 2 for erosion sustainability.
Weighting each prospective score, Pahl's receives a score of 9.2. Pahl's farm uses Roundup (5),
Callisto (6), Outlook (6), Eradicane (7), Strategy (5), Dual (6), Liberty (5), Pounce (4), Warrior
II and Capture. The individual scores they recieved are listed after the name of the pesticide in
parenthesis. Scores were averaged to give a total score for the farm. Sufficient data was unable
to be collected about Warrior II and Capture to accurately assess them. This farm fertilizes in the
spring before planting 80% of their crops. The farm does sidedress 20%. However, because
most fertilization occurs when the plants aren't mature and do not require the massive amounts of
phosphorous and nitrogen that a mature plant requires, those nutrients are at risk of being emitted
from the farm. Also, this farm uses synthetic fertilizers which are extremely susceptible to loss.
This farm does use some cover crops which are the most sustainable means of adding nutrients.
Earthen Path (Steven Schwenn)- Emissions Score: 6.76
The farmland at Earthen Path is sloping, but the farmer works diligently to minimize the
amount of soil that leaves the farm. The fields are covered year round, the farm is surrounded by
riparian barriers (with multiple species in each), the fields are contour tilled when necessary.
Earthen Path Farm lost points because the farmer tills the soil (with a moldboard plow) and
because the fields are not terraced. Earthen Path uses pyrethrins (6), Bt, sabadilla, neem (4),
ryania (3) and spinosad (7). Sufficient data was unable to be collected about Bt and sabadilla to
accurately assess them. This farm uses numerous sustainable fertilizer sources, including cover
crops, fish emulsion, and liquid kelp. This farm surface broadcasts the fertilizer and then
immediately incorporates it (with a horse drawn manure spreader). However, surface
broadcasting leaves the fertilizer exposed to the air longer than and injection or sweep knife
method. Also, this farm fertilizes in the early fall which is the longest timespan from when a
mature crop plant is able to access the available phosphorous and nitrogen. Also, this farm has
some erosion.
Luttke Organics (Dennis Luttke)- Emissions Score: 9.29
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The farm is completely flat and therefore soil cannot leave the farm. No pesticides are
used on the farm. This farm had the third highest fertilizer score and the second highest overall
emissions score. This farm uses cover crops and composted cow manure. This farms uses liquid
and solid manure and the liquid has a very small amount of time that it is exposed to the air.
However, this farm fertilizes in the late fall, decreasing time available to mature or developing
crop plants. The reason for the high score is that this farm has flat land and thus has no issues
with erosion. This drastically reduces the chance of phosphorous loss through particulate.
Schrader Farms (Curt and Keith Schrader)- Emissions Score: 4.59
The farm land at Schrader Farms is sloping and the farmers implement some techniques
to reduce soil erosion. They implement terracing and use 20 to 50% residue during the off
season. The Schraders also 'no till' 45% of their land every year (hence the decimal in their soil
erosion score). Therefore, the soil erosion on that particular 45% of land is lower that year than
in other years and compared to the other 55% of their land. Schrader Farms use Roundup (5),
Select (5) and Dual (6). Roundup and Dual are likely to attach to soil particles and leave the farm
in that manner, while Select is more likely to leach into groundwater. This farm had the second
lowest fertilizer score. This farm uses synthetic fertilizers that are susceptible to loss, they
fertilize in the late fall, and they do not sidedress which means the fertilizers are applied when
the plants least need them, before they are mature enough and after they are harvested. Also, the
farm has erosion issues. They do however, knife inject their fertilizers which exposes them to
the air less and incorporates them immediately.
Big Woods Farm (Hougen-Eitzman)- Emissions Score: 7.98
The farm is completely flat and therefore soil cannot leave the farm. Big Woods Farm
uses Bt, Pyganic (7) and Entrust (6). Both Pyganic and Entrust are likely to attach to soil
particles, but because the farm is flat, are unlikely to leave the farm. Sufficient data was unable
to be collected about Bt to accurately assess it. This farm had the second highest fertilizer score.
The fertilizer sources are very sustainable sources: cover crops and composted manure. The
farm fertilizers in the spring pre-planting but does not sidedress which allows the maturing plant
to get the available nutrients when it most needs it. The farm also surface broadcasts the manure
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but incorporates it into the soil the next day which allows for volatilization and nutrient loss
through other methods. However, this farm has very few problems with erosion so it is difficult
for phosphorous to emit in particulate form.
Duan- Emissions Score: 9.04
The farm is completely flat and therefore soil cannot leave the farm. No pesticides are
used on the farm. This farm uses composted swine manure. The manure is applied in two ways,
through surface broadcast with immediate incorporation for the spring pre-planting, and Chinese
sidedressing (explained in the fertilizer appendix to the methodology). This farm had no erosion
issues.
Mr. Ji- Emissions Score: 9.09
The farm is completely flat and therefore soil cannot leave the farm. No pesticides are
used on the farm. This farm has a very similar structure to the Duan farm and the reason for the
higher fertilizer score is their use of vegetable compost in addition to earthworm composted
manure and large mammal manure. Vegetable compost is broken down over a longer time and
its nutrient are available to plants when they need it most. Also, vegetable compost doesn't have
the same risk of volatilization or loss as manure or synthetic fertilizers.
Mr. Ai- Emissions Score: 5.02
The farmland is sloping and has sandy, highly-erodable soil. The farmer does not rotate
his crops regularly, and leaves it uncovered and without a cover crop in the off-season. He uses a
few terraces (naturally formed) to decrease erosion. No pesticides are used on the farm. This
farm has the lowest fertilizer score. The reasons for this are that the farm uses unsustainable
fertilization sources: urea and superphosphate. Also, the method of application is surface
broadcast with no incorporation. This is for two reasons: the farmer did not have reliable access
to a incorporation device and because he believed that the rain incorporated it into the soil.
Finally, the score is low because the farmer only fertilized in the spring pre-planting which is not
when the crop needs the nutrients the most. Also, the farm has the worst erosion score of 2
which increases phosphorous loss.
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Little Donkey- Emissions Score: 9.24
The farm is completely flat and therefore soil cannot leave the farm. No pesticides are
used on the farm. This farm uses composted swine manure and rapeseed pomace which are
sustainable fertilizer sources. The farm also uses mainly the Chinese sidedressing method, even
when fertilizing in the spring before planting. However, they do not use cover crops, which
would give Little Donkey the best score if they did.
Mr. Liu- Emissions Score: 4.09
The land on this farm is partially sloping, resulting in soil erosion. Farmers have turned a
portion of the land on hillsides into permanent forest, but plant crops on all land less than 25o.
The hillsides also have natural terracing and in places where terracing is not apparent, the
farmers implement contour tilling. In the off season farmers carry eroded soil from the bottom of
the slopes back to the top so that it can be used the next season. The Liu Farm uses Lorsban (3)
and Roundup (5). Lorsban is toxic to many different organism groups, hence its very low score.
It is also very likely to adhere to soil particles and leave the farm via erosion. This farm uses
both unsustainable and sustainable fertilizer sources: urea and pig manure. Also, the farm uses
two methods of application and two schedules of fertilization. This is because a large portion of
the farm is in orange orchards and the other part is in vegetable and row crops. Chinese
sidedressing and a sidedress-only schedule is used in the orchard because the farmer is constantly
fertilizing a mature plant. This type of farming turns out to be very sustainable in terms of
fertilization. The row crops are fertilized in the spring pre-planting and the fertilizer is surface
broadcast with immediate incorporation. This farm also has significant issues with erosion.
Gao Family- Emissions Score: 9.41
This farm is flat and therefore, based on the questions we asked other farms, the Gao
family farm should receive the highest score for sustainable soil erosion. One complication,
though, is that despite the even land on the farm, the Gaos admitted that they still have problems
with soil erosion (albeit minor ones) because of the waterways that flow from the river, through
the farm and back into the river. Therefore, the sustainability of this farm due to soil erosion is
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still very high as in addition to the flatness of the land, the farmers implement a number of
erosion reduction techniques to make sure that as little soil as possible leaves the farm. No
pesticides are used on the farm. This farm had the best fertilizer score and the best score for
overall emissions. The farm has sustainable sources of fertilizer: rapeseed pomace, vegetable
compost, cow manure, manure tea, and cover crops. The farm fertilizes in the spring preplanting and sidedresses. The farm also uses Chinese sidedressing, surface application with
immediate incorporation, and a sweep knife-type method with the use of manure tea. The tea
incorporates immediately and isn't exposed to the air for long. The farm also has no erosion
issues.
Emei Tea Co.- Emissions Score: 6.26
This tea farm is slightly different from other farms because the tea plants are permanent
(unlike crops) and therefore do not necessitate cover crops. Otherwise, despite the sloping land,
the tea farm does everything possible to prevent soil erosion. The Emei Tea Co. uses Bifenthrin
(5), which is very likely to volatilize and leave the farm in that manner. This farm uses
unsustainable fertilizer sources: urea and superphosphate. They also use some rapeseed pomace,
a sustainable choice. However, the farm's unique crop, tea, is conducive to very sustainable
fertilizer methods of application and fertilizer schedules. The farm Chinese sidedresses because
the plant is always mature and because the fertilizer is placed in a trench next to the plant and
covered immediately. However, the farm may have some phosphorous leaching problems
because of erosion.
Mr. Lei- Emissions Score: 5.29
This tea farm, like the previous, does not use cover crops or residue because the tea
bushes are permanent. There are no riparian barriers on this farm and therefore, its score is lower
than that of the other tea farm. Otherwise, similar techniques are true. Mr. Lei uses Roundup (5)
which is likely to to volatilze or attach to soil particles. This farm is also mostly a tea farm and
because of this fertilizer methods of application and fertilization schedules are inherently
sustainable. The farm only sidedresses and uses Chinese sidedressing, comparable to sweep
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knife injection. The fertilizer source is composted manure. However, the score is lower than
expected because of erosion issues.
Loyu- Emissions Score: 9.18
While this farm is almost entirely sloping, the farmer implemented so many effective soil
erosion prevention techniques that no soil left the farm. All cropland is covered with crops or
cover crops year round, plants are intercropped, the land is not tilled, but crop rows are planted in
a contour formation. The farm is surrounded by many plant species in riparian barriers. No
pesticides are used on the farm.The Loyu farm uses swine manure, rapeseed pomace, and
vegetable compost for fertilization. The farm fertilizes pre-planting and sidedresses. The
methods of application are Chinese sidedress and a comparable knife injection fertilization. This
knife injection is from the use of manure tea. The farm uses very sustainable fertilization
methods and has minimal issues with erosion because of all the mitigation techniques used.
Duofu- Emissions Score: 6.00
This farm contains sections that are both flat and sloping. Therefore, the score of 6
applies to the sloping land on the farm, as soil does not erode from the flat lands. On the slopes
the crops are tilled, but not contour tilled and low amounts of residue (20-50%) are left on the
fields in the off-season. Otherwise, the Duofu farmers implement a number of techniques to
sustainably reduce soil erosion. Duofu uses pyrethrum (6) and Bt. Pyrethrum is likely to adhere
to soil particles and not very likely to volatilize. This farm uses sustainable fertilizer sources:
composted manure and rapeseed pomace. The farm fertilizes pre-planting and sidedresses.
However, because of the size, the farm does not Chinese sidedress but sidedresses like it
fertilizes pre-planting. The farm strip surface broadcasts and incorporates immediately. This
increases the time the fertilizer is exposed to the air and no incorporated into the soil. This farm
also has erosion which increases the amount of possible phosphorous emissions.
Conclusion
This assessment of the sustainability due to emissions of farms in the United States and
China allowed us to look at the kinds of risks each farmer takes and how they reduce the risks of
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these harmful emissions from leaving and thus taking required nutrients form their crops.
Farmers can use these sustainability scores do evaluate ways to improve the sustainability of
their farms in the future (and in the process help them maintain nutrient levels within farm
boundaries). We can see that the two top-scoring farms are from the U.S. and China.
There is certainly much to learn from this assessment, including ways in which it can be
improved on in future trials. All pesticide use has risk of emission and that the best way to
reduce risk of emissions of all kinds is to farm on land that is flat. Also, it is important to
fertilize based upon the needs of the crops. Crops need varying amounts of nutrients at different
points of development and often the best policy is to allow the soil to regulate that schedule
through the use of cover crops. At a fundamental level, this assessment brings to light that
farmers across the globe from each other deal with similar issues: from beetles on cabbage and
topsoil loss to phosphorous deficiency. This implies that there needs to be more dialogue
between farmers. What would the change be if some Chinese farmers taught American farmers
about natural pest control (like spiders) and American farmers taught Chinese farmers about the
benefits of cover crops?
This assessment is also useful for looking at the myriad of ways farmers use their land. It
allows us to see if there is a correlation between the unsustainable use of urea and
superphosphate for fertilizers and the state of economic policy in China. It allows us to compare
how farmers approach farming to the actual practices on their farms. This assessment is a crucial
tool in better understanding one of the oldest occupations of mankind.
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Final Emissions Scores
Emissions: Pesticides
10
10
10
10
10
10
10
10
9
8
7
6
6
6
5
5
5
6
5
5
5
4
4
3
2
1
0
Gardens
of Eagan
Earthen
Path
Schrader
Farms
Duan
Mr. Ai
Mr. Liu
Emei Tea
Co.
Loyu
Pesticide score
Emissions: Fertilizers
9
8
8.22
7.95
7.88
7.83
7.27
7.73
7.12
7
7.53
7.26
6.78
6.88
6.01
6
5.63
5.28
5
4.38
4
3.06
3
2
1
0
Gardens
of Eagan
Earthen
Path
Schrader
Farms
Duan
Mr. Ai
Mr. Liu
Emei Tea
Co.
Loyu
Fertilizer score
13
Emissions: Erosion
10
10
10
10
10
10
10
10
9.2
9
8
8
7
7
7
6
6
5
4.4
4
4
3
3
2
2
1
0
Gardens
of Eagan
Earthen
Path
Schrader
Farms
Duan
Mr. Ai
Mr. Liu
Emei Tea
Co.
Loyu
Erosion score
Emissions: Final Score
10
9.29
9.04
9
9.18
7.98
8
7
9.41
9.24
9.09
6.94
6.61
6.76
6.26
6
6
5.29
5.02
5
4.59
4.09
4
3
2
1
0
Gardens
of Eagan
Earthen
Path
Schrader
Farms
Duan
Mr. Ai
Mr. Liu
Emei Tea
Co.
Loyu
Emissions score
14
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