지난해의 가뭄은 가장 막대한 미국의 두 작물인 옥수수와 콩에 큰 타격을 입혔다. 그러나 그것이 몬산토가 그에 저항하도록 조작한 작물에 사용하는 제초제인 라운드업(글리포세이트)에 내성을 지니게 된 풀의 확산을 확실하게 늦추지 못했다. 현재 미국에서 재배하는 모든 옥수수, 콩, 목화의 70% 이상이 글리포세이트에 견디도록 유전적으로 변형된 것이다. 

2011년부터 이러한 풀이 이미 빠르게 퍼지고 있었다. 나는 "몬산토의 '슈퍼잡초' 중서부를 질주하다"라고 예전 글에서 선언했다. 말이 이미 급속도로 속도를 올렸을 때 어떤 단어를 쓰겠는가? 무슨 일이 일어나는지 알고 있으니, 이렇게 해보자: "몬산토의 '슈퍼잡초'가 중서부에 몰려오고 있다."

농기업의 연구 컨설턴트 Stratus의 새로운 보고서에 따르면, 그 말이 지난해의 상황을 훨씬 잘 표현한 것이다. 2010년 영농철부터 그 집단은 제초제 내성에 관하여 31개 주에 걸쳐 "미국의 농부 수천 명에게" 투표를 받았다. 그들이 2012년 영농철에 발견한 것은 다음과 같다:

• 조사를 받은 전체 미국 농민의 약 절반(49%)이 2012년 자신의 농장에 글리포세이트 내성 풀이 있다고 답했고, 이는 2011년 34%에서 상승한 수치이다.
• 내성은 남쪽에서 역시 최악이다. 예를 들어, 조지아 주의 재배자 가운데 92%가 글리포세이트 내성 풀이 있다고 답했다. 
• 그러나 남부의 중앙과 중서부의 주들이 따라잡고 있다. 2011~2012년 네브라스카, 아이오와, 인디애나 주에서 내성을 가진 면적이 거의 2배가 되었다. 
• 해마다 더 빠른 속도로 퍼지고 있다: 총 내성 면적은 2011년 25%에서 2012년 51%로 증가했다. 
• 그리고 문제는 더욱 어려워지고 있다. 더욱더 많은 농장에 적어도 두 가지 종류의 내성 풀이 생겼다. 2010년에는 단 12%의 농장만 그랬는데, 불과 2년 뒤 27%가 되었다. 


슈퍼잡초: 처음에는 질주하고, 이후 폭증했다. Graph: Stratus


그래서 어디의 농부부터 시작하면 될까? 음, 몬산토와 그 동료들은 "다음 세대"의 제초제 저항성 종자를 시험하려고 한다 —그것은 라운드업만이 아니라, 또 다른 2,4-D와 Dicamba 같은 더 독한 제초제에 저항성을 갖도록 조작된 작물이다. 풀과의 화학전을 강화하여 제초제 사용이 급격히 증가하는 것과 함께 더 다양하고, 강력한 슈퍼잡초들이 나타나는 문제가 생길 수 있다. 그것은 David A. Mortensen이 이끄는 펜실베이니아 주립대학의 연구팀의 2011년 평가보고서가 전하는 메시지이다. (그들의 보고서는 지난해의 에서 언급했다.)

그리고 그러한 새로운 종자는 어쨌든 2013년 영농철에는 이용할 수 없다. 미국 농무부의 등록과정을 통과하지 못했다. 미국 농무부가 크리스마스 휴일 동안 Dow의 2,4-D/Roundup 저항성 옥수수를 최종 승인할 것으로 예상되었지만 그렇게 하지 않았다. 그 기관에서는 그 제품을 아직 승인하지 않은 사유를 밝히지 않았는데, Dow에서 지난달 인정했듯이 그 무의사결정이 2014년 초반까지 제품의 도입을 사실상 늦출 것이다. 로이터의 Carey Gillam 기자는 미 농무부의 지연은 새로운 제품에 대한 "농민과 소비자, 공중보건 관계자들의 반대"로 인한 것이라고 지적했다. 그리고 이러한 반대자들이 그에 관하여 "Dow와 미국 규제당국에 우려를 표하며 공격하고 있다."

따라서 공업형 규모의 옥수수와 콩 농민들은 워싱턴 주립대학의 Charles Benbrook이 최근의 논문에서 밝혔듯이, 악성 잡초를 제어하고자 그들이 몇 년 동안 해오던 대로 제초제 사용량을 늘리며 어물어물 넘어갈 것이다. 그것은 농민에게는 상당한 경제적 손실을 뜻한다 —펜실베이니아 주립대학의 Mortensen 씨에 따르면, 제초제 내성을 잡기 위하여 농민들이 2011년 1년에 약 10억 달러의 비용을 사용했다. 그것은 또한 독성 제초제가 하천으로 흘러들어 개구리를 혼란에 빠뜨리고, 인간의 음용수를 오염시킬 가능성이 높아진다는 것을 뜻한다. 

Corn & Soy Digest 라는 무역 잡지에 실린 "제초제 내성 잡초의 관리"라는 기사를 확인해 보는 것이 좋다. 여기에 문제의 핵심이 있다 —"전소(burndown)"는 유럽연합을 포함한 32개국에서 금지된 악명 높은 독성 제초제인 paraquat 같은 광역제초제로 농지의 모든 식생을 단조롭게 만들어 버리는 것을 뜻한다는 것을 지적한다:

내성 문제로 알려진 것들의 경우 가을에 잔류 농약을 추가로 사용하여 전소시키고, 봄에 작물을 심기 전 전소시키는 게 드문 일은 아니다. 다른 농사철에는 또 다른 종류의 잔류 농약을 포함하여 두 가지 이상의 제초제를 시용한다. “당신이 내성 잡초를 초기에 충분히 잡으려 한다면, paraquat는 그걸 방제하는 데 좋은 도구이다. 그러나 한 번 Palmer amaranth(보통 글리포세이트 내성 풀)이 180cm로 크면, 당신은 paraquat로 그것을 확실히 죽일 수 없다"(잡초방제 전문가)고 한다.

그러나 다른 방법이 있다. 내가 누누이 인용한 아이오와 주립대학의 연구자가 행한 2012년의 연구에서는, 만약 농민이 한 해에는 옥수수를 심고 다음해에는 콩을 심는 것만 반복하는 것이 아니라 간단히 귀리 같은 "작은 곡식" 작물만이 아니라 휴한기에 덮개작물, 풀(라운드업 내성도 포함하여) 등의 다양한 작물을 돌려짓기하면, 화학비료의 사용을 엄청나게 줄이고 억제할 수 있다. 그리고 제초제 사용을 줄여 하천에 흘러가는 독을 줄일 수 있다 —"잠재적 수생 독성이 일반적인 옥수수-콩 체계에서보다 더 긴 돌려짓기 체계에서 200배 감소한다고 그 연구에서 지적한다. 그래서 종자 거인과 관행농의 잡초 전문가들의 주장과 달리, 더 많은 -심지어 더 독성의- 화학물질을 사용하는 것이 아니라 "슈퍼잡초"의 가속화에 대응하는 다른 방법이 있다. 


http://goo.gl/x3GLu

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Farmers many times get the bad rap that they’re resistant to change, but that’s not true, especially when their survival depends upon it.

Surveys conducted by the University of Georgia reveal that monumental changes have occurred in a relatively short amount of time as it relates to cotton weed control practices in response to glyphosate-resistant Palmer amaranth pigweed.

During this same time, the cost of weed control in cotton production has roughly doubled.

Based on conservative estimates gathered by UGA researchers, approximately 50 percent of upland cotton in the United States is infested with glyphosate-resistant Palmer amaranth. This resistance developed in response to the widespread planting of glyphosate-resistant cotton varieties.

Early on, as growers were adopting these varieties, surveys were conducted to examine weed control practices. These studies showed that glyphosate use increased — both the number of applications applied and the area to which glyphosate was applied — but there also was  a corresponding decrease in the use of other herbicide classes.

Looking at the widespread nature of glyphosate-resistant weeds — particularly Palmer amaranth pigweed — and the subsequent resistance management strategies, UGA researchers expected there would be another shift in crop production practices.

Understanding these grower practices and how they change, according to the survey, will help fill in the gaps in research and Extension. It also helps to identify potential areas of abuse and prevent additional resistance.

The objective of the study was to determine if cotton weed management in Georgia has changed with glyphosate-resistance Palmer amaranth.

Two surveys were conducted — one was of growers in Georgia about their individual farming practices and the other was of county Extension agents who provided third-party information on a county-wide basis.



Comprehensive survey

A written survey was developed and administered in order to characterize Georgia cotton growers’ production practices before and after the development of glyphosate-resistant Palmer amaranth.

The survey specifically asked growers and Extension agents from across the state to describe the chemical, cultural and mechanical weed control practices that were used on their farms prior to and then following 2005.

Additional questions queried farmers about the costs associated with weed control and about the most significant weeds occurring in cotton.

The surveys looked at the commodities being grown, herbicide use, additional weed management practices, and weed pressure, both before glyphosate-resistant Palmer amaranth — the years 2000 to 2005 — and afterwards, from 2006 through 2010.

Respondents included 65 growers in 16 counties in Georgia and 10 county Extension agents. It encompassed the major row and forage crop areas in the state.

The responding growers were responsible for 13 percent of the state’s cotton, and the total acreage from the county agents responses represented 24 percent of Georgia’s cotton.

Growers produced cotton, peanuts, soybeans and corn, with some livestock, forage and vegetables.

Prior to the development of glyphosate-resistant Palmer amaranth, morningglory was listed as the most troublesome weed pest in row-crop farming.

The growers in the survey said about 78 percent of their acres were infested with glyphosate-resistant pigweed, and the county agents’ number was close to 90 percent of total acreage.

Looking at herbicide use patterns relative to cotton planting and emergence and growth, the survey questioned respondents about the herbicides applied pre-plant and at planting, postemergence over-the-top, and postemergence layby and directed applications.

As expected, with preplant, burndown and at-plant herbicides applied, there was a significant decrease in the acres treated with glyphosate. The use of 2,4-D stayed relatively the same, but there were significant increases in the use of paraquat for controlling Palmer amaranth. The agents saw a significant increase in the use of 2,4-D.

There were significant increases in the amount of diuron, flumioxazin and fomesafen being used, and agents and growers also saw an increase in the amount of pendemetholon being applied in Georgia.

In postemergence treatments, there was a decrease in the amount of glyphosate being applied with respect to the treated acres.



Increase in herbicide use

At the same time, there was a corresponding increase in the amount of glufosinate and metolachlor being used. Similar trends were seen by the county Extension agents who responded.

Growers said post-directed and layby herbicides applied included a decrease in the use of glyphosate while MSMA and diuron stayed about the same.

But there were significant increases in the amount of flumioxazin and metolachlor being used. Agents’ responses were similar, including significant increases in the amount of MSMA and diuron being applied to Georgia cotton acres.

The survey also asked growers how many applications of glyphosate per year were being made. Producers said they were making approximately 2.3 to 2.4 applications of glyphosate per year, both before and after the development of resistant Palmer amaranth.

There was a significant increase in the use of glufosinate for controlling Palmer amaranth. Agents also saw a static number of glyphosate applications but a sizeable increase in the number of glufosinate applications.

Growers are still putting out two applications of glyphosate per year within a crop cycle. However, they might not be placing them on every acre, indicating they may be treating certain fields differently according to the weed pressure.

Looking at costs, growers went from $32 per acre for herbicide weed control to almost $63 per acre. The agents saw an increase of $28 per acre to $68 per acre for herbicide costs.

In 2000 to 2005, 17 percent of growers were hand-weeding 5 percent of Georgia’s cotton acreage at $2 per acre. According to the UGA survey, that has increased to 52 percent of cotton acres being hand-weeded at $24 per acre.

Agents also saw an increase in the amount of acreage being hand-weeded and the associated costs.

The number of acres being subjected to in-row cultivation during the growing season also is increasing.

The survey summarizes that glyphosate-resistant Palmer amaranth is the primary weed problem among Georgia row-crop farmers.

Growers and county agents are reporting similar trends in weed management practices, hand-weeding and cultivation are increasing, glyphosate use — though still high — is decreasing, and at the same time there are increases in the use of other herbicides.

The survey recommends that particular attention be paid to the use of glufosinate, flumioxazin and fomesafen, because of the need to conserve and not over-use, causing more resistance problems.

phollis@farmpress.com


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DYERSBURG, Tenn. — For 15 years, Eddie Anderson, a farmer, has been a strict adherent of no-till agriculture, an environmentally friendly technique that all but eliminates plowing to curb erosion and the harmful runoff of fertilizers and pesticides.



Jason Hamlin, a certified crop adviser and agronomist, looks for weeds resistant to glyphosate in Dyersburg, Tenn.


Related

Invasion of the Superweeds

Michael Pollan and others on what Roundup-resistant weeds mean for American agriculture.

Green

A blog about energy and the environment.

But not this year.

On a recent afternoon here, Mr. Anderson watched as tractors crisscrossed a rolling field — plowing and mixing herbicides into the soil to kill weeds where soybeans will soon be planted.

Just as the heavy use of antibiotics contributed to the rise of drug-resistant supergerms, American farmers’ near-ubiquitous use of the weedkiller Roundup has led to the rapid growth of tenacious new superweeds.

To fight them, Mr. Anderson and farmers throughout the East, Midwest and South are being forced to spray fields with more toxic herbicides, pull weeds by hand and return to more labor-intensive methods like regular plowing.

“We’re back to where we were 20 years ago,” said Mr. Anderson, who will plow about one-third of his 3,000 acres of soybean fields this spring, more than he has in years. “We’re trying to find out what works.”

Farm experts say that such efforts could lead to higher food prices, lower crop yields, rising farm costs and more pollution of land and water.

“It is the single largest threat to production agriculture that we have ever seen,” said Andrew Wargo III, the president of the Arkansas Association of Conservation Districts.

The first resistant species to pose a serious threat to agriculture was spotted in a Delaware soybean field in 2000. Since then, the problem has spread, with 10 resistant species in at least 22 states infesting millions of acres, predominantly soybeans, cotton and corn.

The superweeds could temper American agriculture’s enthusiasm for some genetically modified crops. Soybeans, corn and cotton that are engineered to survive spraying with Roundup have become standard in American fields. However, if Roundup doesn’t kill the weeds, farmers have little incentive to spend the extra money for the special seeds.


Supplemental herbicides were applied on Eddie Anderson’s land to combat weeds that are resistant to glyphosate.

Roundup — originally made by Monsanto but now also sold by others under the generic name glyphosate — has been little short of a miracle chemical for farmers. It kills a broad spectrum of weeds, is easy and safe to work with, and breaks down quickly, reducing its environmental impact.

Sales took off in the late 1990s, after Monsanto created its brand of Roundup Ready crops that were genetically modified to tolerate the chemical, allowing farmers to spray their fields to kill the weeds while leaving the crop unharmed. Today, Roundup Ready crops account for about 90 percent of the soybeans and 70 percent of the corn and cotton grown in the United States.

But farmers sprayed so much Roundup that weeds quickly evolved to survive it. “What we’re talking about here is Darwinian evolution in fast-forward,” Mike Owen, a weed scientist at Iowa State University, said.

Now, Roundup-resistant weeds like horseweed and giant ragweed are forcing farmers to go back to more expensive techniques that they had long ago abandoned.

Mr. Anderson, the farmer, is wrestling with a particularly tenacious species of glyphosate-resistant pest called Palmer amaranth, or pigweed, whose resistant form began seriously infesting farms in western Tennessee only last year.

Pigweed can grow three inches a day and reach seven feet or more, choking out crops; it is so sturdy that it can damage harvesting equipment. In an attempt to kill the pest before it becomes that big, Mr. Anderson and his neighbors are plowing their fields and mixing herbicides into the soil.

That threatens to reverse one of the agricultural advances bolstered by the Roundup revolution: minimum-till farming. By combining Roundup and Roundup Ready crops, farmers did not have to plow under the weeds to control them. That reduced erosion, the runoff of chemicals into waterways and the use of fuel for tractors.

If frequent plowing becomes necessary again, “that is certainly a major concern for our environment,” Ken Smith, a weed scientist at the University of Arkansas, said. In addition, some critics of genetically engineered crops say that the use of extra herbicides, including some old ones that are less environmentally tolerable than Roundup, belies the claims made by the biotechnology industry that its crops would be better for the environment.

“The biotech industry is taking us into a more pesticide-dependent agriculture when they’ve always promised, and we need to be going in, the opposite direction,” said Bill Freese, a science policy analyst for the Center for Food Safety in Washington.


Mr. Anderson, who has about 3,000 acres of soybean fields, is dealing with the pest pigweed. 


So far, weed scientists estimate that the total amount of United States farmland afflicted by Roundup-resistant weeds is relatively small — seven million to 10 million acres, according to Ian Heap, director of the International Survey of Herbicide Resistant Weeds, which is financed by the agricultural chemical industry. There are roughly 170 million acres planted with corn, soybeans and cotton, the crops most affected.


Roundup-resistant weeds are also found in several other countries, including Australia, China and Brazil, according to the survey.

Monsanto, which once argued that resistance would not become a major problem, now cautions against exaggerating its impact. “It’s a serious issue, but it’s manageable,” said Rick Cole, who manages weed resistance issues in the United States for the company.

Of course, Monsanto stands to lose a lot of business if farmers use less Roundup and Roundup Ready seeds.

“You’re having to add another product with the Roundup to kill your weeds,” said Steve Doster, a corn and soybean farmer in Barnum, Iowa. “So then why are we buying the Roundup Ready product?”

Monsanto argues that Roundup still controls hundreds of weeds. But the company is concerned enough about the problem that it is taking the extraordinary step of subsidizing cotton farmers’ purchases of competing herbicides to supplement Roundup.

Monsanto and other agricultural biotech companies are also developing genetically engineered crops resistant to other herbicides.

Bayer is already selling cotton and soybeans resistant to glufosinate, another weedkiller. Monsanto’s newest corn is tolerant of both glyphosate and glufosinate, and the company is developing crops resistant to dicamba, an older pesticide. Syngenta is developing soybeans tolerant of its Callisto product. And Dow Chemical is developing corn and soybeans resistant to 2,4-D, a component of Agent Orange, the defoliant used in the Vietnam War.

Still, scientists and farmers say that glyphosate is a once-in-a-century discovery, and steps need to be taken to preserve its effectiveness.

Glyphosate “is as important for reliable global food production as penicillin is for battling disease,” Stephen B. Powles, an Australian weed expert, wrote in a commentary in January in The Proceedings of the National Academy of Sciences.

The National Research Council, which advises the federal government on scientific matters, sounded its own warning last month, saying that the emergence of resistant weeds jeopardized the substantial benefits that genetically engineered crops were providing to farmers and the environment.

Weed scientists are urging farmers to alternate glyphosate with other herbicides. But the price of glyphosate has been falling as competition increases from generic versions, encouraging farmers to keep relying on it.

Something needs to be done, said Louie Perry Jr., a cotton grower whose great-great-grandfather started his farm in Moultrie, Ga., in 1830.

Georgia has been one of the states hit hardest by Roundup-resistant pigweed, and Mr. Perry said the pest could pose as big a threat to cotton farming in the South as the beetle that devastated the industry in the early 20th century.

“If we don’t whip this thing, it’s going to be like the boll weevil did to cotton,” said Mr. Perry, who is also chairman of the Georgia Cotton Commission. “It will take it away.


Ten resistant species of weeds in at least 22 states are infesting millions of acres.


http://www.nytimes.com/2010/05/04/business/energy-environment/04weed.html?pagewanted=1&_r=3

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In response to the increasing number of weeds resistant to current applications, companies are developing new generations of seeds genetically modified to resist multiple herbicides. This continual insertion of more genes into crops is not a sustainable solution to herbicide resistance, according to the researchers. 



Over-reliance on glyphosate-type herbicides for weed control on U.S. farms has created a dramatic increase in the number of genetically-resistant weeds, according to a team of agricultural researchers, who say the solution lies in an integrated weed management program.

"I'm deeply concerned when I see figures that herbicide use could double in the next decade," said David Mortensen, professor of weed ecology, Penn State.

Since the mid-1990s, agricultural seed companies developed and marketed seeds that were genetically modified to resist herbicides such as Roundup - glyphosate - as a more flexible way to manage weeds, Mortensen said. About 95 percent of the current soybean crop is modified by inserting herbicide-resistant genes into the plants.

"We do understand why farmers would use the glyphosate and glyphosate-resistant crop package," Mortensen said. "It is simple and relatively cheap, but we have to think about the long-term consequences."

The researchers said that increased use of herbicider is leading to more species of weeds that also are resistant to the chemicals.

They report their findings in the current issue of BioScience, noting that 21 different weed species have evolved resistance to several glyphosate herbicides, 75 percent of which have been documented since 2005, despite company-sponsored research that the resistance would not occur.

"Several species have developed amazing biochemical ways to resist the effects of the herbicide," said J. Franklin Egan, doctoral student in ecology, Penn State. "If weed problems are addressed just with herbicides, evolution will win."

One way the weeds develop resistance is to make an enzyme that is insensitive to the herbicide, but still maintains cellular function, Egan said. Weeds have also developed ways for the plant to move the herbicide away from targeted enzymes.

"For instance, glyphosate-resistant strains of Conyza canadensis - horseweed - sequester glyphosate in leaf tissues that are exposed to an herbicide spray so that the glyphosate can be slowly translocated throughout the plant at non-toxic concentrations," Egan said. "To the horseweed, this controlled translocation process means the difference between taking many shots of whiskey on an empty stomach versus sipping wine with a meal."

In response to the increasing number of weeds resistant to current applications, companies are developing new generations of seeds genetically modified to resist multiple herbicides. This continual insertion of more genes into crops is not a sustainable solution to herbicide resistance, according to the researchers.

They add that companies are creating a genetic modification treadmill similar to the pesticide treadmill experienced in the mid-20th century, when companies produced increasingly more toxic substances to manage pests resistant to pesticides.

"Specifically, several companies are actively developing crops that can resist glyphosate, 2, 4-D and Dicamba herbicides," said Mortensen.

"Such genetic manipulation makes it possible to use herbicides on these crops that previously would have killed or injured them. What is more troubling is that 2,4-D and Dicamba are older and less environmentally friendly."

Egan said there are several problems with the treadmill response. First, weeds will eventually evolve combined resistance to Dicamba, 2,4-D and glyphosate herbicides. Globally, there are already many examples of weeds simultaneously resistant to two or more herbicides.

Increased use of 2,4-D and Dicamba applied over the growing corn and soybean means much more of these herbicides will be applied at a time of year when many sensitive crops like tomato and grapes are most vulnerable to injury. Such injury results when these herbicides move from the targeted field during or following an application.

Overuse of chemical weed killers may increase chances that farmers will use the herbicide during inappropriate or non-recommended weather conditions, leading to herbicides drifting from the targeted area and killing or harming other plants and crops.

Egan also said that if farms become too reliant on herbicides, farmers will find it more difficult to use integrated weed management approaches.

Integrated weed management includes planting cover crops, rotating crops and using mechanical weed control methods. Farmers can use herbicides in this management approach, but must use them in a targeted, judicious fashion.

The researchers, who also worked with Bruce D. Maxwell, professor of land resources and environmental sciences, Montana State University, Matthew R. Ryan, post-doctoral student, Penn State, and Richard G. Smith, assistant professor of agroecology, University of New Hampshire, said that in previous studies, integrated weed management had lowered herbicide use by as much as 94 percent while maintaining profit margins for the operations.

"Integrated weed management is really the path forward," said Egan. "We believe these methods can be implemented, and we already have a lot of show that they're effective and straight forward to incorporate."


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1996년 유전자조작 작물이 처음 소개된 이후 미국의 농부들은 이걸 빠르게 널리 받아들이고 있다. 소비자의 반응이나 경제적, 환경적 요인은 일단 차치하고 말이다. 제초제에 내성이 있는 콩과 목화가 가장 많이 퍼졌다 . 우리나라에서는 노린재 피해가 늘고 있는데, 미국은 아직 해충 때문에 고민하는 단계는 아닌가 보다. 그냥 풀을 죽이는 약만 팍팍 치는 듯하네.

다음은 해충에 내성이 있는 목화와 옥수수. 목화는 이래저래 손이 많이 가는 작물이다. 오죽했으면 그것 때문에 내전도 일어났겠는가? 거름도 많이 먹고, 손도 많이 가고... 그래서 돈벌이작물로는 딱이다. 

아무튼 미국산 못 쓰겄네!

 

 

자료는 USDA's National Agricultural Statistics Service (NASS)에서 조사한 걸 바탕으로 만들어졌다.

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