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Create a culture of critique and redrafting in your classroom by adapting the seven-step Audience Response protocol to your subject matter and students’ needs.
Editor’s note: You’ll notice British standard spelling throughout this post. It was authored by a U.K.-based educator as part of our Schools That Work coverage of School 21.
Critique allows students to learn from each other and become accountable for their own ideas. It gives them a glimpse of how the real world would respond to their work, and insight into what is working and what needs redrafting. When the culture is right, students see critique as a gift to redraft their work and reach for a better outcome.
Audience Response is a talk protocol that I’ve created and use in my drama class to empower students in critiquing each other’s work and then redrafting their own. My Audience Response protocol is one of many oracy talk protocols that I use in my daily practice, and I believe that it’s adaptable for teachers across all subjects and levels to aid students in redrafting their work through critical talk.
By using a clear and concise response model to students’ work, the process empowers them to express their views without directly offending or deflating their peers, and it allows them to receive feedback without reacting defensively.
This is a culture that grows over time. I’ve found that although students will fixate on trying to get their work “right” at first, after we nurture this approach to critique, they develop a growth mindset about their work and become open to developing it as part of their process.
If you want to develop a culture of critique and redrafting in your classroom, below you’ll find the Audience Response protocol, and three tips for implementing it.
Audience Response Protocol
1. One group watches another group’s play or presentation of their work.
2. The group watching becomes a critical audience. They keep in mind what they feel that the presenting group should keep, add, or take away.
3. Once the play or presentation is over, you’ll discuss the work. The audience sits in a circle with you, and the students being critiqued sit in an outer circle, facing the centre.
4. Using the protocol of keep, add, and take away, the audience responds critically to the play or work they’ve just seen. They may agree or disagree with each other, or build upon each other’s ideas, helping the presenters understand what’s working, what’s not working, and what they can change. You can also add your own critique during this time.
6. When introducing the Audience Response protocol, give your students sentence stems to help them become comfortable with critical language. Once your students are accustomed to the language and critique process, encourage them to organise their own talk.
8. The groups then swap. The presenters become the critical audience, and the critical audience members become the presenters.
3 Tips for Using the Audience Response Protocol
1. It Takes Time to Build a Culture
The first time you try the protocol, it will probably go wrong. Students may find it strange or feel that they can’t help but respond out of protocol. As an oracy school, we embed talk protocols in our daily routines. And like any routine, you need to nurture it over time to perfect it. Your role — especially at the beginning — is important. Make sure that all students are involved. If your students speak out of protocol, stop and guide them back on track. Over time, you want your students to lead the critique themselves.
2. Hard on the Content, Soft on the Person
You need to model and insist on judging the ideas and not the person. As your students learn to appreciate being critiqued, this approach will come more naturally to them. A negative judgment like, “Sarah, I really think you shouldn’t do your monologue. I think you should change that,” becomes, “I think that Sarah’s monologue should be taken away. It would be better if they added a group scene here to include the reactions of all characters.” The critiquer doesn’t look the person in the eye and criticise him or her. The critical audience is having a discussion with each other; it’s done in a safe protocol with an emphasis on what is best for the piece of art, not the person involved.
3. Use the Feedback
What I learned through creating and using the Audience Response protocol with my students is that they either forgot the feedback or ignored it. I noticed that my students’ work wasn’t improving and realised that, although I was giving them an opportunity to critique, they didn’t know what to do with their feedback. I now encourage them to record their feedback, and I’ve included their decision-making process on what will be redrafted within the Audience Response protocol. In step seven (see above), students voice three things that they’ll commit to change by the next session, and then the critique cycle continues. You can use the Audience Response protocol on the same piece of work multiple times to continue redrafting and developing it.
Critique is embedded into a growth mindset culture. Rather than having students fixated on getting tasks done or being the best, by using critique protocols and nurturing the redrafting process, we can create a culture that builds on the experiential development of making something rather than completing it.
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Dreams Of The New Power Grid
by Photo: Marina Grinshpun/PhotoSpin
A fuel cell for every home: that’s the idea. But there are a few obstacles in the way.
At the nuvera fuel cells lab in Cambridge, Massachusetts, 25-year-old chemical engineer Darryl Pollica stands in front of a prototype 5-kilowatt fuel cell — a miniature powerplant that can make most of the electricity needed by a family of four. Its metal skin has been removed to reveal a cubical frame about 5 feet on each side, packed with tanks, valves, and electronics. Conspicuously taped to the outside of the frame is a Nokia cellphone.
“That’s our mascot,” Pollica says. “We want to shrink this,” he says, opening his arms as if to embrace the entire assembly, “to this,” and he brings them together and points toward the tiny phone.
Pollica’s boss, Nuvera Chief Operating Officer Jeff Bentley, a 25-year veteran of the difficult effort to create cost-effective fuel cells that are relatively small, is a bit more cautious. “Maybe,” he says, looking toward Pollica with almost parental amusement. “But it’s going to take a lot of work.”
“We’re optimists,” Pollica shoots back with a confident smile.
They better be. The year 2001 was supposed to be a memorable one for residential fuel cells; instead, it turned out to be one the industry might prefer to forget. In the late 1990s, several manufacturers announced breakthroughs that, by now, were supposed to have brought the price of fuel cells down to around $5,000 — cheap enough that a lot of homeowners could be enticed to buy one to generate most or all of their electricity.
The implications were enormous: Imagine a nation of houses powered by a nonpolluting, domestic source of energy that relies on simple chemical reactions to cleanly and silently produce electricity from hydrogen gas. Hot water and a small amount of carbon dioxide are the only waste.
Nothing happened. During the past four years, H Power, Plug Power, and the Electric Power Research Institute, among others — some of the most bullish residential fuel cell manufacturers and agencies — promised to install prototype fuel cells in houses to convince people that the technology was a practical source of home energy. Only Plug Power came through. In 1998, the Latham, New York-based fuel cell manufacturer put a 5kW prototype system in one nearby home. That alone was enough for The New York Times to declare that fuel cells were “on the verge of a breakthrough” as an economical energy source. Plug was not able, however, to lower manufacturing costs enough to sell the units to consumers. So, two years later, Plug quietly shelved the project.
Such false starts make it tempting to compare fuel cells to photovoltaics, which produce electricity from sunlight-drenched silicon cells laminated behind glass or plastic. Photovoltaics have for decades captured people’s fancy as a simple and environmentally sound electricity solution, but after years of research and development this technology is still too inefficient and expensive for residential use. But fuel cells have an edge over solar power: In addition to investments by a handful of startups, several major corporations are spending more than $1 billion combined annually on fuel cell research. “There has never been funding into photovoltaics and other renewable energy sources that comes close to the amount of money being put into fuel cell development right now,” says Robert Stokes, vice president of research and deployment at the Gas Technology Institute.
Buoyed by that investment, fuel cell manufacturers are not backing down from their hydrogen-tinged vision of the future. They tout the technology as a way to wean the United States off foreign oil (fuel cells extract their hydrogen from U.S.-produced natural gas), and to rid the country of coal-fired and nuclear power plants. They claim fuel cells are a money-saver. People will still have to buy gas, but a fuel cell uses less of it to make a kilowatt of power than does the local utility. And homeowners can save even more money by using the fuel cell’s hot water output in their home heating system. What’s more, some of the most strident optimists believe that most homeowners will eventually be able to sell excess power from their fuel cells back to the local utility.
But before we get there, the matter of cost has to be resolved. So far, no manufacturer has been able to squeeze the price of a 5kW fuel cell below $30,000 — or $6,000 a kilowatt. Most market research indicates that consumers won’t be interested in the technology until it drops much closer to the price of a gasoline-powered home generator, which can deliver 6kW for about $1,400. Given the cost benefit of natural gas over gasoline and the fuel cell’s more efficient extraction technology, experts predict that fuel cells will become attractive when they reach $1,000 a kilowatt — which probably won’t happen for seven to 10 years. And even then, a fuel cell will probably save money only in places where electricity is expensive, such as in New York or California, where utilities are charging more than 9 or 10 cents per kilowatt-hour.
The key obstacles to reducing the price tag are the “stack,” which makes the electricity, and the “reformer,” the miniature chemical plant that separates the hydrogen from the natural gas. Both use platinum as a catalyst to speed up chemical reactions. Not only is platinum expensive — last year, it ranged from approximately $400 to $650 per ounce — but the United States has to import most of its platinum from politically unstable nations. Manufacturers have already reduced platinum content in fuel cell systems by one-eighth during the past five years, primarily by designing systems that require less platinum in the stack and by mixing the platinum with cheaper metals. But to slash fuel cell costs, they need to make even bigger cuts. So manufacturers are now turning their attention to reducing the platinum in the reformer.
Cost issues seem daunting, but only because many people are looking at them erroneously, says Peter B. Bos, CEO of Polydyne, a Pacific Palisades, California-based consultancy that specializes in fuel cell economics. Bos, who’s considered somewhat radical among fuel cell proponents, says the traditional cost projections don’t factor in what he terms the production learning curve, which, simply put, means it can take years of research and lots of money to capture the first 1 percent of the potential market; but lessons learned during that initial effort spur a second, more efficient manufacturing wave, when production rises steeply and prices drop quickly. With that theory as a guide, Bos expects fuel cell price trends to mirror those of VCRs, air conditioners, and heat pumps. He predicts that 1 percent of U.S. homes will have fuel cells between 2006 and 2010, when a 5kW model will cost roughly $7,000. A few years after that, Bos says, fuel cells will cost only $1,200 and be in half of U.S. homes. But his most radical prediction is 29 years out: “By 2031, 99 percent of the homes in the United States won’t need to be hooked up to the electric grid.”
Size may not be as big a hurdle as cost, but it’s imposing nonetheless. To be acceptable to homeowners, manufacturers realize that a 5kW fuel cell system would have to be shrunk to about the size of a small refrigerator — not quite the dimensions of a cellphone but one-sixth as big as they were just a few years ago. Most of the fuel cell’s excess bulk is in the reformer and in pumps, pipes, and electronics. It is possible through more efficient engineering to trim back these components. But the reformer may be more difficult. It also contains the critical heat exchangers, which manage how hot the various chemical reactions get — and there’s a threshold to how small they can be made. “Think of the radiator on your car,” says Nuvera’s Bentley. “There’s no amount of technology you could pour into car radiators to make them one-tenth their current size.”
Durability is also a problem. Along with hydrogen, the fuel cell reformer generates traces of carbon monoxide. Because this latter gas stains platinum as permanently as ink stains cotton, the stack must be replaced every four or five years at a cost of about 10 percent to 15 percent of the system’s price, according to Bentley. The best estimates are that a residential fuel cell can be engineered to run continuously for 10 years, with one stack replacement.
Even 10 years may not be enough for most homeowners, so the notion that fuel cells will put utilities out of business may be off the mark. Instead, it’s possible that if residential fuel cells gain widespread acceptance it will be because they are owned by the local utility or an energy services firm. The homeowner will get a monthly bill and the company will maintain the unit. “We see distributed power, of which fuel cells are a subset, complementing the existing utility business,” says Dan Rastler, area manager for distributed resources for the Electric Power Research Institute, a nonprofit energy research consortium based in Palo Alto, California.
Some utilities won’t even put fuel cells in homes, but will cluster them in substations instead. The Long Island Power Authority recently fired up 75 5kW Plug Power units at a site in West Babylon, New York, to test the concept. They add enough power to the electric grid to run 100 average-size homes.
Success stories like that — as well as the four decades of fuel cells powering NASA spacecraft and the 3-megawatt systems that are being used in dozens of hospitals, wastewater treatment plants, and military bases for backup power — continue to lure developers into the fuel cell business. Among some of the big names that have begun research recently are 3M, DuPont, General Motors, and United Technologies.
Perhaps the biggest thing that fuel cells have going for them is the unpredictability of worldwide energy supplies. An environmental disaster or a geopolitical crisis that sends energy prices skyward could transform the whole equation, making fuel cells not only a relative bargain at almost any price but the most desirable solution overall. “The issues are energy security, energy quality, and environmental quality, and the fuel cell responds to all three of those,” says Bentley. “There’s nothing else like it.”
Fuel for Thought
In December, 1,660 visitors to the Popular Science Web site responded to a poll about residential fuel cells. Here are the highlights:
49% say $5,000 is the most they would pay for a fuel cell that supplies all their electricity; 29% say $3,000 is their limit, while 20% say they’d shell out $10,000.
36% say they’d think twice about powering their home with a fuel cell because of reliability concerns.
60% voted for automobiles, while 24% chose consumer electronics.
26% believe that electric utilities will be extinct by 2050.
You Couldn’t Make It Up: The Dangers Of Misunderstanding The Power Of The Internet
I recently wrote a guest post on why Common Sense is so vital within any SEO campaign as, unfortunately, this is something that seems to be dwindling in recent generations. So following on from that slightly, I want to discuss how the power of the internet has greatly affected lives across the globe; simply by misusing what is the most powerful tool today.
Here are some funny, sad and downright stupid examples of why the Internet must be used wisely.
Facebook: The number one passion killer.
Since the arrival of Facebook and the word got around, it’s since overtaken Google as the most visited website in the world. For the most part, people use it for chatting, the occasional profile snoop and of course, organising intimate social events in the wide open space of the worldwide web.
Unfortunately, some people have decided that they’d rather use the website to pick up dates, which is fine; except when they are already ‘In a Relationship’.
Recent studies have shown that many marriages have ended in divorce due to Facebook infidelity. Whether it’s by finding previous love interests or simply striking up new ones by ‘Poking’ ‘Lol’ing or ‘Liking’, the truth is the number of people thinking they are being discreet (again by using the WORLD wide web) are rudely mistaken. Private messages and outright flirting via Facebook has decreased trust within relationships and increased the legal fees for divorce lawyers.
So, next time you wish to ‘Poke’ the boy from school who always had lovely blue eyes and borrowed a pencil from you in Maths, think of your partner on the sofa next to you, probably snoring, farting or both, and perhaps weigh up whether it’s really worth it?
The YouTube Success: “Leave the Camera Alone!!”
You may not know the names Chris Crocker, or the kid from Trois-Rivieres, Quebec, or even Harry and Charlie. But I bet if I mentioned “Leave Britney Alone!”, Star Wars Kid and “Charlie bit my finger!” you’d all know exactly what videos I was talking about.
As annoying it is to know who these people are, they prove outright what power the internet has over the destiny of some people in the world. Whether or not you yourself have seen these videos, you’ll most certainly have heard someone talking about them; most likely from watching Channel 4’s RudeTube.
The sad thing is, they haven’t just had their 15 minutes of fame – they are online for life. So next time you think about uploading a video or your friend skateboarding with a firework in his back pocket, maybe just rethink about the consequences and keep in mind the mental affect this will have on your future children.
Call a Doctor: Or just get an online Medical diagnosis
Even i f you are normally a rational person in everyday life, finding something abnormal on your body may spur irrational panic. Unfortunately, this is where every computer should be buried and never dug back up.
Sadly more often than not the first thing people do is log on, type in the abnormality and self-diagnose their rash, lump or spot; often with frightening consequences.
Whether you know of a ‘reliable’ website or not, the internet is the worst place to turn when calmness is required; it’s likely to provoke the complete opposite. If you are ever in doubt in regards to your health, go old school and pick up the phone, make a doctor’s appointment or if in a real emergency, get down A&E rather than relying on Wikipedia.
Email: To, CC, BCC and downright foolishness.
We’ve all done it. Sent an email to the wrong person and then sent a follow up email explaining that we’ve sent it to the wrong person; just in case they didn’t know.
However, there has been recent news in the UK of two men being suspended from their place of work due to emails regarding one of their female flatmates.
Harry and Sebastian swapped emails discussing Jenni, the ex-girlfriend and current flatmate of Harry. Sebastian was interested in dating Jenni and was finding out if Harry would mind. Unfortunately Harry CC’d Jenni in on the emails in which he used offensive language to describe her and the fact they didn’t get on.
As with everything online, it didn’t take much for this to then go viral which then led to the suspension.
Lesson learnt; if you don’t want the whole world to know what you think of someone – don’t put it in black and white.
So, whether you want instant fame and to be mocked in a satirical episode of a new 20th Century Fox cartoon, or like to feel the fear of dying from what is actually prickly heat rash, then the internet is the perfect tool to carry on using without common sense. However for those of us that are mostly sane, we’ll keep using it for finding great holiday deals, arranging house viewings and researching the latest Jamie Oliver recipe.
I hope I’ve highlighted just some of the misuses of the internet and I promise you there will be more; just make sure it’s not you I’m reading about next, please.
Give Your Phone The Power Of A Desktop Pc
Mobile computing has long been dominated by laptop computers, but powerful new smartphones such as the various Android phones–including the new Motorola Droid X–are rapidly becoming the portable computing devices of choice.
However, a lot of tasks, such as word processing and Web browsing, are still more easily accomplished using the larger keyboard and monitor of a traditional laptop or PC. Consequently, most mobile professionals continue to lug around a bulky laptop in addition to their smartphone.
Wouldn’t it be great if you could ditch your laptop, carry just your smartphone, and still be able to work in a Windows PC (or OS X or Linux) environment when you need to? You can do that, with the help of portable apps. In contrast to phone apps–which are designed to run on the handset itself, using the phone’s hardware and operating system–portable apps run on a host computer, using the computer’s RAM and display, but they save all their data and settings to your portable drive (or your phone’s internal memory).
USB Drive ModeAll you need is your smartphone, the USB sync cable that works with it, and the right selection of portable apps, as well as access to a desktop or laptop PC–even if it’s just as a guest.
First, plug your phone into the computer using the phone’s sync cable. Next, select USB Drive mode. This process should work with all operating systems, most smartphones, and most other type of phone that use a sync cable. If your phone doesn’t use a sync cable, you’re out of luck.
[Story corrected on 7/19/10 to reflect the iPhone’s inability to support Drive Mode without jailbreaking.]
Finding Windows XP/Vista/7 Portable AppsIf you’d like to work as if you were at your desk, try chúng tôi Portable. Another useful app is the portable, cross-browser RoboForm2Go, a password manager that is secure and encrypted.
For another good source of useful portable apps, check out the Portable Freeware Collection.
Installing Windows XP/Vista/7 Portable AppsInstalling portable apps in Windows is a fairly straightforward process, similar to installing “normal” programs. The main difference is that with portable apps you need to specify the location where you want to install the app–namely, your smartphone’s internal storage.
If you have never installed portable apps before, going with chúng tôi is probably the easiest way to start. You can choose to download and install the Platform utility, an app launcher similar to the Start menu that makes it easy to install and access your choice of portable apps, documents, and other files.
Or you can try the bundled PortableApps Suite, which includes portable versions of the Firefox Web browser, Thunderbird e-mail client, Sunbird calendar/task app, ClamWin antivirus scanner, Pidgin instant messaging client, Sumatra PDF reader, KeePass password manager, CoolPlayer audio player, PNotes sticky-note tool, and chúng tôi office suite (a decent cross-platform alternative to Microsoft Office). It even has a couple of games.
Keep in mind, however, that the Suite is a 137MB download and that it unpacks to 400MB when installed. The installation process is simple (you just download the installer, run it, and specify your phone’s drive letter), but the package may be overkill for your needs. Personally, I use only the Platform app with Firefox Portable, Chrome Portable, Pidgin Portable, and Notepad ++.
Next: Portable Apps for Mac and Linux
Difference Between Voltage Amplifier And Power Amplifier
An amplifier is an electronic circuit that is used to increase the strength of a signal in terms of voltage, current, power, etc. It accepts a weak signal at the input terminal and produces a raised signal at the output, though the output signal is identical to the input signal. The function that an amplifier performs is known as amplification. The amount of amplification performed by the amplifier is determined by a factor known as gain of the amplifier.
Depending on the applied input signal and generated output signal, the amplifiers are broadly classified into two major types namely,
Voltage Amplifier
Power Amplifier
In this article, we will highlight all the major differences between voltage amplifier and power amplifier by considering different parameters such as basic function, transistor size, transistor gain, load resistance, etc. But, before discussing the differences, let’s start with some basics of voltage amplifier and power amplifier so that it becomes easier to understand the differences between them.
What is a Voltage Amplifier?A voltage amplifier is the one that produces an output signal with increased voltage level when a low voltage signal is input to it. A voltage amplifier is used in such applications where we need signal transmission at higher voltage through a long wire. Therefore, the voltage amplifier is similar to a transformer in the sense that it can increase the voltage level of a signal.
A typical circuit of a voltage amplifier is shown in Figure-1. It consists of one BJT (Bipolar Junction Transistor) and two resistors. Basically, a voltage amplifier is designed to achieve the highest possible voltage gain. Where, the voltage gain of a voltage amplifier is simply the ratio of output voltage to input voltage, i.e.
$$A_v:=:frac{V_{out}}{V_{in}}$$
A voltage amplifier draws a very little amount of power from the load. For these amplifiers, the input signal has very small magnitude, for this reason a voltage amplifier is also called a small signal amplifier.
The voltage amplifiers are used in various applications such as in wireless communication, broadcasting of signals, audio equipment like speakers, etc.
What is a Power Amplifier?As its name implies, a power amplifier is an electronic device which boosts the power level of an input signal. The circuit diagram of a typical power amplifier is shown in Figure-2. It consists of a power transistor, as a normal transistor cannot be used in the power amplification. Because, in a power amplifier, the transistor must be able to handle huge large amount of power.
Since the power of the signal cannot be directly amplified. In actual practice, a voltage amplifier is placed before the power amplifier which increases the voltage level of the signal. This high voltage signal at the input of the power amplifier generates a high current signal, and the product of which provides a signal of high power at the output of power amplifier.
Therefore, the gain of the power amplifier is given by,
$$A_P:=:A_V:times:A_I$$
Where,
$$A_V:=:frac{V_{out}}{V_{in}}: and ::A_I:=:frac{I_{out}}{I_{in}}$$
The power amplifiers are extensively used in several applications like in headphone drivers, TVs, mobiles, music systems, microwave ovens, etc.
Difference between Voltage Amplifier and Power AmplifierThe following table highlights all the significant differences between a voltage amplifier and a power amplifier −
Basis of Difference Voltage Amplifier Power Amplifier
Definition An amplifier which is designed to increase the level of input signal is called a voltage amplifier. A type of amplifier which is designed to boost the power level of the input signal is called a power amplifier.
Alternate name Voltage amplifier is also called small signal amplifier. A power amplifier is also called a large signal amplifier.
Voltage of input signal The input voltage of a voltage amplifier is very low, of the order of approximately few mV. The input voltage of a power amplifier is relatively high of the order of few volts.
Nature of output signal Voltage amplifier has high voltage and low power output. Power amplifier has high power and low voltage output.
Size of transistor used The transistor used in the voltage amplifier circuit is smaller in size. The transistor used in the circuit of the power amplifier has relatively larger physical size.
β value of transistor The transistor used in the voltage amplifier has relatively high β value, around greater than 100. The β value of the transistor used in the power amplifier is low, around 5 to 20.
Type of coupling The R-C coupling is usually used in the voltage amplifier. Power amplifier always uses transformer coupling.
Collector current (IC) The collector current of the voltage amplifier is low, approximately equal to 1 mA. The collector current of a power amplifier is relatively high, greater than 100 mA.
Base region of transistor used The transistor used in the voltage amplifier has thin base region as it handles low current. The base region of transistor used in the power amplifier is comparatively thicker as it required to handle large current.
Load resistance (RC) In the voltage amplifier, the load has high resistance value, around 4 kΩ to 10 kΩ. In the power amplifier, the value of load resistance is low, around 5 Ω to 20 Ω.
AC power output The AC power output of a voltage amplifier is low. The AC power output of a power amplifier is comparatively high.
Output impedance Voltage amplifier has high output impedance, approximately equal to 12 kΩ. The output impedance of a power amplifier is low, around 200 Ω.
Need of heat sink In case of voltage amplifier, there is no need of heat sink. The heat sink is necessarily required in a power amplifier.
Use The voltage amplifier is usually used at the first stage of amplification. The power amplifier is usually used at the last stage of amplification.
ConclusionThe most significant difference between voltage and power amplifiers is that a voltage amplifier increases the magnitude of voltage of the input signal, while a power amplifier raises the power level of the input signal.
The Pros And Cons Of Herbicide
Welcome to the third installment of my GMO series, which aims to expand on a story I wrote for Popular Science’s July issue. In this post, I will discuss herbicide-tolerant crops—among the most common GMOs currently on the market—as well as the technology’s pros and cons. And despite what you may have heard one way or the other, there are both. And it’s complicated.
Farmers are constantly battling pests in the field, whether insects or weeds. No matter what kind of farming it is—organic, conventional, whatever—some level of intervention is required on both fronts. Each of those interventions comes with a cost, whether it’s economic, environmental, or a mixture or both.
For weeds, there are a several common tools, says Steve Powles, a plant scientist at the University of Western Australia and director of the Australian Herbicide Resistance Initiative. The first is simply good agronomy, which includes maintaining crop nutrition; rotating cover crops to promote soil health; and keeping crop rows fairly tight so there isn’t enough room—and eventually, when the crops grow tall enough to form a canopy, sunlight—for unwanted plants to grow. A healthy, well-planned field helps crowd out weeds.
Weeds can still grow, though, so there are various approaches to kill them including: mechanical (tilling or hand-weeding), heat-based (“flaming” with propane torches) and chemical (herbicides).
The best option for weed control, says Powles, is to use a combination of all of these tactics as appropriate for a specific piece of land. And for herbicides and the potential for resistance, he adds: “If you’re getting great weed control with a herbicide, stop using it for awhile.”
The easy fix that wasn’t
Across the developed world, conventional farmers have relied heavily on chemical weed control since the mid-1900s. In 1996, Monsanto made chemical control even easier by bringing herbicide-tolerant soybeans to the market (other crops followed). The seeds were genetically-engineered to withstand a popular broad-spectrum herbicide called glyphosate, marketed as Roundup Ready, which meant farmers could plant the crops, spray the field with herbicide, and call it a day. Monsanto didn’t spark the love affair with herbicides, but extended it, says Stephen Duke, a plant physiologist and glyphosate expert with the USDA Agricultural Research Service: “It continued our dependence on herbicide, but even in the absence of the GMOs, we were pretty much extremely dependent on herbicides. It really didn’t change anything—it just changed which herbicide we were using.”
The upside of the Roundup Ready system was that farmers could stop tilling, which prevented the associated environmental pitfalls. Glyphosate also has a low toxicity—lower than that of caffeine. “It’s probably one of the safest herbicides in terms of environment and human health,” says Keith Solomon, an environmental toxicologist and pesticide toxicology expert at the University of Guelph in Ontario.
As the Roundup Ready GMOs became increasingly popular, glyphosate replaced older chemistries, some of which are more toxic. This, too, was considered a bonus by some. But it came at a cost. “We are seeing a huge increase in glyphosate resistant weed, which is totally expected because of the increased use,” says Andrew Kniss, a weed ecologist at the University of Wyoming. Sometimes these weeds are called “superweeds” in the press, although Kniss says that’s a misnomer. It isn’t that the herbicide-tolerant genes in the GMOs are mixing with the weeds to cause the resistance; instead, it’s just a matter of old-fashioned evolution.
In the US, the biggest problem-weed is glyphosate-resistance palmer amaranth, which was first discovered in Georgia around a decade ago, according to Stanley Culpepper, a weed scientist at the University of Georgia. Since then, he adds, the industry has spent $1 billion to control the weed. Many farmers have returned to hand-weeding..
Worse still, research from Powles group in Australia suggests that the genetic changes in glyphosate-resistant palmer amaranth don’t come at a great cost for the plant. In other words, even in the absence of glyphosate, the plant will remain resistant. This means that in some fields where resistance has run amok, the herbicide is completely lost—we can’t simply give glyphosate a break for a few years and then return to it, because the palmer amaranth will still be immune.
Can we break the herbicide cycle?
It costs up to $256 million and around nine years to develop a new active ingredient for a pesticide. And for herbicides, there are no new options in the pipeline, says Jason Norsworthy, a weed scientist at the University of Arkansas, who adds that the last new herbicide came out in the 1980s. “It’s like climbing a mountain, climbing a cliff. We’re accumulating all these resistant weeds, we’re not accumulating new modes of action. And at some point we’re going to go over the cliff.”
And even if chemical companies find a new molecule that shows promise as an herbicide, it likely won’t be as powerful or useful as glyphosate. Norsworthy adds that in his lifetime, he “will never see another herbicide that will have the impact of global agriculture as glyphosate.”
With glyphosate losing efficacy in many fields, biotech companies are poised to roll out new herbicide-tolerant GMOs that use older chemistries, including 2, 4-D and dicamba. (The former is often called the Agent Orange herbicide in the press, which isn’t quite right. Agent Orange was a mixture of 2,4-D and another herbicide called 2,4,5-T. In Agent Orange production, the 2,4,5-T was contaminated with a dangerous dioxin, which is what likely caused the health problems you hear about).
Many experts I’ve talked to worry that farmers will see the new herbicide-tolerant GMOs as a panacea, sparking a new generation of resistant weeds, although it might not be as widespread as the glyphosate problem because 2,4-D doesn’t work on as wide a range of plants as glyphosate and might not be used as broadly (2,4-D, for example, is ineffective against grasses).
Still, overuse is a worry. “As an agricultural society, we have to get out of the habit of using herbicides until they break, thinking industry is going to save us with a new mode of action,” says Norsworthy.
Powles, who helped successfully battle herbicide-resistant weeds in Australia long before the glyphosate problem started in the US, agrees. The key is to alleviate reliance on herbicides by diversifying weed control. Farmers in the US and beyond must adopt a multiple-pronged approach, says Powles. This includes proper agronomy and various mechanical tactics along with a regular rotation of herbicides, which should be used judiciously as needed. “I have absolutely no doubt that herbicide resistance can be managed in the US,” he adds. “But not without very substantial change to the current paradigm—the current way people think—which is ‘what herbicide and what way.’”
Some states are already implementing diversified weed strategies, including farms under Culpepper’s watch in Georgia. But whether farmers across the country—and world, for that matter—will adopt the approach broadly remains to be seen.
So, the TL;DR version is that while herbicide-tolerant GMOs have played a large role in driving glyphosate resistance, they’re part of a larger systemic problem in modern agriculture, which is overreliance on herbicide. A diversified weed plan—tailored to each farm, depending on location and other details—would be ideal. All of the scientists I’ve talked to on this matter say GMOs could play a role in a sustainable weed system, but only if they are not overused. Of course, biotech companies have an incentive to push their products, which certainly could drive overuse and thus resistance. I don’t have the answer to fixing that, although, as Kniss tells me, public funding for weed management would help.
Updated March 30, 2023: An earlier version of this story stated that Georgia farmers have spent $1 billion hand-weeding cotton fields over the past decade, which isn’t right. The farmers have spent $1 billion controlling Palmer amaranth using a variety of weed management, including hand weeding, herbicides, and more.
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Additional reading:
For more on how we might break the resistance cycle, read: “How we can fight back against herbicide-resistant superweeds,” by Nathanael Johnson at Grist.
For more on the controversy over 2,4-D GMOs, read: “The Next Generation of GM Crops Has Arrived—And So Has the Controversy,” by Brandon Keim at Wired.
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