1. GM and crop yields – an enquiry

2. GM's  failure to yield – the science

EXTRACT: "If we are going to make headway in combating hunger due to overpopulation and climate change, we will need to increase crop yields," says Dr Gurian-Sherman. "Traditional breeding outperforms genetic engineering hands down." (item 2)
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1.GM and crop yields – an enquiry

This is an enquiry e-mail to GMWatch: 

Hi. I am avidly pro non-GMO. I was talking with a man who told me he knows a U.S. farmer who has been using GMO technology for many many years. This farmer claims his yields are twice what they were in the 70s. How does this add up with all the other information I read which says GMOs are failing? I need to know how to respond when I hear something like this. 

Response from GMWatch:

Thanks for the interesting question. The first thing to note is that GM crops only began to be introduced into American agriculture in 1996, so the farmer who's looking at changes in yields from the 1970s is looking at a much longer time period – up to 4 decades rather than just a decade and a half. And he's right that there have been significant improvements in yields in that time, it's just not down to GMOs.

If you look at the GMOs that are available, they are not ones that improve the intrinsic yield of crops. They are not designed to do that. They are designed for herbicide resistance, to make crops resistant to the chemicals, like Roundup, that GM companies like Monsanto produce, so that these chemicals can be sprayed straight onto the GM crop; or they produce a built-in insecticide (Bt) that kills some crop pests when they try to eat the GM crop. That's why there is very little evidence of benefits to farmers from GM crops in terms of yields, as this report shows:
http://www.ucsusa.org/food_and_agriculture/science_and_impacts/science/failure-to-yield.html

And as the 'Failure to yield' report makes clear, the improvements in yields witnessed in American farming are down to the successes of traditional plant breeding. And the GM companies, of course, take advantage of that, whereever they can, by splicing their GM traits into the highest yielding crop varieties available. But those varieties have been made high yielding by traditional plant breeding, not by GM. 

One of the worst things about the hype about how the magic-GM-bullet is going to feed the world (and there's precious little sign of that after a decade and a half!), and do all kinds of other miraculous things, is that it often obscures how little GM crops do that is of significant value to farmers and consumers. Meanwhile, traditional plant breeding is streets ahead of GM crops – you can find out more about this here:
http://www.gmwatch.org/component/content/article/31-need-gm/12348

And conventional breeding is also utilising non-GM biotech techniques that are making it even more successful:
http://www.bangmfood.org/quotes/24-quotes/32-non-gm-biotechnology-is-the-future

There is also a major role in feeding the world for innovative forms of low-tech sustainable agriculture, as used in 'agroecology', and these are particularly suited to the needs of resource-poor farmers in the developing world. Happily, this is starting to be recognized even in high powered reports, like this report co-sponsored by the World Bank and the UN:
http://www.bangmfood.org/feed-the-world/17-feeding-the-world/6-gm-no-solution-to-global-hunger

By the way, you may find these of help with the hype about GM crops. They both also deal with the yield claims sometimes made for GMOs:

10 reasons why we don't need GMOs
http://www.gmwatch.org/10-reasons-why-we-dont-need-gm-foods

GM crops – Just the science
http://www.gmwatch.org/gm-crops-research-documenting-the-limitations-risks-and-alternatives

Hope this helps!
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2.Extract from: 'GM crops – Just the science'
http://gmwatch.org/gm-crops-research-documenting-the-limitations-risks-and-alternatives

[NOTE: View this on the original web page to follow up the numbered references]

Do GM crops increase yield potential?

At best, GM crops have performed no better than their non-GM counterparts, with GM soya beans giving consistently lower yields for over a decade54. Controlled comparative field trials of GM/non-GM soya suggest that 50% of the drop in yield is due to the genetic disruptive effect of the GM transformation process55. Similarly, field tests of Bt insecticide-producing maize hybrids showed that they took longer to reach maturity and produced up to 12% lower yields than their non-GM counterpart56.

A US Department of Agriculture report confirms the poor yield performance of GM crops, saying, "GE crops available for commercial use do not increase the yield potential of a variety. In fact, yield may even decrease.... Perhaps the biggest issue raised by these results is how to explain the rapid adoption of GE crops when farm financial impacts appear to be mixed or even negative57."

The failure of GM to increase yield potential was emphasised in 2008 by the United Nations International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD) report58. This report on the future of farming, authored by 400 scientists and backed by 58 governments, stated that yields of GM crops were "highly variable" and in some cases, "yields declined". The report noted, "Assessment of the technology lags behind its development, information is anecdotal and contradictory, and uncertainty about possible benefits and damage is unavoidable."

Failure to Yield

The definitive study to date on GM crops and yield is "Failure to Yield: Evaluating the Performance of Genetically Engineered Crops". Published in 2009, the study is authored by former US EPA and Center for Food Safety scientist, Dr Doug Gurian-Sherman. It is based on published, peer-reviewed studies conducted by academic scientists and using adequate experimental controls.

In the study, Dr Gurian-Sherman distinguishes between intrinsic yield (also called potential yield), defined as the highest yield which can be achieved under ideal conditions, with operational yield, the yield achieved under normal field conditions when the farmer factors in crop reductions due to pests, drought, or other environmental stresses.

The study also distinguishes between effects on yield caused by conventional breeding methods and those caused by GM traits. It has become common for biotech companies to use conventional breeding and marker assisted breeding to produce higher-yielding crops and then finally to engineer in a gene for herbicide tolerance or insect resistance. In such cases, higher yields are not due to genetic engineering but to conventional breeding. "Failure to Yield" teases out these distinctions and analyses what contributions genetic engineering and conventional breeding make to increasing yield.

Based on studies on corn and soybeans, the two most commonly grown GM crops in the United States, the study concludes that genetically engineering herbicide-tolerant soybeans and herbicide-tolerant corn has not increased yields. Insect-resistant corn, meanwhile, has improved yields only marginally. The increase in yields for both crops over the last 13 years, the report finds, was largely due to traditional breeding or improvements in agricultural practices.

The author concludes: "commercial GE crops have made no inroads so far into raising the intrinsic or potential yield of any crop. By contrast, traditional breeding has been spectacularly successful in this regard; it can be solely credited with the intrinsic yield increases in the United States and other parts of the world that characterized the agriculture of the twentieth century."59

Critics of the study have objected that it does not use data from developing countries. The Union of Concerned Scientists responds that there are few peer-reviewed papers evaluating the yield contribution of GM crops in developing countries not enough to draw clear and reliable conclusions. However, the most widely grown food/feed crop in developing countries, herbicide-tolerant soybeans, offers some hints. Data from Argentina, which has grown more GM soybeans than any other developing country, suggest that yields for GM varieties are the same or lower than for conventional non-GE soybeans.60

"If we are going to make headway in combating hunger due to overpopulation and climate change, we will need to increase crop yields," says Dr Gurian-Sherman. "Traditional breeding outperforms genetic engineering hands down."61

If GM cannot improve intrinsic (potential) yield even in the affluent United States, where high-input, irrigated, heavily subsidized farming is the norm, it would seem irresponsible to assume that it would improve yields in the developing world, where increased food production is most needed. Initiatives promoting GM crops for the developing world are experimental and appear to be founded on expectations that are not consistent with data obtained in the West.

In the West, crop failure is often underwritten by governments, which bail out farmers with compensation. Such support systems are rare in the developing world. There, farmers may literally bet their farms and their entire livelihoods on a crop. Failure can have severe consequences.