Critique of: Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in Midwestern USA beef finishing systems, (2018) by Dr. Paige L. Stanley et al, Michigan State University

Canadian Cattlemen beef photo

Credit: Canadian Cattlemen

A number of recent research reports/reviews have concluded that, contrary to popular opinion, intensive feed-lot systems for finishing beef cattle result in lower greenhouse gas emissions per kg of beef carcass weight than grazing (“grass-fed”) systems (an example here). However, a recent paper from a group at Michigan State University found that, when the soil carbon sequestration benefit is included with a well-managed grazing system, the balance is reversed. Because of the dramatic nature of this finding and a long-term personal interest in soil carbon sequestration, I have reviewed their paper in detail. I conclude that their results are not realistic nor supported adequately by their research methodology.

Dr. Stanley et al describe research where beef pasture research fields in Michigan were converted from continuous grazing to managed-rotational grazing. After four years, they reported that the organic carbon (OM) content in the upper 30 cm of soil increased 40% from 34 to 48 tonnes/ha – or an average of 3.6 t/ha/year.

If it is assumed that soil organic matter is 58% carbon, this equates to an average OM addition of 6.2 t/ha/year. And if it’s assumed (generously, 2018 reference here) that about 25% of the organic matter (tops and roots), fixed by the forage crop during the four years after grazing, remains in the soil after the four years, this equates to about 25 t/ha/year of annual organic matter addition. Actual crop organic matter production must have been somewhat larger to account for the material removed and respired by grazing animals.

To put this in perspective, 25t/ha/year is about equivalent to the grain, stover, root and root exudates produced by a 190 bushel/acre corn crop, assuming grain represents 40% of total OM .

I don’t believe that this is credible.

So why the discrepancy? There is no suggestion that the authors fudged their data and no evidence for such, but here are some possible explanations.

Firstly, the authors give no accounting of how the manure produced in the non-grazing season was used – the manure coming from hay apparently purchased from off-station and used to feed cows and over-wintering calves. The authors state that no commercial fertilizer was used in this research so manure likely supplied the fertility need, especially for potassium for alfalfa (not clarified in the research description).  Manure addition would have also provided organic matter.

Secondly the authors measured the organic carbon content in the upper 30cm of soil at both the beginning and end of the four-year period, but apparently made no adjustment for possible changes in soil bulk density (g/cm3 of dry soil). A change in soil weight per volume could have affected the results – though very likely not nearly enough to trigger a 40% increase in measured soil OM.

Third, the authors appear to have only one valid replicate comparison for the change in soil organic matter content. They do present data for three sample locations but only one comparison involves the same soil type measured both before and after (i.e., a “sandy loam” soil).

The paper has some other weaknesses which cause concern. It’s essentially devoid of statistical analysis and most of the calculations are based on data from elsewhere including Michigan averages and global numbers provided by the International Panel on Climate Change or other sources. But yet the authors present their results to three (sometimes four) significant figures, implying unjustified precision. One significant-figure precision would be more appropriate.

In summarizing, this is not an attempt to attack the integrity of researchers or institution, or to understate the importance of the issue under consideration. However, I don’t believe that the results provide more than a hint that soil organic matter might be enhanced by well-managed grazing in a beef system; and this, in turn, could reduce the net greenhouse gas emissions in beef production.

Final note: I did try twice, without success, to contact the senior author before drafting the comments provided above.




What’s Your View on Mandatory Labelling of GM Foods? It depends so much on whether you have ‘Skin In The Game’

This column has two parts: The first discusses why the prospect of mandatory labelling of foods containing GM ingredients is viewed different if you are a farmer. The second is a critique of a research paper by Kolodinski and Lusk on public attitudes to short-term mandatory GM labelling in Vermont. Each is about 1200 words.

GLP Label GM Food

The on-going debate has heated again in North America about mandatory labelling of foods containing genetically modified/genetically engineered ingredients (also known as GM, GE and GMOs; the abbreviation GM will be used mostly in this column). That’s probably because of recent proposals made by the United States Department of Agriculture (USDA) on labelling options – a response to an earlier law mandating such passed by the American government on July 27, 2014.

The federal law was triggered by a similar law passed by the State of Vermont in 2014, becoming effective on July 1, 2016 – and a worry in Washington that other American states would also institute their own state-specific rules for mandatory labelling – effectively creating a nightmare for national food companies forced to comply with a potentially complex mess.

The federal law eliminated the right of states, including Vermont, to pass/implement their own labelling laws – but introduced a series of related debates on how to label, what to label, how to enforce  and more. The federal law gave USDA two years to develop the labelling specifics – and hence the proposals released recently.

That this is occurring at all is the result of a largely successful campaign by organizations opposed to genetically engineering in agriculture who have used a ‘right to know’ theme on labelling as an early step in attempting eliminate most/all genetically modified ingredients from the food system.

This is an approach which has worked very well for them in Europe where the combination of government requirements for mandatory labelling and anti-GM campaigning have essentially eliminated GM ingredients from foods in grocery stores. The one huge exception, of course, involves food products made from/by farm animals which are fed GM-based feeds; there is an inadequate supply of non-GM protein-rich feed available to European livestock farmers. And, despite the best efforts of anti-GM pressure groups, these products remain on grocery shelves – at least for now.

There is broad concern that what worked in Europe could also work in North America, meaning loss of the large benefits which GM have meant – both economic and environmental – for food and fibre production in the United States and Canada. Hence the strong opposition to mandatory labelling among many biotechnology companies, farmers and other biotech supporters in these countries.

While the strongest voices in support of mandatory GM labelling have come from anti-GM groups and commercial entities which will profit from GM-ingredient exclusions, support has also come from some individuals – commonly academics and journalists – generally known to be supportive of the use of GM technology in agriculture.

Their rationale is a belief that if/when mandatory GM labelling does occur, unlike in Europe, most North American consumers will adjust to this quickly; they will learn to ignore words on labels like ‘contains genetically engineered ingredients’ knowing that this has no significance to human health (the exception being ingredients deliberately engineered to improve health). Most of these proponents of mandatory labelling have been clear that their opinions are based not so much on solid research – for there is scarcely any – but rather intuitive feelings about human nature and experience with consumer whims.

To be fair on research, there is plenty of survey data. Jayson Lusk and his colleagues, former at Oklahoma State University, now at Purdue University, have done monthly surveys of consumer attitudes to many things including GM labelling. A late June 2018 survey report from the International Food Information Council Foundation (an industry-funded group) found 47% of Americans avoid foods known to be genetically engineered and, further, that “uncertainty about which foods are genetically modified is the primary reason for not avoiding [GE] foods.”

However, what consumers tell surveyors is often very different from what they do in practice. See, for example, this review by Alexander Stein of the EU Commission, “Acceptance of ‘GM food’ in Europe: What people say and do.”

Stein includes this graphic:


Pro-mandatory-labelling advocates know this discrepancy well, and their position seems more instinctive. If I can generalize, it’s “Other approaches aren’t solving the problem – i.e., lack of broad consumer/support for GM products – so why not try mandatory labels? Let’s give it a shot.”

Very apparent, at least to me, is the fact that virtually none of those professionals advocating labelling actually grows farm crops – GM or not – to provide for family income. Few if any know the ‘joy’ of harvesting corn-borer-damaged, lodged corn or of filling insecticide boxes on planters – or of deciding which herbicide to use on weed escapes in a non-GM crop knowing that every choice is likely to work only partly, or cause crop damage, and will cost hundreds (more likely thousands) of dollars to apply. None of them have kids whose attendance at summer camps depends on protecting crop yields and quality from pest damage, and the cost of doing so.

If mandatory labelling means loss of markets for GM crops as ‘right to know’ proponents intend, the consequences for farmers will be far bigger than an “Oops, guess I was wrong.”

(Yes, I recognize that farmers growing GM-free ‘identity preserved’ crops receive premiums for their efforts, but that was not the case in pre-GM days, nor will it be again if the GM option is withdrawn.)

To use the vernacular, farmers have ‘skin in the game.’ Well-meaning academics and journalists don’t. In my view that makes a big difference.

As one of those farmers, I have no idea whether mandatory GE labelling will work or not. But in the absence of good clear evidence for the former, I need more than “let’s give it a shot.” I also support credible voices who say food labelling should be reserved for meaningful information on health and nutrition – and not the scare tactics of albeit-very-strong voices of the anti-GMO crowd.

Please note that this is not a blanket condemnation of top researchers and quality journalists – but rather a difference in viewpoint on one – albeit very significant – issue.

An additional reason for caution involves the key question of what, actually is a GM or genetically modified/engineered crop, animal or food (or ‘biologically engineered’ to use the USDA’s apparent wording preference)?

Nathanel Johnston addressed this well in his classic, It’s practically impossible to define ‘GMOs’ . Pro-biotech labelling proponents generally have something far less comprehensive in mind than many activists. And a quick check of postings on Twitter shows that the food industry is all over the map on what’s to be in and what’s not.

Anyone who thinks the noise will down once mandatory labelling is in place is naive in my view. It simply shifts from ‘whether’ to ‘what’ – not to mention the real reason for the activists’ campaign: elimination.

Another concern stems from a discussion by Mark Lynas in his great new book, Seeds of Science. He describes how, in earlier days of seeking public assurance of precautions being taken by biotech researchers, technicians allowed themselves to be photographed in attire resembling space suits. Casually dressed photographers a few feet away obligingly conveyed the message to the rest of the world: ‘GMOs must be dangerous if research workers need to dress like that.’

Lynas states, “It was a classic example of how precautionary regulations aimed at reassuring the public can have the opposite effect.”

Precautions inherent in the Cartagena Accord for introducing GM crops into the developing world have served – intentionally or inadvertently – to inform people in those countries that GM crops represent special danger – unlike all other methods for genetic improvement.

That brings me to a June 2018 paper by Kolodinski and Lusk, entitled Mandatory labels can improve attitudes toward genetically engineered food. It purports to show that the introduction of mandatory labelling of GM-containing foods in Vermont led to a “19% reduction in opposition to GE foods.” Given that this paper has received international attention and has been cited several times as proof that the labelling approach works to quell public concern, I’ve discussed it in some detail, below.

The research involved telephone survey opinions of Vermont residents on five dates between March 2014, about the time the Vermont legislation was passed, and March 2017, well after the date of enactment of the Vermont law in mid 2016 and it’s negation by a federal law four weeks later. Those surveyed were asked to give a 1 to 5 answer to the question, “Overall, do you strongly support, somewhat support, have no opinion, somewhat oppose, or strongly oppose the use of GMOs in the food supply?” The authors compare results from this survey to a US national on-line survey repeated on about the same dates with the question: “How concerned are you that the following pose a health hazard in the food that you eat in the next two weeks?” The authors attempt to equate the two surveys, using the differential between two-survey results on the five different dates to judge relative attitudes in Vermont compared to those nationally. But in truth, the comparison is very weak given the very different nature of the two questions and survey methods – and the authors do acknowledge that somewhat.

The authors use several different statistical models for analysis but all methods essentially divide the survey results into two time categories – three surveys completed before July 1, 2016 versus two after – with the assumption being that the existence of labelled food in grocery stores beginning July 2016 was the dominant factor in influencing/changing public attitudes.

This assumption, in turn, is based on a more basic assumption/statement that, to use their words, “there were no accompanying campaigns by pro- or anti-labeling groups designed to sway voter’s attitudes toward GE.”

But knowledge of the political system says this is highly unlikely. Almost every high-profile government law is implemented after lots of lobbying by interested groups and public campaigns – based on the knowledge that politicians mostly do what public pressure tells them to do. That would seem especially true for a highly charged issue like GM labelling. Remember that the legislative debate in Vermont followed high-profile public plebiscites on mandatory labelling in California and Washington State.

Indeed, a Google check tells us that the authors’ statement and assumption is clearly false. Take a minute to check this web site by a group called VT Right to Know GMOs listing many dozens of public events/rallies dating back to 2012. Even Vandana Shiva spoke to pro-labelling rallies in Vermont .

A related web site demonstrates the local and national media frenzy which existed in 2014 as the Vermont bill was being debated/approved.

An intriguing fact about the VT Right to Know web site is that all of its entries cease after August 4, 2016. Up until that date there are massive postings, one or more per week. After that date, total silence. It’s as if this activist group closed up shop and moved elsewhere – maybe back to the USRTK home base in Oakland, California.

When I tried a Google media search for the year 2017 with the words ‘Vermont’ and ‘GMO’ or ‘genetic engineering,’ I came up with almost nothing.

Of course, this fits a narrative that once mandatory labelling is in place, everything quietens down and the anti-GM folks are satisfied. A more likely explanation, at least to me, is that given the shift of national focus away from Vermont, why would any mainstream national NGO spent time in a tiny state with slightly over 600,000 residents (about 0.2% of the US)?

But is this really what we could expect on a larger national scale? Why would anti-GM folks stop with mandatory labels when their stated goal is much larger?

I don’t live in Vermont but my guess is that there was huge public attention peaking in 2014 and that it was maintained as the state and nation watched to see if court challenges by major biotech companies on the legitimacy of the Vermont law were successful. (They weren’t but this process continued until September 2016.) After that, as noted above, all GM-related attention left Vermont.

A final question is the extent to which food products were actually labelled during that window between July 1 2016, when the Vermont law came into force, and July 27, when negated by US statute. Kolodinsky and Lusk are vague on that matter.

Not finding much on the web, I contacted my friend Dr. Mary Mangan (@mem_somerville) in Boston and she provided this report. (Thanks also to .) While totally anecdotal it does describe the 3-6 month phase-in which Vermont grocery retailers had after July 1, 2016 for compliance. Vermont shoppers were obviously exposed to some GM food labelling but we may never know how much.

And that brings us back to the Kolodinsky and Lusk data. They show these average survey ratings in Vermont for the five dates, with a ‘5’ meaning strongly oppose GMOs, a ‘1’ meaning strongly support and a ‘3’ meaning neutral.

Survey date
March 2014 March 2015 March 2016 Nov 2016 March 2017
Average rating 3.714 3.775 4.012 3.474 3.715
Standard deviation 1.007 1.0337 1.183 1.367 1.159


The most intriguing result for me – i.e., beyond the statistical reality that all survey numbers are the same – is that the level of concern at the beginning and end of the three-year survey period was identical, 3.71.

Personally, I might have expected greater concern in March 2014 given that this coincided with the legislative vote, local media hype, and related VT Right to Know efforts.  It may have taken some time for the sustained frenzy to trigger greater public concern; hence, higher values in 2015 and early 2016. The drop in Nov 2016 might have represented a local view that the ‘problem is solved’ and the fact that USRTK had left the state. But why is there such a rebound in public concern from Nov 2016 to March 2017? That rebound is ignored in the authors’ discussion.

(At the risk of adding complexity, I note the authors make much of differences in average scores between the Vermont and national surveys on the five dates. While, personally skeptical about the validity of this, I do note in their data that the national average score descended from 3.360 in Nov 2016 to 3.188 in March 2017, even as the Vermont score rose. Whatever happened in Vermont was probably local.)

So what do we learn from this paper about the experience in Vermont. My impression is not very much. And this is before considering that the definition of GM used in the Vermont legislation was tailored to provide key exemptions to accommodate special state interests, notably dairying – a taste of what lies ahead as special interests lobby in Washington to have their interests addressed in whatever emerges as the national standard.

I suppose the study served a useful purpose for those looking for support for their prior opinion that mandatory labelling is the way to go. For farmers with major concerns about the risks to personal income and family wellbeing, the doubts remain as big as ever.