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Sat Nov 21, 2020, 03:21 PM

Climate and Health Effects of Conventional and Rotational Crop Practices in Iowa.

(Note: This post, and many of my earlier posts in this space, contains some graphics which may not be accessible to Chrome users because of a recent upgrade to that browser, but should work in Firefox and Microsoft Edge. When my son has time, he will adjust the file system for a website he's building for me to make these graphics usable in Chrome, but he seldom has that much time on his hands. Interested parties, should they exist, can still read my posts including the graphics, but regrettably must use a browser other than Chrome. Apologies - NNadir)

The paper I'll discuss in this post is this one: Fossil Energy Use, Climate Change Impacts, and Air Quality-Related Human Health Damages of Conventional and Diversified Cropping Systems in Iowa, USA (Natalie D. Hunt,* Matt Liebman, Sumil K. Thakrar, and Jason D. Hill, Environ. Sci. Technol. 2020, 54, 18, 11002–11014)

From 2002 until 2014, the Editor of Environ. Sci. Technol. was Jerald L. Schnoor, a Professor of Civil and Environmental Engineering at Iowa State University. I have long been a dedicated reader of this journal for decades, and became highly disciplined about how I read it about 12 years ago. Shortly after turning his editorial responsibilities at the journal, Dr. Schnoor came to speak at Princeton University, and as someone who appreciated his efforts at the journal, I made a point of attending the lecture. I don't recall the details of his talk all that well - he is an expert on water use - but I do remember his remark on how appreciative he is that he has tenure, since his research on water use was not in general consistent with unabashed praise for the corn industry.

Many years ago, when I was writing over in the E&E forum on this website, there was a person there who used to write all the time about how wonderful corn ethanol was as an automotive fuel. Ethanol, which was one of the first of the "renewable energy" schemes to become widely embraced, was a Carter era program for addressing the oil shocks of the 1970's. This scheme, which is still in force today, and is probably the most prominent Carter era policies to have survived since his Presidency, led to the destruction of the Mississippi Delta ecosystem, a point, if I recall correctly, Dr. Schnoor addressed in his lecture at Princeton.

Jimmy Carter is clearly a wonderful human being, and interestingly, is the only US President to have participated in a nuclear accident clean up, one of the Chalk River Nuclear Accidents, in the 1950's. As President, much to the chagrin of the Secret Service, he toured the Three Mile Island Reactor after it melted down during his administration.

He is, famously, still alive, well into his 90's. All of his younger siblings are dead, all three of them having succumbed to pancreatic cancer, two in their 50's, one in her 70's. Former President Carter is, again, still quite alive and still doing wonderful things, like planting trees on his farm, one of which was cut down recently and rendered into a very beautiful guitar. The guitar represents carbon that has been removed from the atmosphere and sequestered. A few hundred billion guitars like that and we can sequester as much carbon as we will release this year even as we live in the so called "Renewable Energy Era."

Jimmy Carter's energy policies as President were basically anti-nuclear and favored so called "Renewable Energy." I voted for Jimmy Carter for President twice, and I certainly don't regret doing so. This said I consider his decision to forego nuclear fuel reprocessing and thus offer up a Christian "moral example" for the world, to have been a tragedy, perhaps mitigated that nuclear fuel reprocessing technology in his time as President was a relatively primitive, and relied on the silly use of nuclear "waste" dumps.

Jimmy Carter's energy policies are often praised on the left, but even as I am clearly a leftist in most ways, I consider his energy policies to have been terrible.

The idea of constructing so called "Nuclear waste" dumps is still, inexplicably, popularly represented as a "solution" to the "problem" of the "waste" problem, which I find amazing, since there are zero components of used nuclear fuels that are not potentially useful, some of which are incredibly useful and surely represent materials that can solve environmental problems that are otherwise intractable. It is, I think, therefore a good thing that such dumps were never constructed, and if Jimmy Carter's policies slowed the process of building them down, this is an unintended positive result. The usefulness of used nuclear fuels includes addressing environmental problems other than climate change, notably persistent chemical pollutants, although the only tool capable of addressing the vastly larger scale problem of climate change is, whether it is generally recognized or not, nuclear energy.

The ever popular so called "renewable energy" did not work to address climate change; it is not working to do so; and it will not work to do so. The reason is connected with the physics of energy, specifically the energy to mass ratio and the thermodynamic (and thus environmental) and economic superiority of continuous and predictable processes.

The laws of physics are not subject to reversal by political positions, including those driven by wishful thinking.

Since the Carter administration, the more or less general policy of the Democratic Party - my party, for which I vote 100% of the time - has been consistent with Carter policies and inconsistent with policies with the potential to save a dying planet. We once produced the most anti-nuclear candidate for President ever to run for the office, Michael Dukakis. Although my own views in the 1970's were more or less entirely consistent with Carter policies, by the late 1980's I had changed my mind, and I had to do one of those "hold my nose" things in voting for Michael Dukakis for President, but I voted for him anyway.

Not all of our Democratic Party's nuclear policies have been terrible. In the 1990's Vice President Al Gore negotiated an agreement with the pre-Putin Russians to purchase highly enriched uranium removed from Russian nuclear weapons, which was blended down with depleted uranium and consumed in nuclear reactors, saving hundreds of thousands of lives that would have otherwise have been lost to air pollution, as well as reducing, albeit moderately, the threat of nuclear war. I greatly approved of this "Sword to Ploughshares" policy, although regrettably, it did not address what I regard as the critical element in any effort to minimize the worst of climate change, plutonium. While I regretted the Clinton Administration's cancellation of the IFR, it occurs to me now that many superior breeder technologies have evolved since then, notably the advanced "breed and burn" concepts represented by many advanced designs. (I don't like liquid sodium cooled reactors, although I am very fond of other types of liquid metal reactors.)

The problem with nuclear energy - besides the very stupid selective attention of journalists from the New York Times on down - is probably connected with scaling up too quickly. (The great energy thinker Vaclav Smil as made this point.) Even so, the rapidly scaled and engineered reactors based on 1950's and 1960's technology - produced in a Golden Age of American science and engineering - did a remarkable job of producing energy with extremely low environmental and health costs in comparison to all other technologies. Nevertheless the restraint placed on nuclear technology has not entirely been a loss although tremendous damage has been done. We might have done much better, but we can recover. It is technically feasible, I think, to seriously address climate change, and - while considerably more difficult - even to reverse it to a limited extent. This would involve, however, waking up. There has never been a better time than 2020 to do just that, to wake up.

Anyway...about the paper...and about corn...

The corn ethanol debacle was the first indication to me that so called "renewable energy" was not all it was cracked up to be, that a law of unintended consequences might apply.

From the introduction to the paper:

The intensification of modern conventional agriculture has been effective at increasing crop yields, yet it has come at great cost to the environment and human health from fossil energy consumption and generation of emissions that contribute to climate change and reduced air quality. In 2014, United States agriculture comprised 1.7% of US primary energy consumption and in 2017, comprised 8.4% of total greenhouse gas (GHG) emissions,(1,2) driven by carbon dioxide (CO2) emissions from soil carbon loss and fossil fuel use, nitrous oxide (N2O) from nitrogenous fertilizer use, and methane (CH4) from ruminant livestock production.(3) Increased concentrations of GHGs in the atmosphere cost society via harm to human health, property damage due to floods, and losses in agricultural productivity.(4)

Agriculture is also a major contributor to atmospheric fine particulate matter (PM2.5) via the production and application of farming inputs and field operations.(5) PM2.5, which adversely affects air quality and human health, is either emitted directly as a product of combustion or as dust (primary PM2.5), or forms in the atmosphere (secondary PM2.5) from reactions among ammonia (NH3), nitrogen oxides (NOx), sulfur oxides (SOx), and volatile organic compounds (VOC).(6,7) Due to its small size, PM2.5 can enter the lungs and bloodstream, leading to health effects that include chronic obstructive pulmonary disease, acute lower respiratory illness, ischemic heart disease, and lung cancer.(8) Chronic exposure to PM2.5 generates societal costs via increased risk of premature death.(8,9) In the US, emissions of agricultural NH3 are the dominant driver of PM2.5-emissions related damages, which derive largely from fertilizer application and storage and application of manure. Emissions of PM2.5 also result from diesel fuel production, herbicide production, dust from field operations, and fossil fuel combustion by farm machinery.(5,7,8,10,11) Recent research has shown, for example, that PM2.5 from maize production in the US is responsible for 4300 premature deaths annually.(5)

Overall, increasing energy and resource efficiency while reducing environmental impacts is an important goal for improving the sustainability of agricultural systems. Because agricultural systems are vulnerable to energy price fluctuations, reducing reliance on fossil energy can reduce farm financial volatility and increase profitability, while decreasing fossil energy-related environmental damages. Additional strategies to mitigate GHG emissions from cropping systems include improving fertilizer and manure management, maintaining below- and above-ground soil carbon, and reducing reliance on synthetic inputs.(12) Methods for reducing PM2.5-related emissions and resulting human health impacts include substitution of high NH3-emitting fertilizers with lower ones, using precision agricultural techniques, and selecting crops requiring less nitrogen fertilizer.(5,10,13)

Strategies for simultaneously reducing multiple environmental impacts are especially of interest. Among these is the diversification of conventional corn-soybean cropping systems, which has been shown to deliver several agronomic and environmental benefits, including increased per-hectare corn and soybean productivity, greater resilience to weed and pest infestations, and reduced dependence on synthetic herbicides.(14−17) Diversified cropping systems can also have reduced rates of soil erosion and nutrient discharge to the environment,(15) lower freshwater toxicity loads(14) and enhanced soil functioning.(18−21) The fossil energy use, climate change, and air quality implications of such strategies have not been widely explored.

This study examines the cradle to farm-gate fossil energy consumption, and climate change and air quality damages of three cropping systems differing in levels of crop diversity...


The authors conducted their research at the Iowa State University's Marsden Farm in Boone County, IA, and as it involved modification of crop procedures with each modification requiring a year's growth season, the experiment has been on going since 2002, eighteen years. The author's utilized a two, three and four crop rotation scheme. The two year corn/soybean cycle with Haber (industrial synthetic) fixed nitrogen in the form of ammonium nitrate (which, unlike plutonium, has been involved in diversion for terrorist purposes leading to large losses of life) and urea. This nitrogen is largely obtained using chemistry driven by either dangerous natural gas or dangerous coal. The three year crop rotation scheme involved corn-oat/soybean/red clover rotations. The four year rotation scheme was a corn-oat/soybean/alfalfa/alfalfa system.

Two herbicide application schemes were explored, the conventional (CONV in the graphics below) and Low (LOW in the graphics below) approaches.


The system boundaries are shown in the following figure:



The caption:

Figure 1. Flowchart of system boundaries, system outputs, and impacts.


The tracking of particulate matter (PM), and emissions of greenhouse gases (including nitrous oxide and methane), and the consumption of dangerous fossil fuels were all followed by using the GREET (The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) tool for life cycle analysis. Tractors were propelled by diesel engines.

Additional work included a consideration of dust as a generator of particulate matter. The particulate matter is the chief culprit, apparently, in the 4300 deaths occurring each year from farm related air pollution, a surprisingly large number, albeit much smaller than the six to seven million deaths reported to occur each year from combustion of dangerous fossil fossil fuels and "renewable" biomass. The death toll associated with the release of radioactive materials by the much, in fact, endlessly discussed, destroyed reactors at Fukushima is vanishingly small when compared to these two figures.

Phosphorous - although depletion of its ores is a very, very, very serious matter for future generations - and potassium were not considered in this study.

Ammonia is not tracked in the GREET system and was tracked using a different approach. (The release of ammonia is one of the prime drivers, along with phosphorous, of the destruction of the Mississippi River Delta ecosystem.)

On the subject of economic damages the authors write:

Damages from emissions of GHG were monetized using the social cost of carbon (SCC), which considers damages to human health, property due to flood risk changes, and impacts to agricultural productivity as a result of climate change.(4) In this study, we applied a SCC of $43 Mg–1 of CO2e emissions (2017 dollars, with 3% discount rate).(4) Human health damages as a result of chronic exposure to primary and secondary PM2.5 were monetized using the United States Environmental Protection Agency (EPA) mortality risk valuation or value of statistical life (VSL). VSL assigns monetary value to an individual’s avoided risk of mortality due to exposure to environmental pollution, so as to facilitate the comparison and aggregation of overall social costs.(9,46−48) Here, we used a VSL estimate of $9.1 M per life (2017 dollars, with 3% discount rate) and multiplied it by the number of premature deaths per gram of air pollutant emitted.(49)


It sounds a little cold-blooded to me, but $9.1M per life seems reasonable, particularly because lives lost by pollution generally involve rather expensive medical treatments on the way out the door, which matter, although not quite as much as the economic productivity lost when the investment in a life results in a shorter productive span. Again, it's cold-blooded, but reasonable all the same.

Some graphical results:



The caption:

Figure 2. Mean annual fossil energy consumption (a) as affected by contrasting rotation systems and herbicide regimes across system components of diesel, seed, N fertilizer, and herbicide production, field operations, and grain drying and (b) as normalized by annual harvested dry commercial crop yields, including corn, soybean, oat grain and straw, and alfalfa. Error bars indicate one standard error of the annual mean annual total energy consumption.




The caption:

Figure 3. Mean annual GHG emissions (a) as affected by contrasting rotation systems and herbicide regimes across system components of diesel, N fertilizer, and herbicide production, field operations, N application, and grain drying and (b) as expressed in GHG emission species. Error bars indicate one standard error of the annual mean total emissions.




The caption:

Figure 4. Mean annual emissions of (a) primary PM2.5 and secondary PM2.5 precursors of (b) NH3, (c) NOx, (d) SOx, and (e) VOC by rotation system and herbicide regime across system components of diesel, N fertilizer production, herbicide production, fugitive dust, field operations, N application, and grain drying. Error bars indicate one standard error of the annual mean total emissions. The legend provided in panel b describes all panels.




The caption:

Figure 5. Mean annual damages from GHG emissions (a) as affected by contrasting rotation systems and herbicide regimes across system components of diesel, N fertilizer, and herbicide production, fugitive dust, field operations, N application, and grain drying and (b) as expressed in GHG species. Error bars indicate one standard error of the annual mean total economic damages.




The caption:

Figure 6. Mean annual economic damages from PM2.5-related emissions (a) as affected by contrasting rotation systems and herbicide regimes across system components of diesel, N fertilizer, and herbicide production, field operations, N application, fugitive dust, and grain drying and (b) as expressed in emissions species. Error bars indicate one standard error of the annual mean total economic damages.




The caption:

Figure 7. Mean annual combined economic damages from GHG and PM2.5-related emissions (a) as affected by contrasting rotation systems and herbicide regimes across system components of diesel, N fertilizer, and herbicide production, field operations, N application, fugitive dust, and grain drying and (b) as expressed by type of economic damage. Error bars indicate one standard error of annual mean total economic damages.


Tables from the paper:








Some remarks from the discussion/conclusion:

...The potential for scaling up such diversified cropping systems could have significant impacts on existing markets, including potential shifts in supply and demand for corn and soybean amidst newly introduced small grain and forage crops. Large-scale shifts to more small grains and forages could constrain domestic corn production, resulting in increased corn prices whereby farmers become incentivized to revert to growing previous corn-soybean rotations. Concurrently, potential expanded production of small grains and forages could result in reduced prices, again, incentivizing farmers to revert back to growing corn and soybean. Nonetheless, economic analyses of such scenarios found that scaling up diversified systems to 20–40% of arable cropland in Iowa (2–4 million ha) could occur without generating price incentives favoring existing corn and soybean rotations.(22)


Here, we estimated changes in the damages associated with GHG and PM2.5-related emissions as a result of implementing diversified cropping systems and an alternative herbicide regime. More diverse cropping systems that include recycled manure and biological nitrogen fixation by forage legumes, such as the 3- and 4-year rotation systems studied here, may not only require less fossil energy but also generate less GHG and PM2.5-related emissions, while maintaining primary agronomic functions. This will be a priority in agriculture in the face of a changing climate and a growing and increasingly affluent global population. Incorporation of a diverse suite of practices and inputs will aid in maintaining systems that are weed-suppressive, productive, profitable, and protective of environmental quality and human health. As shown in the present study, increased reliance on ecological processes and thereby reduced reliance on synthetic inputs can maintain agronomic functions and decrease environmental damage.


I am a critic of biofuels as practiced now, which rely essentially on batch process water and energy intensive fermentation/distillation schemes. This said, agriculture, an essential human activity for meeting human development goals (which I believe to be potentially coterminous with environmental goals in a nuclear powered world), does represent a path for the removal of carbon dioxide from the air. Much has been made of corn stover and other chaff as a potential carbon source, regrettably again in an enzymatic fermentation setting. Another alternative however is reforming using high temperature supercritical water or - in so called "dry reforming" - supercritical high temperature carbon dioxide as an oxidant. Both cases give access to hydrogen carbon oxide mixtures known as "syn gas," and thus to sustainable fuels for tractors and other requisite mobile systems. It is well understood that diesel engines, in particular, are amenable to running on the wonder fuel dimethyl ether, for which many routes from syn gas. Dimethyl ether has an atmospheric lifetime of about 5 days, and thus cannot be considered a greenhouse gas, in contrast to methane, ethane, propane and butane. Syn gas can basically be utilized to replace all applications for dangerous petroleum (including utilization in the chemical industry) and all applications for dangerous natural gas. In fact, carbon monoxide, via the Boudouard Equilibrium, can realize combustion in reverse, one can make carbon from carbon monoxide, and carbon monoxide from carbon dioxide.

All that is required is heat, which is readily available from nuclear sources.

I trust you are safe and well, and that you will be able to enjoy the upcoming holiday in a safe and yet enjoyable way.

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