Category Archives: Blog

Non-toxic yesterday, but toxic today

In the 1940s a group of competent toxicologists led by William B. Deichmann conducted a number of thorough studies using state-of-the-art methods to conclude that the active ingredient dichloro-diphenyl-trichloroethane, or DDT, could be safely released to the environment for its use as insecticide. DDT was one of the first wide spread synthetic pesticides, and its widespread use led to resistance in many insect species.

ddt-good-for-me  ddt-recommended ddt-uses

As can be seen in the pictures, DDT was promoted to be used as insect repellent directly on human skin, to treat food products, or to impregnate the wall paper of your children’s room, so they won’t be bothered by mosquitoes. Tender images, such as a mother feeding a baby were used in commercial campaigns to basically sell poison. (*)

In the early 1970s, a scientific article authored by Deichmann (1972) himself and other studies provided enough evidence for the US Environmental Protection Agency to finally forbid the use of DDT as it became known to be toxic to humans, persistent in the environment, travel long distances in the upper atmosphere, and accumulate in fatty tissues of living organisms.


Rising evidence

What did actually happen between the 1940s and the 1970s? Why was DDT first considered innocuous or degradable and 30 years later banned and labelled as poisonous for humans, wildlife and the environment?There are several possible answers to these questions.

In the fist place, the ecotoxicity of certain chemicals when applied in small doses may only appear through cumulative effects (cf. Time is needed for problems to arise, or to become evident.

Second, and most importantly, the capacity of science to detect the adverse effects of a certain molecule released to the environment can progress substantially in 30 years.Problems that were overlooked or remained undetected in the past could be later on well understood and documented. (And the amount of scientific evidence that needs to be accumulated to be able to bend the arm of the chemical industry in court cases is not a minor detail).

The most skeptical opinions, in the third place, would argue that DDT was banned once the patent for exclusive production expired, and /or when the industry was ready to release a new product on the market. But these are just speculations.

Take home!

What’s important to take home is that examples such as this one should teach us about the long-term risk (uncertainty) associated with the widespread release of toxins into the environment, either as synthetic molecules or through toxin-producing plants (e.g., Cheeke et al., 2012). Alarming ideas such as the commercial release of genetically engineered microorganisms for soil amendment have been underway for a while (e.g. Viebahn et al., 2009), with unknown consequences for soils and the environment.

When it comes to releasing new technologies for food and agricultural production, I’d say it makes sense to follow precautionary principles. Releasing toxins into the environment: another case of organised irresponsibility…


(*) I believe that, nowadays, the baby in the early campaigns of DDT has been replaced by the term ‘sustainability’, which is also used in commercials and websites that advertise poison or toxin-producing plants.


Cheeke, T.E., Todd N. Rosenstiel, and Mitchell B. Cruzan. 2012. Evidence of reduced arbuscular mycorrhizal fungal colonization in multiple lines of Bt maize. American Journal of Botany 99, 700-707. DOI: 10.3732/ajb.1100529

Deichman, W.B., 1972. The debate on DDT. Arch. Toxikol. 29 (Springer), 1 – 27.

Viebahn, M., Smit, E., Glandorf, D.C.M., Wernars, K., Bakker, P.A.H.M., 2009. Effect of genetically modified bacteria on ecosystems and their potential benefits for bioremediation and biocontrol of plant diseases – a review. E. Lichtfouse (ed.) Sustainable Agriculture Reviews 2, Springer, p.45. doi 10.1007/978-90-481-2716-0_4.

Green, sustainable, smart or ecological?

The increasing recognition that current agriculture is unsustainable, responsible for the loss of biodiversity and habitats, for the rapid exhaustion of non-renewable resources, and for serious impacts on the climate, the environment and people’s health, leads to the continuous emergence of neologisms to express the need for a new global agricultural model. Examples of these include:

  • Sustainable intensification
  • Ecological intensification
  • Agroecological intensification
  • Climate smart agriculture
  • Evergreen agriculture
  • Eco-efficient agriculture
  • Conservation agriculture
  • Biodiverse farming (Kremen et al)

These terms have many things in common, yet the nuances are not minor. Their definitions do share concepts, terms and intensions, but the political discourses and political actors (in science, development and business) associated with their use differ markedly.

Sustainable vs. ecological

In 2014 I published a paper where I reflected upon the uses of the terms sustainable versus ecological intensification. Who uses each term, in which context, and what for? Multinational seed and agrochemical companies, as well as the fertiliser industry or the biotechnology sector adopted sustainable intensification (and sustainability in general) as an umbrella term in their commercial campaigns. The same holds for the international development sector such as the Consultative Group on International Agricultural Research (CGIAR), the Food and Agriculture Organisation of the United Nations (FAO), the World Economic Forum (Davos, 2012), the Montpellier Panel (2013) or the Sustainable Development Solutions Network (SDSN, 2013), and by national policies such as the ‘Feed the Future’ programme of the US Government.

Sustainability is a soft concept, as opposed to a hard one, and thus its definition depends on who defines it, when and in what context. In that paper I noted: (i) that as long as the term sustainability remains vague, ambiguous and poorly defined then any form of agricultural intensification may in principle be portrayed as ‘sustainable’; (ii) that ecological intensification was a better suited term, as it implies an intensive use of the natural functionalities that ecosystems offer, by promoting ecological processes through landscape design. Instead of opposing agriculture and nature, the idea is to integrate both in order to improve agricultural production. Ecological intensification would be then sustainable in its nature, as well as sustained by nature.

What is intensification?

In economics, intensification is a term used to refer to the replacement of one factor (or input) for another one in order to increase efficiency. I use the term ecological intensification to refer to the replacement of inputs by ecological processes in order to increase resource use efficiency. Biodiversity in agricultural landscapes plays a major role at fostering such ecological processes. Ecological intensification describes a transition, a pathway, from current unsustainable agriculture to agroecological landscapes and sustainable food systems. This pathway may describe gradual changes or ruptures, depending on both the starting point and the final aim, as well as on the social-ecological context in which the agroecosystem operates.

How about agroecology?

During the last Latin American Congress on Agroecology organised by SOCLA, bringing together four thousand participants in La Plata, Argentina I was invited to debate with Miguel Altieri on agroecology vs. ecological intensification. The audience was surprised to discover that our respective presentations pointed in the same direction, did not contradict one another, and were complementary in terms of concepts and examples. This is not surprising because, after all, I am… an agroecologist!

afiche congreso

I see agroecology as the scientific discipline necessary to contribute to understand, evaluate and design ecologically intensive landscapes. Agroecology brings in the necessary knowledge and tools to support the above-referred transition, a transition that I call ecological intensification. Yet I understand Miguel’s and SOCLA’s derogatory position regarding the use of terms such as ecological or sustainable intensification. There is risk of creating confusion by using different terms to refer to the same ideas. After all, as Miguel often says, since the emergence of agroecology the term (and the movement!) has been first ignored, then attacked, and now is being co-opted.

Sustainable Intensification strikes back

Recently, the South American regional consortium of agricultural ministries known as PROCISUR adopted Sustainable Intensification (SI) as one of its strategic pillars to contribute to regional development. Guess what? In my new position, I was invited as focal point to represent Argentina at the regional round table on SI. Just when I thought the debate was over, I was confronted again with the discussion on what is sustainable and what not, what is intensification, and whether intensification can ever be considered sustainable, etc. etc. This time, however, and given the fact that the mandate came from our ministries, not just from my own country but also from neighbouring countries where I have little chance to influence ministerial policies, I decided to take a more pragmatic approach.

We already know what intensification means and, in the eye of a minister of agriculture, if it brings about added value and employment generation in rural areas then it is most welcome. But if we are going to talk about sustainable intensification, let us first define what we mean by sustainability. One way to start is to consider the planetary boundaries (see Figure). For any agricultural model to be considered sustainable it must allow us to stay within a safe operating space in our earth system, considering these nine global indicators, and propend towards social equity while safeguarding cultural diversity and values. Unfortunately that’s not the case at the moment. We’ve already crossed some critical boundaries, and agriculture is largely responsible for that.

Planetary boundaries

To transition towards sustainability, our agricultural research for development efforts should contribute to:

1. Reduce the dependence of agriculture on non-renewable resources
2. Reduce its impacts on the environment and nature (soil, water, air, organisms, genomes)
3. Restore the productive capacity of degraded soils
4. Reduce the current expansion of the agricultural frontier onto marginal and/or biodiversity rich areas
5. Maximise resource use efficiency through the optimisation of ecological processes
6. Adapt to and contribute to mitigate climate change
7. Promote the necessary technological and organisational innovations
8. Design compatible value chains and guarantee systems
9. Offer opportunities for farming families to remain in rural areas
10. Align the agricultural agenda with the UN Sustainable Development Goals

If we can agree on this Decalogue as a minimum set of goals to achieve sustainable intensification – or, by the same token, climate smart or ecoefficient agriculture – then we can move away from pompous terms and endless debates about multiple possible paradigms. Then, irrespective of the term chosen, we will be able to generate new narratives and political messages to foster the much-needed change. But once again, I hope I do not upset anyone by saying that it is hard to imagine how such transition could be accomplished, how these ten goals could be achieved, without the insights from and the practice of agroecology.

Feeding the world with soil science?

The open-source journal SOIL of the European Geosciences Union is not just open source but also interactive. After a ‘traditional’ peer-review process is completed, scientific papers are posted on-line for the wider community to react to and comment on them. I was invited to contribute a piece about the contribution of soil science to achieving the UN Sustainable Development Goal 2 (SDG2): End hunger, achieve food security and improved nutrition and promote sustainable agriculture.  Euphemistically, the paper is entitled: Feeding the world with soil science: embracing sustainability, complexity and uncertainty. You are most welcome to have a look at it and leave your comments, questions and suggestions.

The paper revolves around the idea that feeding a growing and wealthier population, while providing other ecosystem services and meeting social and environmental goals, poses serious challenges to soil scientists of the 21st Century. In particular, three dimensions inherent to agricultural systems shape the current paradigm under which science has to contribute knowledge and innovations: sustainability, complexity and uncertainty. The current model of agricultural production, which is also often the source of inspiration to propose solutions for future challenges, fails at internalising these dimensions. It simply does not provide the necessary means to address sustainability, complexity or uncertainties. Part of the problem is that these are soft concepts, as opposed to hard goals, and so their definition and their translation into concrete actions is always subjective. In my view, in order to propose viable solutions to reach SDG2 soil science must contribute the necessary knowledge to:

(i) produce food where it is most needed;

(ii) decouple agricultural production from its dependence on non-renewable resources;

(iii) recycle and make efficient use of available resources;

(iv) reduce the risks associated with global change; and

(v) restore the capacity of degraded soils to provide ecosystem services.

This paper examines what the concepts of sustainability, complexity and uncertainty mean and imply for soil science, focusing on the five priorities enunciated above. It also summarizes and proposes new research challenges for soil scientists of the 21st Century.

Soil restoration

Particularly the last point, on the restoration of degraded soils (that occupy currently 25% of the land available for agriculture) is one of the key lines of action that I discuss in this paper.

The figure (click to enlarge) describes in a simple way the process of soil degradation, from left to right, and that of soil restoration, right to left. Restoration measures may result after time in soil conditions that are inferior to the original soil quality. The capacity of soil to restore its properties, or a management practices to facilitate that, is referred to as hysteresis of soil restoration (from Tittonell et al., 2016).


Soil science and the UN Sustainable Development Goals

What can soil scientist do to contribute to achieving the United Nations Sustainable Development Goals (SDGs)? Plenty of things indeed. The achievement of UN SDGs depends largely on ecosystem services and many of these depend in their turn on key soil functions.  This is well explained in this graphical abstract published by Keesstra et al. (2016) in the open-source journal SOIL of the European Geo-scineces Union.

Graphical abstract (for print) 20151223 Slide1

In this FORUM paper we explore and discuss how soil scientists can rise to the challenge of reaching the UN SDGs both internally, in terms of our procedures and practices, and externally in terms of our relations with colleague scientists in other disciplines, diverse groups of stakeholders and the policy arena. To meet these goals we recommend the following steps to be taken by the soil science community as a whole:

(i) Embrace the UN Sustainable Development Goals, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030.

(ii) Show the specific value of soil science: Research should explicitly show how using modern soil information can improve the results of inter- and trans-disciplinary studies on SDGs related to food security, water scarcity, climate change, biodiversity loss and health threats.

(iii) Given the integrative nature of soils, soil scientists are in a unique position to take leadership in overarching systems-analyses of ecosystems;

(iii) Raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services;

(iv) Improve the transfer of knowledge through knowledge brokers with a soil background;

(v) Start at the basis: educational programs are needed at all levels, starting in primary schools, and emphasizing practical, down-to-earth examples;

(vi) Facilitate communication with the policy arena by framing research in terms that resonate with politicians in terms of the policy cycle or by considering drivers, pressures and responses affecting impacts of land use change; and finally

(vii) all this is only possible if researchers, with soil scientists in the frontlines, look over the hedge towards other disciplines, to the world-at-large and to the policy arena, reaching over to listen first, as a basis for genuine collaboration.



“No excuse to make the same mistakes…”

The Mansholt letter is a letter that Sicco Mansholt, the person who designed the current model of specialised agriculture in The Netherlands wrote to the European Union in 1972, at the end of his life, acknowledging that the model he designed was actually ‘wrong’. This is part of a series of interviews compiled by Het Nieuwe Instituut to make this letter public at the World Expo in Milan. In this interview we see Pema Gyamtsho, Bhutan’s former Ministry of Agriculture, who aimed at turning Bhutan into the first wholly organic nation.

Agriculture, nature and the yellow press

In my current job coordinating a natural resources and environment program in Argentina I often come across complex issues labelled as ‘conflict’ between agriculture and nature conservation. The presumed damaged caused by wild animals to agriculture and livestock is a particularly tough one. From wild herbivores such as guanacos or deer competing for grass against sheep and cattle, to grain-eating birds shopping through mature grain crops, or pumas and foxes dining on tender lambs or chicks, such cases make it repeatedly to the national and local press and cause agitation amongst farmers. This has been the case of, for example, the poor mourning dove.

Slide1 The mourning dove became a new ‘plague’ to the sunflower crop. And how does our cultural wisdom deal with plagues? Control them! Poison them! Shoot them! Part-time hunters are always ready to jump at any opportunity to justify their shooting (and their polluting the place with lead and noise); much better still when this can be done in the name of ‘nature management’. This is exactly what happened with the poor mourning dove.


Granted, mourning doves are perhaps not your favourite wild bird, they are not what you may call emblematic biodiversity, but they do have their ecological function, their place in nature. Other bird species, such as local parrots or the migratory cauquén, experienced a similar fate. (The cauquén, which lands on agricultural fields in big flocks, was even accused of generating soil compaction! Later on research showed that this was total nonsense).

Who eats what… and how much?

What’s the best way to deal with this kind of conflict? Let’s recur to science, to knowledge, to information, I would say. Or, as Julieta von Thungen, responsible for this line of work in our program puts it: “we should do what we know best; and we do know how to count”. And counting they did. Jaime Bernardos, Sonia Canavelli and their teams monitored mourning doves, their temporal and spatial dynamics during the cropping season, their presence, distribution and feeding patterns in sunflower fields and the level of damage they caused, expressed as a percentage of the harvest that was lost to the birds. And what did they find? See for yourself:

Slide3In short, lots of fields with insignificant damage, with less than 1% of the harvest lost, and a few fields with about 30% harvest losses. Does this justify going out to shoot mourning doves or poison them, creating risks for other species as well?

Such a pattern in the reaction of farmers and the civil society is common to most agriculture-nature conflicts and it is largely driven by perceptions. Once an animal species is perceived to be a plague there is no way of stopping this type of behaviour.

Science to the rescue?

Here again science has a crucial role to play by providing hard evidence, knowledge and information. Not just about leves of economic damage; there is also evidence that choosing the right species of trees to plant around fields, such as deciduous species that grow less than 15 m tall, can reduce the population of potentially damaging birds such as doves and parrots. By contrast, it seems that evergreen species like Eucalyptus and Pines are very attractive for their nesting.

Unfortunately the funding necessary for the type of field work necessary to monitor presence, incidence and damage – which in the case of mourning doves involves just a field car, fuel and man-hours, whereas for the puma it would involve installing a large number of sensor infrared cameras, and a lot of patience – comes only after the problem started, often too late to prevent it.

Moreover, such basic research may also be discouraged through insufficient academic reward, as the results are not always attractive to the editors of high impact journals due to lack of scientific novelty. And, as we scientist know all too well, poor publication records translate into even less funding. Who should be doing this kind of less-rewarding, basic, but extremely useful research?

I have no immediate answer to this. But one possibility is to establish what is known as ‘observatories’ of sustainability, similar to those used to monitor the impact of tourism. Imagine a portion of a landscape or territory under human use in which all the basic environmental and biodiversity monitoring research is done over sufficiently long periods of time, generating the necessary data to inform discussions and decisions. Some examples of this already exist. Let me investigate a bit more and come to that in another post.

Meanwhile, when it comes to agriculture-nature conflicts, let us please stay away from the yellow press.

Running on empty

Will there be enough oil to sustain future food production? Why is current agriculture so dependent on fossil energy? To explore these questions it is perhaps a good idea to examine our ecological footprint from the very beginning of our history on earth.  Our planet originated 4,500 million years ago. Photosynthesis exists for about 3,500 million years but vertebrate land animals and plants only appeared about 400 million years ago. Dinosaurs were there between 230 and 65 million years ago. We humans have been on earth for merely 2 million years, and for most of that time we’ve been marauding around, hunting, gathering fruits and roots, and looking quite different than we do today.


Settling down

Between 10,000 and 5,000 years ago – on the last second of our existence you may say – we decided to set camp, became sedentary and started farming, in a period in which the climate became milder, warmer. Agriculture was a ‘successful’ strategy for our species, starting almost simultaneously in different parts of the world that were not connected by then, and leading to the first population boom. The expansion of our species, half-farming, half-hunting and gathering, led to profound modification of the previous ecosystems around the world. This period coincided approximately with the massive extinction of other species of megafauna (other than human) that took place during the Quaternary.

This moment of our history is seen by some scientists as a key period to study earth living system’s resilience, given that two important processes took place at the same time. Namely, human population growth and climate change – do these sound familiar? A couple of papers published by Barnosky a few years back tried to put some figures behind the dynamics of human and other megafauna populations over the last hundreds of thousands of years. Human expansion, according to Barnosky, is one of the major drivers of extinction of hundreds of megafauna species around the world.

Replacement and addition

If, as Barnosky explains, instead of the total number of individuals we consider the total biomass of humans and of all the extinct megafauna species, then we see a sort of ‘replacement’ of such species by humans. That is, the total biomass that went extinct coincides approximately with that of all humans. The sum of total megafauna biomass – human and non – represents the carrying capacity of Earth, as determined by the incoming solar radiation through plant photosynthesis. In other words, this is the capacity of the Earth to sustain the life of megafauna populations with plant biomass.

Total megafauna biomass declined rapidly during the massive extinctions of the Quaternary and it took about 10,000 years to reach again the level that corresponds to Earth’s carrying capacity. This level was achieved once again around the time of the industrial revolution, as can be seen in the figure below.

megafaunaWhat is most striking in this figure put up by Barnosky (2008) is that the beginning of the industrial revolution, when the world human population starts becoming increasingly urban, marks also the beginning of the expansion in numbers of another category of megafauna: domestic livestock. When we now add up humans, wild animals and livestock, the result is that we are currently keeping about ten times more megafauna biomass than the estimated carrying capacity of the Earth! How is this possible?

Eating fossil fuels

Earth’s carrying capacity, as mentioned above, is determined by the rate of plant photosynthesis. That is, by the ability of plants to turn solar energy into feed energy. Nowadays, to be able to sustain such numbers of animals and humans on Earth we are consuming not only the photosynthetic energy that is capture every year, but also all of that that was captured over hundreds of millions of years. All that energy is stored in fossil fuels: oil, charcoal, gas, tar, etc. These fossil fuels represent a net subsidy to our energy balance on Earth. For example, it is calculated that about 70% of the energy contained in a cereal grain produced using the methods of industrial agriculture comes from fossil fuels (check out this book that appeared already about a decade ago: Eating Fossil Fuels).

About 1500 oil equivalents per year are necessary to feed a person in the developed world. That represents about 6 barrels per person per year. At peak oil production, back in 1979, the maximum oil extraction rate was about 5.5 barrels per person per year, not even half of what is needed in the developed world. All predictions towards the future, both from the public and private sector, point to a reduction in the annual rates of extraction, even when new sources and methods of extraction are considered (e.g. shale gas/fracking). And we know that, as a resource becomes increasingly scarce, its price tends to go up (or so they said in the courses of Economics I ever took).

In conclusion, we are running on empty. And what’s worse, many of the recommendations made to ‘sustain’ agricultural production in the poorest areas of the world, may actually lead to an increased dependence of smallholder farmers on fossil fuels. An example of this is the recommendation to use synthetic nitrogen fertiliser, which requires large amounts of fossil energy to be produced. Do we want to make smallholder farmers dependent on a resource that is becoming increasingly scarce? What would this mean for future (and current!) global food security? We ought to come up with alternatives.

Food produced vs. food delivered

A relatively small proportion of the food produced in the high-yielding regions of the world is actually delivered to the food system. Not just because of waste, which accounts for anything between 30 and 50% from post-harvest and manufacturing through to trade and consumption. Here, ‘delivering’ means how much food enters the food system in the form of edible items (even before it is wasted). A global study by Cassidy et al. (2013) calculated this proportion using energy units.

They expressed the productivity of all the crops in calories per ha per year (to be able to compare apples and pears) and mapped them per region. They assumed that an average person requires 2700 Kcal per year. With these two pieces of information they calculated the number of people that could the fed per ha of agricultural land on the basis of its current productivity. Note that 2700 Kcal is greater than the actual human needs, which fluctuate according to physical constitution between 1800 and 2100 Kcal per person per year. By considering 2700 Kcal they are already assuming a certain level of inherent value chain inefficiency, which gives more conservative estimates.

Potential vs. actual delivery

The map they developed shows that the most productive areas of the world can potentially feed 8 to 10 people per ha on the basis of current productivity, while the least productive regions can feed barely 3 to 4. But then they produced another map, that estimates how many people are effectively fed per ha of land. They developed this new map by computing the fraction of the total energy contained in a crop that is delivered to the food system in the form of edible energy.

For example, in the case of maize (or corn), only ca. 25% of the energy contained in the crop is delivered as edible energy, be it in the form of maize grain, meal or flour, or transformed into meat, milk, fructose, bier or candies, etc. This is because maize is used as raw material by different non-food industries, such as paint additives, plastics or biofuels. But also, because a large proportion of the harvest is used to feed livestock, which is inherently inefficient, as we all know.

Maize represents perhaps the most extreme case. But when we consider all cereals together (maize, wheat, rice, barley, oats, rye, sorghum, millet, etc.) yet 46% is used directly as food (raw or processed), 34% to fed livestock, and 20% used by the non-food industry.

Source: ES Cassidy, PC West, JS Gerber, JA Foley, 2013. Redefining Agricultural Yields: From Tonnes to People Nourished per Hectare. Environmental Research Letters 8 (3), 8
Source: ES Cassidy, PC West, JS Gerber, JA Foley, 2013. Redefining Agricultural Yields: From Tonnes to People Nourished per Hectare. Environmental Research Letters 8 (click to enlarge)

Based on this information for the most important crops globally (not just cereals), Cassidy et al. built the above map, that shows the fraction of the total agricultural production delivered to the food system. In the most productive areas of the world, barely 20 to 30% of the food produced is delivered to the food system. In areas dominated by smallholder farming 80 to 100% of the food produced is delivered – i.e. consumed at home or traded locally. This does not mean though that food systems are necessarily more efficient, as post harvest losses can still be high in many of these regions.

These are – again – global estimates, based on a number of assumptions, and they may therefore be questioned. Yet they contribute further evidence to understand why increasing agricultural production in developed countries will continue to have a limited impact on achieving global food security (see also this previous post). Most of the non- or hardly renewable resources such as fossil fuels, rock phosphate, soils or (fossil) water are used in these regions to produce food that will never reach a human stomach.