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Bioinvasions, industrial agriculture and environmental transformations

Bioinvasions, industrial agriculture and environmental transformations

By Dr. Ing.Agr. Walter A. Pengue

The combined effects of human-caused bioinvasions threaten efforts to conserve agrobiodiversity, maintain the productivity of the agricultural system, sustain the functioning of natural ecosystems, and indeed protect environmental security, food security, or human health.


The human being is a key actor in the processes of diffusion of plant and animal species throughout the world.

The case of agriculture, carried to the confines of the five continents for centuries, is a paradigmatic example of this transformation process, which on the one hand allowed the installation and expansion of basic crops for world food, but on the other and followed by a a much more disorderly and pulsating form accompanied only some processes that involved the arrival at new destinations of different species, with impacts of all kinds.

Both accidentally and deliberately, through migration, transportation, farm machinery, species transfers, and trade, humans continue to disperse ever-increasing numbers of species across once-insurmountable barriers, such as they were mountain ranges, oceans, jungles, deserts, the most inhospitable areas or climate-hostile areas. Among the most far-reaching consequences of this rearrangement is the increase in biological invaders, which can be considered as species, whose presence is detected by the success of their installation and which proliferate in different environments. They are distributed to the detriment of native species and ecosystems.

In our days, assuming a world without limits or with few limitations, and considering the effects of bioinvasions in agriculture, is not only an interesting exercise but an essential analysis, in terms of the costs not only economic, but also ecological, social and even that their installation in rural areas can generate on the living and production spaces of millions of agricultural producers.

However, despite the permanent arrival of new species of plants, animals and microorganisms, the fate of these new immigrants can be very dissimilar.

Few species survive and only a small fraction naturalizes and gains ground to the detriment of native species or of the implanted crops themselves. Of those that manage to become naturalized, the majority also do not cause a substantive alteration in the new territories. However, others do. Among the latter, several may be the reasons that have made it possible to achieve significant success in dissemination and among them we find: the possibility of escaping natural predators, reproductive strategies, the benefit achieved by disturbances (changes in land use or technology ), the absence of biological controllers, the use of new climatic scenarios or changes in the climate and the possibility of occupying vacant niches left by other species.

An invasive plant can not only produce changes in the ecosystem where it enters but can contribute or completely alter the fire regimes, the nutrient cycle, hydrology and energy balances of a native ecosystem, as well as significantly decrease the abundance or survival of native species.

In the case of temperate areas, the main crop pests are exotic species. The combined expenses of pest control and crop losses or treatment of agricultural products imply the application of an "extra tax" (and a huge benefit for the coffers of agrochemical corporations) to the production of food, fibers, fodder, agrofuels which generally is sometimes transferred to the poorest producers and consumers.

Although the bibliography on bioinvasions in agriculture is already quite rich and extensive, much less is the study of the economics of bioinvasions, in terms of a clear identification and allocation of direct and especially indirect costs of bioinvasive processes. Moreover, until today, the global cost of diseases in plants and animals, or the treatment and control of invasive species, is partially evaluated.

A biological invasion occurs when organisms, transported by whatever means, reach new territories, often very distant. This transport process can be unwanted or promoted, as sometimes happens with “new crops” or genetic materials considered productive in one place and potentially useful for other spaces and destinations, without a complete analysis of all the processes involved. There these individuals proliferate, disperse and manage to persist.

In a strict sense, invasions are not a new phenomenon or exclusively human-caused. However, the geographic magnitude, frequency and number of species involved have grown enormously as a direct consequence of the expansion of transport and trade in the last five hundred years and in particular in the last two hundred. Not to mention the changes produced with the globalization of trade and the fall of trade barriers, since the end of the 20th century. Few habitats on earth remain free of species introduced by humans and much less can be considered immune to this dispersal, especially that linked to the introduction or transformation processes of modern agriculture.

From a purely ecological point of view, the adverse consequences of biological invasions are diverse and interconnected, ranging from important changes on the dominant species in a community, the physical properties of the ecosystem already mentioned, the cycle of nutrients, of water, of the energy as well as the plant productivity of that community.

The combined effects of human-caused bioinvasions threaten efforts to conserve agrobiodiversity, maintain the productivity of the agricultural system, sustain the functioning of natural ecosystems, and indeed protect environmental security, food security, or human health.

The most serious ecological threat produced by an invasive species is the destruction of entire ecosystems, often by invasive plants that spread in the territory of the native ones or the increase so much the costs of control in an agroecosystem, that they make it economically unviable and productively.

In the case of agriculture, invasive species have spread widely. While in many cases, the crop competes with native species, generally that are part of native grasslands (grasses and broadleaf), they are controlled through agronomic management, herbicides, other practices or more sustainable methodologies such as those based on practices and agroecological management. Likewise, there are some invasive species that expand steadily within agricultural systems, especially in large areas where the potential for agricultural expansion favors agro-industrial transformation processes.

In the case of the expansion of industrial agriculture, the main promotion for the control of bioinvasions is through the use of agrochemicals, especially herbicides. The herbicide business expanded intensively in world agriculture, especially in intensive production models. Increasing consumption is accompanied by increasing resistance or tolerance in weeds.

In the last decade, the arrival of transgenic crops has had a direct relationship with these processes. The main crops, especially soybeans and corn, were in this first layer of transgenic events, designed to be tolerant to those herbicides of greater knowledge and worldwide expansion, such as glyphosate or tolerant to the attack of lepidoptera or with both joint events.

Herbicide resistant transgenic soy is the main event spread throughout the world, and especially in the Argentine Republic.

The new event associated with the agronomic model known as direct sowing was the package offered in the country to deal with the most important weeds such as Aleppo sorghum and grass (Cynodon dactylon), both grasses.

Sorghum from Aleppo is one of the most burdensome weeds in temperate climate agriculture and has been a serious problem in Argentina since the 1930s.

The appearance of biotypes resistant to glyphosate currently adds an additional level of problems to the already complex conflict of the control of this bioinvasive that is transforming and has transformed fields and productive systems throughout the country.

Sorghum of Aleppo is considered one of the ten main weeds of world agriculture.

It has accompanied the proposals of temperate and subtropical agriculture in practically all the regions of the world where it arrived, either by chance or brought as a forage species, especially recommended for its high productivity and adaptability in adverse climates. Also due to its biomass production as well as its certain palatability, it was an attractive element for livestock.

In Argentina, Aleppo Sorghum (Sorghum halepense) entered recommended as a forage plant both by the government and by the seed companies at the beginning of the 20th century (around 1900).

It quickly spreads in the northern region of the country and also in the same way, its pernicious effect on the fields is perceived. In two decades it becomes a plague of agriculture and is declared as such and from there a struggle begins by mechanical means of all kinds and later chemicals that brought only partial victories to farmers at the cost of enormous costs, efforts and losses.

At the beginning of the bioinvasion of conventional Aleppo Sorghum, only a few isolated technicians warned early on the implications of all kinds that the intensification in the sowing of Aleppo Sorghum could generate on the economic structure of the rural sector at the beginning of the century. Thus, Dr. William Cross, Director of the Tucumán Agroindustrial Experimental Station, warned through his writings and research on the process in the making.

Impacts that went through the colonization of the fields by Aleppo Sorghum and the tremendous costs for its eradication, effects on farmers in terms of their discouragement and abandonment of agricultural practice, economic costs and losses of fields that merited a greater dedication for its social effects and others.


Despite Cross's early warning, the reaction of the Argentine government at the time was late and still partial. Since the declaration of the plague in the 1930s (20 years after its introduction), the species was practically installed throughout the country or even continued to be expanded at the expense of its sowing as forage, until the creation of a Commission to Combat the Sorghum of Aleppo, of course it was not possible to eradicate and in many cases even to control the invasion. The diffusion works, the means used, the publications were late actions that could not stop the diffusion.

The same agricultural machinery facilitated expansion without yet fully understanding all the reproduction mechanisms and capacities of the species in question.

Just as Aleppo Sorghum is a very serious weed, considered by many to be “the perfect weed” or “farmers' nightmare”, due to its bioinvasive capacity and its reproduction and adaptation mechanisms, the agrochemical industry dedicated enormous efforts to “control it. ”.

In the mid-1970s, the herbicide glyphosate was developed, one of the herbicides best known to farmers. It is one of the best-selling herbicides since then, but whose explosive jump in consumption occurred since the mid-nineties.

Glyphosate is a broad-spectrum, non-selective and systemic herbicide, highly effective in killing any type of plant, which is absorbed mainly by the green parts of plant tissues. Once entered into the plant, it inhibits the action of shikimic acid, an obligatory step towards the synthesis of three essential amino acids, present in higher plants and certain microorganisms, but not in animals.

Global glyphosate sales exceed $ 2 billion and it is estimated that they will be around $ 3 billion over the next five years, equivalent to more than 40,000 tons of active ingredient. Glyphosate covers more than 60% of the total world sales of non-selective herbicides, and it will grow even higher as transgenic events related to its consumption are massively incorporated, especially soy and corn.

This first wave of transgenic events has been adopted by more than 10 million farmers in 22 countries occupying around 100 million hectares in the eleven years since the technology has been commercially diffused. So far they occupy 7% of the total available agricultural land in the world. Until today, the main interest of the companies that commercialize these products are focused on those countries that, due to their territorial dimension and consumption of agrochemicals, present availability for technological absorption. 57% of these territories correspond to soybeans and 25% to corn. Altogether 68% of the transgenic released respond to products that are tolerant to herbicides (especially glyphosate), 19 to insecticides (they are tolerant to attack by Lepidoptera) and 13% are tolerant to both.

Between the United States (54 million hectares), Argentina (18 million), Brazil (11.5 million), Canada (6.1 million) and China (3.5 million) they reach 92% of the entire world surface occupied with genetically modified plant organisms. New countries with large territories such as India and South Africa, number on average about two million each. The other countries have occupied territories with much less area involved.

The technological package that arrives in Argentina has transgenic soybeans and glyphosate herbicide at its center. Today, the dissemination of herbicide-resistant transgenic corn is also being promoted with new "stacked" events, in a folder to be approved or already approved and commercially released by the SAGPyA of Argentina. Transgenic crops have been a reality in the countryside and the Argentine agri-food system for ten years.

The technological package of RG Soybeans and glyphosate, under the direct seeding system, came for two things: to control and reduce the problematic control of weeds and its simplification and to promote agriculturalization through a successive sequence of agricultural crops, especially at the beginning. wheat and soy.

The type of recombinant DNA technology incorporated into the new seeds responds to an intensive package in the use of inputs that integrates an easily appropriate practice such as direct sowing with a strong increase in the consumption of herbicides, fertilizers, insecticides, seed cures, mineral oils. and irrigation, widely promoted both from certain sectors of the public or private sphere.

All this process has led to an accelerated "agriculturization" of the system, a "soybeanization" of the model that eliminated the mixed approach and transformed, especially but not only the entire Pampean Region, into an eminently monoproductive area. The new soybeans are the basis of the intensive agricultural production model that currently reaches a business of 11,000 million dollars in Argentina between grains and by-products. But if, on the one hand, the field faces a growing economic concentration, a significant push from corporations, a tremendous distortion in prices and relative costs, to which we must add the unfair dumping of the most developed economies through the agricultural subsidies, on the other hand, the "productive efficiency" of Argentine agriculture, is based on a relevant natural subsidy and an overexploitation of the same that puts warning lights on the way in which the soil, biodiversity and natural resources are being used in this country.

In the general framework of agriculture, the nineties may be remembered in the Argentine case as the “input decade”, since the explosion in the consumption of agrochemicals that facilitated a phenomenal increase in primary production has been clearly marked. which went from 26,000,000 million tons of grains and oilseeds in 1988/89 to more than 94,000,000, a record for Argentine granary production, due to the highest historical production of soybeans, corn and wheat. Nor on the surface the growth does not stop. The planted area has grown compared to the previous cycle (2006/2007) and went from 28.98 to 30.28 million hectares. In other words, that following the mad rush generated by international prices, producers have incorporated more than one million hectares to intensive agriculture. It fell for the 2008/2009 campaign due to the already remanded tele-theater between the camp's denouement board and the government, but soybeans and their crops will grow again in the current campaign.

RG soybeans (resistant to the herbicide glyphosate) were already adopted at five years by all Argentine farmers, acquiring the seed + herbicide package, mainly due to the relative cheaper price of both offered (within the country) by multinational companies and comfort in handling. This rate of technology adoption has no time-scale precedent to match it.

In the speed of technological adoption, Argentina in the case of transgenics far exceeds that of countries with a strong agricultural and technological base such as the US or Canada. This new technology surpassed historical milestones such as the arrival of corn hybrids or even the rapid process of pasture refining, with the incorporation of alfalfa at the beginning of the century. The development of these first transgenic crops has not responded as it was tried to show in a new Technological Revolution that would contribute to alleviate pressing human and environmental problems, but at least by analyzing this first batch of events it is observed that they constitute a new tool of the The same agricultural model of the Green Revolution, which, although it allowed to increase the physical yields of crops, also produced extremely serious environmental and socioeconomic consequences. Technological changes and international commodity prices, together with the much improved adjustment of the gross margin relative to other crops for the producer, facilitated this explosion. It continues under the paradigm of an agricultural system supported –not sustainable– on the conspicuous use of natural resources, with a continuous load of inputs and increasing energy demands, in order to maintain the response of the synthetic crops implanted.

Argentina is one of the countries where the conservationist technique of direct sowing has had more roots and one of the factors that facilitated the transition from a historical model of mixed agricultural production towards permanent agriculture.

With this technique, it has been possible to reduce soil erosion and even recover them, by using a stubble cover on the surface that protects them from the impact of rain or wind, but at the cost of an increasing use of chemical inputs, especially herbicides and fertilizers and on the other hand with impacts on the microbial flora of the soil and changes in the pest population together with new diseases in crops.

In response to the demand for direct sowing, there were important improvements in the germplasm of the soybean varieties, achieving better adapted lines and a higher agronomic performance for the different maturity groups, which have even allowed progress on environmentally friendly areas. very susceptible, towards the northeast and northwest of the country, as we said by directly opening the agricultural border.

In direct sowing, the stubble from the previous crop, especially in its volume and quality, is very important. These remains facilitate the incorporation of organic matter through bacterial activity and other soil organisms. The agronomic approach of direct sowing could also eventually be applied in an agroecological production model, as in that case, it should eliminate some elements that condition the system in the extensive plane (herbicides).

For this reason, I highlight this difference, by currently promoting what we can call, an industrial direct seeding model, which partly fulfills the same objective of not using the plow and if using the stubble on the surface, applies herbicides for control of weeds (chemical control) and an increasing load every year in volume of agrochemicals for the control of these weeds, which increase on the other hand in tolerance and resistance.

However, other groups of weeds enter the system as well as new pests and diseases that require more agrochemicals for their control. The already highly costly attack on soybean crops in the Southern Cone by Asian soybean rust (Pakophora paquirrichi) is just one example of this process.

It is striking how the issue of sustainability is handled in that country. The discourse on sustainability and “eco-efficiency” has been co-opted in Argentina by the promoters of this no-till model. Behind them are the large agrochemical and seed companies, which promote the benefits of their products. They are accompanied by a court of dependent researchers subjugated by the lights of an economic model that nurtures and supports their partial investigations.

The direct sowing system, growing at the national level –especially in Córdoba, Santa Fe and Buenos Aires– and also strongly promoted at the regional scale, needs basic inputs to sustain its success, which in addition to agrochemicals, demand for adequate machinery, which have grown in the decade with the same trend as the first. The main basic input of direct seeding was to sustain itself exclusively on the conspicuous use of the herbicide glyphosate -whose characteristics are beginning to be reviewed again today- and that in Argentina, has had an unprecedented expansion in consumption throughout the world, reaching in 2006 values ​​close to 180 million liters of commercial drug (in 1990 consumption did not reach one million equivalent commercial liter).

As of the year 2000, there has also been a growing expansion of the Pampean model towards other ecoregions that are much more environmentally and socially sensitive, such as the Argentine NOA, where transgenic soybeans, direct seeding and glyphosate along with a greater use of agrochemicals begin to applied with intensity. Added to this is the arrival of a new farmer, little linked to the local and its culture: the Pampean producer. This brings its productive logic together with greater capitalization and technical training and knowledge of new technologies. I have called this process of imposing a new productive model in the Pampas on other ecoregions that "are not Pampas".

With the pampeanization there is a strong transformation of the rural sector in the NOA (northwestern Argentina) and the arrival of new technologies, products, changes in use patterns and volumes of application of agrochemicals.

Towards the middle of this first decade of the 21st century, and even earlier, the appearance of Aleppo sorghum bushes that are resistant to the herbicide glyphosate and that must be controlled with other herbicides are detected in the northern fields, which went towards transgenic soybeans. . The bushes are apparently resistant to the herbicide and therefore have been called SARG: Glyphosate Resistant Aleppo Sorghum. However, until today, the mechanisms of this resistance are not clearly known.

From that moment, the short period of control without problems for farmers begins to be shortened and other forms of management begin to be suggested, always based on the use of old and well-known herbicides such as MSMA, paraquat, 2,4 D or in mixtures with glyphosate. All combinations whose controls are more partial than glyphosate, more costly economically and with greater environmental impact.

In addition to being a serious problem the case of bioinvasion with SARG due to the mere fact of its serious effects, it must be borne in mind that it is not a common, annual weed but that it has special strategies of permanence, reproduction and is a perennial .

In 2007, the areas where the SARG was found not only involve the provinces of the Argentine NOA but there are also stands of the biotype, in other Argentine provinces such as Santa Fe, Córdoba, Corrientes or Santiago del Estero. Apparently the entire country could be compromised.

Although only after a first official campaign, less than 100,000 hectares are affected by SARG, using official data, around 100,000,000 total hectares potentially or likely to be affected at the beginning of the bioinvasion are at stake. . Only for agriculture, with essential grains for export, the surface amounts to more than 30,000,0000.

The SARG monitoring campaign finds the country still "disarmed" in the face of the need for a biotype monitoring strategy in different ecoregions, despite the seriousness that the expansion and extension of this Aleppo Sorghum may involve on a territorial scale .

The problem deserves to be faced in a comprehensive and holistic way and not partial and under a short-term scenario, as it seems to have been faced up to now.

The institutional and economic scenarios unfortunately show that Argentina will continue to bet on the intensification of its transgenic-based agriculture and will accompany only with reactive actions its response to the potential effects of the appearance of problems such as the emergencies of pests and weeds, as shown in the case of the emergence of SARG, a "new" resistant Aleppo.

Almost eighty years later, government policy actions seem to be copied from those raised by the Secretary of Agriculture in the 1930s. From the creation of a new Committee to Fight Resistant Pests to the partial forms of communication used and the demand towards farmers, as if these were the culprits of the instance of appearance of Sorghum, they only allow to express the worrying situation that the problem Again, it is not being reviewed holistically and comprehensively and with responses that involve restorative and stabilizing actions of the agroecosystem, even at the cost of initial economic losses in the framework of this process.

In the ever-constant recurrence of a problem-a solution already raised from the foundational foundations of modern agricultural chemistry by Justus von Liebig, the 21st century promoters of biotechnology companies and their partners in synthetic agrochemistry celebrate the new scenarios to come.

Dr. Ing. Agr. Pengue - National University of General Sarmiento, ICO. - ProECO, Ecological Economy Program, GEPAMA, FADU, UBA.

Based on the work: BIOINVASIONS AND BIOECONOMY: THE CASE OF ALEPO'S SORGHUM IN ARGENTINE AGRICULTURE (PENGUE, WA, MONTERROSO, I and BINIMELIS, R, 2009).

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