Flora and Fauna
Nature in Latin AmericaWinter 2005
The Dilemma of Biodiversity Conservation
Agricultural Expansion in Argentine PampasOtto T. Solbrig
In the last ten years Argentine agriculture has experienced the largest transformation in over a hundred years. Grain production in the pampas has doubled, and soybean production tripled. Exports of cereals and oil seeds have increased dramatically, and poultry and beef production and exports are also on the rise. Agriculture has sustained a failed state during the country's biggest financial and social crisis.
Armadillos, foxes, nutrias and capybaras still roam the pampas, Argentina's extensive grasslands. Their numbers have even increased with no till agriculture, a conservation technique that significantly reduces soil erosion and conserves soil moisture, but also lowers the costs of production. Avifauna, including Rheas, now find a friendly habitat in grazing fields. Yet large mammals such as pumas, and pampa deer survive only in a few enclaves. Little evidence exists regarding invertebrates, yet the soil fauna has greatly increased on account of no-till agriculture that has removed plowing, a major source of soil disturbance.
Evidence about the impact of agricultural transformation on fauna is still mixed and tentative. The original vegetation structure has of course been displaced by agriculture. Yet the native species are still there- as a study by Paul Lewis has shown-augmented by introduced weeds. These species exist in abandoned houselots, along highway rights of way, and adjacent to railroad tracks and embankments. Some evidence of reduction in species such as large mammals; however, theres is also that most species are surviving. More important than species numbers are the ecological services they provide. So far, although further study is needed, there is no evidence of serious problems with decomposition or nutrient or water cycling.
One serious problem is the lack of natural reserves. A few private bird sanctuaries exist, but there is no sizable biological reserve other than the Parque de la Sierra Ventana, that is not representative of the flora and fauna of the region. The need of several large reserves to provide refuge for the native flora and fauna is very urgent.
The major change in the agricultural production of in the pampas has made soybeans its principal crop. It would be useful to study in a systematic way the effect of soybean monocropping on biodiversity.
Since 1990, soybeans production has increased by 66 % worldwide (from 108 million tons in 1990 to 179 million in 2002). The United States, Brazil and Argentina. in that order, account for most of the increase (88%). In the United States, soybean cultivation has displaced maize, with little impact on native biodiversity (the prairie was displaced by agriculture 150 years ago). In Brazil, the expansion of soybean growing is concentrated in Goias and Mato Grosso, displacing the rich native biota of the savannas and the Amazonian forest. What impact has expansion of soybean growing had on biodiversity in the Argentine pampas?
At first blush it would look as if the pampas has a similar situation to that in the United States, since the bulk of the soybean growing has taken place in the former pampa grassland transformed by agriculture in the first half of the 20th century. As in the U.S., soybean growing has displaced maize as well as sunflowers. Yet a closer inspection reveals that the situation is more complex and that soybean growing has had some negative impact on pampa environment and the sustainability of Argentine agriculture.
A Brief Historical Survey of Pampean Agriculture
Cattle raising and agriculture have been the principal economic activities in the Argentine pampas, vast grassland covering about 2000 square miles. Its native flora (Cabrera 1960) and fauna is not terribly abundant. Today only remnants of the native flora survive along railroads right of way, roadsides, and land not good for farming.
Agriculture in the pampas was always very dynamic. Labor was relatively short as was capital, but land was plentiful. Consequently a very extensive system of land use developed, that slowly became capitalized. In the colonial and early independence days ,the principal activity was raising cattle on the open range, with agriculture restricted to a belt around the city of Buenos Aires. In the second half of the 19th century, wheat growing for export developed and soon the pampas became one of Europe's breadbaskets. Meantime quality cattle raising for export to Great Britain and other parts of Europe became a lucrative activity alternating with wheat growing. This alternation was a very sustainable system of land use, as grazing restored the soil fertility that was lost during the years of agriculture. The 1930s world depression followed by World War II trade disruption and then by anti-rural policies in the first government of Perón that transferred resources from agriculture to industry, produced a serious depression in the rural sector in the late 1940s and early 1950s.
Starting in the 1970s, a concerted and very successful effort to revitalize agriculture adopted "green revolution" technologies such as the use of chemical fertilizers and pesticides, replacement of horses with tractors and introduction of high yielding varieties of wheat and maize. The new capital-intensive technologies required a greater level of knowledge than prior systems. They succeeded in increasing production and yields of the major crops of the time: wheat, corn, sorghum, and sunflowers. Yet the government persisted in taxing agricultural exports to keep internal food prices low. The 1970s and 1980s were a period of social unrest, and high inflation, and of a bewildering array of economic policies. Their effect on the rural sector was to slow down the rate of growth and to increase the indebtedness of farmers.
With the accession to the presidency of Carlos Menem in 1989, these policies were reversed. Agricutural regulation of agriculture was reduced significantly and exports taxes eliminated. This ushered into a period of enormous growth for pampean and Argentine agriculture in general. Production doubled in ten years, a very remarkable achievement. Leading this revival was the growing of soybeans, a new crop for the country.
A very minor crop in the 1960s and 70s, soybean growing expanded in the 1980's and especially in the 1990s when production and cultivated surface tripled. After the mid1990s, two new developments increased the profitabiity of soybean growing. One was the introduction of no-till agriculture. The other was the introduction of genetically modified RR soybeans that meshed very well with no-till and further reduced the costs of production. Coupled with a very significant demand for this product and its high prices, soybeans became the crop of choice in Argentina (as well as in Brazil and the United States). The result has been a boom in agriculture that has supported the economy of the country during its worst recorded economic depression. Unfortunately it also has increased a tendency towards monocropping in the pampas that may not be altogether healthy.
The Conflict Between Agriculture and Conservation
Agriculture is the major transforming agent of natural landscapes. Other economic activities such as mining and urbanization have an even greater local impact, but they occupy only between 3 and 5% of the land surface of the world, while agriculture and animal grazing occupy about 40%. Yet humans need food to survive and with a growing population it is impossible to reduce the agricultural surface. Over the centuries agriculture has not only transformed natural landscapes, it often has degraded them to the point where farming is no longer possible. Much of the formerly rich agricultural land of the Mediterranean basin is now abandoned wasteland, for example. Awareness of the possibility of ecological disasters drives the push for the development and adoption of sustainable conservation agricultural practices.
Crops remove nutrients from the soil, and continuos farming is not possible even in the richest lands without some nutrient restoring practice. Fallow, a traditional technique, takes at least half to one third of the land out of production. Fertilizing with the use of animal manure and other sources of decomposing organic matter ,has also been used to restore soil nutrients. A more recent practice is the use of commercial fertilizers such as guano or Chilean nitrates. The development of cheap ways of producing nitrates during WWII led to the commercial availability of chemical fertilizers now in widespread use worldwide in areas of intensive agriculture and has allowed monocropping.
The growing of the same crop year after year leads to the accumulation of that plant's diseases and pests. Crop rotation has been the time-honored way to reduce crop damage due to pests and diseases. The development of powerful chemical pesticides has allowed farmers to control plant pathogens thereby encouraging monocropping.
Yet the use of chemical fertilizers and pesticides has a number of negative secondary effects. Organic fertilizers such as manure are incorporated slowly into the soil. Excessive use is highly polluting, that seldom happens. Chemical fertilizers on the other hand are very soluble and any amount not used immediately by the plant tends to run-off into surface watercourses or into the water table contaminating water supplies in cities. Unforeseen effects are algal blooms and eutrofication of lakes and even the ocean. Today all the estuaries of rivers that irrigate farming areas show unmistakable effects of contamination from chemical fertilizers with negative effects on fish and aquatic plants.
Many Argentine farmers have adopted conservation practices, especially no-till agriculture that reduces soil erosion. For maximum effect, no-till requires crop rotation and the avoidance of plowing. No-till in Argentina is used primarily with soybeans. 60% of the agricultural surface in the pampas is in no-till, a remarkable achievement. Yet only a third of farmers practice exclusively and continuously no-till and also carry out crop rotation. Without continuous no-till and crop rotation the benefits of this technology are diminished significantly. Because of cost considerations, Argentine farmers use little chemical fertilizer, tending to rely on the ability of the soybean to fix nitrogen from the air. But soybeans remove phosphorous from the soil that sooner or later will have to be restored to maintain soil fertility.
In other words, the picture is somewhat clouded regarding the environmental impact of the expansion of soybean growing in Argentina. On the one hand, Argentine farmers must be congratulated for having adopted conservation practices at a higher rate than most other countries including the United States. The reduced rate of use of chemical fertilizers and pesticides is also commendable. On the other hand less than half of the farmers are practicing conservation techniques, and the tendency to expanding agriculture into marginal areas and of monocropping soybeans is very worrisome.
There is little concrete information so far regarding negative effects of soybean monocropping, but the little there is indicates an increase in soil erosion and some contamination of water courses and acquifers. If we are to lessen the contradictions between agricultural production and nature conservation, we must study these questions with care.
Otto T. Solbrig, Harvard?s Bussey Professor of Biology, emeritus, is co-author of Globalization and the Rural Environment published by the David Rockefeller Series on Latin American Studies/Harvard University Press. His research includes population ecology and natural resource use, especially renewable resources in Latin America.