A flooded agricultural field, in Argentina. Courtesy
EL PAÍS offers the América Futura section openly for its daily and global information contribution on sustainable development. If you want to support our journalism, subscribe here.
A virtually unknown creature has awakened beneath the South American plain. The water table, the accumulation of groundwater beneath the soil, is increasingly rising in the region’s plains as a result of the loss of deep-rooted native vegetation and the imbalance between the water demand that the climate exerts on plants and those that they can support. A phenomenon derived from the rapid and ferocious agricultural expansion, which is causing increasingly serious flooding.
The depth at which the water table is found varies depending on the harmony between water consumption and precipitation. Made up of solid particles, pieces of rock, organic remains and empty spaces that retain liquid, this underground mantle is rising in level in some regions of the Southern Hemisphere. “Also known as napa, it works like a sponge under our feet: when all its pores are filled with water, it rises to the surface, generating permanent floods,” explains Esteban Jobbágy, agronomist and author of a study that shows the dramatic ecological scenario that the Argentine pampas offer. Its plains have become a natural laboratory to evaluate the hydrological effects of dryland agriculture. One that, in the last 40 years, has advanced without brakes over the territory.
As pointed out The study, published in the journal Science, The savage deforestation of fields for planting and changes in land use are altering the hydrological balance in large areas of South America. Forests of thorn trees, carob trees, savannahs and grasslands—vegetation of the Chaco-Pampeana ecoregion adapted to aridity—that in the last 40 years have been eliminated and replaced by dry annual crops. “Fields tilled for generations begin to fill with puddles, slowly transforming into permanent lagoons, overflowing rivers and flooding entire towns in the provinces of Córdoba, San Luis and Santa Fé, among others,” says the scientist.
The transformation of the natural landscape in the last half of the century has its origin in the global demand for cereals. A market that, according to the Food and Agriculture Organization of the United Nations (FAO), it will skyrocket even more, leading to the rapid conversion of wide swaths of native South American grasslands and forests into pure agricultural land. These flat landscapes, home to some of the most productive soils in the world, are particularly sensitive to alterations in water cycle dynamics. “From which we still have a lot to learn. Many of the inhabitants of the plain live a couple of meters above the water table, however, the majority do not even know that it exists,” says the scientist. According to what the measurements in his study indicate, the water table went from being between 12 and 6 meters below the surface to 4 and 0 meters today. Which implies an increase in levels of 17 cm per year in different parts of the Pampas region.
“By changing the type of vegetation we change the system’s capacity to empty the water, to dry it,” says Jobbágy. Despite the great drought that the region has been suffering for years, the water cannot evaporate. “If we look at the records of recent decades, what rains here is less than what the sun can steal, but the landscape maintains the water on the surface, which floods more and more frequently,” he explains.
A flood in an Argentine agricultural community. Courtesy
This phenomenon, about which so little is known, began with the “Soy Boom,” which arrived in the mid-seventies, causing a predatory expansion of the agricultural frontier in the country. Currently, the production of this cereal colonizes between half and two thirds of the cultivated Argentine plain. “The rest is almost all corn planting, accompanied by wheat and barley, depending on the summer or winter season,” says Jobbágy about “an agriculture that has grown on a large scale adjusting to savage capitalism. There are still small producers who work their small plots, but the large areas, some of hundreds of thousands of hectares, are in the hands of large companies.” The recent increase in the international price of wheat due to the war in Ukraine predicts that Argentina will further expand the cultivated area for the in-demand product.
“We are talking about a country that barely has territorial planning, with very little regulation, where lands have passed from hand to hand in a very violent way. Some provinces are discussing normative ideas to turn them into regulations, but they are only the first steps,” explains the scientist.
The findings of their research reveal the escalation of flooding associated with the expansion of rainfed agriculture in South America and the effects of the rise of the water table, “but its impacts and risks are still poorly known, constituting major sustainability challenges.” , he warns.
To stop the increasing instability of the system, the study in which it has been immersed for years makes an urgent call for the implementation of land use policies that support agriculture, water management and rural populations in a smarter way. . “And that they also integrate the conservation of the little nature that we have left, those little pieces of forest, wetlands and grasslands,” says Jobbágy.
In the scientist’s words, social and environmental justice are completely intertwined in the agricultural landscape of the Argentine plains. “Which poses many challenges. We are a country that practically lives off the export of grains and these hydrological changes can put the good living of the territory and the people in check,” says the author of the study published in June.
As he concludes, the results of the work are an opportunity to better understand the impacts of the transformation of natural landscapes into crop fields and their hydrological effects below the ground. Also for the design of policies that help find the balance of the ecosystem. “We have changed the way in which the plain stores and transports water, giving rise to an unknown creature, one that began to wake up decades ago and that will not easily return to sleep. Only with good agreements will we learn to live with it.”
2023-09-18 04:30:00
#beast #nature #awakened #plains #South #America
