A new watercourse is playing havoc with farmland and roads and even threatening a city but also highlights the potential cost of the countrys dependence on soya beans
argentina river But unlike the deep-rooted forest it has replaced which absorbed large amounts of groundwater all year round soya bean has short roots and grows only a few months of the year.
This has caused the aquifer beneath the Morro basin to rise, and increased the speed of the subterranean flow in turn triggering the collapse of the areas permeable soil.
Around 2008, farmers started to report the appearance of shallow run-off channels, but in the last five years, the pace of the erosion quickened dramatically and those streams have become deep trenches.
Climbing down the side of one of the new gullies, Jobbgy claws at the cliff wall and a clod of soil dissolves in his hand. Its basically dust, he says.
When it gets soaked, it becomes really unstable, and what looks like a solid becomes a liquid. this humble river moves a lot of sediment despite the relatively gentle incline, Jobbgy explains.
That leads to a second problem for farmers: sometimes entire fields downstream can disappear overnight when rivers dump layers of sediment up to a metre (3ft) thick.
Alberto Panza: This used to be totally flat pasture land. Photograph: Uki Goi for the Guardian Alberto Panza, a 41-year-old cattle rancher, is one of the few holdouts refusing to lease his land to the giant soya-bean conglomerates that have largely replaced Argentinas small farmers.
Driving his battered pick-up truck along a dirt road, Panza remarks on how deserted the land looks today: no longer are there any gauchos Argentinas cowboys riding bareback through the fields. Farmhouses have been demolished to open up additional land to lease to soya producers.
Many farmers now live in the city, says Panza. Its easier to move out and lease your land to a company than to farm it yourself.
Arriving at his ranch, Panza walks into what can only be described as a Martian landscape. In the middle of a field, a giant canyon more than 60 metres wide and 25 metres deep drops abruptly away, a deceptively slow current of water at the bottom.
Panzas farm was cut in two by the canyon. This used to be totally flat pasture land, he says. A tall electricity pole lies on its side on the river bed, its cables still attached to poles standing on the other side.
Because the river keeps changing course, Panza has been unable to build a bridge or a path through the waters to reach the other side of his land.
With less than one third of the Morro basin left covered in forest or grasslands and nearly half devoted to soya and maize the government of San Luis has finally stepped in to try to save the basin from becoming a river delta.
The Ro Nuevo carves out a canyon. Photograph: Handout The government reacted after the new water courses started threatening the outskirts of the city of Villa Mercedes and two major roads that carry much of the international overland trade between Argentina and neighbouring Brazil.
At the San Luis office of the National Institute for Agricultural Technology (Inta), three scientists Claudio Senz, Juan Cruz Colazo and Mario Galvn have been studying the Morro basin for the last 10 years.
Partly due to their efforts, the province passed an emergency law in 2016 obliging landowners to preserve 5% of their farms as forest or pasture and to plant water-consuming winter crops when their land is not being used for soya bean.
The government tells us that so far about 60% of the farmers in the basin have made a commitment to meet these obligations, says Galvn.
But this just a grain of sand, cautions Senz.
The loss of small farmers has compounded the problem: the agri-conglomerates have little incentive to rotate crops or preserve the sustainability of the soil, he said.
If a plot becomes unusable, they simply move on to lease in another area, leaving the owners to deal with the problem. Its a system that not only erodes the soil, it also erodes the agricultural know-how of the landowners.
Jobbgy spends much of his time on the field, measuring the flow of the new rivers, trying to chart their ever-changing courses and developing links with the few remaining farmers.
Many landowners now have a very volatile link with their land, he says. With the demolition of so many farmhouses, the soul of the land is being lost. As long as the system works, all is fine. But when nature rears up and says: Enough!, it becomes a very difficult situation to reverse.
This story was published with the support of the European Forest Institute and Lookout Station the EFIs new initiative connecting journalism and science around the topic of climate change Read more: https://www.theguardian.com/world/2018/apr/01/argentina-new-river-soya-beans