RS: floods compromise soil fertility and will leave some crops unrecoverable, experts point out
Specialist in agricultural engineering at the Hydraulic Research Institute of the Federal University of Rio Grande do Sul (IPH/UFRGS), Fernando Meirelles states that some areas were completely destroyed by the flood. “We already have a total loss of soil, where there is simply rock. Where there was farming, there is only rock. We don’t know the extent yet, but it won’t be small”, he assesses.
Meirelles highlights that, in these cases, there is nothing to do. According to the expert, the second scenario—which some producers in Rio Grande do Sul will have to face when the waters recede—will be dealing with the layer of sediments, such as sand, clay and gravel.
“It was a very violent and very fast flood. We are going to have a completely irregular deposition of coarse sediments that do not have a positive impact on fertility”, he analyzes.
Director of Research and Innovation at Embrapa, Clenio Pillon highlights that the entity will seek to quantify and map, in partnership with the Technical Assistance and Rural Extension Company (Emater), the areas where the soil was totally or partially removed.
However, he states that some preliminary information already allows a photograph of the impact to be taken. “There are places that suffered intense soil removal. This was more visible in the Mountain Region, where there are areas with greater slope, especially on the banks of rivers, which had very important rapids and crops that were affected had very significant soil losses.”
According to Pillon, in lower regions, where water moves less intensely, there may be an accumulation of nutrients that were removed from higher areas, contributing to increasing the fertility of these fields. But he warns that there is also a risk of contamination.
“Eventually there is also a risk of accumulation of contaminating elements, especially because this water has passed through several locations, industries, removed animal and human waste, and possibly other types of waste that could cause some type of concern.”
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Impact on main agricultural production
The researcher recalls that the state is among the most important in the country in agricultural production, which will have negative impacts at a national level.
“Rio Grande do Sul is the second largest food producer in Brazil. 14% of national production is in RS. It is the largest producer of rice and wheat, the second largest producer of soybeans, the third largest producer of pigs, the larger quarter of chicken and milk.”
The most recent report on the 2023/2024 harvest from the Riograndense Rice Institute (Irga) points out that, of the approximately 900 thousand hectares of irrigated rice, 758 thousand hectares had been harvested.
Of the remaining 142 thousand hectares, almost 23 thousand hectares were completely lost. Another 18 thousand were partially submerged by the waters, leaving 101 thousand not affected by the floods.
According to the National Supply Company (Conab), before the tragedy, around 17% of rice had not yet been harvested in the state. The entity estimates a loss of 230 thousand of the 7.1 million tons, due to heavy rains. “Half of our rice is produced in the Uruguay basin, which did not suffer as much from the flood issue”, ponders Meirelles.
In addition to being the main rice producer, Rio Grande do Sul is the second largest soybean producer in the country. According to Conab, around 35% of the oilseed crop was still to be harvested. Losses are expected to reach 700 thousand tons of grain.
By Brasil 61
