Due to the floods in April and May of last year, Serra Gaúcha lost more than 85% of the carbon stock in the soil of the region’s orchards. Replenishing this important nutrient may take between 14 to 40 years.
The information comes from a study released by agronomy professor Gustavo Brunetto from the Federal University of Santa Maria (UFSM) at the RS Resilience and Sustainability seminar held at the Federal University of Rio Grande do Sul (UFRGS). The event discussed topics related to the impacts of last year’s flood, aspects of climate change, and alternative solutions to face the concerning scenario.
In the case of the soil, Professor Gustavo Brunetto explained that the floods are likely to compromise the work of farmers seeking fertility in their crops. He contextualized that the cities of Serra Gaúcha were among the most affected regions by the rain in a short period.
“This stimulated the runoff of water on the surface, the transfer of soil from higher parts to lower parts, and as a result, we had significant consequences and damages.”
He explained that the first damage was the loss of soil, especially the top layer, since not all the water was able to infiltrate.
“Therefore, we had a loss of nutrients that are normally in the soil and are sources for plants to grow, produce, and have a quality product.”
Part of the organic matter and nutrients went to lower parts of the terrain and also into surface waters.
“In the future, this could lead to water contamination. This damage occurred due to excessive precipitation. We had soil loss in uncultivated areas as well as in cultivated areas.”
Risks
He assessed, based on the study conducted in the city of Bento Gonçalves, for example, that there was also a decrease in phosphorus levels in the landslide areas.
“If the areas that were degraded by excessive rain are re-incorporated into agriculture, the farmer will have to buy more fertilizer. As a result, he will likely see an increase in his costs on the property.”
The loss of phosphorus, as Brunetto noted, can lead to water contamination. “We had a loss of organic matter in the soil. Consequently, we lost an important source that will provide nutrients for the plants.”
Solutions
The UFSM professor identifies that to replenish nutrients, knowledge and investment are necessary. He stated that strategies are needed so that in the future, when this happens again, there is a possibility to minimize this problem. He also points out that leveling the soil is necessary for the farmer to be able to cultivate his area again.
The researcher reiterates that the way forward is to use recognized and accepted techniques in agronomy, such as liming (a practice to correct acidity, neutralize aluminum, and provide calcium and magnesium) and fertilization.
“We need to implement the use of cover crops that can be utilized.”
He advocated for conservationist management practices. In addition to the use of cover crops, the use of terraces in areas, for example, of perennial fruit crops. “It is a way to retain water, stimulate water infiltration, and reduce water and soil loss.”
Social Impact
In addition to the diagnosis about the soil, the event pointed out other impacts, such as the social aspect. Economics professor Gibran Teixeira from the Federal University of Rio Grande (Furg) explained that the floods in the state left a disaster that requires public policies in light of job losses and declining revenue.
To give an idea, he exemplified that in municipalities with only 10% of the population affected, there was a loss of four jobs for every thousand inhabitants, in addition to salary reductions and decreased health assistance.
“The greater the municipality’s exposure to the flood area, the more there are losses of formal employment, declines in municipal revenue, increases in leptospirosis cases, and reductions in visits and all basic health assistance,” says the professor.
In cities with a higher level of exposure (with more than 50% of the population affected), there was the highest volume of formal job losses, admissions, and consequently, a greater decrease in ICMS.
“It practically paralyzed the state’s economy, especially in those municipalities that had a higher level of exposure to flooding,” he emphasized.
Source: Agência Brasil