Degradation reduces the soil’s planting capacity, but research suggests it can be restored
Study published in the magazine Applied Soil Ecology analyzed the impact of desertification in the Caatinga and found that degradation reduces soil functionality by more than 50%, reducing its ability to support plant growth and promote human and animal well-being. Another consequence highlighted by the article is the reduction in carbon sequestration.
The investigation was conducted by scientists from UFC (Federal University of Ceará) and Greenhouse Gas Innovation Research Center (RCGI) from USP.
Fifty-four soil samples obtained during dry and rainy seasons were analyzed in three different territories of the Irauçuba Desertification Center, in northern Ceará, each of which has areas of native, degraded and restored vegetation.
The reduction of more than 50% in soil functionality was calculated through several physical, biological and chemical analyses in areas degraded by human action. From a physical point of view, the soil was significantly compromised, mainly due to compaction caused by animal trampling.
“This phenomenon reduces porosity, preventing water infiltration and, consequently, ends up accelerating the soil erosion process”says Antonio Yan Viana Lima, a PhD student at Esalq (Luiz de Queiroz College of Agriculture) at USP, a researcher at RCGI and the first author of the article.
“From a biological point of view, the indicators of microbial composition, carbon content and enzymatic activity were favorable for vegetation growth and carbon sequestration”says Lima. “But we saw little variation in chemical indicators between the areas studied, including between restored and degraded areas. This shows that biological components are important indicators of soil health because they respond readily to human disturbances.”says the researcher.
“In restored areas, we found that, by preventing human action, it is possible to achieve physical, chemical and biological indexes close to their original composition”says Arthur Pereira, professor at UFC and coordinator of the study.
According to him, the restored areas are fields that were completely fenced off more than two decades ago in order to prevent human activity and the movement of animals. No species were planted in these fields, because the idea was to see if and how the vegetation could regenerate naturally without such interference.
“The interesting thing is that the results of the analyses in these areas, in all aspects, were very close to what was seen in the areas of native vegetation. Thus, over the course of two decades, it has been possible to recover the health of the soil, which may also be promising for carbon sequestration, since these lands recorded higher values of total and microbial carbon stocks.”says Pereira.
METHODOLOGY
The study used the tool Soil Management Assessment Framework (SMAF) in the semiarid region. Used to assess soil health, this tool is based on calculations performed by algorithms that place the results of the factors analyzed on a scale of 0 to 100, with 100 being the most positive. From this, a final number is reached that corresponds to a soil health index.
The group of researchers is now expanding the analysis to the other 3 desertification centers in the semi-arid region, to verify, with the help of SMAF, whether the situation observed in Irauçuba represents the entire caatinga and whether there are other techniques for recovering degraded soils.
These new ventures are being developed within the Caatinga Microbiome Initiative project, an inter-institutional initiative, created in 2022, which involves more than 20 professors and researchers from Brazil and abroad, with the aim of studying the Caatinga microbiome and its relationship with soil health.
The research is part of several projects under the RCGI’s Nature Based Solution programme, which is an Engineering Research Centre (CPE) formed by FAPESP and Shell, with support from several companies. Among the center’s initiatives is project 53, which develops integrated agricultural systems, a strategy of creating a variety of productions in the same area, respecting the seasonality of each crop.
The article Grazing exclusion restores soil health in Brazilian drylands under desertification process can be read here.
With information from FAPESP Agency.
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