Article

Degradação dos solos – abordagens teóricas e estudos de casos, ao longo de 25 anos (1994 – 2019), no âmbito do LAGESOLOS (1)

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Abstract

ABSTRACT This paper addresses soil erosion, land degradation, geotourism, geodiversity and geoconservation, carried out by LAGESOLOS members (Laboratory of Environmental Geomorphology and Soils Degradation), in the last 25 years. Some sites within 10 states have been surveyed, so far, taking into consideration different techniques and methodologies, to investigate soil erosion, such as experimental stations, stakes placed around the gullies, to monitor their retreat, and currently we have been using modern techniques, such as VANTs, to monitor gullies and rills. These investigations have led us to publish over 100 papers, in national and international journals, over 20 books and over 40 chapters in national and international publications, besides over 100 papers in Brazilian and International Conference and Symposium proceedings. More recently, we have also been looking at geotourism, geodiversity and geoconservation, which has led us to understand and to contribute towards this new field, within Geography; everything in partnership with Brazilian and oversea researchers. Keywords: Soil erosion. Land degradation. Experimental station

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Thesis
Most of the soils in the world were developed under forest cover, but from the end of the 1700s (industrial revolution) the burning of coal caused a significant change in the way to use the soils, now excavated, mined and occupied. With the cities growing, it became necessary to intensify deforestation in order to provide new areas for these cities (BLUM, 2018). The general objective of the present work was to identify and map the types of soils, using toposequences, in a farm, located in the city of Silva Jardim, preparing soil mapping (1:10.000) and productive units mapping. For this, the Dom Bosco farm was chosen, where soil sequences from a transect were analyzed, with the opening of 9 soil trenches, respecting the positions of slope top, slope middle and slope base. Morphometric data and agricultural use were collected from the use of UAV and GNSS; which made possible to create a series of characterization maps. The orthophotomosaic generated has presented high resolution, it was possible to identify different agricultural cultures and uses. Studies on the different uses of the farm are complex, this entire area was initially deforested, with citrus culture being stablished, and later these areas gave up space to pasture, much of them degraded. The farm morphographic characterization reveals gently undulating hills, with an altitude between 3 meters and 65 meters, with 88% of the declivity varying from 3% to 45%. Plain areas can be observed, influenced by the local drainage scheme up to the Dam of Juturnaíba. It is interesting to note also that 32% of the areas have a slope of 20% to 45%, meaning that despite of being considered low altitude, a part of these hills have a higher slope, which requires an understanding and differentiated treatment in these areas that together to Argisoil-type soil become highly susceptible to erosion. As per the slopes curve, most of it (60%) presents a straight pattern. The farm's soils follow the clear sequence pattern of Ultisols and hydromorphic soils at the base of their slopes extending to the plains. Micromorphology points to A horizonts with contents mixed with subsuperficial materials, being called Ap horizont. Cutan presence was noted at several Bt horizonts. Soil mapping shows predominancy of RO mapa de solos mostra a predominância de Red-Yellow argisoil, yellow argisoil and gleisoil. It were defined and mapped 7 productive units that replace the production tract scheme, previously used at the farm. It is expected that the productive units mapping carried out may help agricultural production management, as well as soil handling, avowing its degradation. This way, this study area can be set as an example for other areas in the region.
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ABSTRACT The erosion process acts naturally on soils and rocks modifying the relief, and the soils are a factor that influences its occurrence and intensity. The prevention and recovery of these events require resources and planning that consider the specifics of the physical environment, in addition to the social conditions of urban development. In this sense, this study aims to make a spatiotemporal analysis associated with physical parameters of the soil of the gully located in the southern portion of the lower Parnaíba river watershed, in area of the municipality of Miguel Alves, state of Piauí, developed in sediments from the Piauí Formation. For this purpose, satellite images from the years 2007 and 2017 were used. Soil samples were collected on the slopes of the erosive features, carrying out laboratory tests (density and porosity), in addition to field tests (photographic records, recognition of the area and sample collection). The laboratory analyzes followed the methods of Teixeira et al. (2017). With the completion of the work, it was noticed an increase in the gully process in the period studied, increasing its coverage area by (21.85%), in a more detailed analysis scale related to the physical aspects of the soil, it is observed that its characteristics demonstrate great susceptibility to erosion processes, which contributed, along with anthropogenic influences, to accelerate erosion in the area.
Article
Full-text available
The erosion process acts naturally on soils and rocks modifying the relief, and the soils are a factor that influences its occurrence and intensity. The prevention and recovery of these events require resources and planning that consider the specifics of the physical environment, in addition to the social conditions of urban development. In this sense, this study aims to make a spatiotemporal analysis associated with physical parameters of the soil of the gully located in the southern portion of the lower Parnaíba river watershed, in area of the municipality of Miguel Alves, state of Piauí, developed in sediments from the Piauí Formation. For this purpose, satellite images from the years 2007 and 2017 were used. Soil samples were collected on the slopes of the erosive features, carrying out laboratory tests (density and porosity), in addition to field tests (photographic records, recognition of the area and sample collection). The laboratory analyzes followed the methods of Teixeira et al. (2017). With the completion of the work, it was noticed an increase in the gully process in the period studied, increasing its coverage area by (21.85%), in a more detailed analysis scale related to the physical aspects of the soil, it is observed that its characteristics demonstrate great susceptibility to erosion processes, which contributed, along with anthropogenic influences, to accelerate erosion in the area. Key words: Gully. Soil erosion. Monitoring.
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