Processos Pedogenéticos E Susceptibilidade Dos Solos À Degradação No Semiárido Brasileiro

Abstract

As relações dos processos pedogenéticos específicos e a susceptibilidade dos solos à degradação no semiárido nordestino ainda não foram satisfatoriamente esclarecidas. Esse entendimento pode subsidiar intervenções e políticas públicas que atenuem e/ou revertam à degradação dos solos. O objetivo dessa pesquisa foi avaliar a relação entre processos pedogenéticos específicos e a susceptibilidade dos solos a degradação/desertificação nas microrregiões do Seridó e Cariri. Foram atualizadas as classes de solos das unidades de mapeamento (UM) dos estados da Paraíba e Rio Grande do Norte. Essas novas UM foram sobrepostas com áreas fortemente degradadas (AFD). Áreas degradadas estão predominantemente associadas com Luvissolos Háplicos Pálicos abrúpticos e Neossolos Litólicos Eutróficos típicos e fragmentários no Seridó e com Luvissolos Crômicos Órticos típicos e vertissólicos no Cariri. O predomínio da agropecuária na maioria das AFD confirma a forte pressão antrópica sobre o meio ambiente. A mudança textural abrupta aumenta a susceptibilidade dos Luvissolos e Planossolos à degradação. Antrossolização pode acelerar a erosão, salinização, sodificação e solodização. Como consequência tem-se perdas de solos, de sua qualidade física e assoreamento de corpos hídricos. As relações entre processos pedogenéticos e degradação das terras são compreendidas com a avaliação dos solos em níveis categóricos mais elevados (subgrupo).

Effects of Degradation on Soil Attributes Under Caatinga in the Brazilian Semi-Arid

“…Thus, in this research we seek to evaluate the physical, chemical and biological attributes of soil layers exposed on the surface by land degradation, where even after interventions and actions towards reforestation, it still has a slow capacity for vegetation regeneration. This scenario is similar to that observed for other regions in the SAB, where extensive heavily degraded areas have truncated soils, with subsurface horizons of high unavailability for agricultural use exposed on the surface (CGEE, 2016;Macedo et al, 2021).…”

Seasonal precipitation and anthropogenic pressure affect the water quality of reservoirs in the highland humid forest enclaves

“…From this perspective, area surrouding of the Lagoa do Paó reservoir show a predominance of Leptic Luvisols (Loamic, Differentic) (IUSS Working Group WRB, 2022) formed by orthogneiss and granodiorite migmatites, whose main characteristics are: i) high nutrient levels (eutrophic soils), with P contents that can reach 50 mg dm -3 (Santos et al, 2017); ii) soil horizons with a sandy and/or average texture over clayey layers (abrupt textural change), which decreases soil permeability and considerably increases the risk of erosion (Macedo et al, 2021); iii) a chromic character, due to the occurrence of primary iron oxides such as hematite and/or pedogenic iron oxides formed from the weathering of biotite in the melanocratic band of the gneiss parent material (Câmara et al, 2021); iv) temporary hydromorphy, with the common occurrence of features related to the reduction of Fe oxides.…”

Assessment of Soil Quality of Smallholder Agroecosystems in the Semiarid Region of Northeastern Brazil

“…This mainly occurs when high Na + concentrations enhance colloidal dispersion, reduce soil permeability, and deteriorate the soils structure, indicating a regressive process of pedogenesis. This mechanical dispersion of clay from soil into water also may avoid considerable losses of the surface layer of these Luvisols, which are highly susceptible to erosion, with consequent exposure on the soil surface of horizons with high levels of salts (salinization) and sodium (sodification) [37].…”

“…The considerable Ca 2+ contents in the agroecosystems reflect both management practices commonly used in the semiarid region, such as manure application and incorporation of crop residues in soils [15], and the hydrolysis of easily weatherable primary minerals, such as feldspars and plagioclase, present in the leucocratic layers of the gneiss parental material [35]. These plagioclases are also the primary source of Na + release in soils, and their importance in BS can be explained by agricultural practices occurring directly in the subsurface horizon (textural B), especially given the occurrence of erosion processes [37].…”

“…Agricultural practices, especially manure application and cover crops, are responsible for inputting these macronutrients crucial to sustainable soil fertility and crop production, and thereby providing agroecosystem services. However, the application of manure with high rates of phosphates and nitrogenous compounds, followed by runoff and leaching, can contribute directly to the salinization of groundwater, primarily due to the greater susceptibility to erosion processes in the region due to the occurrence of Luvisols, with abrupt textural changes associated with sloping to strongly sloping relief [37]. In this sense, it is still important to conduct research defining the critical environmental limit of these nutrients for the Brazilian semiarid soils to avoid the pollution of natural resources.…”