Qualidade de solo em áreas de cambissolo com diferentes manejos de pastagem

Abstract

ResumoAtualmente, busca-se nas atividades agrosilvopastoris a obtenção do maior retorno dos investimentos com equilíbrio social e sem degradar o meio ambiente. O objetivo deste trabalho foi avaliar a qualidade física e química de um Cambissolo, após 30 anos sob dois manejos de pastagens. O trabalho foi realizado em uma microbacia situada na Bacia do Alto Rio Grande (MG), em dois tipos de manejos de pastagem extensiva comuns na região: pastagem nativa sem queimada anual e pastagem nativa manejada com queimada anual, e em uma área de reserva legal que serviu de referência. Nessas áreas foram analisados: CTC pH7,0 , matéria orgânica, densidade e porosidade do solo. De acordo com os resultados obtidos concluiu-se que os valores de densidade do solo, matéria orgânica, capacidade de troca de cátions e macro porosidade não diferiram na camada de solo analisada (0-10 cm) nos dois manejos estudados. Os polígonos formados no gráfico radial, comparando a área referência com os dois manejos estudados, são de magnitude e formato diferentes ao formado pelos valores de referência, indicando que o manejo sem queimadas anuais deve ser melhorado em relação à densidade do solo; já o manejo com queimadas anuais deve ser melhorado em relação à densidade, matéria orgânica, capacidade de troca de cátions e macroporosidade do solo. Palavras-chave: Atributos físicos, atributos químicos, degradação do solo AbstractCurrently, we seek to agronomy, forestry and pastoral activities to achieve the greatest return on investment with social equity, without degrading the environment. The objective of this study was to evaluate the physical and chemical quality of a Inceptisol after 30 years under two grazing managements. The study was conducted in a watershed located in the Upper Rio Grande (MG) in two types of extensive grazing managements common in the region: native pasture without burning native pasture and annual managed with annual burning, and a legal reserve area used as a reference. These areas were analyzed: CTC pH7,0 , organic matter, soil density and porosity. According to the results obtained it was concluded that the values of bulk density, organic matter, cation exchange capacity and macro porosity did not differ in the analyzed soil layer (0-10 cm) in two management studies. The polygons formed in the radial graph, comparing the reference area with the two management studies, are of different magnitude and the shape formed by the reference values, indicating that the annual burning without management should be improved in relation to the density of the soil, whereas the management with annual fires should be improved in relation to the density, organic matter, cation exchange capacity and soil macroporosity.

Phytosociological Survey of Weeds on Degraded and Well-Managed Pastures: Agronomical and Ecological Implications

“…It appears that physical attribute is closely related to the soil structure when analyzing soil density (Valle, 2018). In this way, density monitoring over time is the key part in investigating the use and management of soil physical quality (Ferreira, 2012). Higher soil density values are observed in the levels of degradation N 2 and N 3 , both in surface and in depth, confirming the evidence of compaction (Table 2).…”

“…Considering that an aeration porosity lower than 0.10 m³ m -³ or 10% is harmful to agricultural production by compromising the soil gas exchange, it is noted that all macroporosity values are lower than this reference value (Table 2). Since macropores are scarce, the diffusion of CO 2 and O 2 in the water predominates over the diffusion in the air (Ferreira, 2012) and also compromising the infiltration of water into the soil (Oliveira et al, 2015). Threfore, under extreme conditions of compaction of the soils, some weeds have adapted to this unfavorable situation.…”