Abstract
In Amazonia, the main causes of deforestation are systems based on slash-and-burn agriculture. The objective of this work was to evaluate temporal changes in the soil chemical attributes after the vegetation has been slashed and burned in an area of native forest in the Western Amazon. For this study, four hectares of forest in Cruzeiro do Sul, State of Acre, Brazil, was slashed and burned. The soil in the study area was classified as Ultisol (Argissolo Amarelo Distrófico típico). Soil samples were collected over the course of one year, the first one being collected 16 hours after the burn and the others at 30, 60, 90, 150, 210, 270, and 360 days after the burn. The soil surface layers were more sensitive to fire action. Ashes from vegetation burn increased pH values, basic cations, and C values only in the first months, resulting in higher basal saturation values (V%). The practice of slash-and-burn after 12 months resulted in lower values of pH, Ca, Mg, K, and P and higher values of Al and H, as well as saturation by aluminum in the soil, indicating this practice contributes to the reduction of soil fertility.
Highlights
The Amazon region comprises an area of approximately six million km2, representing 40% of the rainforest areas of the world, occupying most of the Brazilian territory, and extending into the neighboring countries (Laurance et al, 2001)
This system is based on slash-and-burn agriculture, which is the practice of preparing an area for planting by cutting, drying, and burning the natural vegetation in a patch, which is used for cultivation for a short period of time, after which it is left fallow for a long duration (Pedroso Júnior, Murrieta, & Adams, 2008; Morton et al, 2008)
The selected area is in a smooth-wavy relief, with an altitude of 210m, and the soil is classified according to the Brazilian Soil Classification System (BSCS) as typical Dystrophic Yellow Argisol (Santos et al, 2013)
Summary
The Amazon region comprises an area of approximately six million km, representing 40% of the rainforest areas of the world, occupying most of the Brazilian territory, and extending into the neighboring countries (Laurance et al, 2001) This region has a great diversity of environments with mosaics of multiple vegetation and habitat types whose balance depends on the climate, water quality, soil, nutrient cycling, and other environmental characteristics. The main cause of deforestation is the farming system followed by the Amazonian family farmers for their livelihood This system is based on slash-and-burn agriculture, which is the practice of preparing an area for planting by cutting, drying, and burning the natural vegetation in a patch, which is used for cultivation for a short period of time, after which it is left fallow for a long duration (Pedroso Júnior, Murrieta, & Adams, 2008; Morton et al, 2008). This practice is low cost and easy to adopt and has persisted due to the low fertility of most soils in the region, the high cost of fertilizers and correctives, and the lack of adequate policies to foment and provide relevant technical assistance to this segment of producers
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