Temporal evaluation of soil chemical attributes after slash-and-burn agriculture in the Western Brazilian Amazon

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.

Improved agronomic practices and high yielding rice varieties maintain soil health and enhance yield and energy use efficiency under shifting cultivation landscapes of eastern Himalayas

“…The study was conducted to assess the improved Jhum practices (cultivation of rice across the slopes in lines, using 50% of RDN through organic and inorganic means) and rice genotypes for successfully growing in same site for continuous 3 years. Soil pH is generally enhanced by input of ash from burning in shifting cultivation (Saplalrinliana et al, 2016) that leads to the formation of oxides and release of cations like Ca 2+ , Mg 2+ , and K + (Chatterjee et al, 2022; Neto et al, 2019), especially when the soils are acidic (Chatterjee, 2012; Chatterjee et al, 2022). Addition of basic cations like Ca 2+ , Mg 2+ , and K + due to biomass burning (Chatterjee et al, 2022), reduction in surface runoff and soil loss as relative to traditional Jhum systems may enhanced the soil pH (Chatterjee et al, 2016).…”

The search for a sustainable alternative to slash-and-burn agriculture in the World's rain forests: the Guama Model and its implementation

“…Table 3 gives an example [19]. (12) 555 (17) 484 (12) royalsocietypublishing.org/journal/rsos R. Soc. Open Sci.…”

“…The effect may endure for no more than, perhaps, a year, depending upon the base status of both soil and biomass [ 43 ]. The study of da Silva Neto et al [ 17 ] on an Amazonian ultisol showed that base-saturation peaked at two to three months post-burn and dropped below its starting value within 12 months; no changes occurred below 20 cm depth. However, acid-extractable P in the top 10 cm only, halved from the forest value immediately post-burn and continued to fall away.…”

“…The context is S-B agriculture on the highly weathered, acid soils that are typical of rain forest environments. Most authors agree on the short-term impacts of a burn on soil pH and cations [11,[15][16][17][18], but the possible key role of phosphorus (P) has been markedly elusive and contradictory.…”

Avaliação da variação morfológica, anatômica e fitoquímica de >i<Banisteriopsis caapi>/i< (Spruce ex Griseb.) C.v. Morton e >i<Psychotria viridis>/i< Ruiz & Pav em diferentes ambientes, teor de alcaloides e citotoxicidade do chá Ayahuasca

“…A produção de substâncias ativas em plantas é complexa pois sua composição, metabolismo (Sutcliffe, 1980), biossíntese e acúmulo é fortemente correlacionada com as associações ambientais (Holopainen and Gershenzon 2010;) e variam com as características ambientais envolvidas . O solo, o clima e a disponibilidade de água são os principais fatores (Silva Neto et al 2019) que desafiam a adaptação das plantas (Honda, Pilon, and Durigan 2019).…”