Soil organic matter pools in a tropical savanna under agroforestry system in Northeastern Brazil

Abstract

RESUMO -This study aimed at quantifying total organic carbon stocks and its pools in Acrisol under agroforestry systems with six (AFS6) and thirteen years old (AFS13), slash-and-burn agriculture (SBA) and savanna native forest (SNF) in northeastern Brazil. Soil samples were collected at 0-0.05 m, 0.05-0.10 m, 0.10-0.20 m and 0.20-0.40 m depths in the dry and rainy seasons to evaluate total organic carbon (TOC) stocks and labile carbon (LC), fulvic acid fraction (C-FAF), humic acid fraction (C-HAF), humin (C-HF) and microbial biomass carbon (Cmic) contents. Additionally, carbon management index (CMI) was determined. Higher TOC stocks (97.7 and 81.8 Mg ha -1 for the 0-0.40 m depth in the dry and rainy seasons, respectively) and LC, humic substances and Cmic contents were observed in the AFS13 in all the depths. CMI also was higher in the AFS13 (0-0. 05 m: 158 and 86; 0.05-0.10 m: 171 and 67, respectively for the dry and rainy seasons) especially when compared to the SBA (0-0.05 m: 5.6 and 5.4; 0.05-0.10 m: 5.3 and 5.8, respectively for dry and rainy seasons). The agroforestry systems increased soil quality through the conservation of organic matter and can be considered an excellent strategy to assurance sustainability in tropical soil of Northeastern Brazil Palavras-chave: Soil quality; Microbial biomass; Carbon management index. 0-0,05 m; 0,05-0,10 m; 0,10-0,20 m; e 0,20-0,40 5 m: 158 e 86, 0,10 m: 171 e 67, respectivamente, nas estações seca e chuvosa), especialmente quando comparado com 05 m: 5,6 e 5,4; 0,10 m: 5,3 e 5,8, respectivamente, nas FRAÇÕES DA MATÉRIA ORGÂNICA DO SOLO NO CERRADO SOB SISTEMA AGROFLORESTAL NO NORDESTE DO BRASIL ABSTRACT -Este estudo teve como objetivo quantificar os estoques de carbono orgânico total e de suas frações em um argissolo sob sistemas agroflorestais com 6 (SAF6) e 13 anos de idade (SAF13), agricultura de corte-e-queima (ACQ) e floresta nativa de Cerrado (FNC) no Nordeste do Brasil. As amostras de solo foram coletadas nas estações seca e chuvosa, nas camadas de m, para avaliar os estoques de carbono orgânico total (COT) e os teores de carbono lábil (CL), fração ácido fúlvico (C-FAF), fração ácido húmico (C-FAH) e humina (C-FH) e carbono da biomassa microbiana (Cmic

Biological properties of disturbed and undisturbed Cerrado sensu stricto from Northeast Brazil

“…The higher TOC content in undisturbed Cerrado sensu stricto indicates that the presence of plant litter contributes to an increase in organic C, whereas soil disturbance through the slash-and-burn practice promotes a strong decrease in TOC content (Tabi et al, 2013;Leite et al, 2014). The decrease in organic C can have a major impact on soil, leading to an overall decline in soil quality due the reduction in available water capacity, nutrient status, and soil structure (Kimble et al, 2001).…”

Short Communication: Soil carbon pools in different pasture systems

“…AND -Andropogon gayanus; BRA -Brachiaria brizantha; PAN -Panicum maximum; CYN -Cynodon dactilon; AFS -Agroforestry system; NV -native vegetation. 4 CMI < 100 (Table 2), indicating high plant input and minimal soil disturbance (Leite et al, 2014). According to Blair et al (1995), a CMI < 100 indicates a strong negative impact of management practices on a soil ecosystem.…”

“…Specifically, the agroforestry system showed a higher CMI than in the Brachiaria, Panicum, and Cynodon. The absence of trees and different pasture management practices reduce the C management index over time, reflecting a decrease in the potential to restore pre-existing carbon stocks (Leite et al, 2014). The agroforestry system showed highest carbon stock values and high C sequestration rate for the rainy and dry seasons, whereas Brachiaria, Panicum, and Cynodon showed the lowest C stock and a high C loss (Fig.…”

Microbial biomass and organic matter in an oxisol under application of biochar

“…In tropical soils from Brazil, the maintenance and enhancement of carbon (C) stocks is challenging, since the decomposition of organic C by soil microorganisms is fast and stimulated by high temperatures and soil moisture (Santos et al 2011;Leite et al 2014). The adoption of suitable soil management practices becomes important to provide regular inputs of organic C and, therefore, increase C stocks.…”