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Santiago W.R.,Federal Rural University of Amazonia | Vasconcelos S.S.,Embrapa Amazonia Oriental | Kato O.R.,Embrapa Amazonia Oriental | Bispo C.J.C.,Natura Inovacao e Tecnologias de Produtos Ltda | And 2 more authors.
Acta Amazonica | Year: 2013

The success of oil palm (Elaeis guineensis Jacq.)-based agroforestry systems (oil palm-AFS) depends on sustainable soil management, especially of soil chemical and microbiological characteristics. Our objective was to evaluate the impact of oil palm-AFS on soil mineral and microbial nitrogen (N) in contrasting rainfall seasons. We evaluated different soil nitrogen (N) forms (microbial-N, nitrate, ammonium) and soil carbon concentration in oil palm-AFS with low and high diversity of species planted, which were compared with an adjacent 13-yr-old secondary forest. Most variables (total N, C:N ratio, microbial-N, microbial-N:total N ratio, ammonium, and net nitrification rate) varied only in response to rainfall seasonality. Soil C was significantly higher in the high diversity AFS (15.6 mg g-1) than in the secondary forest (13.0 mg g-1). In the rainy season, nitrate concentration (5.1 mg N kg-1 soil) was higher in the high diversity AFS than in other vegetation types; consequently, the average soil ammonium concentration (9.6 mg N kg-1 soil) was significantly lower in the high diversity AFS. Net N mineralization in the low diversity AFS (0.1 mg N kg-1 soil day-1) in the dry season was significantly lower than in other vegetation types. The soil variables were more sensitive to the rainfall seasonality than to the conversion of secondary forest to oil palm-based agroforestry systems. Source


de Carvalho W.R.,University of Amazon | Vasconcelos S.S.,Embrapa Amazonia Oriental | Kato O.R.,Embrapa Amazonia Oriental | Capela C.J.B.,Natura Inovacao e Tecnologias de Produtos Ltda | And 2 more authors.
Agroforestry Systems | Year: 2014

The current expansion of the oil palm (Elaeis guineensis Jacq.) in the Brazilian Amazon has mainly occurred within smallholder agricultural and degraded areas. Under the social and environmental scenarios associated with these areas, oil palm-based agroforestry systems represent a potentially sustainable method of expanding the crop. The capacity of such systems to store carbon (C) in the soil is an important ecosystem service that is currently not well understood. Here, we quantified the spatial variation of soil C stocks in young (2.5-year-old) oil palm-based agroforestry systems with contrasting species diversity (high vs. low); both systems were compared with a ~10-year-old forest regrowth site and a 9-year-old traditional agroforestry system. The oil palm-based agroforestry system consisted of series of double rows of oil palm and strips of various herbaceous, shrub, and tree species. The mean (±standard error) soil C stocks at 0-50 cm depth were significantly higher in the low (91.8 ± 3.1 Mg C ha-1) and high (87.6 ± 3.3 Mg C ha-1) species diversity oil palm-based agroforestry systems than in the forest regrowth (71.0 ± 2.4 Mg C ha-1) and traditional agroforestry (68.4 ± 4.9 Mg C ha-1) sites. In general, no clear spatial pattern of soil C stocks could be identified in the oil palm-based agroforestry systems. The significant difference in soil carbon between the oil palm area (under oil palm: 12.7 ± 2.3 Mg C ha-1 and between oil palm: 10.6 ± 0.5 Mg C ha-1) and the strip area (17.0 ± 1.4 Mg C ha-1) at 0-5 cm depth very likely reflects the high input of organic fertilizer in the strip area of the high species diversity oil palm-based agroforestry system treatment. Overall, our results indicate a high level of early net accumulation of soil C in the oil palm-based agroforestry systems (6.6-8.3 Mg C ha-1 year-1) that likely reflects the combination of fire-free land preparation, organic fertilization, and the input of plant residues from pruning and weeding. © 2014 Springer Science+Business Media Dordrecht. Source


da Silva C.M.,Federal University of Para | da Silva C.M.,Federal Rural University of Amazonia | Vasconcelos S.S.,Laboratorio Of Analise Of Sistemas Sustentaveis | Mourao Junior M.,Laboratorio Of Analise Of Sistemas Sustentaveis | And 4 more authors.
Acta Amazonica | Year: 2016

The soil carbon dioxide (CO2) efflux dynamics and its controlling factors of Amazonian agroforestry systems are poorly understood. The objective of this study was to evaluate the temporal variation of soil CO2 efflux in oil palm-based agroforestry systems and the relation between efflux and biotic (microbial and total soil carbon, microbial respiration, fine roots, individual components of agroforestry systems (AFS)) and abiotic factors (soil moisture and temperature). The measurements were taken during the less rainy (December 2010) and rainy (May 2011) periods. The soil CO2 efflux was highest during the rainy season, probably due to increased microbial activity influenced by climatic factors coupled with biotic factors. The soil CO2 efflux correlated positively with soil moisture and microbial biomass carbon and negatively with soil temperature and metabolic quotient, but these correlations were weak. The soil CO2 efflux was sensitive to the type of agroforestry system and to rainfall seasonality. © 2015, Instituto Nacional de Pesquisas da Amazonia. All rights reserved. Source

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