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2 resultados encontrados para: AUTOR: Cardoso, Irene M.
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1.
Artículo
*En hemeroteca, SIBE-San Cristóbal
Distribution of mycorrhizal fungal spores in soils under agroforestry and monocultural coffee systems in Brazil
Cardoso, Irene M. ; Boddington, Claire (coaut.) ; Janssen, Bert H. (coaut.) ; Oenema, Oene (coaut.) ; Kuyper, Thomas W. (coaut.) ;
Contenido en: Agroforestry Systems Vol. 58, no. 1 (2003), p. 33-43 ISSN: 0167-4366
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
B1535 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal
Resumen en: Inglés |
Resumen en inglés

Deep-rooting trees in agroforestry systems may promote distribution of spores of arbuscular mycorrhizal fungi (AMF) at deeper soil levels. We investigated the vertical distribution of AMF spores in Oxisols under agroforestry and monocultural (unshaded) coffee systems in on-farm experiments (Brazil). The number of AMF spores was considered as an indicator of mycorrhiza incidence in soil. Spores were extracted from 0–1, 2–3, 5–7.5, 10–15, 20–30, 40–60 cm soil-depths in agroforestry and monocultural coffee systems, of three different age groups (young, medium-aged and old), using centrifugation methods, and counted. Fine roots were collected and dry-weighed from 0–30 cm in young and old systems and from several depths in medium-aged systems. Soils were characterised with respect to texture, pH, organic matter, calcium, magnesium, phosphorus and potassium. Agroforestry had a higher percentage of spores (12–21% of the total number of spores) and roots (on average 1.5 g L–1 soil) in deeper layers (20–60 cm), and a lower percentage (79–88%) closer to the surface (0–15 cm) than the monocultural fields (respectively 3–12%, 0.6 g L–1 soil and 88–97%). Greater numbers of spores in the deeper soil layers may be explained by greater amounts of roots and may be an indicator of greater incidence of mycorrhiza in agroforestry than in monocultural coffee systems. Greater mycorrhizal incidence at deeper soil layers in the agroforestry system may change the dynamics of phosphorus cycling in soil, making this nutrient more available to plants.


2.
Artículo
*En hemeroteca, SIBE-San Cristóbal
Phosphorus pools in oxisols under shaded and unshaded coffee systems on farmers' fields in Brazil
Cardoso, Irene M. ; Janssen, Bert H. (coaut.) ; Oenema, Oene (coaut.) ; Kuyper, Thomas W. (coaut.) ;
Contenido en: Agroforestry Systems Vol. 58, no. 1 (2003), p. 55-64 ISSN: 0167-4366
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
B1536 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal
Resumen en: Inglés |
Resumen en inglés

Phosphorus (P) is a primary limiting nutrient for crop production in weathered tropical soils. The deficiency is mainly caused by sorption of phosphate onto Al- and Fe- (hydr)oxides. We hypothesise that the distribution of soil P among various pools is influenced by land use. Our objective was to characterise the soil inorganic (Pi) and organic P (Po) pools and to compare the various pools at different depths in agroforestry (shaded) and monocultural (unshaded) coffee cultivation systems. The study was carried out in the Atlantic Coastal Rainforest domain, Brazil, with Oxisols as the dominant soil type. Soils were collected from four farmers' coffee (Coffea arabica L.) fields, two agroforestry and two monocultural systems. Three profiles were sampled per field, at depths of 2–3, 10–15 and 40–60 cm. A simplified sequential P fractionation was carried out, using resin, 0.5 M NaHCO3, 0.1 M NaOH, 1 M HCl and concentrated HCl as extractants. Sum-P (resin, NaHCO3 NaOH, 1 M HCl and concentrated HCl) ranged from 370 to 830 mg kg–1. Concentrated HCl extracted the largest portion (74%), followed by NaOH (22.5%). Labile (sum of resin, NaHCO3 and NaOH) P ranged from 13 to 40% of Sum-P. The major part (62%) of the labile fraction was Po. In the agroforestry fields, the amount of Po decreased less with depth and the percentage of Po in labile pools was higher than in monocultural fields. This suggests that agroforestry maintains larger fractions of P available to agricultural crops by influencing the dynamics of P through the conversion of part of the Pi into Po, thereby reducing P losses to the unavailable pools.