Foliar nutrient levels of native tree species from Central Amazonia. 2. Campina

Adult leaves of 14 woody species were sampled in the campina at km 62 of the road Manaus - Caracaraí. The lamina were classified as to their size and analysed for N, P, K, Ca, Mg and Na. Comparing the foliar levels of the bioelements to relevant data for other neotropical woody vegetation, they are much below those of forests from geochemically richer areas (Amazon várzea and certain other floodplains, volcanic areas) and resemble the foliar bioelement levels of terra firme vegetation

Soil Carbon in Agroforestry Systems: An Unexplored Treasure?

Soil organic matter (SOM), which contains more reactive organic carbon (C) than any other single terrestrial pool, plays a major role in determining C storage in ecosystems and regulating atmospheric concentrations of carbon dioxide (CO2)^1^. Agroforestry, the practice of growing trees and crops in interacting combinations on the same unit of land^2^, primarily by resource-poor smallholder farmers in developing countries, is recognized as a strategy for soil carbon sequestration (SCS) under the Clean Development Mechanism (CDM) of the Kyoto Protocol^3^. The understanding about C storage and dynamics under agroforestry systems (AFS), however, is minimal. Our studies under various AFS in diverse ecological conditions in five countries showed that tree-based agricultural systems, compared to treeless systems, stored more C in deeper soil layers up to 1 m depth under comparable conditions. More C is stored in soil near the tree than away from the tree; higher SOC content is associated with higher species richness and tree density; and C3 plants (trees) contribute to more C in the silt- + clay-sized (<53 µm) fractions that constitute more stable C, than C4 plants, in deeper soil profiles4 - 8. These results provide clear indications of the possibilities for climate change mitigation through SCS in AFS, and opportunities for economic benefit - through carbon trading - to millions of smallholder farmers in developing countries

Relationship between soil, landscape and geological substrate of the sandy coastal plain of São Paulo state

Atributos morfológicos de 28 pedons, descritos e amostrados em cronossequências, e datações absolutas por luminescência (TL e LOE) e 14C foram utilizados para elucidar os principais fatores envolvidos na formação e evolução dos Espodossolos nos depósitos marinhos quaternários da planície costeira do Estado de São Paulo. Os solos estudados localizam-se nos municípios de Bertioga (Baixada Santista), Cananeia e Ilha Comprida (Litoral Sul). Essa abordagem, pouco comum nos estudos dos ambientes de planície costeira brasileiros, possibilitou as seguintes interpretações: (a) o relevo, a dinâmica hídrica e o tempo (incluindo as variações do nível relativo do mar) são os principais condicionantes da diferenciação espacial dos Espodossolos nos terraços marinhos; (b) os Espodossolos mais antigos e bem drenados, devido às condições de relevo e rebaixamento do nível do lençol freático, apresentam grande variabilidade e diversidade de seus horizontes e atributos morfológicos, diferindo daqueles mal drenados (antigos ou jovens), em que os horizontes são mais homogêneos; (c) os Espodossolos mais antigos, quando bem drenados, mostram-se em avançado estádio de degradação, enquanto os mal drenados encontram-se bem preservados, indicando que a sua gênese e permanência na paisagem estão ligadas ao relevo, que, por sua vez, controla a dinâmica hídrica; (d) os Espodossolos mais evoluídos e antigos, dotados de horizontes cimentados (orstein), podem ser considerados indicadores pedolitoestratigráficos dos depósitos marinhos pleistocênicos da Formação Cananeia; e (e) a gênese do horizonte orstein se deu em condições topográficas e hidrológicas pretéritas diferentes das atuais, indicando se tratar de solos poligenéticos ou paleossolos.This paper presents the results of morphological properties and absolute dating by luminescence and 14C of 28 pedons from Quaternary marine deposits located in three counties along the coast in São Paulo State, Brazil: Bertioga, Cananéia, and Ilha Comprida. The objective was to provide evidence to elucidate the main processes of the genesis of Spodosols. This approach, which is unusual in research concerned with Brazilian Quaternary coastal plains, resulted in the following interpretations: (a) relief, hydrologic conditions and time were the main soil formation factors responsible for the spatial differentiation of the Spodosols in marine terraces; (b) The horizon morphologic features of the most aged and well-drained Spodosols are highly variable and diverse. On the other hand, poorly drained Spodosols (old or young) are more homogeneous; (c) the oldest Spodosols, when well-drained, are in an advanced degradation stage while the poorly drained are well-preserved. This suggests that the genesis and permanence of the Spodosols on the landscape depend on the relief features controlling the hydrologic dynamics; (d) the most aged and developed Spodosols with orstein horizons can be considered lithostratigraphic indicators of marine deposits of the Pleistocene age in the Cananéia Formation; (e) the orstein horizon genesis took place under ancient topographic and hydrologic conditions that differ from the current. This indicates that such Spodosols are polygenetic or paleosols.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)FAPES

La genèse des podzols

Les podzols sont des sols acides de milieux forestiers caractérisés par l'accumulation de fer (Fe) et d'aluminium (Al) dans l'horizon B (horizon B podzolique). Ils couvrent de vastes étendues des zones boréales et tempérées humides et sont associés à des substrats à texture grossière. La connaissance des mécanismes responsables de la formation des podzols est essentielle à la compréhension, la modélisation et la gestion des écosystèmes forestiers, agricoles et aquatiques et à la prévision de leurs réactions face à des changements des conditions environnementales. Quatre théories majeures, ou modèles conceptuels, ont été proposées afin de représenter la genèse des podzols : la théorie des fulvates (Stobbe et Wright, 1959; McKeague et al., 1978), la théorie de la proto-imogolite (Farmer et al., 1980; Anderson et al., 1982), la théorie des compartiments chimiques (Ugolini et Dahlgren, 1987) et la théorie des polymères d'AI (Browne, 1995). Celles-ci ont mis en relief le rôle de certains processus tels que la création et le transport de complexes organo-métalliques, la synthèse de la proto-imogolite et la néoformation d'imogolite, l'altération des minéraux par l'acide carbonique (H2CO3) ainsi que la formation de complexes polymériques dissouts de type Al-silice (Si). L'importance accordée à chacun de ces processus varie toutefois en fonction de la nature des milieux prospectés lors de la définition d'une théorie particulière. L'absence d'une théorie globale et intégrée de la genèse des podzols est aussi liée à la compréhension incomplète de la dynamique des podzols, à l'omission de certains processus importants et à l'apparente opposition entre les théories.Podzols are acidic soils of forested areas characterized by the pedogenic accumulation of iron (Fe) and aluminum (Al) in the B horizon (podzolic B horizon). Podzols cover large areas of the wet temperate and boreal zones and are associated to coarse parent materials. Knowledge on podzol genesis is of considerable interest with respect to the understanding, modelling and management of forested, agricultural and aquatic ecosystems and to the forecasting of soil changes in response to environmental perturbations. Four theories, or conceptual models, were formulated to describe podzol formation: the fulvate theory (Stobbe and Wright, 1959; McKeague etal., 1978), the proto-imogolite theory (Farmer et al., 1980; Anderson etal., 1982), the theory of chemical compartments (Ugolini and Dahlgren, 1987) and the Al polymer theory (Browne, 1995). Each theory emphasizes the role of specific processes such as the formation and transport of organo-metallic complexes, proto-imogolite synthesis and imogolite precipitation, mineral weathering by carbonic acid (H2CO3) and the formation of poiynuclear Al-silicate soluble complexes. However, the relative importance attributed to any of these processes varies as a function of the properties of the sites explored by the authors of a given theory. The absence of an integrated theory of podzol genesis also reflects our incomplete understanding of podzol dynamics, the fact that important processes have been left out and the apparent opposition between theories.Podsols sind saure Bôden waldiger Milieus, charakterisiert durch die Anhâufung von Eisen (Fe) und Aluminium (Al) im B-Horizont (podsolischer B-Horizont). Sie bedecken ausgedehnte Flâchen der nôrdlichen und feuchten gemassigten Gebiete und werden mit Substraten grober Textur in Verbindung gebracht. Die Kenntnis der Mechanismen, die zur Bildung der Podsols fuhrt, ist unerlàsslich fur das Ver-stàndnis, die Modellierung und Bewirtschaftung der Forst-, Landwirtschaft- und Wasser-Okosysteme und fur die Vorhersage ihrer Reaktionen auf Verànderungen in den Umweltbedingungen. Vier Haupttheorien oder Denkmodelle wurden zur Darstellung der Genèse der Podsols vorgeschlagen : die Theorie der Fulvate (Stobbe und Wright, 1959; McKeague etal., 1978), die Proto-Imogolit-Theorie (Farmer et al., 1980 ; Anderson et al.,1982), die Théorie der chemischen Abteilungen (Ugolini und Dahlgren, 1987) und die Al-Polymer-Theorie (Browne, 1995). Diese Theorien haben die RoIIe bestimmter Prozesse hervorgehoben, wie die Bildung und den Transport organischmetallischer Einheiten, die Synthèse des Proto-lmogolit und die Neubildung von lmogolit, die Verânderung der Minérale durch die Kohlensâure (H2CO3) sowie die Bildung von aufgelôsten Polymer-Einheiten des Typs Al-Silizium (Si). Die Bedeutung, die jedem dieser Prozesse zugemessen wird, variiert jedoch je nach der Natur der bei der Aufstellung einer bestimmten Théorie untersuchten Milieus. Das Fehlen einer globalen und integrierten Théorie der Entstehung der Podsols hàngt auch mit dem unvollstàndigen Verstândnis der Dynamik der Podsols, dem Weglassen gewisser wichtiger Prozesse und dem offenbaren Gegensatz zwischen den Theorien zusammen

Fertility and suitability of the Spodosols formed on sandy beach ridges interspersed with Swales in the Kelantan - Terengganu Plains of Malaysia for kenaf production.

A study was conducted to evaluate the suitability of sandy soils in the Kelantan - Terengganu Plains (Peninsular Malaysia) and suggest measures to improve their fertility for kenaf production. The coastal landscape is scarcely utilized for crop production due to the inherently low soil fertility, nutrient imbalance and water deficit which can seriously inhibit crop growth. Three sandy Spodosols with humus - rich spodic horizon were found, locally named as Rhu Tapai, Rudua and Jambu Series with sandy matrix (>95% sand), low CEC (0.16-4.52 cmolc kg-1) and high acidity (pH 4-5). The mineralogy data showed quartz (dominant), with gibbsite, hematite and feldspars in trace amounts that result from high degree of weathering. The Corg of Bs and Bhs horizon was about 2%, with C/N ratio of 14 to 25, respectively; this can be exploited for kenaf production. Hence, we evaluated these sandy Spodosols for kenaf production using Wong (2009) Crop-Suitability Classification and found the soil to be marginally suitable under Class 4 described as 4Dnt where D stand for drainage, n for nutrient and t for texture. The major limitations were found to be excessive drainage, nutrient imbalance and sandy texture. Therefore, management practices recommended to improve the soils are (1) mulching the soils with different types of organic materials to retain water and plant nutrients; and (2) irrigating the soils during the dry period. If these agronomic practices are carried out, these soils could be productively used for growing kenaf