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Aims: Ecosystem changes in the mesic savannas of West Africa are resulting in the formation of patches of ‘forest islands’ around local communities in an otherwise open savanna landscape. There have been conflicting reports on the origin of these forest islands with a very limited understanding of their biogeochemistry. This study evaluated the soil mineralogical and chemical characteristics of forest islands and their surrounding ecosystems comprising croplands and open savannas in Burkina Faso, Ghana, and Nigeria to provide information on the processes leading to the formation of forest islands. Methods: Soil mineralogy was determined using X-ray diffractometry (XRD) while the soil nutrients were analysed with ICP-OES and the other soil chemical properties were determined using standard conventional methodologies. Results: Overall, we found that quartz, kaolinite with significant quantities of 2:1 silicate minerals dominated the soil matrix irrespective of land use type. The minerals identified in most of the locations were independent of land use type. This suggests that the forest island formation is not directly related to soil mineralogy. Forest islands showed differences in soil nutrient contents, being richer in exchangeable potassium and dibasic cations than their surrounding savannas and agricultural fields. This superior fertility status of the soils could contribute to the luxuriant growth of the vegetation leading to the development of forest island. The soil nutrient characteristics of the ecosystem types reflect the land use practices with the forest island having higher nutrient and organic carbon contents. Conclusions: The study provided insight into how human-originated soil nutrient enhancement has induced forest island establishment in open savanna landscapes.

FIG. H. T. I ‒ Répartition des sites amérindiens avec leur numéro d’inventaire propre à l’opération de Petit Saut (BPS 1 : lire site no 1 de l’inventaire des sites du barrage de Petit Saut). Les implantations pointées d’un rond noir correspondent aux sites de plein air, les autres figurent l’ensemble des sites à polissoirs à l’exception des sites 307 et 308 situés dans le secteur 69 (cf. fig. 7) et localisés hors de la zone présentée. À droite, sur le schéma représentant la zone côtière et Ko...

International audience; Amazonian rainforests, once thought to be pristine wilderness, are increasingly known to have been widely inhabited, modified, and managed prior to European arrival, by human populations with diverse cultural backgrounds. Amazonian Dark Earths (ADEs) are fertile soils found throughout the Amazon Basin, created by pre-Columbian societies with sedentary habits. Much is known about the chemistry of these soils, yet their zoology has been neglected. Hence, we characterized soil fertility, macroinvertebrate communities, and their activity at nine archeological sites in three Amazonian regions in ADEs and adjacent reference soils under native forest (young and old) and agricultural systems. We found 673 morphospecies and, despite similar richness in ADEs (385 spp.) and reference soils (399 spp.), we identified a tenacious pre-Columbian footprint, with 49% of morphospecies found exclusively in ADEs. Termite and total macroinvertebrate abundance were higher in reference soils, while soil fertility and macroinvertebrate activity were higher in the ADEs, and associated with larger earthworm quantities and biomass. We show that ADE habitats have a unique pool of species, but that modern land use of ADEs decreases their populations, diversity, and contributions to soil functioning. These findings support the idea that humans created and sustained high-fertility ecosystems that persist today, altering biodiversity patterns in Amazonia.

O objetivo deste estudo é determinar granulometria, mineralogia e atributos químicos de fertilidade do solo em Terra Preta Arqueológica. As amostras de solo foram coletadas nas Comunidades do Marajó e Gregostone, em Parintins, Amazonas, Brasil. As amostras foram secas ao ar e desagregadas manualmente com o auxílio de um rolo de madeira e separadas granulometricamente usando peneiras de malha 2 mm. Foram feitas medidas de pH, matéria orgânica, P, K, Fe e Al trocável, além de difratometria de raios X. Os resultados obtidos mostraram que os solos estudados apresentam características ácidas. Na terra preta do Marajó, a classificação textural foi franco-argiloarenosa, com elevados teores de matéria orgânica, P e Al trocável, e baixo teor de K. Na terra preta do Gregostone, a classificação textural foi francoarenosa. Os difratogramas de raios X mostraram basicamente as mesmas reflexões mineralógicas para os sítios de terra preta do Marajó e Gregostone, que possuem a presença majoritária de caulinita e quartzo.

Based on recent insights about intensive soil husbandry by some Neolithic farmers combined with the required techniques for efficient use of stone tools, this research questions the emphasis in the experimental archaeology literature on felling of large trees by stone-axe-wielding males working alone. To reflect conditions after the short fallows now thought to have been favored by farmers using stone tools, young (8–12 years) and small (3.5–5.6 cm diameter) Quercus hemisphaerica (laurel oak) trees were felled in this study by both male and female participants. Felling with a stone axe required an average of 75 more strokes than for felling a similar sized tree with a steel axe. One novel finding in this study is that when the Quercus hemisphaerica (laurel oak) saplings were bent over/tensioned by a co-worker, the predicted numbers of felling strokes declined by 123 (73%) for stone axes and by 15 (72%) for steel axes. We also observed no effect of sex on felling efficiency with stone axes. These results suggest that stone-tool wielding farmers of both sexes worked together to clear trees from their fallowed fields.

El biocarbón es el producto resultante de la transformación termoquímica de la biomasa vegetal por pirólisis. Sirve como enmienda en suelos y presenta beneficios en la producción agrícola. El objetivo del presente estudio fue evaluar el efecto del biocarbón en el rendimiento y la respuesta de variables agronómicas de un maíz comercial en Maravatío, Michoacán. El biocarbón se obtuvo de biomasa seca de olotes de maíz usando un reactor de pirólisis. Se aplicó en suelos arcillosos biocarbón finamente triturado a tasas de 1% (T1), 2% (T2) y un control 0% (T0). Las dosis fueron calculadas con base en el peso del suelo de la capa arable (10 cm). La dosis de fertilización fue 200N-80P-150K-30S para los tratamientos y el control. El diseño fue en bloques al azar con cuatro repeticiones de 9 m2 cada una. La comparación de medias se realizó con la técnica de Tukey-Kramer. Los resultados indican un incremento en el rendimiento de 1.2 Mg ha-1 (T1) y 1 Mg ha-1 (T2), con respecto al control (T0). El peso de la mazorca, de grano por planta, olote y longitud de mazorca, presentaron la siguiente tendencia, T1 > T2 > T0. El diámetro de tallo y peso seco de la planta fue mayor en T1. La altura de la planta y diámetro de tallo fue mayor en T2. La profundidad de raíz no presentó diferencias significativas entre los tratamientos; sin embargo, la tendencia en el desarrollo lateral de raíces fue T2 > T1 > T0 que sugiere un efecto positivo para el desarrollo y exploración de la raíz que podría explicar el incremento en el rendimiento. Se concluye que el biocarbón es una alternativa viable para aumentar la producción de maíz y favorece el desarrollo vegetativo de la planta en la región Oriente del estado de Michoacán.

Historical land use and soil management left behind anthropic soils such as Amazonian Dark Earths (Terras Pretas de Indio - pretic Anthrosols), Anthropic shell mounds (Sambaquis - terric Anthrosols), and Plaggen soils (plaggic Anthrosols), enriched in soil organic matter and soil fertility. The objective of this study was to compare soil organic matter quantity and quality of these tropical and temperate anthropic soils among each other and against their adjacent non-anthropic soils. All anthropic soil horizons had enhanced total contents of C, N, P, K, Ca, Mg and Fe, reflecting a soil organic matter and nutrient enrichment compared to their reference soils, mostly expressed by the Sambaquis. In order to better understand the mechanisms of soil organic matter stability, besides black carbon analysis, topsoils and subsoils were incubated in the laboratory at 10 °C and 30 °C and the emitted CO2 was recorded for 44-days. The Plaggen soil released the highest amount of CO2 at 30 °C, being two to three times higher compared to Terra Preta de Indio and Sambaqui anthropic horizons. The highest mean residence times (MRT), between 38 and 63 years, were calculated for the subsoils of the anthropic soils incubated at 10 °C. In the artificial system of this study, the stability of anthropic soil horizons under study was not generally enhanced when compared with their reference soils. However, enhanced stability of total organic carbon (TOC) was indicated by a negative relationship between black carbon portion of TOC and the relative amount of CO2-C released from TOC of all anthropic soils. During the incubation period of 44 days, the cumulatively mineralized amount of soil organic carbon (SOC) in the top of anthropic soils at 30 °C was three to six times as high as that at 10 °C. Consequently high temperature under tropical conditions should have stimulated the decay of organic matter, which however was not reflected by high TOC contents found in Terra Preta and Sambaqui samples, corroborating their low degradability in the long term. Therefore, we propagate that a high stability of carbon stocks exists in anthropic soil horizons, which may become a promising opportunity for the establishment of a new generation of anthropic soils with improved soil fertility and soil organic matter using the principle of soil-biochar systems.

Biochar, used as a soil amendment, arose from the influx of new understanding of the origin of the “Terra Preta” soils rediscovered in the Amazon. Current theory assumes that active measures were taken centuries ago (CE 450–950) to enrich soils with burnt biomass (char), bone, and manure. These active measures over time resulted in extremely fertile soils rich in plant nutrients, microbial activity, and reactive functional groups that influence cation exchange capacity and a host of other physicochemical soil properties. A wealth of research resulting from this rediscovery has demonstrated that laboratory and commercial grade biochar may enhance soil health and plant growth and can be used as a soil amendment in forestry, agriculture, degraded landscapes, and contaminated soils. However, not all biochars are alike or have the same uses, as variable feedstocks and thermoconversion conditions influence biochar properties. Similarly, the landscape to which they are applied will express variable reactions due to differences in soil type, climate, vegetation, and management. In this chapter the occurrence, production and properties of biochar, and how these properties influence specific soil conditions and reactions is described. We then discuss the proposed, prescribed, and applied uses for biochar on the landscape. We finish with mention of potential hazards from biochar use and gaps in our knowledge.

Archaeological Dark Earth (ADE) is a layer of anthrosol (syn. anthroposol) visually characterized by dark color mainly due to homogenous charcoal inclusion, and substantial enrichment by nutrients in comparison to surrounding soils. ADE is distributed from the tropics (Amazonian Terra preta, African ADE), moderate climatic zones (European ADE) up to the Arctic (kitchen middens). Although ADE soils have been studied also in other regions of the world, they have no special regional names. All types of ADE developed as a result of deliberate and/or unintentional deposition of domestic/occupational wastes, charred residues, bones, shells, and biomass ashes from prehistoric up to recent times. ADEs have optimum C : N ratio for effective mineralization, stable organic matter content, reduced acidity, higher CEC and C, N, P, Ca, Mn, Cu, Zn, Mn, Mg, Fe, Sr, and Ba content in comparison to surrounding soils. The unclear remains the level of ADEs enrichment by these elements as enrichment factors for different elements are based on different analytical approaches from plants-available up to total contents in the soil. Although generally highly productive, comparison of herbage production and crop yields between ADEs and natural soils are still rare. The distribution and persistence of anthropogenic activities leading to the formation of ADEs indicate that they are subject to the continual formation.

By: A. Sutopo, Yuliyanto Key Words: Terra preta, Pyrolysis, Corn Int. J. Agron. Agri. Res. 16(1), 16-21, January 2020. Abstract Terra preta is a black soil found in the Amazon basin in the 15th century with the main characteristics of black and loose has the nature of resistant to leaching, able to provide and maintain nutrients in a very long time, whereas in Indonesia the availability of such land has not yet existed so it is necessary to make and apply terra preta soil with mineral soil base material mixed with charcoal, bones burned with pyrolysis combustion system and other organic materials. In enriching microorganisms, mycorrhizal fungi are added which function to increase nutrient absorption, increase plant resistance to biotic and abiotic stresses, able to maintain growth and production stability. The study aims to determine the effect of the application of terra preta planting media with pyrolysis combustion systems on the growth and production of corn plants using polybags. The results showed that the application of terra preta in general had a good effect on the growth and production of corn compared to plants that only used mineral soil or control media. Application of T1: 100% terra preta treatment on observations of plant height and stem diameter showed the best treatment. On observation of the number of leaves, of wet weight and dry weight of root, canopy, corn seed, corn cob and corn husk of T5 treatment: mineral soil + 15gr mycorrhizae + 80% terra preta showed the best treatment. A. Sutopo, Yuliyanto. The effect of Terra preta media using pirolysis system on growth and production of corn (Zea mays L). Int. J. Agron. Agri. Res. 16(1), 16-21, January 2020. https://innspub.net/ijaar/effect-terra-preta-media-using-pirolysis-system-growth-production-corn-zea-mays-l/, A. Sutopo, Yuliyanto. The effect of Terra preta media using pirolysis system on growth and production of corn (Zea mays L). Int. J. Agron. Agri. Res. 16(1), 16-21, January 2020. https://innspub.net/ijaar/effect-terra-preta-media-using-pirolysis-system-growth-production-corn-zea-mays-l/

The aim of this study was to evaluate diuron sorption, desorption and degradation in two anthropogenic soils (Terra Preta de Índio - TPI) in contrast to a sandy soil (Quartzarenic Neosol - NQo). Sorption-desorption studies were performed by the batch equilibrium method and biodegradation in biometric bottles using radiolabeled diuron in 14C. Freundlich coefficient (Kf) values ranged from 13.50 to 50.41 µmol(1-1/n) L1/n kg-1 in TPI-2 and TPI-1, respectively, indicating very high diuron sorption in anthropogenic soils, following the order: TPI-1 ≥ TPI-2 > NQo (99.10, 98.95 and 60.8%, respectively). Diuron desorption was very low in anthropogenic soils, ranging from 1.36 (TPI-1) to 1.70% (TPI-2), and 24% to NQo. Accumulated diuron mineralization to 14C-CO2 was < 3% at 70 days after herbicide application, regardless of the assessed soil. Formation of 35 and 44% residue bound to TPI-2 and TPI-1 was observed, higher than to NQo (17%). In contrast, the residue extracted from NQo varied from 72 to 91%, ranging from 48 to 83% for TPI-1 and TPI-2 during the incubation period. The degradation half-life (DT50) of diuron in anthropogenic soils was of 66.65 and 68.63 days for TPI-1 and TPI-2, respectively, while a period of 88.86 days was observed for NQo. The formation of only one herbicide metabolite in all soils was evidenced. The application of diuron in arable areas in the presence of anthropogenic Amazonian soils may lead to inefficient chemical weed control, since these soils may reduce herbicide soil bioavailability due to high OC contents, where high sorption and low herbicide desorption are noted, as well as faster degradation compared to sandy soil.

High fertility of the terra preta soils is often attributed to the high concentration of aromatic compounds found in these soils. Chemical characterization of two soil samples collected from different locations in Botswana has shown some similar properties with terra preta. Fourier Transform Infrared (FTIR) analysis revealed five common absorption bands between the soil samples and the aromatic compounds. The common bands were found to be due to the vibration of the benzene ring thus indicating traces of aromatic compounds in the soil samples. X-ray diffraction (XRD) revealed the existence of only two major nutrients which are magnesium and calcium in the studied samples. The soil pHs were found to be 6.8 for the ploughing field soil and 7.4 for backyard garden soil sample which are higher than the previously reported pH of terra preta which ranges from 5.0 to 5.4.

Amazonian Dark Earths (ADEs) are highly fertile soils in areas with predominance of unfertile soils. However, the variation in nutrient availability between regions and the resilience of ADEs to modern agricultural use is still little known, particularly regarding micronutrient contents. Hence, the present study synthesized current information of ADE impacts on extractable micronutrient (Cu, Ni, Fe, Mn, Zn, B) contents at different soil depths and assessed in detail the role of both soil depth and land-use type on extractable Cu, Ni, Fe, Mn and Zn in nine ADEs and adjacent (ADJ) soils from different Amazonian regions. The land-use systems chosen were secondary old (OF) or young (YF) forests, and agricultural systems (AS) in Iranduba, Belterra and Porto Velho. Only eight studies compared extractable (Mehlich-1) micronutrient contents at 21 sites with ADEs and ADJ soils, but only four studies included depths greater than 30 cm, and B and Ni were evaluated in only one study. Higher Mn and Zn, but lower Fe contents were found in ADEs both from literature data and in the present study, especially in the first 30 cm depth. Increases in extractable Ni and Cu in ADEs varied according to the site and the land use considered. Micronutrient contents tended to decrease with depth, but varied depending on the element, site, soil type and land use. Sites with modern agriculture showed few differences in extractable micronutrient contents, except for a decrease in Fe in Belterra and Mn in Porto Velho. Considering the high amounts of some micro- and macronutrients in ADEs further work is warranted concerning soil management and nutrient balance in plants grown on these soils.

This article compares Western permaculture theory and practice with the indigenous agricultural system of the Kichwa-Lamistas in the Department of San Martin in High Amazon Peru. It draws on indigenous theory and collaborations with the Kichwa-Lamistas to argue that the bioculture of the latter represents an alternative not only to modern, industrialized agriculture but also to permaculture. The article profiles the agroecological system used by the Kichwa-Lamistas, which employs agroforestry, the use of anthropogenic Terra Preta soils, and other sustainable practices. Although both the Kichwa-Lamista chacra (farm) and the permaculture farm or garden represent, in theory, two forms of closed-loop, polycultural, agroforestry-based subsistence farming, we argue that the enactments of reciprocity and other spiritual components of Kichwa-Lamista bioculture constitute an alternative to permaculture’s rootedness in scientific, materialist, and universalist traditions, which ultimately treat the natural world as other.

The Visual Evaluation of Soil Structure (VESS) is a straightforward and practical method for characterising and scoring soil structural and physical quality, ideally suited to evaluate and monitor soil degradation in remote and undeveloped areas. The research presented here tested for the first time the feasibility of using VESS in the Amazon basin, under the specific land uses and soils (Oxisol and “Terra Preta de Indio”) of the region, and its relation with quantitative soil properties commonly used as indicators of soil physical quality. The evaluated areas, which had never been subjected to mechanisation, chemical fertilisation nor tillage, were “Terra Preta de Indio”/Anthropogenic Dark Earth; Regenerating Forest; Slash and Burn; Pasture; and Pristine Forest. The results showed that the quantitative properties were less sensitive at revealing signs of degradation than VESS and that VESS brought to light evidence of historic land use change and limitations to crop productivity. VESS was significantly correlated with soil resistance to penetration. However, VESS had difficulty capturing surface sealing, but the hands on approach to VESS allowed the user to identify these problems, despite not being listed in the reference chart. Overall, VESS was a more integrated soil quality indicator, providing more information about different soil functions than the quantitative properties, it was also a more practical method to perform making it ideal for tracking soil degradation and structural quality in similarly challenging situations. However, more research is required to fully enable VESS to capture structural quality in ‘sandified’ soils, caused by the slash and burn method widely used in the Amazon region.

Relict charcoal hearths are round or elliptical earthen platforms up to 11 m in diameter and a widespread feature of historical industry that supplied charcoal used in the production of iron in furnaces or smelters. The iron industry dominated Litchfield County, Connecticut, and surrounding areas in the northeast United States throughout the 19th century, peaking in ∼1850. The large number of charcoal hearths in this region is a relic of >150 years of widespread iron production. In this study, we describe the architecture and soil stratigraphy of 26 charcoal hearths in Litchfield County. This contribution aims to (1) compare soils that comprise the charcoal hearths with “natural” adjacent soils, (2) measure the thickness of topsoil developed upon the hearths, and (3) characterize the stratigraphy associated with these features. Results indicate that the black topsoils overlying the charcoal hearths contain residual charcoal and are on average 2.6 times thicker than adjacent Cambisols. Charcoal hearths display two or more black, charcoal-rich strata separated by layers of reddish-brown soil low in charcoal content indicating multiple episodes of use. We also find that many charcoal hearths have been stabilized with boulders on the downslope side during construction and repeated use. Overall, the results presented here provide significant information regarding the construction, use, and associated impacts of earthen platforms for charcoal production in the northeast United States, with further relevance to other areas where historical charcoal production occurred.

Terra preta is a “hot” topic in the environmental sciences. From an anthropogenic soil type of local relevance, terra preta has been transformed by soil scientists into a techno-scientific object that helps to escape the global ecological crisis. The commodification goes along with a mythification that does not spare the scientific sphere.This paper contributes to the history of terra preta research. It traces not only the history of science of Amazonian Dark Earths (terra preta de índio) but the history of knowledge of terra preta taking explicitly into account indigenous contributions. Five major phases are distinguished. In the beginning knowledge on terra preta was local indigenous knowledge. The scientific object “terra preta” was created in the context of archaeological research and has then been reframed as a carbon-sequestering soil in the context of the rising global warming debate in the early 1990s. This development led to a de-contextualization of terra preta and to commodification, giving rise to the biochar industry. Commodification included mythification of terra preta, stressing its ancient, prehistoric roots. Both processes ‐ commodification and mythification ‐ can also be found within the scientific sphere. This seems to indicate that not only terra preta has become a commodity, but that also research on terra preta shows signs of commodification.

Wie riecht und f��hlt sich der Boden unter uns an? Wie entsteht in der Natur fruchtbarer Boden? Welche Lebewesen tummeln sich da unter unseren F����en und wie k��nnen wir selbst fruchtbaren Boden gewinnen? Mit dem vorliegenden Unterrichtsmaterial k��nnen Sie gemeinsam mit Sch��ler*innen den Boden entdecken. Die Module er��ffnen verschiedene Perspektiven auf das Thema Boden und sind f��cherverbindend konzipiert. Inhalte und Fachmethoden aus den F��chern Deutsch, Kunst und Naturwissenschaft bzw. Biologie werden mit dem Material angesprochen. Die Unterrichtsmodule greifen Themen und Fachbegriffe aus Rahmenlehrpl��nen auf, wie die Erkundung von Lebensr��umen und die Wechselwirkungen von Organismen.

Im Lehrmaterial ist das Thema Pflanzenkohle und ihre Anwendung im g��rtnerischen und landwirtschaftlichen Bereich didaktisch aufbereitet. In den Blick gelangt dabei die Geschichte und Wiederentdeckung der Terra Preta im Zuge arch��ologischer und anthropologischer Forschungen sowie die gegenw��rtige Herstellung von Pflanzenkohle und Terra-Preta ��hnlichen Substraten durch die Kompostierung und die Anwendung der Substrate. Zudem wird der Beitrag der Terra-Preta-Technik zum Klima- und Bodenschutz und zur nachhaltigen Ressourcennutzung vermittelt. Mit den vorliegenden Modulen soll BBNE konkret, sichtbar und erlebbar und die nachhaltigkeitsorientierten Kompetenzen an konkrete berufliche Handlungs- und T��tigkeitsfelder gekn��pft werden. Ziel ist sowohl die vertiefte kognitive Auseinandersetzung mit dem Thema Pflanzenkohle, als auch die Aneignung praktischer Kompetenzen zur Pyrolyse und Kompostierung sowie der Transfer des Erlernten in eigene Kompostkonzepte oder Pflanzversuche. Die Auszubildenden sollen zudem Pflanzenkohle vor dem Horizont nachhaltiger Entwicklung kritisch diskutieren und bewerten.

This research on the escalation of nutrient status aims to determine the effect of giving Terra Preta Biochar Padi (Tetadi) on ex-gold mining land to P-available land in Nagari Padang Sibusuk Sijunjung Regency, West Sumatra. Soil samples were taken from the former gold mining soil with a depth of 0-20 cm randomly. This research was conducted using a completely randomized design with 6 treatments and 4 replications consisting of control (A), Tetadi 10 tons / ha (B), Tetadi 15 tons / ha (C), Tetadi 20 tons / ha (D), Tetadi 25 tonnes / ha (E), and Tetadi 30 tonnes / ha. The results showed that giving Terra Preta Biochar Rice to ex-gold mining land could increase the highest available P of soil in the treatment of rice Terra Preta Biochar 30 tonnes / ha with the results of the 5% DMRT statistical test very significantly different from the control treatment and 10 tonnes / ha and 15 tonnes / ha. Soil pH also showed the highest increase in the treatment of 30 tonnes / ha with a pH value of H2O of 5.7 and followed by a pH of KCl with a value of 4.6 and statistical test results showed that the treatment of 30 tonnes / ha was also very significantly different from control and treatment.

Amazonian Dark Earths (ADEs) are fertile soils for agricultural production as well as important archaeological resources for understanding the pre-Columbian past of the Neotropical lowland rainforest. ADEs are threatened by expanding land exploitation and there is a need to develop efficient approaches to soil mapping and analysis for documenting these soils. In this paper we assess the potential of satellite remote sensing and proximal soil sensing to map, predict and monitor ADEs in land affected by agro-industrial development. We use instruments based on portable x-ray fluorescence (PXRF) and electromagnetic induction (EMI) as well as high-resolution satellite data (Spot 6) for detailed soil surveys at a 10-ha ADE site now mainly used for soybean production on the Belterra Plateau, Pará, Brazil. We predict the regional occurrence of ADE in a c. 250km2 test area centred on the known ADE site São Francisco using satellite data. Multivariate adaptive regression splines models were parameterised for predictions of soil organic carbon (SOC), cation exchange capacity (CEC), phosphorus (P) and depth of the A horizon in ADEs from sensor data – both from individual sensors and in sensor combinations. Combining sensors gave the best validation results: the highest modelling efficiencies (E) were 0.70 (SOC), 0.88 (CEC) and 0.74 (for both P and A depth). The most powerful single proximal sensor outputs in the predictions were Sr from the PXRF data and magnetic susceptibility (MSa) as measured by the EMI instrument. In the regional satellite based model we located 17 previously unrecorded ADE sites >2ha. Ground control checks showed that 10 out of 11 sites were correctly classified. We conclude that these sensors are useful in studies of ADE in deforested cropland and provide new opportunities for detailed studies of the archaeological record.

Soils with a high weathering degree present great difficulties for management of phosphorus (P) fertilization due to their high adsorption rates. The magnitude and velocity of the P retention phenomena in these soils is still poorly understood and has great importance to effective management of soil phosphorus. The objective of this study was to evaluate the adsorption and desorption kinetics and phosphorus adsorption irreversibility (hysteresis) in highly weathered soils. For this purpose, we selected four soils: Xanthic Ferralsol-1 (FR-1), Xanthic Ferralsol-2 (FR-2), Rhodic Ferralsol (FR-3) and Hortic Anthrosol “Terra Preta de Índio” (AT). Adsorption followed by desorption experiments in Stirred flow chamber were performed. From obtained data, parameters related to P kinetics were estimated, considering the presence of two types of adsorption and desorption sites (fast and slow), estimating also the hysteresis index. It was observed that FR-2 and FR-3 showed higher P adsorption and most of the adsorbed P was at first 100 min of evaluation. Furthermore, in FR-1, FR-2 and FR-3, approximately half of adsorption occurred by rapid sites (F which is the fraction of fast sites ranging from 0.45 to 0.55), while AT adsorption was lower (qmax = 48.95 mg kg^−1) and occurred slower (F = 0.33). In FR-2 and FR-3, between 71 and 72% of adsorbed P was not desorbed, while in AT, only 11% of P was irreversibly adsorbed. The P kinetics in highly weathered soils proved to be a process governed by the fast sites on adsorption and slow sites on desorption, resulting in high levels of hysteresis.

Increasingly, archaeological research in Amazonia is revealing complex precolonial occupation in areas around riverine confluences. In 2014, the first site-based archaeological investigations were undertaken in Gurupá, Pará, Brazil, a municipality that spans the region of the Xingu-Amazon confluence. The Portuguese controlled access to Amazonia from 1623 onward through a network of settlements organized around Gurupá. Results from extensive excavations of terra preta sites, landscape archaeology, and analysis of ceramic evidence suggest that this was also a precolonial crossroads. Carrazedo, once a booming historical town (Arapijó), sits atop a significantly larger terra preta site. Excavations in historical and precolonial sectors of Carrazedo found well-preserved remains, including a precolonial house terrace complex. The extent of terra preta and earthworks at Carrazedo indicate that the precolonial occupation was more intensive than the colonial-historical period occupation. Regional survey revealed colonial-historical period sites consistently overlying expansive precolonial sites, the density and extent of which suggest a major precolonial center at the Xingu-Amazon confluence. Overall, ecological and landscape modifications appear to have been more intense in the precolonial past than during later periods. Short- and long-distance settlement networks also differed during the two periods. This as-of-yet understudied region promises to shed new light on deep-time human-environment interactions and spatial organization in the humid tropics of Amazonia.

“Terras Pretas de Indio” are anthropic Amazonian soils rich in pyrogenic black carbon, which might be responsible for the soil long-term stability and high fertility. This black carbon, produced by the Indians while handling their residues, became a model material for agriculture and environment. The key question to answer for artificially reproducing the desired agricultural properties of the Terra Preta de Indio is whether the black carbon structure found today in these soils is the same as produced by the ancient Indians, or whether its structure results from long-term complex physical, chemical and biological activities in the soil. To address this question, this work investigates the depth dependence of the properties from a soil collected from the Balbina site, in Presidente Figueiredo, Amazonas State, Brazil. The black carbon structure and the soil composition are investigated, with special emphasis on the poorly studied microbiological composition (fungi, bacteria, arbuscular mycorrhizas). The comparative analysis between the properties from shallower (newer) and deeper (older) soil strata indicates that, while soil composition exhibits depth dependence, the pyrogenic black carbon structure does not. This finding suggests that this model material should be reproducible by repeating the pyrolysis conditions utilized in their production.

Driving practices of Amazon native inhabitants are an example of positive feedback in carbon storage acting as a key element in soil fertility and stability. The anthropogenic Amazonian Terra Preta do Indio (Indian Dark Earth) soils are rich in pyrogenic black carbon and the Rio Negro (Black River) also exhibits plentiful apparently similar black-carbon particles. In this context, we characterized the structural, morphological and elemental properties of the long-lived stable carbon-based structures present in sediments of the Amazonian Rio Negro and in two Terra Preta do Indio soils from two different geographic regions. Optical microscopy, Raman spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques are utilized. The structural analysis displayed that these carbon structures exhibit similar nanocrystallite structures, despite their different geographic location and environment. The Terra Preta do Indio-carbons are however, more defective and the quantitative elemental analyzes indicate they have greater variety of nutrients, such as P and Ca, than Rio Negro sediment-carbons.

The socio-economic values of fertile and carbon-rich Dark Earth soils are well described from the Amazon region. Very recently, Dark Earth soils were also identified in tropical West Africa, with comparable beneficial soil properties and plant growth-promoting effects. The impact of this management technique on soil microbial communities, however, is less well understood, especially with respect to the ecologically relevant group of arbuscular mycorrhizal (AM) fungi. Thus, we tested the hypotheses that (1) improved soil quality in African Dark Earth (AfDE) will increase soil microbial biomass and shift community composition and (2) concurrently increased nutrient availability will negatively affect AM fungal communities. Microbial communities were distinct in AfDE in comparison to adjacent sites, with an increased fungal:bacterial ratio of 71%, a pattern mainly related to shifts in pH. AM fungal abundance and diversity, however, did not differ despite clearly increased soil fertility in AfDE, with 3.7 and 1.7 times greater extractable P and total N content, respectively. The absence of detrimental effects on AM fungi, often seen following applications of inorganic fertilizers, and the enhanced role of saprobic fungi relevant for mineralization and C sequestration support previous assertions of this management type as a sustainable alternative agricultural practice.

6 páginas.-- 5 figuras.-- 1 tabla.-- 31 referencias, Purpose: Charcoal production during the nineteenth century transformed landscapes in the Brazilian Atlantic Forests in Rio de Janeiro city. These paleo-territories were studied to improve our understanding of how this activity altered soil properties. By comparing their humic acids (HA) with those extracted from a Terra Preta de Índios (TPI) site, we showed that the aging of charcoal in soils alone is sufficient to generate recalcitrant organic material with high cation exchange capacity (CEC). Materials and methods: The soils were sampled: at the center of the area affected by the ancient charcoal kiln (center of the kiln—CK), at the dump site (D—local deposition of charcoal residues not used for marketing, downstream of the ancient charcoal kiln), and from the surrounding soil, upstream of the kiln, as a control (natural soil—NS). Elemental analysis and fertility characterization of the soil samples were performed. Solid-state 13C nuclear magnetic resonance (NMR) spectra were obtained from their humic acids (HA). These spectra were compared against HA data on TPI. Results and discussion: As shown by solid-state 13C NMR spectroscopy, the soil organic matter (SOM) fraction which is high in charged functional groups (the so-called humic acids—HA) was extracted from areas rich in ancient charcoal and dominated by recalcitrant carboxylated aromatic structures (aged charcoal). This peculiar SOM explains the observed high cation exchange capacity (CEC). It yields a fertile soil with a high resistance against degradation by potential intensive use. Comparable results are described in the literature for SOM of TPI. Conclusions: The high structural similarity between the HA from the soils under the paleo-charcoal kilns and from TPI supports the hypothesis that just the natural weathering and biochemical reworking of charcoal in soils, together with ash input, is sufficient to generate fertile and resilient soils with peculiar SOM and properties commonly associated with the high fertility and C sequestration potential of TPI, This study was financially supported by the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq)

Amazonia contains a vast expanse of contiguous tropical forest and is influential in global carbon and hydrological cycles. Whether ancient Amazonia was highly disturbed or modestly impacted, and how ancient disturbances have shaped current forest ecosystem processes, is still under debate. Amazonian Dark Earths (ADEs), which are anthropic soil types with enriched nutrient levels, are one of the primary lines of evidence for ancient human presence and landscape modifications in settings that mostly lack stone structures and which are today covered by vegetation. We assessed the potential of using moderate spatial resolution optical satellite imagery to predict ADEs across the Amazon Basin. Maximum entropy modeling was used to develop a predictive model using locations of ADEs across the basin and satellite‐derived remotely sensed indices. Amazonian Dark Earth sites were predicted to be primarily along the main rivers and in eastern Amazonia. Amazonian Dark Earth sites, when compared with randomly selected forested sites located within 50 km of ADE sites, were less green canopies (lower normalized difference vegetation index) and had lower canopy water content. This difference was accentuated in two drought years, 2005 and 2010. This is contrary to our expectation that ADE sites would have nutrient‐rich soils that support trees with greener canopies and forests on ADE soils being more resilient to drought. Biomass and tree height were lower on ADE sites in comparison with randomly selected adjacent sites. Our results suggested that ADE‐related ancient human impact on the forest is measurable across the entirety of the 6 million km2 of Amazon Basin using remotely sensed data.

Open cycles of organic carbon and nutrients cause soil degradation. Procedures such as ecological sanitation (EcoSan), bioenergy and Terra Preta practice (TPP) can contribute to closing nutrient cycles and may, in addition, sequester carbon. This paper introduces three projects in Karagwe, Tanzania, and their applied approach of integrated resource management to capture carbon and nutrients from different waste flows. Substrates derived from these case studies, biogas slurry, compost and CaSa-compost (containing biochar and sanitized human excreta), were assessed for their nutrient content by analysis of the total element composition. Evaluation focused on potential impacts of the tested amendments on the nutrient availability in the soil as well as on the local soil nutrient balance. Results revealed that all substrates show appropriate fertilizing potential compared to literature, especially for phosphorus (P). CaSa-compost was outstanding, with a total P concentration of 1.7 g dm-3 compared to 0.5 and 0.3 g dm-3 in compost and biogas slurry respectively. Furthermore, these soil amendments may reduce acidity of the soil, with a calculated liming effect of 3.4, 2.6 and 7.8 kg CaO for each kg of nitrogen added for biogas slurry, compost and CaSa-compost respectively. To offset negative P balances in Karagwe, about 8100, 6000 and 1600 dm3 ha-1 are required for biogas slurry, compost and CaSa-compost respectively. We conclude that especially CaSa-compost might offer immediate positive effects to crop production and nutrient availability in the soil. Key words: Ecological sanitation, bioenergy, Terra Preta practice, biochar, biogas slurry, compost, soil amendments, soil improvement, waste as resource.

During an archaeological excavation of a Slavic settlement (10th/11th C. A.D.) in Brunkendorf (Wendland region in Northern Germany), a thick black soil (Nordic Dark Earth) was discovered that resembled the famous terra preta phenomenon. For the humid tropics, terra preta could act as model for sustainable agricultural practices and for long-term CO 2 -sequestration into terrestrial ecosystems. The question was whether this Nordic Dark Earth had similar properties and genesis as the famous Amazonian Dark Earth in order to find a model for sustainable agricultural practices and long term CO 2 -sequestration in temperate zones. For this purpose, a multi-analytical approach was used to characterise the sandy-textured Nordic Dark Earth in comparison to less anthropogenically influenced soils in the adjacent area in respect of ecological conditions (pH, electric conductivity, cation exchange capacity, amino sugar) and input materials. Total element contents (C, N, P, Ca, Mg, K, Na, Fe, Cu, K, Zn, Mn and Ba) were highly enriched in the Nordic Dark Earth compared to the reference soil. Faecal biomarkers such as stanols and bile acids indicated animal manure from omnivores and herbivores but also human excrements. Amino sugar analyses showed that Nordic Dark Earth contained higher amounts of microbial residues being dominated by soil fungi. Black carbon content of about 30 Mg ha − 1 in the Nordic Dark Earth was about four times higher compared to the adjacent soil and in the same order of magnitude compared to terra preta . The input materials and resulting soil chemical characteristics of the Nordic Dark Earth were comparable to those of Amazonian Dark Earth suggesting that their genesis was also comparable. Amazonian Dark Earth and Nordic Dark Earth were created by surface deposition and/or shallow soil incorporation of waste materials including human and animal excrements together with charred organic matter. Over time, soil organisms degraded and metabolized these materials leaving behind deep black stable soil organic matter. The existence of the Nordic Dark Earth in the temperature zone of Europe demonstrates the capability of sandy-textured soils to maintain high soil organic matter contents and nutrient retention over hundreds of years. Deeper insights are needed urgently to understand soil organic matter stabilization mechanisms in this sandy soil to promote conceptual models for sustainable land use and long-term C sequestration. It is argued that the knowledge of Nordic Dark Earth probably was an important part of the Viking–Slavic subsistence agriculture system, which could have had a great impact on the development of the Viking age emporia in the 9th/10th C. A.D.

Amazonian Dark Earths (ADE) are the result of human modification of the Amazonian landscape since pre-Columbian times. ADE are characterized by increased soil fertility compared to natural soils. In the Amazonian forest, soil fertility influences understory herb and fern species composition. However, little research has been done to evaluate the effect of ADE on the composition of the understory community. We evaluated the effects of ADE and soil in 36 plots (150 m × 4 m) established in a Bolivian moist forest (La Chonta). For each plot, we determined soil nutrients, and the composition, richness, and abundance of terrestrial fern, angiosperm herb, and understory palm species. We found that the presence of ADE created a gradient in soil nutrients and pH that affected the understory species composition especially of ferns and palms. Additionally, the higher nutrient concentration and more neutral soil pH on ADE soils caused a decrease of ferns species richness. We therefore conclude that the current composition of the understory community in this particular Bolivian forest is a reflection of past human modifications of the soil.

The stability of soil organic matter (OM) in Amazonian anthropogenic soils, Terra Preta de Índio (TPI), is still not completely understood. The large contribution from black carbon (BC) and minerals to these soils is well-known; OM stability is therefore frequently explained by these properties, providing intrinsic recalcitrance (BC) and chemical protection against decomposition (OM-mineral associations), but the relative importance of both mechanisms that underlie the stability are not yet understood. In order to better understand the sources and decay processes of soil OM in these soils, we studied the molecular composition using pyrolysis gas-chromatography/mass-spectrometry. To this end, several soil OM fractions of samples from two TPI soils and an adjacent Xanthic Acrisol that served as a reference soil (REF) were studied (0–2 m depth). A sequential fractionation was applied in order to better understand the composition of soil OM pools with different association to the soil matrix. The studied soil OM fractions included the free light fraction (FLF; i.e., charcoal and litter), the occluded light fraction (OLF; charcoal and litter within aggregates), 0.1 M NaOH extractable OM (EX; comparable with the combined humic acid and fulvic acid fractions), and the remaining residue (RES; treated with HF/HCl; comparable with the humin fraction). The largest contribution to the total soil OM was found for EX and/or RES, the sum of which varied between 79% and 98% (Ave. 90.8%, n = 18). The minor contribution from the OLF (Ave. 4.4%) indicates that stabilisation within aggregates was not a major factor that contributed to OM stability in the studied profiles. Differences in molecular composition between the fractions were larger than those between profiles or with depth. The EX fraction showed the lowest contribution from plant (lignin phenols) and BC (PAHs, indenes, aromatics) derived products. The RES fraction showed a significantly larger contribution from BC related pyrolysis products compared to the EX. This non-extractable BC that is present in the RES after removal of the light fractions may reflect preferential binding of PAHs to minerals or, alternatively, the presence of highly condensed macromolecular polyaromatic structures. Changes with depth within the EX and RES fractions showed a larger contribution from products derived from BC in the anthropogenic horizons. Furthermore, the OM composition in EX and RES indicated that the degree of degradation of OM in anthropogenic horizons was relatively low. Apart from these similarities for anthropogenic horizons, the chemical composition of soil OM also showed large differences between both TPI soils. TPI-1 showed large variation between horizons while TPI-2 showed only minor changes with depth; this may be related to different phases of human occupation with time and/or a different soil usage.

The old paradigm that Amazonia's tropical ecosystems prevented cultural development beyond small-scale shifting agricultural economies, that had little environmental impact, no longer holds true for much of Amazonia. A diversity of archaeological evidence, including terra preta soils, raised fields, causeways, large habitation mounds, geometric earthworks, and megalithic monuments, all point to considerable cultural complexity and environmental impacts. However, uncertainty remains over the chronology of these cultures, their diet and economy, and the scale of environmental impact and land use associated with them. Here, we argue that a cross-disciplinary approach, closely coupling palaeoecology and archaeology, can potentially resolve these uncertainties. We show how, with careful site selection (pairing small and large lakes, close proximity to archaeological sites, transects of soil pits) and choice of techniques (e.g., pollen, phytoliths, starch grains, charcoal, stable isotopes), these two disciplines can be successfully integrated to provide a powerful tool for investigating the relationship between pre-Columbian cultures and their environment.

Pyrogenic carbon (C) is produced by incomplete combustion of fuels including organic matter (OM). Certain ranges in the combustion continuum are termed ‘black carbon' (BC). Because of its assumed persistence, surface soils in large parts of the world contain BC with up to 80% of surface soil organic C (SOC) stocks and up to 32% of subsoil SOC in agricultural soils consisting of BC. High SOC stocks and high levels of soil fertility in some ancient soils containing charcoal (e.g., terra preta de Indio) have recently been used as strategies for soil applications of biochar, an engineered BC material similar to charcoal but with the purposeful use as a soil conditioner (1) to mitigate increases in atmospheric carbon dioxide (CO2) by SOC sequestration and (2) to enhance soil fertility. However, effects of biochar on soils and crop productivity cannot be generalized as they are biochar-, plant- and site-specific. For example, the largest potential increases in crop yields were reported in areas with highly weathered soils, such as those characterizing much of the humid tropics. Soils of high inherent fertility, characterizing much of the world's important agricultural areas, appear to be less likely to benefit from biochar. It has been hypothesized that both liming and aggregating/moistening effects of biochar improved crop productivity. Meta-analyses of biochar effects on SOC sequestration have not yet been reported. To effectively mitigate climate change by SOC sequestration, a net removal of C and storage in soil relative to atmospheric CO2 must occur and persist for several hundred years to a few millennia. At deeper soil depths, SOC is characterized by long turnover times, enhanced stabilization, and less vulnerability to loss by decomposition and erosion. In fact, some studies have reported preferential long-term accumulation of BC at deeper depths. Thus, it is hypothesized that surface applied biochar-C (1) must be translocated to subsoil layers and (2) result in deepening of SOC distribution for a notable contribution to climate change mitigation. Detailed studies are needed to understand how surface-applied biochar can move to deeper soil depths, and how its application affects organic C input to deeper soil depths. Based on this knowledge, biochar systems for climate change mitigation through SOC sequestration can be designed. It is critically important to identify mechanisms underlying the sometimes observed negative effects of biochar application on biomass, yield and SOC as biochar may persist in soils for long periods of time as well as the impacts on downstream environments and the net climate impact when biochar particles become airborne.

Amazonian Dark Earths (ADE) or Terra Preta de Índio formed in the past by pre-Columbian populations are highly sustained fertile soils supported by microbial communities that differ from those extant in adjacent soils. These soils are found in the Amazon region and are considered as a model soil when compared to the surrounding and background soils. The aim of this study was to assess the effects of ADE and its surrounding soil on the rhizosphere bacterial communities of two leguminous plant species that frequently occur in the Amazon region in forest sites (Mimosa debilis) and open areas (Senna alata). Bacterial community structure was evaluated using terminal restriction fragment length polymorphism (T-RFLP) and bacterial community composition by V4 16S rRNA gene region pyrosequencing. T-RFLP analysis showed effect of soil types and plant species on rhizosphere bacterial community structure. Differential abundance of bacterial phyla, such as Acidobacteria, Actinobacteria, Verrucomicrobia, and Firmicutes, revealed that soil type contributes to shape the bacterial communities. Furthermore, bacterial phyla such as Firmicutes and Nitrospira were mostly influenced by plant species. Plant roots influenced several soil chemical properties, especially when plants were grown in ADE. These results showed that differences observed in rhizosphere bacterial community structure and composition can be influenced by plant species and soil fertility due to variation in soil attributes.

a b s t r a c t Carbonized materials are responsible for maintaining a high level of fertility and soil organic matter in soils such as the Amazonian Dark Earths, also known as Terra Preta. It is hypothesized that an enriched biochar, which will have long term stability similar to Terra Preta, can be synthesized by mixing biochars with manures, minerals and clays and heating the mixture at low temperatures. This treatment will promote bonding between the mineral and the organic phases, which may occur naturally after several years of aging in soil. This paper describes the characterization of an enriched biochar by a range of analytical methods. Examination of the enriched biochar showed that it has high concentrations of exchangeable cations, available phosphorus and high acid neutralizing capacity. Structural analysis of the enriched biochar reveals a microstructure that suggests that bonding has indeed occurred between the biochar and mineral phases. Using natural 13 C abundance and a two-pool exponential model, the half-life of enriched biochar-C was estimated to be 104 years in a clayey soil.

Spectroscopic techniques including X-ray photoelectron spectroscopy (XPS) can identify particular chemical groups of humic acids (HA) from “Terra Preta de Indios” (TPI) or Amazonian dark earth, the highly fertile anthropogenic soil found in the Amazonian region. The high fertility and resilience of these soils cannot be explained by their chemically inert pyrogenic C content alone, but the natural aging of this C generates reactive carboxyl functional groups attached directly to the recalcitrant polycondensed aromatic backbone. Through spectroscopic techniques used in this work, the HA fraction (the alkaline-soluble organic matter that precipitates at low pH) of the TPI soil was compared with humic and fulvic acids, obtained by oxidizing activated charcoal with sodium hypochlorite. The yields recovery of HA-like substances was 12 and 28 wt% by using 10 and 20 cmol L−1 of oxidizing agent, respectively. X-ray photoelectron spectroscopy, energy dispersive X-ray, and solid-state 13C nuclear magnetic resonance (13C NMR) spectroscopies were used to evaluate the elements and structures present in all samples. XPS C 1 s spectra of HA extracted from TPI soil and from prepared HA showed aromatic structures (C = C and π–π* shake-up satellite peak) bounded to carboxyl groups (COOH). The morphology and polycondensation level of aromatic C were evaluated by scanning electron microscopy (SEM). The similarities of the spectra indicated that the used method was efficient to obtain an organic amendment similar to TPI soil organic matter.

Ancient anthrosols known as Amazonian dark earths or terra preta are part of the human built landscape and often represent valuable landscape capital for modern Amazonian populations in the form of fertile agricultural soils. The fertility, resilience, and large stocks of carbon in terra preta have inspired research on their possible role in soil fertility management and also serve as an example for a growing biochar industry it is claimed will sequester carbon for climate change mitigation. Although there is considerable scientific and public interest in terra preta, there is still much debate and little concrete knowledge of the specific processes and contexts of its formation. Research indicates that the formation of terra preta occurred mainly in midden deposits, themselves patterned around habitation areas, public areas, and routes of movement. Data from topographic mapping, soil analyses, and excavations in three regions of Amazonia demonstrate a widespread pattern of anthrosol formation in ring-shaped mounds surrounding flat terraces that extend across large areas of prehistoric settlements. It is hypothesized that there is a widespread type or types of occupation where the terraces were domestic areas (houses or yards) surrounded by refuse disposal areas in middens which built up into mounds over time, forming large deposits of terra preta and creating what could be called a ‘middenscape’. Initial results support the hypotheses, showing the interrelationship of residential and public areas, anthrosols, routes of movement, and natural resources. The patterning of anthrosols in ancient settlements indicates the use of space and can therefore serve as a basis for comparison of community spatial organization between sites and regions.

Since 1965 I have made several attempts to estimate the native population of Amazonia in 1492. My original method was to determine rough habitat densities, which project to totals for Greater Amazonia of from 5.1 to 6.8 million. I have rejected this method, given that the denser populations were mostly clustered rather than evenly dispersed. I nevertheless still believe that a total of at least five to six million is reasonable and as many as 10 million when dense terra preta populations are considered.

Approximately 600 million people lack access to safe drinking water, hence achieving Sustainable Development Goal 6 (Ensure availability and sustainable management of water and sanitation for all by 2030) calls for rapid translation of recent research into practical and frugal solutions within the remaining 13 years. Biochars, with excellent capacity to remove several contaminants from aqueous solutions, constitute an untapped technology for drinking water treatment. Biochar water treatment has several potential merits compared to existing low-cost methods (i.e., sand filtration, boiling, solar disinfection, chlorination): (1) biochar is a low-cost and renewable adsorbent made using readily available biomaterials and skills, making it appropriate for low-income communities; (2) existing methods predominantly remove pathogens, but biochars remove chemical, biological and physical contaminants; (3) biochars maintain organoleptic properties of water, while existing methods generate carcinogenic by-products (e.g., chlorination) and/or increase concentrations of chemical contaminants (e.g., boiling). Biochars have co-benefits including provision of clean energy for household heating and cooking, and soil application of spent biochar improves soil quality and crop yields. Integrating biochar into the water and sanitation system transforms linear material flows into looped material cycles, consistent with terra preta sanitation. Lack of design information on biochar water treatment, and environmental and public health risks constrain the biochar technology. Seven hypotheses for future research are highlighted under three themes: (1) design and optimization of biochar water treatment; (2) ecotoxicology and human health risks associated with contaminant transfer along the biochar-soil-food-human pathway, and (3) life cycle analyses of carbon and energy footprints of biochar water treatment systems.

Background: Terra preta do indio or ‘dark earth’ soils formed as a result of a long-term addition of organic matter by indigenous peoples in Amazonia. Aims: Here we report on the first study of productivity, allocation and carbon cycling from a terra preta plot in eastern Amazonia (Caxiuana, Para, Brazil), and contrast its dynamics with a nearby plot on infertile soil (ferralsols). Methods: We determined total net primary production (NPP) for fine roots, wood, and canopy and total autotrophic respiration (rhizosphere, wood, and canopy respiration) from two 1-ha plots on contrasting soils. Results: Both gross primary productivity (GPP) (35.68 ± 3.65 vs. 32.08 ± 3.46 Mg C ha−1 year−1) and carbon use efficiency (CUE) (0.44 ± 0.06 vs. 0.42 ± 0.05) were slightly higher at the terra preta plot. Total NPP (15.77 ± 1.13 Mg C ha−1 year−1 vs. 13.57 ± 0.60 Mg C ha−1 year−1) and rates of fine root production (6.41 ± 1.08 vs. 3.68 ± 0.52 Mg C ha−1 year−1) were also greater at the terra preta plot vs. the tower plot. C...

International audience; Mankind is actually facing serious issues due to the overexploitation of fossil fuels, biomass, soils, nitrogen, and phosphorus. It is claimed that biochar addition to soil improves C sequestration to prevent CO2 from atmospheric cycling. Biochar addition should also increase soil fertility in a similar way as anthropogenic dark earths of Central Amazonia. Previous studies have shown that biochar stimulates plant growth and increase fertilizer efficiency, especially when biochar is combined with organic fertilizers such as compost. However, little is known about optimum addition amounts and mixture ratios of biochar and compost. Indeed most experiments to mimic Terra preta de Indio focused on biochar alone or biochar in combination with mineral fertilizers. Therefore, we studied optimum biochar and compost amounts and mixture ratios with respect to plant response and soil fertility. We tested the effect of total amount from 0 to 200 Mg/ha, and biochar proportion from 0 % to 50 % biochar, of 18 different compost mixtures on growth of oat (Avena sativa L.) and soil properties in a fully randomized greenhouse study with sandy and loamy soil substrates. We sampled soil substrates before and after plant growth and analyzed plant growth and yield, total organic carbon (TOC), total nitrogen (TN), mineralized nitrogen (Nmin), soil reaction (pH), and electrical conductivity (EC) applying standard procedures. Results show that biomass production was increased with rising biochar and compost amounts. Oat plant height and seed weight was improved only with rising biochar amounts, but not with compost amounts. This could be explained by increase of total organic C and total N but not by plant-available ammonium and nitrate. The positive influence of composted biochar on plant growth and soil properties suggests that composting is a good way to overcome biochar’s inherent nutrient deficiency, making it a suitable technique helping to refine farm-scale nutrient cycles.

Terra Preta de Indio (TPI) and Terra Mulata (TM) are anthropogenic soils from the Amazon region and are rich in stable organic matter (OM). The formation and incorporation of OM in these soils has recently been under investigation. Organic geochemical analysis is an appropriated tool for the assessment of the sources of OM. Therefore, we have used the distribution of different acid classes preserved in the free and bound soil fractions of 12 samples from two contrasting anthropogenic soils (TPI, TM) and an adjacent soil, in order to infer the sources of OM and the magnitude of non-cultural influence on the formation of anthropogenic soils. The major acids in both fractions (i.e. free and bound) were n-saturated, branched and unsaturated alkanoic acids, hydroxyalkanoic acids, bile acids and lignin/suberin derived aromatic acids. In general, the acids in the free and bound fractions appeared to be complementary and together provided valuable information about OM incorporation into anthropogenic soils. Different incorporation of ω-hydroxyalkanoic acids (C22, C24 and C28) and 9(10),16-dihydroxyhexadecanoic acid, and presence/absence of bile acid showed a distinct genesis for the soils. The influence of modern vegetation was revealed by bound ω-hydroxyalkanoic acid (C22, C24 and C28) distributions only in the topsoil profiles of TPI and TM, indicating that organic geochemical analysis is a useful approach in the investigation of ancient human deposits in tropical archaeological soils.

Fertile dark anthrosols associated with pre-Columbian settlement across the Amazon Basin have sparked wide interest for their potential contribution to sustainable use and management of tropical soils and ecosystems. In the Upper Xingu region of the southern Amazon, research on archaeological settlements and among contemporary descendant populations provides critical new data on the formation and use of anthrosols. These findings provide a basis for describing the variability of soil modifications that result from diverse human activities and a general model for the formation of Amazonian anthrosols. They underscore the potential for indigenous systems of knowledge and resource management to inform efforts for conservation and sustainable development of Amazonian ecosystems. Antrossolos escuros e férteis associados a assentamentos pré-colombianos em toda a bacia amazônica têm despertado interesse por sua contribuição potencial no uso e manejo sustentável de solos e ecossistemas tropicais. Na região do alto rio Xingu, no sul da Amazônia, pesquisas sobre assentamentos arqueológicos e populações indígenas contemporâneas oferecem novos dados relevantes sobre a formação e o uso dos antrossolos. Os resultados fornecem uma base para a descrição da variabilidade de modificações no solo oriundas de diversas atividades humanas e um modelo geral para a formação de antrossolos amazônicos. A pesquisa mostra o potencial dos sistemas indígenas de conhecimento e manejo de recursos em contribuir na conservação e no desenvolvimento sustentável de ecossistemas amazônicos.

This manuscript presents the Raman characterization of the stable carbon materials found in a special type of soil, named Terra Preta de Indio (Indian Dark Earths). The Terras Pretas de Indios have been studied as a potential model for sustainable agriculture in the humid tropics. The stability of organic matter and the long-term high-level of ion exchange capacity in these soils are due to unusually high amount of black carbon. Here, we show how Raman spectroscopy can be used to characterize the stable carbon content in the Terras Pretas de Indios (TPI-carbons). The tangential stretching mode (G band) and the disorder-induced mode (D band) are analyzed in comparison to laboratory-produced amorphous carbons at different degree of disorder used here as reference materials. Statistical analysis show predominance of sp2 phase and crystallite sizes within the limit range between nanographite and amorphous carbons, while Raman mapping of a TPI-carbon grain shows that the surface is more disordered than the grain core. The analysis used here can also differentiate the TPI-carbon structures from different types of charcoal. Copyright © 2012 John Wiley & Sons, Ltd.

The increasing demand of fossil fuels and decreasing light oil proven reserves lead to a future scenario of abundant coke production from the refinement of non-conventional fossil hydrocarbons. This paper highlights the possibility of using coke as an agrichar for preparing fertile soils resembling Amazonian terra preta. It is suggested that this alternative may contribute to both the capture of greenhouse gas by afforestation and the increase of rainfall by the albedo effect. It is proposed that the ideal agrichar must function as a store of nutrients in the form of graphene substituted NPK groups at the micropore molecular structure, providing habitat for plant friendly microorganism inside its macropores. The possibility of a sink effect connecting nutrient storage with microorganisms has also been proposed. A preliminary discussion on the possible coking procedures to improve the resulting agrichar efficacy, three options for large scale desert greening using agrichar as well as recommendations for further research are presented.