Soil Exhaustion Research Articles

Soil changes in a subtropical seasonal forest chronosequences in the south of Brazil

ABSTRACT: The abandonment of field crops and the vegetation recovery in exhausted soils have been a recently studied subject as a way to assess the forest role on the soil recovering. The aim of this study was assess changes in the chemical(14 variables) and grain size (sand, silt, and clay) soil features in four forests chronosequences grew over abandoned field crops in the edge of the Brazilian Southern plateau, Rio Grande do Sul State. There were selected 25 forests aging from 5 to >100 years old in areas of slopes and highlands where samples of Leptosols and Regosols were collected at 15cm in depth. The Fisher's Discriminant Analysis showed that some variable groups of soils can distinguish significantly the soils under different forest ages. Six chemical features of soil fertility were the best monitoring indicators of areas impacted by agriculture. Changes in soil did not occur in a linear way towards time.

Abstract 4530: Tissue distribution, excretion and pharmacokinetics of the environmental pollutant and the tobacco smoke constituent dibenzo[a,l]pyrene in mice

Abstract Polycyclic aromatic hydrocarbon (PAH) has been shown to induce cancers after metabolic activation. DB[a,l]P is the most potent carcinogenic PAH found in tobacco smoke to date in rodent model systems. DB[a,l]P has been identified in mainstream cigarette smoke, soil and diesel exhaust particulate. Studies reported in the literature including our own demonstrated that administration of DB[a,l]P by i.p. or oral application in mice is known to induce tumors in organ sites including oral cavity, ovary, lung, mammary and liver. We further demonstrated that DB[a,l]P exerts its oral tumorigenicity mainly through the formation of its diol epoxides. However, detailed studies aimed at elucidating the tissues distribution and biological fate of DB[a,l]P remain to be determined. Therefore, a radiotracer experiment was conducted. Six weeks old female B6C3F1 mice received a single dose of [3H]-DB[a,l]P (1.512 Ci mmol-1 in dimethyl sulfoxide, 1.07 mg Kg-1 body weight) via gavage and were individually housed in metabolism cages (the same strain of mice used in carcinogenicity studies). Mice were randomly assigned into 7 groups (3/group) and sacrificed at0, 40 min, 2 h, 6 h, 24 h, 72 h and 1 week after carcinogen administration. Feces, urine, blood and tissues including ovary, mammary, uterus, liver, stomach, intestine, pancreas, spleen, kidney, bladder, and lung were collected. Approximately 8.5 ± 0.93% and 73.21± 9.58% of the radioactivity was eliminated in feces after 6 and 24 h, respectively. After 72 h and 1 week, 89.94 ± 7.00% and 91.40 ± 7.23% of the radioactivity was recovered in feces, respectively. The total urine excretion of the radioactivity was less than 2% after 1 week. We constructed the log (plasma level)-time curve for [3H]-DB[a,l]P given in a single oral dose to describe the absorption and elimination rate process, and a linear plot was observed on the elimination phase from 6 hr to 1 week (γ2 = 0.999). Therefore, the pharmacokinetic analysis of DB[a,l]P was conducted using a one compartment open model using Phoenix® WinNonlin 6.3 (Pharsignt Corp, Mt. View, CA). In Plasma, DB[a,l]P reached its Tmax at about 10 hr and the elimination half-life (t1/2) was about 49 h. We found that tissues in digestive tract including stomach and intestine reached their highest radioactivity after 40 min, followed by lung after 2 hr, for remaining tissues, mammary, liver, pancreas, kidney and blood (6 hr), and ovary, uterine, spleen and bladder (24 hr). After 1 week, the concentration of radioactivity in stomach and intestine dropped to less than 2% of the radioactivity measured at 24 h; however, more than 20% of the radioactivity in ovary, mammary, lung and liver (target tissues) were retained. The varied elimination rates of radioactivity among blood, target tissues and non-target tissues may provide insights that can, in part, account for the carcinogenicity of DB[a,l]P. Support: CA173465 and ES020411. Citation Format: Kun-Ming Chen, Yuan-Wan Sun, Cesar Aliaga, Alaa Awad, Krishne Gowda, Shantu Amin, Karam El-Bayoumy. Tissue distribution, excretion and pharmacokinetics of the environmental pollutant and the tobacco smoke constituent dibenzo[a,l]pyrene in mice. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4530. doi:10.1158/1538-7445.AM2015-4530

Singapore. Nature contained: Environmental histories of Singapore Edited by Timothy P. Barnard Singapore: NUS Press, 2014, Pp. x, 328, Figures, Plates, Tables, Bibliography, List of Contributors, Index.

Nature contained: Environmental histories of Singapore Edited by TIMOTHY P. BARNARD Singapore: NUS Press, 2014, Pp. x, 328, Figures, Plates, Tables, Bibliography, List of Contributors, Index. doi: 10.1017/S0022463414000770 This is an extraordinarily absorbing book. On starting my first reading I had not thought that there would be much of interest for me. Having read the outputs of, and for a brief time been involved in, Peter Boomgaard's pioneering, wide-ranging and ambitious Leiden-based EDEN project (Ecology, Demography and Economy in Nusantara) from 1993, it seemed that Singapore, as a developed world city, would have little to offer in environmental terms. How could any consideration of the environmental history of this small island state match the achievements of Boomgaard and his team in understanding the complexities of the Indonesian environment and its mutual human and environmental transformations? Well, of course it can't. But what Barnard's edited volume does is provide a fascinating introduction to what were important environmental moments and events not only in the history of Singapore, but also to its influence on the environmental history of other parts of Southeast Asia. As we might expect, in any consideration of Singapore, due attention is given to the sustained exploitation of nature for the purpose of capitalist development and the insertion of Singapore into a global economic system; the British colonial study, control, classification, and display of the natural world in the interest of furthering scientific understanding, and expressed in museums, research institutions, and learned societies; and the postcolonial construction of Singapore as an integrated and disciplined urban and 'garden' space. I very much liked the editorial device of commencing each chapter with a relevant extract from 'documents, interviews, and accounts of the events that influenced the chapters' (p. 5). So, for example, the chapter on Alfred Russel Wallace is prefaced with an excerpt from his The Malay Archipelago-, and the chapter on the Raffles Museum is preceded by extracts from The Annual Reports of the Raffles Museum and Library, newspaper accounts, and visitors' memories. The volume addresses many issues which have suffered from relative neglect in accounts of Singapore's history or have been influenced by uninformed conceptions of modern Singapore. Tony O'Dempsey examines environmental change in Singapore during the nineteenth century, reminding us that Thomas Stamford Raffles did not start with a clean slate. The island was already home to indigenous fishing communities; but more importantly Chinese Teochew farmers had settled there from the late eighteenth century and begun to cultivate gambier and pepper, which had enormously deleterious effects on the tropical rainforest in that both crops required substantial amounts of timber for processing and their cultivation resulted in soil exhaustion. The importance of this activity should not be understated in transforming the island's environment, and early colonial attempts at addressing the situation resulted in the establishment of a Forestry Department in 1884 to protect and reserve forests, by which time much damage had already been done. Habitat change also led to an upsurge in the number of human and domestic livestock and animal deaths from tiger attacks, a subject addressed in a chapter by Timothy Barnard and Mark Emmanuel. …

Mass migration through soil exhaustion: Transformation of habitation patterns in the southern Netherlands (1000 BC–500 AD)

Long-term archaeological data gathering in the southern Netherlands may deliver an unprecedented regional comparison that could be exemplary for the Pleistocene sand areas of the Northwest European Plain. On a micro-scale level, it has become clear that Bronze Age (2000–800 BC) and Iron Age (800–12 BC) farmers intensively used the landscape, resulting in a relatively dense distribution pattern of settlements all over the ridges and planes of the cover sand landscape. However, this agricultural use of the landscape—related to the “celtic field” system—led to a process of soil degradation by increased acidification during which Umbric Podzols gradually transformed into Carbic Podzols that could no longer be used as farmland. According to established “models,” this process of “secondary podzolization” particularly affected those sections of the landscape that were dominated by dry sandy soils with a low loam content (loam=clay and silt, between c. 10% and 20%). In the Late Iron Age (250–12 BC), the changing soil conditions resulted in a dramatic shift in the habitation pattern that clearly manifests itself in the Roman period (12 BC–410AD); on the local scale, the habitation moved from the degenerated soils to nearby areas with better soil conditions (higher loam content), which became more densely inhabited now than in the Bronze Age/Early Iron Age (2000–500 BC). The introduction of new land management (in the later Iron Age, and also by Romans) could also have been important for soil degradation. The areas where the Roman period settlements concentrated became also the areas where we can find the early medieval habitation (447–751AD) and where the Plaggic Anthrosols started to develop in the late medieval period (1270–1500AD). This paper is based on the analysis of soil properties.Measured loam values of soil samples (n=181) in Veldhoven, southern Netherlands, are in agreement with the described model that the plaggen cover is located on soils containing high combined silt and clay content (>25%) and that Carbic Podzols with no plaggen cover have low combined silt and clay content (<15%). Local spatial as well as vertical variations in loam content of sand layers have shown to occur, warning against single parameter research. Other potential causes for the deviation of the model are as follows: (a) impact of fluctuating groundwater levels; (b) impact of different hydrological properties in the shallow subsurface, depending on the grain size and transmissivity of the sediments; (c) organic matter content; (d) land management; and (e) climate change.

Climate Change and the Retreat of the Atlantic: The Cameralist Context of Pehr Kalm's Voyage to North America, 1748–51

Pehr Kalm’s voyage to America in 1748–51 produced a treasure trove of observations about climate, soil, and other matters of natural history. A close reading of Kalm’s travel journal, published writings, and correspondence reveals a deep ambivalence about the operation of the natural order in the New World. Kalm’s fieldwork and interviews with settlers charted processes of species extirpation, degeneration, soil exhaustion, and climate change. This interest in the environmental impact of settlement reflected in great part Kalm’s commitment to cameralist science. Kalm’s American voyage was a direct extension of his earlier biosprospecting tours in the Old World. He and his Swedish contemporaries hoped to transform the natural order of the nation through schemes of acclimatization and internal colonization. Such ambitions were in turn framed within a universal history of climate change. Kalm’s experience in the New World confirmed the global scope of these processes, while stressing the risk and uncertainty associated with projects of climate improvement. In this sense, Kalm’s voyage offers an important yet neglected entry point into the history of climate science.

Founding Farmers: Jefferson, Washington, and the Rhetoric of Agricultural Reform

From the 1780s to the 1820s, American political leaders often responded to problems of soil exhaustion and western emigration by promoting a dual program of agricultural reform and domestic manufacturing. They believed that a better system of land management and a more self-sufficient domestic economy could ensure social and political stability while still allowing for national progress and prosperity. Combining economic and ethical modes of improvement, they urged American to stay put, to adopt more efficient practices of soil conservation, crop rotation, and livestock production, and to develop a more permanent sense of place. While establishing a number of agricultural societies and engaging in their own personal experiments, these leaders also harnessed the written word, cultivating a vision of enlightened agriculture in a variety of literary genres, from natural history to georgic poetry, travel narratives to agricultural addresses, private letters to public reports. Such writings demonstrate an incipient ecological awareness and express a growing anxiety about the political and environmental durability of the United States. If Americans elevated personal profit above the common good, these leaders feared, then the fragile ecosystem of their republican empire would decline into ruin. (1) Thomas Jefferson was among the figures who preached this message of agricultural reform. In Notes on the State of Virginia (1787), his first and second inaugural addresses (Portable 290-95, 316-21), and much of his personal correspondence, Jefferson described his ideal nation as a loose confederacy of states united in a republic and rooted in the soil. He imagined that available lands in the West would allow a majority of citizens to participate in agricultural labor, preferably as small who sold their surplus produce to the market while still maintaining a degree of self-sufficiency. Alongside this agrarian ideal, however, Jefferson voiced an anxiety about tobacco culture, soil exhaustion, and the curse of slavery, while in his Farm Book he recorded an ambitious effort to restore the fields of Monticello through a seven-year cycle of crop rotation. He designed a new moldboard plow and imported new varieties of seeds and sheep in an effort to improve American agriculture. Likewise, in a collection of letters written to the English agronomist Arthur Young and published in 1801, George Washington complained that American had ruined the land base that defined their cultural identity. He worked to diversify his crops at Mount Vernon and made plans to rent his lands to English schooled in the art of soil improvement. (2) agricultural writings of these farmers represent a form of early American environmental activism that invites our critical attention. As Andrea Wulf argues in her recent study of Jefferson, Washington, and their contemporaries, The founding fathers have often been cast as the haloed demigods of the American Revolution ... but what has long been missing from this picture is their lives as and gardeners, which both reflected and influenced their political thinking and patriotism (103). (3) Typically, historians have traced the roots of American conservation to a much later date, often to the work of George Perkins Marsh (in the 1860s) or Gifford Pinchot (in the 1900s), but a similar commitment to environmental management also existed in the early national era. (4) For Jefferson and Washington, the success of the US nation-state depended on the scientific study and sustainable harvest of its natural resources, and in their arguments for agricultural reform they advanced a doctrine of efficiency that anticipated the conservation movement of the early twentieth century. These early American writers embraced a vision of sustainable agriculture that inspired the Populist Party of the late nineteenth century; in the twentieth century, their ideas resurfaced among neoagrarian writers who began to challenge industrial agriculture; and today, the same core values have shaped the contemporary local-foods movement. …

Boosting African farm yields

For tens of millions of people in rural Africa, life has gotten harder in recent years. Reliant on erratic rains, working exhausted soil and hobbled by decades of underinvestment and neglect, many have sunk deeper into poverty as agriculture — the mainstay of the region’s economy — continues to face neglect. A growing number of African governments and UN and non-governmental agencies argue that unless urgent efforts are made to raise crop yields, build transportation and marketing systems and adopt modern, sustainable farming methods, the continent will fail to reach its development goals and the rural majority will reap only meagre harvests.

Abolition and Plantation Management in Jamaica, 1807–1838

With the abolition of the transatlantic slave trade in 1807, the British colonies in the West Indies went through significant economic, demographic, social, and political adjustments. The central problem faced by planters revolved around increasing competition from the new sugar zones in the world market, in a situation in which they could not count on the constant replenishment of new enslaved laborers from Africa.Dave St. Aubyn Gosse's book addresses this issue through a careful analysis of the management of the Jamaican slave plantations between 1807 and 1838. This is a topic that has been extensively explored within the historiography of the British Empire. In the context of Seymour Drescher's argument with Eric Williams, historians such as J. R. Ward, Michael Craton, James Walvin, and B. W. Higman questioned the then-consecrated interpretations of the economic crisis of British slavery at the turn of the nineteenth century, examining the innovative responses of the West Indies planters to the end of the slave trade, including substantial changes in slave management practices and technological improvement of their sugar plantations. St. Aubyn Gosse dialogues with these revisionist publications reviewing the classical interpretations of the economic decline of the West Indies, and he follows closely the argument that Selwyn Carrington developed for the period prior to 1807.Based on the crop accounts series for the plantations that have substantial managerial correspondence, the author examines how planter management affected production levels and therefore the pace of economic decline. The managerial structure of plantations directed from a long distance — a result of widespread absenteeism — produced a series of distortions in the functioning of the sugar business, in view of the divergent interests of owners residing in the metropolis and their representatives on the ground. Disputes over gains in the short term and the long term often put them on opposite sides. The same problems that affected sugar production in the context of a general crisis affected attempts at economic diversification. Coffee plantations faced problems quite similar to those faced by sugar plantations regarding their inability to improve slaves' health and achieve a sustainable population growth. Both also overexploited the available labor force.Perhaps the most positive aspect of the book is its ability to demonstrate how Jamaican planters and their agents were crucial actors in their own economic ruin, as they contributed significantly to worsening the living conditions of the slave population between 1807 and 1833. With the conjuncture of shrinking sugar and coffee prices and restricted labor supply, the planters only offered in response “poor plantation management,” which proved to be fatal “in the era that called for bold, creative leadership” (p. 4). The management patterns were at the heart of the conflicts between masters, managers, and slaves, and they helped to deepen the crisis of slavery. The great Jamaican slave revolt of 1831–1832, decisive for the abolition of slavery in the British Empire in the following year, should be read in light of the failure to improve the material life of enslaved laborers and the efforts to increase plantation productivity after 1807.Despite its merits, the book shares two common problems with the ones it criticizes. I refer to the lack of due attention to environmental issues and the isolated treatment of Jamaica in relation to other New World slave zones. The ecological argument on soil exhaustion produced by the practices associated with large-scale slave commercial monoculture was a distinctive aspect of the decline thesis formulated by Eric Williams. Jamaica as a sugar zone was an area already deeply exploited in the early nineteenth century, unable to cope with the new commodity frontiers of that time. Much of the extra work demands imposed on slaves (especially the exhausting job of digging cane holes) derived from the environmental damage caused by almost a century of intensive sugar production. From this first problem comes the second problem. To properly understand the failures of plantation improvement in Jamaica, in particular its inability to cope with the drop in sugar and coffee prices in the world market, it would be necessary to incorporate into the analysis what was happening in the new zones of sugar and coffee production. The crisis of the Jamaican slave economy was largely an outcome of the economic success of slavery in Cuba and Brazil. If, on the one hand, we should congratulate the author of this competent and important book, on the other hand we should point out that to better understand the crucial period of 1807–1838, it will be necessary to incorporate perspectives that deal with the Caribbean as a totality beyond its imperial frontiers and that bring new lenses to the role of environmental conditions on the development of the Caribbean plantation economy.

Amoral Abolitionism: Frederick Douglass and the Environmental Case against Slavery

Ellis’s essay reconstructs the history of environmental crisis—the crisis of Southern soil exhaustion—at the heart of the antebellum slavery debates. Through readings of landscape in My Bondage and My Freedom, the essay argues that in the 1850s, Douglass displaces the moral and sentimental antislavery rhetorics for which he is known in favor of a newly pragmatic antislavery logic focused on slavery’s unsustainability—its tendency to exhaust the soil. This argument has two main aims: to explore Douglass’s engagement with ecological and economic antislavery rhetorics, and, more broadly, to consider the relevance of his pragmatic turn to modern ecocriticism as it reexamines the role of ethical sentiment in its project going forward.

Diversity patterns of indigenous arbuscular mycorrhizal fungi associated with rhizosphere of cowpea (Vigna unguiculata (L.) Walp.) in Benin, West Africa

Assessment of diversity and understanding factors underlying species distribution are fundamental themes in ecology. However, the diversity of native arbuscular mycorrhizal fungi (AMF) species in African tropical agro-ecosystems remains weakly known. This research was carried out to assess the morphological diversity of indigenous AMF species associated with rhizosphere of cowpea (Vigna unguiculata (L.) Walp.) in different agro-ecological zones (AEZ) of Benin and to examine the effects of soil chemical properties, climatic factors and agricultural practices on this diversity. Results showed that, in Benin, cowpea was grown by farmers in very exhausted soils, where available phosphorus and potassium were deficient. The indigenous AMF spore density was on average 202 spores per 100 g dry soil and there was no difference in the density among the agro-ecological zones (P = 0.56). Fifteen AMF morphospecies belonging to eight genera (Gigaspora, Scutellospora, Racocetra, Acaulospora, Funneliformis, Rhizophagus, Glomus and Claroideoglomus) were detected. The computed species richness estimators indicated that a limited number of additional undetected morphospecies are probably present in cowpea fields. According to analysis of similarity (ANOSIM), the arbuscular mycorrhizas community composition of the Sudanian zone and Guinean zone were not significantly different (r = −0.01; P = 0.517). The diversity of AMF morphospecies in the fields was weak with prevalence of Glomeraceae (92%). Furthermore, AMF diversity and evenness indices were negatively correlated with annual rainfall (P < 0.01) and with available phosphorus (P < 0.05). However, no significant correlation was observed between AMF diversity indices and soil organic carbon. Ultimately, this study tends to confirm that soil management practices (tillage, soil disturbance) have negative effect on AMF diversity.

Sensitivity of Plant and Soil Indices in Evaluating the Long-Term Consequences of Soil Mining from Reserves of Phosphorus, Potassium, and Magnesium

Mineral fertilizer production and distribution in Poland prior to 1991 were subsidized by the state. Demand for low-cost products exceeded substantially their production. During the transformation to market-oriented economy, the subsidy on fertilizers was removed and the demand from agriculture dropped dramatically. In 2008/2009 mineral fertilizer consumption reached only 122 kg nitrogen–phosphorus–potassium (N–P–K) per 1 ha and the N/P/K ratio remained 1:0.3:0.4. This tendency is disturbing because the soils in Poland are commonly acidic and poor in available K and Mg. Nitrogen fertilization and high-yielding crops compound the process of soil depletion. The objective of this article was an evaluation of soil and plant index sensitivity for soil exhaustion from P, K, and Mg. Two factorial experiments were carried on in 2003–2009 in a four-crop rotation: winter rape–winter wheat–maize–spring barley. The first factor was treatment without P, K, or Mg and a control treatment fertilized with all the macronutrients and the second one had five levels of N. For determination of plant fertilizer recommendations, official methods have been used (Egner DL, Schachtschabel). The nutrient requirements of crops were evaluated by determining the concentrations of N, P, K, and Mg in plant dry matter and N status of cereals with the nitrogen nutrition index (NNI) and Soil Plant Analysis Development (SPAD) tests. The soil was depleted for a 7-year period from analyzed macronutrients that led to a decrease of available forms of P, K, and Mg, but only a slight crop reduction. Only maize and rape crops, with high nutritional requirements, responded with a decreased yield pursuant to the lack of long-term fertilization with P, K, and Mg. There was a close correlation between K2O exhaustion and N rates. Soil indices have been more sensitive than plant indices.

Study on Agronomically and Economically Dominant Cropping Patterns in Some Selected Areas of Barisal District

The study area was Shanuhar village of Babugonj Upazila of Barisal district, which was selected purposively based on agronomic suitability of growing Rabi crops. Necessary data were collected through focus group discussion (FGD) with 30 farmers including small, medium, and large farm households, school teachers, village leaders all the remaining by using pre design check list and structure schedule during May 2007 considering Rabi season of 2006-2007. Usually, farmers of the village could not sow their crops within the optimum time. They transplanted Aman rice in late due to inundation of land and planting of Rabi crops in late because of land unsuitability and long duration of T. Aman rice. Boro rice was adopted about 75% of the cropped area in Rabi season and but yield was low because of inadequate irrigation facilities. In contrast wheat needs comparatively less irrigation than Boro rice. Moreover, mungbean, mustard, lentil and grass pea produce reasonability good yield in rainfed condition. About 20- 25 % land become suitable for seeding wheat by first week of December after harvesting NfV T. Aman which indicated good prospect of growing wheat in the study village. Wheat is a more profitable Rabi crop than other crops like grass pea, mustard, lentil. Farmers earned the highest per hectare gross return (Tk.98646) and gross margin (Tk.22870) from the Wheat – Aus rice -T. Aman rice pattern whereas Boro rice - Fallow - T. Aman pattern produced the lowest gross return (Tk.65918) and gross margin (Tk.10134). Higher benefit was achieved from the pattern Wheat –Aus rice -T. Aman rice because of less production cost and high price of wheat grain, though three cereals crops could exhaust soil nutrient so that Mungbean-Aus rice – T. Aman pattern may be alternate option to sustain soil health as well as productivity of the selected area. DOI: http://dx.doi.org/10.3329/bjar.v37i1.11177 Bangladesh J. Agril. Res. 37(1): 55-65, March 2012

Some regularities of anthropogenic transformation of gray forest soils

It is shown that, in the Nizhni Gorod oblast, plowing of gray forest soils, which amount to about 50% in the structure of arable lands, is accompanied by a change in their morphology, properties, and regimes. The degree of transformation is determined by the character of anthropogenic impact, which led to the formation of soils with a different level of soil improvement and exhaustion.

Correlação entre teor de umidade e eficiência energética de resíduos de Pinus taeda em diferentes idades

O crescente uso da biomassa florestal para a geração de energia leva empresas do setor de base florestal a preocuparem-se com a inclusão desta opção no uso múltiplo das florestas. Nesse sentido, o objetivo deste trabalho foi verificar a influência da idade de árvores de Pinus taeda nas propriedades energéticas de seus componentes, e a relação existente entre o teor de umidade do material queimado e seu potencial de geração de energia útil para um sistema energético, de modo a determinar a idade ideal para se intervir nos plantios, otimizando o uso de todos os componentes das árvores, sem o esgotamento do solo. Foram realizadas análises energéticas nas folhas, galhos, copa e casca de Pinus taeda com 10, 12, 14 e 24 anos em delineamento experimental completamente casualizado sob esquema fatorial. Os resultados demonstraram que todas as idades podem ser utilizadas para fins de geração de energia. Houve correlação negativa significativa entre poder calorífico líquido e teor de umidade, possibilitando o ajuste de equação para a determinação do poder calorífico líquido em função do teor de umidade dos componentes avaliados nas diferentes idades.

Phytomining: New Method for Rhenium Production

Abstract The scattered rhenium in the environment around copper and molybdenum mines and copper processing factories is a potential source for rhenium production. Phytomining is an inexpensive and environmentally friendly method for extracting rhenium and remediating exhausted soils near copper mines and ore-dressing regions.

Canopy transpiration of pure and mixed forest stands with variable abundance of European beech

Summary The importance of tree species identity and diversity for biogeochemical cycles in forests is not well understood. In the past, forestry has widely converted mixed forests to pure stands while contemporary forest policy often prefers mixed stands again. However, the hydrological consequences of these changes remain unclear. We tested the hypotheses (i) that significant differences in water use per ground area exist among the tree species of temperate mixed forests and that these differences are more relevant for the amount of stand-level canopy transpiration ( E c ) than putative complementarity effects of tree water use, and (ii) that the seasonal patterns of E c in mixed stands are significantly influenced by the identity of the present tree species. We measured xylem sap flux during 2005 (average precipitation) and 2006 (relatively dry) synchronously in three nearby old-growth forest stands on similar soil differing in the abundance of European beech (pure beech stand, 3-species stand with 70% beech, 5-species stand with E c was 50% higher in the beech-poor 5-species stand than in the two stands with moderate to high beech presence (158 vs. 97 and 101 mm yr −1 ); in the dry summer 2006, all stands converged toward similar E c totals (128–139 mm yr −1 ). Species differences in E c were large on a sapwood area basis, reflecting a considerable variation in hydraulic architecture and leaf conductance regulation among the co-existing species. Moreover, transpiration per crown projection area ( E CA ) also differed up to 5-fold among the different species in the mixed stands, probably reflecting contrasting sapwood/crown area ratios. We conclude that E c is not principally higher in mixed forests than in pure beech stands. However, tree species-specific traits have an important influence on the height of E c and affect its seasonal variation. Species with a relatively high E CA (notably Tilia ) may exhaust soil water reserves early in summer, thereby increasing drought stress in dry years and possibly reducing ecosystem stability in mixed forests.

Relationship between dieldrin uptake in cucumber fruits and methanol–water extractable residue in soil

We investigated the relationship between dieldrin concentrations in soil samples extracted with a 50% (v/v) methanol–water solution and dieldrin concentrations in four cultivars of cucumber fruits grown in 12 fields. Regression analysis showed significant (p<0.01) relationships between dieldrin concentrations in soil samples extracted with a 50% (v/v) methanol–water solution and dieldrin concentrations in four cultivars of cucumber fruits. Varietal differences were reflected in the slope of the regression lines. The fruit concentration factor (FCF), calculated as the dieldrin concentration in the fruits divided by the exhaustive soil concentration, indicated that dieldrin accumulation in cucumber fruits in summer is more than that in winter. Further, we found that the precision of this prediction method increased when we analyzed the same variety of cucumbers that were collected during the same harvesting periods, which were then extracted using 50% (v/v) methanol–water.

‘MORAL ECONOMY’ AND PEASANT REVOLUTION IN RUSSIA: 1861–1918

The ‘moral economy’ thesis was first propounded by E. P. Thompson and then developed by James C. Scott, and centres on the idea that in pre-capitalist societies social relations are grounded in a p...

Fluctuations in the size of Lake Chad: consequences on the livelihoods of the riverain peoples in eastern Niger

Recent level changes in Lake Chad are associated with large area changes because the lakebed is almost flat. They have deeply impacted the lifestyle of local populations. The Mober are the main ethnic group living in the surroundings of Bosso, in eastern Niger near the Yobe River and in Lake Chad. They were initially herders and farmers who developed flood-retreat farming and sophisticated irrigation systems. But their main activity during high Lake levels was fishing: it provided food as well as substantial incomes, thanks to the export of smoked and dried fish. Since 1973, Lake Chad has shrunk, mainly because of the decrease in rainfall in its southern hydrological basin, on the border between Chad and the Republic of Central Africa. On the border between Niger and Nigeria, the Yobe River discharge was more stable but it provided a minor input to the Lake. Large areas with rich soils, termed here as polders by analogy with those of the Bol region in Chad, became available and allowed maize, cowpeas, sorghum and vegetables farming without irrigation or fertilizer. This system is governed by the “bulama,” chiefs of the villages and of the land that is still abundant. However, without any return of the Lake on the polders, there is a serious risk of soil exhaustion. Sweet pepper farming has been developed on the sandy Yobe borders since 1960, partly thanks to the local farmers’ ancient knowledge of irrigation techniques. It requires an investment of capital to buy fertilizers, pesticides, and gasoline for the motor pumps. This farming system may not only provide high incomes, but it also promotes inequality between men and women on the one hand and on the other hand, between poor farmers, who must borrow money and who have to sell their harvest immediately, and those who are able to store their products and wait for the best prices. The Mober of Bosso were able to adapt to rapid changes in the level of the Lake firstly without public intervention due to their long-lasting pluriactivity. However, their ability to cope with stronger changes induced either by climate or by large projects aiming at restoring high Lake Chad levels should be carefully monitored.

Feasibility study on the use of soil washing to remediate the As–Hg contamination at an ancient mining and metallurgy area

Soils in abandoned mining sites generally present high concentrations of trace elements, such as As and Hg. Here we assessed the feasibility of washing procedures to physically separate these toxic elements from soils affected by a considerable amount of mining and metallurgical waste (“La Soterraña”, Asturias, NW Spain). After exhaustive soil sampling and subsequent particle-size separation via wet sieving, chemical and mineralogical analysis revealed that the finer fractions held very high concentrations of As (up to 32,500 ppm) and Hg (up to 1600 ppm). These elements were both associated mainly with Fe/Mn oxides and hydroxides. Textural and geochemical data were correlated with the geological substrate by means of a multivariate statistical analysis. In addition, the Hg liberation size (below 200 μm) was determined to be main factor conditioning the selection of suitable soil washing strategies. These studies were finally complemented with a specific-gravity study performed with a C800 Mozley separator together with a grindability test, both novel approaches in soil washing feasibility studies. The results highlighted the difficulties in treating “La Soterraña” soils. These difficulties are attributed to the presence of contaminants embedded in the soil and spoil heap aggregates, caused by the meteorization of gangue and ore minerals. As a result of these two characteristics, high concentrations of the contaminants accumulate in all grain-size fractions. Therefore, the soil washing approach proposed here includes the grinding of particles above 125 μm.