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It is nowadays recognized the P-Y curves-based methods are the most commonly used methods for the analysis and design of pile foundations under lateral loads. Such methods have the advantage to account for the non-homogeneity of soil properties and the non-linear pile/soil interface behavior as well. The paper aims at presenting a practical method to define a hyperbolic function describing the P-Y curves along the pile whose parameters, namely the initial reaction modulus and the limit lateral soil resistance, are correlated with the SPT N-value. The study is based on an extensive interpretation of several full-scale pile loading tests; the test piles being fully instrumented by strain gauges to derive the bending moment profiles along the pile. Finally, the predictive capability of the proposed method was demonstrated by comparing the predicted load-deflection curves by the software SPULL to the experimental ones obtained from lateral loading tests on simply instrumented full-scale piles.

The main purpose of this study is to substantiate the relationship between the coefficient of vibrocreep and the frequency of dynamic vibration exposure based on laboratory dynamic triaxial tests using sandy soil as an example. These studies were carried out as part of the design of new metro stations and tunnels in the city of Moscow. As a result of the tests performed, experimental dependences were obtained between the value of the coefficients of vibrocreep, the frequency of dynamic vibration impact and the value of lateral pressure in the chamber of a triaxial device, which, in fact, characterizes the depth of the studied soils. It has been established that with an increase in the value of the lateral pressure, the value of the vibration soundness coefficient also increases. At the same time, with an increase in the frequency of dynamic action, a decrease in the coefficient of vibrocreep is observed. The obtained dependences allow predicting the vibrocreep of sandy soils depending on the depth of occurrence and the intensity of the dynamic impact. The scientific novelty of the performed research lies in the generalization of a large number of unique laboratory studies performed in order to predict the vibrocreep of sandy soil and develop new geomechanical models of soil behaviour under dynamic man-made impacts.

The effect of clay and humic materials in the control of nitrate leaching from sandy soil was established through a column experiment. In a PVC column with 3 inches dia and 45 cm length packed with sandy soil, six leaching at 15 days intervals were performed. Nitrogen was added @ 150 kg ha-1. The results of the study indicated the significant influence of clay @ 40 t and humic acid @ 20 kg ha-1 were efficient in the control of NO - and NH + N leached through the column and a corresponding increase of retension of N in soil. The linear equation model was used to ascertain the influence of the physiochemical characteristics on the leaching of nutrients.

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Soil Characteristics Under Savanna and Natural Forest on the Bateke Plateau in the Democratic Republic of Congo. One of the major constraints for the natural replenishment of the fertility of savanna sandy soils is the continual shortening of fallow in the traditional slash and burn system. On the Bateke plateau, agroforestry appeared as one of the alternative systems to cope with soils poverty. This study is a preliminary assessment of soil nutrient contents up to 120 cm deep, under natural savanna and forest, developed on the same parent material with kaolinite as dominant clay and to assess the opportunity to support agroforestry. Ninety composite soil samples were collected and analyzed. Mean comparisons and discriminate analyses were used for statistical purpose. The result of statistical analysis did not show significant differences in soil composition. The high yields in shifting cultivation after forest clearance could be explained by the contribution of organic matter, due to large quantities of ashes that improves the nutrient balances in the soil. Agroforestry is then justified not only because of its high supply of organic matter, but also because it can really shorten the fallow duration.

Effect of the use of biochar and leaves of Tithonia diversifolia combined with mineral fertilizer on maize (Zea mays L.) and the properties of ferralitic soil in Kinshasa (DRC). Description. This article deals with the improvement of the productivity of (poor) sandy and acidic soils in Kinshasa (DRC) using local natural resources in addition to mineral fertilization. Objectives. The objective of this study was to evaluate the effect of ground charcoal (biochar) and Tithonia diversifolia leaves combined with mineral fertilizer on soil properties and on the performance of the maize crop. Method. Five treatments and an eyewitness: T0 (control), T1 (N120 P141 K134), T2 ([N60 P71 K67] + 30 t·ha-1 biochar), T3 ([N60 P71 K67] + 8 t·ha-1 T. diversifolia), T4 ([N120 P141 K134] + 30 t·ha-1 biochar), T5 (N160 P188 K179) repeated four times were compared in a randomized complete block. Physical and/or chemical analyses were carried out on the ground, on T. diversifolia leaves and on maize biomass. Results. The results showed that application of biochar and T. diversifolia leaves combined with mineral fertilizers increased the carbon content, the potassium content and the cation exchange capacity of the soil as well as grain yield, exports of mineral elements and the apparent coefficient of mineral elements use by the crop. Treatments under biochar reduced acidity and aluminum saturation with an improvement of the soil's phosphorus availability. Taking into account the acceptability index, the T3 (AI = 3.06), T4 (AI = 2.92) and T2 (AI = 2.14), it would be possible for these treatments to be easily accepted by farmers. Conclusions. The results of this study provide an opportunity to improve the productivity of poor soils in Kinshasa and to increase the crop performance for a period of two campaigns with the use of biochar and T. diversifolia leaves in addition to mineral fertilizer.

The permanent deformation of the road subgrade soil accumulated during passage of the cyclic loads is mainly due to the post-compacting and plastic flow mechanisms according to a study by the National Cooperative Highway Research Program in 2004. The main objective of the paper is to develop a relationship between the parameters a an d b of a power model and the usual physical properties of subgrade soils. The parameters a and b are assumed to represent the post-compacting and plastic deformation, respectively. Highlighting the link between the parameters a and b and the mechanisms of permanent deformation was the basic assumption which helped developing correlations. Data collected on nine different samples of soils characterized and having undergone cyclic triaxial tests permanent deformation were used to develop relationships. A distinction was made between the relationship parameter for clay and sandy soils. Indeed, clay soils with lower air permeabilities behave differently when compared to post-compaction sandy soils. However, a single relationship was developed for the parameter b, because the observed behavior appears similar for clay and sandy soils. Both correlations have coefficients of determination about 0.6. Also, comparison of the measured and predicted permanent deformation was done on the clay of St-Narcisse and sand of Fossambault. The results are generally good, despite a case of discrepancy observed. [ABSTRACT FROM AUTHOR]

Use of Aquatic Plants, mainly as Soil Amendment, in the Thua Thien Hue Province, Central Vietnam. 2. Field Practices, Survey among Farmers, and Possible Impact on the Tam Giang Lagoon Ecology. The sandy soils of the coastal area of Central Vietnam, particularly in the Thua Thien Hue Province, have a limited natural fertility. Amending these soils with organic materials is the most important way to improve their productivity. In this region, numerous farmers are fertilizing their soils with aquatic plants collected from the Tam Giang lagoon. The present study aims to provide quantitative and qualitative data on this local practice, based on a survey among the farmers and on field observations carried out at the beginning of 2005. Among the 60 interviewed farmers, 38 (63%) use aquatic plants to fertilize their crops, mainly sweet potatoes, cassava, chili, tobacco, and vegetables. Rice and peanuts are not commonly fertilized by this way. This practice is particularly popular in the communes located in the North of the lagoon, where the proportion of lands fertilized in this way is sometimes higher than 20%, whereas in the sandy zone between the lagoon and the sea, it is generally around 10 to 20%. The most used species are Najas indica, Vallisneria spiralis, Potamogeton malaianus plus various algae species. Following the farmers' estimations, the quantities actually used vary from 0.45 to 10 tons of fresh matter per year and per farm, with an average of 3.5 tons. The farmers are not at all conscious of the possible ecological impact of collecting plants for agricultural uses, particularly on the sustainability of the lagoon resources. Many of them believe that the plant biomass reduction that they have observed in recent years in the lagoon is mainly due to the development of aquaculture.

Agricultura Use of Aquatic Plants, mainly as Soil Amendment, in the Thua Thien Hue Province, Central Vietnam. 1. Inventory, Abundance and Chemical Characterization of Collected Plants. The use of aquatic plants for various purposes, and notably as organic amendment for sandy soils with low inherent fertility is a frequent empirical practice in Central Vietnam. In the Thua Thien Hue Province, the Tam Giang lagoon covering 22,000 ha represents a source of exogenous biomass potentially important for agriculture. The present study makes an inventory of the submerged macrophytes and the algae occurring in the lagoon during the period of February-April 2005. Twelve species of macrophytes (belonging to the Potamogetonaceae, Najadaceae, Cymodoceaceae, Hydrocharitaceae, Ceratophyllaceae, and Haloragaceae families) and five of algae (belonging to the Ulvaceae, Cladophoraceae, Characeae, and Gracilariaceae families) were identified. Their abundance varies significantly following species and location in the lagoon. Indeed, the salt concentration, the water depth and the type of sediments in which the macrophytes are anchored are submitted to large variations depending on position in the lagoon. The highest values of fresh biomass measured for monospecific vegetal mats were observed for Vallisneria spiralis (3.1 kg.m-2), Najas indica (2.9 kg.m-2), Halodule tridentata (2.5 kg.m-2) and Cymodoceae rotundata (2.3 kg.m-2). The concentrations of main elements were determined in samples of all plant species. In the macrophytes, the following ranges of element concentrations (in % of dry matter) were found: N 1.0 to 3.5; P 0.08 to 0.45; K 1.0 to 4.2; Mg 0.3 to 1.4; Ca 0.7 to 2.8; Na 0.7 to 7.6. These variations indicate that the fertilization capacity of aquatic plants when they are used as soil amendment can vary to a large extent according to the species. Even more contrasted element concentrations were found for the algae. The Na concentrations in the collected plants can be partly explained by the salinity level met in the sampling areas.

One of the major constraints for the natural replenishment of the fertility of savanna sandy soils is the continual shortening of fallow in the traditional slash and burn system. On the Bateke plateau, agroforestry appeared as one of the alternative systems to cope with soils poverty. This study is a preliminary assessment of soil nutrient contents up to 120 cm deep, under natural savanna and forest, developed on the same parent material with kaolinite as dominant clay and to assess the opportunity to support agroforestry. Ninety composite soil samples were collected and analyzed. Mean comparisons and discriminate analyses were used for statistical purpose. The result of statistical analysis did not show significant differences in soil composition. The high yields in shifting cultivation after forest clearance could be explained by the contribution of organic matter, due to large quantities of ashes that improves the nutrient balances in the soil. Agroforestry is then justified not only because of its high supply of organic matter, but also because it can really shorten the fallow duration. [ABSTRACT FROM AUTHOR]

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Résumé: L’étude présentée dans le cadre de cet article constitue la synthèse d’analyses tracéologiques réalisées sur plus de 900 artefacts en silex provenant de cinq sites datés du Mésolithique ancien (Ede, Evergem, Doel et Verrebroek) et récent (Hempens), situés dans la région des sols sablonneux du nord de la Belgique et des Pays-Bas. Les résultats fonctionnels obtenus, intégrés dans un contexte archéologique, paléo-environnemental et chronologique bien défini, portent un nouvel éclairage sur la fonction des industries mésolithiques et au-delà sur le fonctionnement des campements et des modalités d’occupation et d’exploitation de ces territoires. Il apparaît notamment que dans cette région, tous les gisements sont des sites résidentiels saisonniers de durée d’occupation brève, s’insérant dans un cycle de déplacements planifié. L’étude a également permis de mettre en évidence, l’émergence dans la région des sols sableux d’un nouvel artisanat lié au travail des plantes. [ABSTRACT FROM AUTHOR]

Copyright of Biotechnologie, Agronomie, Societe et Environnement is the property of Les Presses Agronomiques de Gembloux and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Biotechnologie, Agronomie, Societe et Environnement is the property of Les Presses Agronomiques de Gembloux and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Raw wastewaters were massively spread on sandy luvisols near Paris from 1899 to 2002, leading to high trace metals (TM) pollution of soils. Mass balance calculations were performed on a soil profile to assess vertical migration of TM. The contamination was estimated by subtracting the natural pedo-geochemical background of the horizons. TM inputs were estimated using Cr as an invariant. It is shown that Pb and Cr remained in the surface horizon, while Ni, Cd, Cu and Zn migrated downward, being more or less trapped depending on the physicochemical properties of the horizons. To cite this article: C. Dère et al., C. R. Geoscience 338 (2006). [Copyright &y& Elsevier]