Sunday 31 July 2016

Adsorption and desorption kinetics and phosphorus hysteresis in highly weathered soil by stirred flow chamber experiments

Soil and Tillage Research, 162 (2016) 46–54


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.

Friday 15 July 2016

Dernières nouvelles de 42 vieilles parcelles Indicateurs d’évolutions pédologiques infra-centenaires en Néoluvisol de lœss nu, sous contrainte d’applications continues de matières fertilisantes

Étude et Gestion des Sols, 23, 2016, 143-162



Ce travail présente un bilan des impacts de 85 ans d’apports d’engrais chimiques N, P, K, d’amendements basiques et organiques sur la composition et les propriétés d’un Néoluvisol de lœss, en comparaison à des situations témoins sans apport. Cette expérimentation de longue durée est menée depuis 1928 en sol nu dans le dispositif des 42 parcelles à l’Inra de Versailles. Le bilan repose sur les résultats analytiques d’échantillons collectés en 2014 dans l’ensemble des horizons de surface. Les résultats sont confrontés à des données disponibles du sol initial de 1928. L’objectif est de préciser la nature et l’ampleur des évolutions physicochimiques, induites en moins d’un siècle, et d’identifier les processus pédologiques qui en sont à l’origine.
En absence d’entrée de matières organiques (MO), de forts contrastes s’observent en fonction de la nature des apports minéraux, mais aussi dans les parcelles témoins : en 2014, d’une parcelle à une autre, l’écart maximal de pH est de 5,3 unités (3,5-8,8) et la CEC varie de 5,2 à 14,4 cmol+/kg. La garniture cationique varie de plus de 98 % de Ca échangeable dans les sols chaulés, à plus de 96 % d’Al échangeable dans les sols acides. Le carbone organique a perdu 50 à 75 % de la valeur initiale en 1928, et les teneurs en argile s’étendent entre 13 et 20 %. Des teneurs significatives de Mnéch s’observent dans les sols denses, alors que Feéch est détectable prioritairement dans les sols acides. Par contre, sous amendement de fumier, l’ambiance physicochimique est très différente, notamment par l’abondance de C organique (43-50 g/kg) et une forte valeur de la CEC, supérieure à 22 cmol+/kg.
La nature, l’ampleur et la diversité des propriétés physicochimiques enregistrés dans les horizons de surface des sols des 42 parcelles en 2014 témoignent de différents processus pédologiques en jeu, actuels ou dans le passé. Dans les sols témoins, sous la seule contrainte de la minéralisation progressive des MO et des conditions atmosphériques, les propriétés et la composition ont considérablement changé : une acidification de 1-1,5 unités de pH, la lixiviation d’une proportion notable de cations bivalents et l’apparition de quantités significatives d’Al échangeable sur le complexe d’échange, une baisse de la CEC et une perte d’argile de 2 à 3 %. La migration d’argile, l’argilluviation, processus caractéristique dans les luvisols, apparaît amplifiée sous traitements ‘monovalents’, notamment sous apport de Na où la perte d’argile par lessivage peut atteindre jusqu’à 5 à 6 %. Sous apport de K, la perte d’argile est moindre, liée à un processus d’illitisation des particules de smectite par rétrogradation du K. De plus, les apports de phosphate naturel ou de superphosphate semblent également favoriser la migration d’argile, alors que les amendements basiques et de fumier limitent, voire stoppent le processus. Dans les traitements ‘acides’, sous apports d’engrais ammoniacaux ou de sang desséché, les cations échangeables initiaux (Ca, Mg, K, Na) ont été quasi-totalement lixiviés, et remplacés par l’Al. La forte aluminisation du milieu implique un processus de dissolution minérale, affectant en premier lieu les argiles fines (smectites). Les faibles valeurs de la CEC illustrent la perte notable de charges fixes liée à la dissolution partielle des smectites. Néanmoins, l’impact de l’altération en milieu acide sur la granulométrie apparait négligeable, car la teneur en argile dans les sols acides reste inchangée par rapport à 1929. Deux pistes sont envisagées pour expliquer ce constat : un processus de microdivision par l’altération de minéraux phyllosilicatés de taille limoneuse fine et leur transformation en particules argileuses, ou alors un processus de néoformation de phases secondaires à partir de Si, Al et/ou Fe libérés par dissolution d’argiles fines en milieu acide. Enfin, un processus d’agrégation à l’échelle des particules d’argile par le développement de liaisons fortes entre les particules d’argile et des phosphates-Al (ou –Fe) formés en milieu très acide est suspecté dans les sols sous phosphate d’ammoniaque conduisant à la sous-estimation de la fraction < 2 μm lors d’analyses granulométriques courantes.
La palette très étendue de propriétés physicochimiques des horizons de surface dans les 42 parcelles souligne un laps de temps court en pédologie pour leurs changements, d’ordre infra-centenaire. Pour assimiler ces changements opérés en surface au développement de processus pédologiques, il est nécessaire à la fois de suivre l’ampleur et la chronologie des évolutions par l’analyse d’échantillons de la collection historique et d’étendre l’étude des impacts aux horizons E, BT, et C profonds. Ces travaux sont actuellement en cours.

Thursday 14 July 2016

Effects of different cooking methods on some chemical and sensory properties of Galega kale

International Journal of Food Science and Technology
DOI: 10.1111/ijfs.13181


Kale (Brassica oleracea L. var. acephala) is rich in bioactive phytochemicals such as phenolic compounds and vitamins. However, cooking the plants can cause important changes in composition. The objective of this study was to investigate the effect of some domestic cooking processes (boiling, steaming, microwaving and pressure cooking) on several quality parameters of Galega kale. Boiling had the strongest effect on the antioxidant capacity (the IC50 was four times higher than in the fresh sample), total phenolics (losses of 76.4–77.9%) and colour (ΔE = 17.79–19.12). Microwaving caused the greatest loss of soluble solids (80.8–82.2%). Steaming seems to be the best method for retaining the nutrient and antioxidant capacity of kale (100% ash, 71–77.5% soluble solids, 100% antioxidant capacity, 67–71% total phenolics, 62–71% chlorophyll). However, steamed kale was awarded the lowest sensory scores, indicating the difficulty in reconciling nutritional value and sensorial quality. Use of discriminant statistical techniques enabled the classification of 100% of samples.

Monday 11 July 2016

Optimization of the process of aromatic and medicinal plant maceration in grape marc distillates to obtain herbal liqueurs and spirits

Journal of the Science of Food and Agriculture
DOI: 10.1002/jsfa.7822


Herbal liqueurs are alcoholic beverages produced by the maceration or distillation of aromatic and medicinal plants in alcohol, and are also highly valued for their medicinal properties. The process conditions, as well as the number and quantity of the plants employed, will have a great influence on the quality of the liqueur obtained. The aim of this research was to optimize these important variables.

A Box–Benhken experimental design was used to evaluate the independent variables: alcohol content, amount of plant and time during the experimental maceration of plants in grape marc distillate. Four plants were assessed, with the main compound of each plant representing the dependent variable evaluated with respect to following the evolution of the maceration process. Bisabolol oxide A in Matricaria recutita L., linalool in Coriander sativum L. and eucalyptol in Eucalyptus globulus Labill. were quantified using a gas chromatography-flame ionization detector. Glycyrrhizic acid in Glycyrrhiza glabra L was determined using a high-performance liquid chromatography-diode array detector. Other dependent variables were also evaluated: total phenolic content, color parameters and consumer preference (i.e. appearance).

The experimental designs allowed the selection of the optimal maceration conditions for each parameter, including the preference score of consumers: 70% (v/v) of ethanol, 40 g L−1 plant concentration and a maceration process of 3 weeks. 

Sunday 3 July 2016

Second-generation bioethanol of hydrothermally pretreated stover biomass from maize genotypes

Biomass and Bioenergy, 90 (2016) 42–49


Twelve maize genotypes, were agronomically evaluated and their stover hydrothermally pretreated in a temperature range of 210–225 °C to assess the effects of genotype and pretreatment severity on stover recalcitrance toward bioethanol conversion. Maize genotypes exhibited significant variation for biomass yield and all agronomic evaluated, while among all cell wall constituents measured in the unpretreated stover, only ash content showed differences among genotypes. The pretreatment severities assayed impacted most stover compositional traits, and the glucose recovered after enzymatic hydrolysis displayed a similar profile among genotypes with similar genetic background. Harsher pretreatment conditions maximized the potential cellulosic bioethanol production (208–239 L/t), while the mildest maximized the bioethanol from the hemicellulosic hydrolysates (137–175 L/t). Consequently, when both pentose and hexose sugars were considered, the total potential bioethanol produced at the lowest and highest pretreatment temperatures was similar in all genotypes (292–358 L/t), indicating that the lowest temperature (210 °C) was the optimal among all assayed. Importantly, the ranking of genotypes for bioethanol yield (L/ha) closely resembled the ranking for stover yield (t/ha), indicating that breeding for biomass yield would increase the bioethanol production per hectare regardless of the manufacturing process. Similarly, the genetic regulation of corn stover moisture is possible and relevant for efficient energy production as biomass moisture has a potential impact on stover transportation, storage and processing requirements. Overall, these results indicate that local landrace populations are important genetic resources to improve cultivated crops, and that simultaneous breeding for production of grain and stover bioethanol is possible in corn.

Friday 1 July 2016

F sorption/desorption on two soils and on different by-products and waste materials

Environmental Science and Pollution Research (2016) 23, 14676–14685
DOI: 10.1007/s11356-016-6959-8


We used batch-type experiments to study F sorption/desorption on a forest soil, a vineyard soil, pyritic material, granitic material, finely and coarsely ground mussel shell, mussel shell calcination ash, oak wood ash, pine-sawdust, slate processing fines, and three different mixtures that included three components: sewage sludge, mussel shell ash, and calcined mussel shell or pine wood ash. The three waste mixtures, forest soil, pyritic material, and shell ash showed high sorption capacity (73–91 % of added F) and low desorption, even when 100 mg F L−1 was added. All these materials (and to a lower extent wood ash) could be useful to remove F from polluted media (as certain soils, dumping sites, and contaminated waters). The vineyard soil, the granitic material, mussel shell, slate fines, and pine-sawdust were less effective in F removal. In most cases, sorption data fitted better to the Freundlich than to the Langmuir equation. These results can be useful to program the correct management of the soils, by-products, and waste materials assayed, mostly in situations where F concentrations are excessive and F removal should be promoted.