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1.
Soil bulk density varies among sites as well as microhabitats, and in different years at the same site. Bulk density is a highly variable parameter that introduces undefined but significant errors to abundance field data of soil microfauna when given in individuals per g soil dry mass (sdm). Such data are not comparable among sites, microhabitats and years and they are unsuitable for comparative ecological field studies. Soil corer sampling technique, defined as soil surface square units (e.g. 1 cm2), is recommended to overcome the methodological imprecision of estimating abundance of soil microfauna from field studies in ind·g sdm. This removes consideration of variable soil bulk density and enables us to establish abundance values directly in ind·cm−2 without any recalculations. Resultant data are comparable both spatially and temporally. Abundance data as individuals per m2 is a commonly used unit for soil meso-, macro- and megafauna.
Résumé
La densité apparente du sol est extrêmement variable aussi bien selon les sites que selon les microhabitats, ainsi que selon les différentes années sur un même site. La variabilité de ce paramètre induit des erreurs mal définies, mais significatives, dans l'estimation des abondances de la microfaune du sol lorsque celles-ci sont produites en termes de nombre d'individus par gramme de sol sec. De telles données ne sont pas comparables entre sites, microhabitats, ou années, et ne sont donc pas utilisables pour des études d'écologie comparative. La méthode d'échantillonnage par carottage du sol sur une surface connue (par exemple 1 cm2) est recommandée afin de maîtriser l'imprécision liée aux estimations par poids de sol sec. Cela permet de s'affranchir du paramètre de densité apparente du sol et permet de donner directement des valeurs d'abondance en nombre d'individus par cm2 sans aucun calcul. Les données ainsi exprimées sont comparables, à la fois spatialement et temporellement. Le nombre d'individus par m2 est une unité communément utilisée pour la méso-, macro- et mégafaune. 相似文献2.
Longevity of microbial and enzyme activity and their influence on NPK content in pressmud vermicasts
Total microbial population and their activity (CO2 evolution), macronutrients (N, P, K) and enzymes (dehydrogenase and phosphatase activities) in the uningested pressmud, fresh casts and 15- and 30-d-old pressmud vermicasts of two composting worms, Lampito mauritii and Eudrilus eugeniae, have been determined. Enhancement of microbial population and activity, NPK content and enzyme activities in the fresh casts are due to enhanced mineralization of nutrients, high substrate concentrations and high moisture level. As the vermicast become aged, there is a reduction in the moisture level leading to reduction in microbial population and activity. Consequently reduced microbial activity leads to reduced enzyme activity and NPK contents. Dryness of aged vermicasts implies the loss of N through volatilization, leaching and denitrification. Reduction in P is due to lesser conversion of organic to inorganic P due to reduced microbial activity. Loss of K input is due to leaching.
Résumé
La population microbienne totale et son activité (dégagement de CO2), les nutiments (N, P, K) et les activités enzymatiques (déshydrogénase et phosphatase) dans des résidus de canne à sucre (bagasse), ainsi que dans des turricules frais et des turricules âgés de 15 et 30 j, formés à partir de ce matériau organique par deux vers de terre composteurs, Lampito mauritii et Eudrilus eugeniae, ont été étudiés. L'augmentation de la population bactérienne et son activité, des teneurs en N, P, K et des activités enzymatiques dans les turricules frais sont liés à un accroissement de la minéralisation des nutriments, à la forte concentration en substrat organique et à la forte teneur en eau. Lorsque les turricules vieillissent, la réduction de cette teneur en eau conduit à une diminution de la population bactérienne et de son activité. Ceci conduit également, par conséquent, à une diminution des activités enzymatiques et des teneurs en N, P, K. La dessiccation des turricules entraîne une perte d'azote par volatilisation, lessivage et dénitrification. La réduction des teneurs en phosphore est due à une moindre conversion du P organique en P inorganique par les microorganismes. La perte de potassium se fait par lessivage. 相似文献3.
Christian Kampichler Alexander Bruckner Andreas Baumgarten Aline Berthold Sophie Zechmeister-Boltenstern 《European Journal of Soil Biology》1999,35(3):135
Field mesocosms can overcome the simplicity and deficiencies of laboratory based experimental designs. This study deals with a number of possible side effects of a mesocosm technique that involves deep-freezing of soil monoliths to eliminate soil fauna, wrapping in nets of various mesh-size to control faunal immigration and replanting in the field. We used Berlese-Tullgren sets in the field to directly inoculate mesocosms with microarthropods. After 6 months of exposure, the number of collembolans equalled control level whereas immigration and inoculation of oribatids accounted for only 30% of the control. The number of ciliates, their distribution into feeding groups, and the numbers of nematodes, tardigrades and rotifers were not significantly affected by the elimination of mesofauna. We also did not detect significant treatment specific effects on microclimatic conditions within the litter layer of the mesocosms. Furthermore, we compared the monolith approach with a technique using sieved soil as a time-saving alternative. Water capacity and infiltration rate of mesocosms made of sieved soil did not differ from mesocosms made of monoliths, but NH4+ losses were significantly higher in sieved soil when defaunated by deep-freezing. We conclude that the investigated mesocosm technique has little side effects and recommend the use of monoliths in mesocosm studies.
Résumé
La mise en œuvre de mésocosmes au champ peut être une alternative pour pallier la simplicité et aux imperfections des expérimentations en laboratoire. Cette étude aborde les différents effets secondaires potentiellement générés par une approche en mésocosmes, impliquant successivement i) une défaunation des monolithes de sol par congélation intense, ii) leur enrobage au moyen d'une toile de vide de mailles dans le but de contrôler l'immigration de la faune, iii) leur replacement au champ. À l'aide d'appareils de Berlèse-Tullgren utilisés sur place, les mésocosmes ont été ensuite directement inoculés avec les micro-arthropodes extraits. Après 6 mois d'incubation, l'abondance des collemboles est similaire à celle observée initialement dans le sol témoin alors que l'abondance des oribates, par immigration et inoculation, atteint seulement 30% de l'abondance observée dans le sol témoin. L'élimination de la mésofaune n'a pas affecté le nombre de ciliés et leur distribution dans les différents groupes trophiques, ni le nombre de nématodes, de tardigrades et de rotifères. De même, nous n'avons pas mis en évidence de manière significative d'effets secondaires, spécifiques au prétraitement des monolithes sur les conditions microclimatiques régnant au sein de la couche de litière dans les mésocosmes. L'approche en monolithes de sol est aussi comparée avec une approche par tamisage du sol, en tant que technique alternative permettant un gain de temps. La capacité de rétention en eau et le taux d'infiltration mesurés dans les mésocosmes constitués de sol tamisé et ceux constitués de monolithes de sol ne différent pas, mais les pertes en NH4+ sont significativement plus élevées dans les mésocosmes faits de sol tamisé, après l'étape de défaunation par forte congélation. Nous concluons que la technique mésocosme proposée ici présente peu d'effets secondaires et nous recommandons l'utilisation de monolithes de sol pour des études en mésocosmes. 相似文献4.
Pierre Arpin Jean-François Ponge André Faille Patrick Blandin 《European Journal of Soil Biology》1998,34(4):167
Beech integral biological reserves of the Fontainebleau forest (France) display varied site conditions due to geomorphological heterogeneity and to interactions between biological components of the ecosystem. Taking examples in shifts observed in plant communities following gap opening, the authors show that, as Oldeman viewed it, tree-fall gaps seem to be the driving force in sylvigenesis as well as a source of spatial biodiversity. Studies carried out on macromorphological features of humus profiles and on the behaviour of soil invertebrate communities (Lumbricidae and Nematoda) pointed out two key aspects of forest functioning. First, the renewal of the forest ecosystem is linked to the dynamics of humus forms and of soil animal functional groups, featuring the regeneration of trees. Second, tree-fall gaps are places where the forest ecosystem is destabilized and thereafter may renew itself or on the contrary may evolve towards another ecosystem, showing either a co-adaptation between the sylvigenetic and the edaphic cycle, or a discordance between these two cycles. These two aspects (co-adaptation and discordance), important from the point of view of fundamental ecology and forest management, suggest a need for further field research.
Résumé
La hêtraie des réserves biologiques intégrales de la forêt de Fontainebleau offre des situations naturelles variées en fonction de l'hétérogénéité géomorphologique et des interactions entre les composantes biologiques de l'écosystème. Prenant comme exemple l'évolution des associations végétales au sein des clairières, les auteurs montrent que, selon la conception d'Oldeman, le chablis apparaît comme l'élément moteur de la sylvigénèse et un facteur important de biodiversit é spatiale. Des études portant sur la caractérisation macromorphologique des profils d'humus et le comportement des peuplements d 'invertébrés du sol (Lumbricidae, Nematoda) mettent en avant deux points importants pour le fonctionnement de l'écosysteme forestier. Premièrement, le renouvellement de l'écosystème est associé à la dynamique des humus et des groupes fonctionnels de la pédofaune, façonnant ainsi la niche de régénération. Deuxièmement, les clairières apparaissent comme une zone de rupture de l'écosystème forestier pouvant lui permettre, soit de se renouveler, soit d'évoluer vers un autre écosystème, montrant ainsi soit une co-adaptation entre le cycle sylvigénétique et le cycle édaphique, soit une discordance entre ces deux cycles. Cette approche fonctionnelle par le biais de la biologie des sols suggère une réflexion touchant autant l'écologie fondamentale que la gestion forestière. 相似文献5.
Michael Traugott 《European Journal of Soil Biology》1998,34(4):189
Carabid larvae and adults were collected by pitfall trapping and soil sampling for a period of 1 year from an organic potato field in western Austria. The main results and conclusions were the following. (i) Larval catches enriched the total species spectrum (n = 49) by 6 %. Recording of pre-adult stages seems to be necessary for a complete registration of a beetle coenosis. (ii) Twenty species were caught in adult as well as in larval stages, representing apparently the autochthonous Carabidae of the investigated field. (iii) The use of soil sampling enriched the larval ground beetle spectrum and provided additional data on the life cycle of certain species. Therefore additional methods to pitfall trapping are stated to be important. (iv) Epigaeic activity of winter larvae surpassed that of adults during late autumn, winter and early spring, whereas summer larvae lived mainly hemiedaphicly. (v) Third instar larvae showed the highest pitfall catches in most species, which was probably caused by their higher epigaeic activity and greater activity radius. (vi) Life cycles of Nebria brevicollis, Loricera pilicornis, Calathus fuscipes, Amara aulica, Harpalus rufipes, Bembidion lampros and B. properans are presented and discussed. Data of larvae support the concept of species which reproduce a second time or show two breeding cohorts throughout the year. (vii) Carabid larvae may possess interesting predation value in the regulation of certain pests due to a phenology and habitat that differ from that of adult beetles.
Résumé
Dans un champ de pommes de terre cultivé biologiquement dans l'ouest de l'Autriche, les larves et adultes de différentes espèces de carabes ont été récoltés par piégeage Barber et échantillonnage de sol pendant 1 an. Les principaux résultats et conclusions sont les suivantes. (i) La capture de larves a enrichi tout le spectre de l'espèce (n = 49) de 6 %. L'enregistrement des étapes pré-adultes semble donc être nécessaire pour obtenir une image complète d'un peuplement de coléoptères. (ii) Les vingt espèces de larves et d'adultes récoltées semblent bien représenter la composition de carabes autochtones de la zone étudiée. (iii) L'échantillonnage du sol a enrichi le spectre larvaire carabiques et a fourni des données supplémentaires sur le cycle de vie de certaines espèces. Des méthodes complémentaires au piégeage Barber semblent donc être importantes. (iv) Tandis que les larves en été sont principalement semi-édaphiques, l'activité épigée des larves en hiver a surpassé celle des adultes pendant l'automne, l'hiver et le début de printemps. (v) En raison probablement de leur activité épigée plus élevée et de leur rayon d'action plus grand, c'est dans les pièges Barber que le plus grand nombre de larves de troisième stade de la plupart des espèces a été observé. (vi) Les cycles de développement de Nebria brevicollis, Loricera pilicornis, Calathus fuscipes, Amara aulica, Harpalus rufipes, Bembidion lampros et B. properans sont présentés et discutés. Les données larvaires confirment l'idée que ces espèces se reproduisent deux fois par an ou que deux cohortes successives peuvent se reproduire chaque année. (vii) En raison d'une phénologie et d'un habitat qui diffèrent de celui des coléoptères adultes, les larves de carabes pourraient jouer un rôle important dans la régulation de certains parasites. 相似文献6.
Jrme Cortet Annette Gomot-De Vauflery Nicole Poinsot-Balaguer Lucien Gomot Christine Texier Daniel Cluzeau 《European Journal of Soil Biology》1999,35(3):115
A critical review of biological parameters used to indicate pollutant impact on soil quality was conducted. These parameters mention some soil invertebrates. The value of an indicative organism depends on its life expectancy, life style and specific importance. Nematodes, mites, collembolans, enchytraeids, earthworms, isopods and molluscs are good potential biological indicators. Biological indicators of bioaccumulation and biological indicators of effects (toxicological and ecological) can be distinguished. Bioaccumulation studies are difficult to interpret, as wide variations could be found, depending on taxonomic group, habitat, organ studied, soil type or even pollutant type. Some groups, such as Collembola, require in depth bioaccumulation studies. It is suggested to use a pool of macro-concentrators, including at least some earthworm, isopod and gastropod species. Toxicological indicators have been well studied and their lethal and sublethal pollutant effects are well known. However, studies have focused on only a few species, such as the earthworm Eisenia foetida or the collembolan Folsomia candida. These studies should be extended to other zoological groups, as well as to several species from the same group, to generate a representative test battery. Exposure biomarkers and physiological change studies should be emphasised, as they act as very early warning systems of contamination. Data are currently lacking on how soil biological processes malfunction due to pollution. We need to explore the links between pollutant effects on soil fauna and pollutant effects on soil functioning. Concerning ecological indicators, studies should develop sampling techniques and parameters, which are specific to ecotoxicological goals. Before-after impact control procedures should be carried out, to eliminate the background noise of the study site and only evaluate the influence of pollutants. On the other hand, ecological indices, such as taxonomic diversity or richness, should be used carefully especially concerning chronic pollution. Effects of pollutants on biological cycle studies seem very promising, but need further information on the life history strategies of many species. Furthermore, the pollutant tolerance of rare species should be considered. The different types of biological indicators yield complementary information on pollutant effects. They all need standard procedures. In this context, studies should be extended and diversified, and associate bioaccumulation, toxicological and ecological indicators to provide better information on soil quality.
Résumé
Une liste critique des paramètres biologiques utilisés dans certains travaux pour indiquer l'impact des polluants sur la qualité des sols a été établie. Ces paramètres font référence à un ou plusieurs invertébrés du sol. Le rôle d'organisme indicateur dépend de leurs caractéristiques biodémographiques, de leur mode de vie, de leur taille spécifique. Les nématodes, acariens, collemboles, enchytréides, vers de terre, isopodes et gastéropodes sont potentiellement des indicateurs biologiques. Indicateurs biologiques de bioaccumulation et indicateurs biologiques d'effets (toxicologiques et écologiques) peuvent être distingués. Les études de bioaccumulation sont difficiles à interpréter, car de fortes variations sont observées. Ces variations dépendent du groupe taxonomique étudié, de l'habitat, de l'organe étudié, du type de sol ou bien encore du type de pollution. Certains groupes, comme les collemboles demandent des études plus poussées à ce sujet. Il est suggéré d'utiliser un pool de macro-concentrateurs, avec au moins des espèces de vers de terres, isopodes et gastéropodes. Concernant les indicateurs toxicologiques d'effets, les études les plus nombreuses concernent les effets létaux et sublétaux. Toutefois ces études concernent peu de groupes taxonomiques (essentiellement le vers Eisenia foetida et le collembole Folsomia candida), et devraient être étendues à d'autres groupes zoologiques, ainsi qu'à différentes espèces du même groupe, afin de créer une batterie de tests représentatifs. Les travaux concernant les biomarqueurs et les changements physiologiques devraient être amplifiés, car ils permettent d'obtenir des systèmes d'alarme très précoces concernant l'impact des contaminants. Un manque persistant de données concerne les conséquences de pollutions sur le fonctionnement des écosystèmcs. Il est en effet important désormais d'explorer les liens entre les effets des polluants sur la faune du sol et les effets réels de ces mêmes polluants sur le fonctionnement des sols. Concernant les indicateurs écologiques, les travaux entrepris devraient développer des méthodes d'échantillonnage et des paramètres spécifiques au domaine écotoxicologique. Ainsi, il est préconisé d'entreprendre des études combinant les approches synchroniques et diachroniques. afin d'éliminer le bruit de fond induit par le site d'étude et évaluer uniquement l'influence du polluant. En outre, les indices écologiques, comme la diversité ou la richesse taxonomique, doivent être utilisés avec précautions, particulièrement lors des études de pollution chronique. Par ailleurs, les études concernant les effets de polluants sur les cycles biologiques semblent prometteuses, mais demandent de meilleures connaissances concernant les stratégies de vies des différentes espèces étudiées. De plus, la tolérance aux pollutions des espèces rares devrait être fortement prise en considération. Les différents types d'indicateurs biologiques fournissent des informations complémentaires. Ils demandent tous une standardisation des protocoles. Dans ce contexte, les études devraient être développées et diversifiées et associer les indicateurs de bioaccumulation avec les indicateurs biologiques d'effets pour améliorer l'information sur la qualité des sols. 相似文献7.
8.
Quartz crystals have been found in colluvial materials overlying outcrops of ultrabasic rocks in New Caledonia. Two types of crystals were recognized on the basis of inclusions within their structures. These are designated here as type a and type b. Type a crystals are pyramidal.Crystals of type a have two kinds of liquid inclusions. One kind consists of fluid in primary cavities 5–30 μm in diameter. Because the fluid consists of a single liquid phase, it must have been entrapped at low temperature ( 30°C) as the crystals were being formed. Microscopic examinations indicate that this liquid phase is fresh water rather than saline water. The second kind of liquid inclusions consists of fresh water that penetrated to the hearts of type a crystals by means of secondary fissures and was trapped in secondary cavities. Beside these liquids, solid inclusions are minute automorphic grains of quartz distributed throughout the crystals.In the rather scarce crystals of type b, it is difficult to distinguish primary from late inclusions, both of which can occur in quartz. However, the cavities contain two-phase inclusions: liquid phases and vapour bubbles. The liquid is saline water which was entrapped at a temperature of at least 120°C.Thus, the study of the liquid inclusions in type a and b quartz crystals demonstrates that: (1) type b crystals have crystallized in a warm and saline medium; consequently, they are detrital; (2) pyramidal quartz of type a is believed to have been formed in this pedologic environment. Within the colluvium in which they occur, weathering of peridotitic rock by meteoric water could provide the necessary silicon for crystal growth.It is postulated that minute “seeds” crystallized and sprinkled down periodically on the growing surfaces of the type a crystals and were then engulfed by further growth to become inclusions. The presence of minute quartz “seeds” as inclusions indicates that these large pyramidal crystals were formed within a soil void.The abundant secondary fissures containing fresh water are surprising in such well preserved mineral grains. The fissures and fluid inclusions would be expected to make the quartz grain more readily subject to weathering and dissolution than normal for the mineral.The presence of secondary water within quartz crystalz underscores the hazards of assigning all elements found through chemical analyses of minerals to their lattice structure.The study of fluid inclusions within crystals seems to offer an approach in pedology and surface geology for identification of environmental conditions under which soils were formed and sediments deposited.
Résumé
Des cristaux de quartz ont été découverts dans des matériaux colluviaux recouvrant les pentes d'un massif de roches ultrabasiques altérées en Nouvelle Calédonie.L'étude de leurs inclusions intracristallines a permis de distinguer deux types de cristaux: a et b; les cristaux de type a sont pyramidés.Les cristaux de type a présentent deux familles de cavités. Des cavités d'origine primaire (5–10 μm) ont un remplissage monophasé d'eau douce, piégée donc à une température 30°c C. Des fissurations tardives des cristaux ont fait pénétrer de l'eau non saline jusqu'au coeur des cristaux. Cette eau douce est piégée dans des cavités secondaires. A côté des liquides piégés, les cavités contiennent des inclusions solides, il s'agit de très petits cristaux de quartz automorphes.Les cristaux de type b sont peu nombreux, leurs inclusions fluides sont salines et biphasées (liquide et bulles de retrait) et ont été emprisonnées à une température au moins égale à 120° C (données de la microthermométrie de ces inclusions).L'étude des inclusions des quartz a et b démontre que si les quartz b ont cristallisé dans un milieu salin à température élevée et sont, par conséquent, détritiques dans cet horizon pédologique, il apparaït que les quartz pyramidés a se sont formés dans ce niveau même. L'altération des roches péridotiques par des eaux météoriques ayant fourni la silice nécéssaire à cette croissance cristalline.La présence de petits germes de quartz qui ont périodiquement saupoudré les faces de croissance des cristaux pyramidés avant d'être piégés lors de la poursuite de la cristallisation démontre que le quartz se développait dans une cavité du sol permettant à ces petits cristaux de se déposer sur des faces de croissance.Il est remarquable de rencontrer dans ces cristaux un champ fissural très important. Ces fissures accentuent la vulnérabilité des quartz vis à vis de l'altération et de la dissolution.D'une façon générale, la mise en évidence d'eaux pénétrées tardivement à l'intérieur des cristaux doit rester à l'esprit afin de ne pas attribuer au réseau cristallin les éléments chimiques détectés lors d'analyse globale des cristaux.L'étude des inclusions intracristallines peut donc apporter des renseignements quant aux conditions règnant dans les milieux pédologiques. 相似文献9.
Long term flux measurements of different crop species are necessary to improve our understanding of management and climate effects on carbon flux variability as well as cropland potential in terrestrial carbon sequestration. The main objectives of this study were to analyse the seasonal dynamics of CO2 fluxes and to establish the effects of climate and cropland management on the annual carbon balance.CO2 fluxes were measured by means of the eddy correlation (EC) method over two cropland sites, Auradé and Lamasquère, in South West France for a succession of three crops: rapeseed, winter wheat and sunflower at Auradé, and triticale, maize and winter wheat at Lamasquère. The net ecosystem exchange (NEE) was partitioned into gross ecosystem production (GEP) and ecosystem respiration (RE) and was integrated over the year to compute net ecosystem production (NEP). Different methodologies tested for NEP computation are discussed and a methodology for estimating NEP uncertainty is presented.NEP values ranged between −369 ± 33 g C m−2 y−1 for winter wheat at Lamasquère in 2007 and 28 ± 18 g C m−2 y−1 for sunflower at Auradé in 2007. These values were in good agreement with NEP values reported in the literature, except for maize which exhibited a low development compared to the literature. NEP was strongly influenced by the length of the net carbon assimilation period and by interannual climate variability. The warm 2007 winter stimulated early growth of winter wheat, causing large differences in GEP, RE and NEE dynamics for winter wheat when compared to 2006. Management had a strong impact on CO2 flux dynamics and on NEP. Ploughing interrupted net assimilation during voluntary re-growth periods, but it had a negligible short term effect when it occurred on bare soil. Re-growth events after harvest appeared to limit carbon loss: at Lamasquère in 2005 re-growth contributed to store up to 50 g C m−2. Differences in NEE response to climatic variables (VPD, light quality) and vegetation index were addressed and discussed.Net biome production (NBP) was calculated yearly based on NEP and considering carbon input through organic fertilizer and carbon output through harvest. For the three crops, the mean NBP at Auradé indicated a nearly carbon balanced ecosystem, whereas Lamasquère lost about 100 g C m−2 y−1; therefore, the ecosystem behaved as a carbon source despite the fact that carbon was imported through organic fertilizer. Carbon exportation through harvest was the main cause of this difference between the two sites, and it was explained by the farm production type. Lamasquère is a cattle breeding farm, exporting most of the aboveground biomass for cattle bedding and feeding, whereas Auradé is a cereal production farm, exporting only seeds. 相似文献
10.
The effect of different residual bulking agents (paper, cardboard, grass clippings, pine needles, sawdust and food wastes) in mixtures with sewage sludge (1:1 dry weight) on the growth and reproduction of Eisenia andrei, Bouché 1972 was studied in smallscale laboratory experiments with batches of sixty earthworms. The maximum weight achieved and the highest growth rate were attained in the mixture with food waste (755±18 mg and 18.6±0.6 mg day−1 respectively) whereas the smallest size and the lowest growth rate was achieved in the mixture of sewage sludge with sawdust (572±18 mg and 11±0.7 mg day−1 respectively). The earthworms showed much higher reproductive rates in the paper and cardboard mixtures (2.82±0.39 and 3.19±0.30 cocoons earthworm−1 week−1 respectively) compared to the control with sewage sludge alone (0.05±0.01 cocoons earthworm−1 week−1). 相似文献
11.
L. P. Canellas J. G. Busato L. B. Dobbss M. A. Baldotto V. M. Rumjanek F. L. Olivares 《European Journal of Soil Science》2010,61(3):375-383
We employed CP/MAS 13C NMR spectroscopy and classical humus fractionation to evaluate the behaviour of soil organic matter (SOM) resulting from long‐term sugar cane production when harvested without burning. Soil samples were collected at two depths (0–0.2 and 0.2–0.4 m) from a tropical Entisol cropped with sugar cane for 55 years at Campos dos Goytacazes (Brazil), either with or without burning crop residues when harvesting. Continuous incorporation of sugar cane residues increased carbon (C) content and promoted changes in SOM, including increases in humins, humic acids and aromatic C moieties. Sequential extraction methods showed enhanced amounts of available forms of nitrogen (N), sulphur (S) and phosphorus (P). Moreover, 31P NMR analysis revealed an increase in organic P as diester phosphates of plant origin in the humic acids fraction. The increased macronutrient bioavailability of labile forms of N, P and S could be partially related to the more hydrophobic nature of SOM observed in soil samples collected from areas that were not burnt. These results show that the long‐term non‐burning management of sugar cane harvest promotes the hydrophobic character of SOM and a more conservative and sustainable management of soil fertility. Matière organique du so let stockage de nutriments en manègement de longue durée et pas brûlé de la cane au sucre Résumé Le comportement de la matière organique du sol (MOS) a étéévalué sur une plantation de canne à sucre de longue durée, sans brûlis, par spectroscopie CP/MAS 13C NMR et la méthode classique de fractionnement et caractérisation de l’humus. Des échantillons de sol ont été prélevés dans une plantation de canne à sucre en culture continue depuis 55 ans, installée à Campos dos Goytacazes (Brésil) sur un entisol tropical. L’échantillonnage a été réaliséà 0–0.2 m et 0.2–0.4 m de profondeur sur des parcelles sous différents modes de mise en culture: parcelles comportant des récoltes précédées de brûlis des résidus et d’autres sans brûlis. L’incorporation continue des résidus de canne à sucre a provoqué l’augmentation du carbone (C) et des variations de la matière organique du sol (MOS), avec notamment l’augmentation des teneurs en humines, acides humiques et carbone aromatique. Les méthodes d’extraction séquentielle ont permis de détecter l’augmentation des quantités d’azote (N), de soufre (S) et de phosphore (P) disponibles. En outre, l’analyse RMN 31P effectuée sur les fractions d’acides humiques a révélé une augmentation des quantités de phosphore organique sous forme de diester de phosphates d’origine végétale. L’augmentation de la biodisponibilité de macronutriments (formes labiles de N, P et S) pourrait partiellement être attribuée au caractère hydrophobe de la matière organique plus expressif sur les échantillons de sol prélevés dans les parcelles sans brûlis. Ces résultats montrent que la pratique de non‐brûlis des résidus, à long terme, dans les plantations de canne à sucre, favorise le caractère hydrophobe de la matière organique du sol provoquant une gestion plus conservatrice et durable de la fertilité des sols. 相似文献
12.
Physical Properties of Vetch Seed 总被引：1，自引：2，他引：1
The physical properties of vetch seed were evaluated as a function of moisture content. The average length, width and thickness were 5·19, 4·33 and 3·63 mm, respectively, at 10·57% dry basis (d.b.) moisture content. In the moisture range from 10·57 to 20·63% d.b., studies on rewetted vetch seed showed that the thousand seed mass increased from 55·47 to 59·03 g, the projected area from 23·52 to 29·05 mm2, the sphericity from 0·837 to 0·859, the true density from 1286·2 to 1369·9 kg m−3, the porosity from 33·08% to 39·68% and the terminal velocity from 9·94 to 10·33 m s−1. The static coefficient of friction of vetch seed increased the linearly against surfaces of four structural materials, namely, rubber (0·350–0·387), aluminium (0·319–0·367), stainless steel (0·202–0·328) and galvanised iron (0·312–0·361) as the moisture content increased from 10·57 to 20·63% d.b. The bulk density and the shelling resistance decreased from 860·8 to 826·2 kg m−3 and from 148·73 to 62·68 N, respectively, with an increase in moisture content from 10·57 to 20·63% d.b. 相似文献
13.
Mathematical Modelling of Vacuum Pressure on a Precision Seeder 总被引：12，自引：0，他引：12
The purpose of this research was to determine the optimum vacuum pressure of a precision vacuum seeder and to develop mathematical models by using some physical properties of seeds such as one thousand kernel mass, projected area, sphericity and kernel density. Maize, cotton, soya bean, watermelon, melon, cucumber, sugarbeet and onion seeds were used in laboratory tests. One thousand kernel mass, projected area, sphericity and kernel density of seeds varied from 4·3 to 372·5 g, 5–77 mm2, 38·4–85·8% and 440–1310 kg m−3, respectively. The optimum vacuum pressure was determined as 4·0 kPa for maize I and II; 3·0 kPa for cotton, soya bean and watermelon I; 2·5 kPa for watermelon II, melon and cucumber; 2·0 kPa for sugarbeet; and 1·5 kPa for onion seeds.The vacuum pressure was predicted by mathematical models. According to the results, the final model could satisfactorily describe the vacuum pressure of the precision vacuum seeder with a chi-square of 2·51×10−3, root mean square error of 2·74×10−2 and modelling efficiency of 0·99. 相似文献
14.
Changes of soil organic carbon and its fractions in relation to soil physical properties in a long-term fertilized paddy 总被引：1，自引：0，他引：1
Seul Bi Lee Chang Hoon Lee Ki Yuol Jung Ki Do Park Dokyoung Lee Pil Joo Kim 《Soil & Tillage Research》2009,104(2):227-232
Soil organic carbon (SOC) has an important role in improving soil quality and sustainable production. A long-term fertilization study was conducted to investigate changes in SOC and its relation to soil physical properties in a rice paddy soil. The paddy soils analyzed were subjected to different fertilization practices: continuous application of inorganic fertilizers (NPK, N–P–K = 120–34.9–66.7 kg ha−1 yr−1 during 1967–1972 and 150–43.7–83.3 kg ha−1 yr−1 from 1973 to 2007), straw based compost (Compost, 10 Mg ha−1 yr−1), a combination of NPK + Compost, and no fertilization (control). Soil physical properties were investigated at rice harvesting stage in the 41st year for analyzing the relationship with SOC fraction. Continuous compost application increased the total SOC concentration in plough layers and improved soil physical properties. In contrast, inorganic or no fertilization markedly decreased SOC concentration resulting to a deterioration of soil physical health. Most of the SOC was the organo-mineral fraction (<0.053 mm size), accounting for over 70% of total SOC. Macro-aggregate SOC fraction (2–0.25 mm size), which is used as an indicator of soil quality rather than total SOC, covered 8–17% of total SOC. These two SOC fractions accumulated with the same tendency as the total SOC changes. Comparatively, micro-aggregate SOC (0.25–0.053 mm size), which has high correlation with physical properties, significantly decreased with time, irrespective of the inorganic fertilizers or compost application, but the mechanism of decrease is not clear. Conclusively, compost increased total SOC content and effective SOC fraction, thereby improving soil physical properties and sustaining production. 相似文献
15.
Freshwaters ecosystems continue to face pressures from pollution, flow regime alterations, habitat destruction and exotic species invasions despite their unique biodiversity. In Europe, National Parks and Special Areas of Conservation aim to provide protection of ‘aggregate’ biodiversity, yet inspection of priority species lists for these sites often reveals a focus towards terrestrial species. In regions such as the Alps and the Pyrénées, this is a particularly serious problem because climate change and other anthropogenic pressures (e.g. hydropower, tourism) are causing widespread hydrological modification which is likely to drive changes in aquatic species abundance, diversity and distribution. Improved understanding of the diversity of rare plants and animals is necessary so efforts can be cost-effectively targeted to conserve the maximum number of species, whilst a clearer picture of these species’ distributions is a precursor to targeting conservation efforts. This paper reports results of a study into the diversity and distribution of 17 endemic mayflies, stoneflies and caddisflies from 598 rivers sites across southern France. Endemic macroinvertebrates were found only at sites in the Pyrénées mountain range with richness peaking at 1500–1800 m above sea level. Nine of these 17 species were recorded from <20 sites and two (Protonemura angelieri, Rhithrogena kimminsi) were found at only 10 sites. Despite both the rarity of these species and threats to their existence, none of them have any current conservation status. New conservation policies for freshwater ecosystems in the French Pyrénées need to be developed as a priority due to the rarity of many aquatic species in this area, growing threats to their existence (habitat modification, hydrological change), and to recognise their importance in food webs that may include other rare species of conservation value. 相似文献
16.
This paper summarizes results from 8 years (1996–2003) of eddy covariance-based ecosystem CO2 exchange measurements at the Borden Forest Research Station (44°19′N, 79°56′W). The site represents a mid-latitude, 100-year-old, mixed deciduous and coniferous forest dominated by red maple, aspen and white pine. The years 1996 and 1997 were relatively cold, had a late spring and received below average photosynthetic photon flux density (PPFD). This contrasts with an early spring, warmer soil and air temperatures during 1998–1999, and with distinctly wet year of 2000 and dry years of 2001–2003. The combination of early spring, warmer air and soil temperature and relatively high level of PPFD was associated with higher net ecosystem productivity (NEP) that peaked during 1999. Photosynthetic capacity was reduced and NEP showed a mid-growing season depression during the dry years of 2001–2003. Annual average ecosystem respiration (R) determined from a light response model was 30% less than R derived from a logistic respiration equation, relating night time CO2 flux and soil temperature. However these independently determined R values were well correlated indicating that the site is unaffected by fetch and spatial heterogeneity problems. Based on the combined 8 years of growing season daytime data, an air temperature of 20–25 °C and a vapor pressure deficit (VPD) of 1.3 kPa were found to be the optimal conditions for CO2 uptake by the canopy. Over the 1996–2003 period, the forest sequestered carbon at an average rate of 140 ± 111 gC m−2 y−1. The corresponding gross ecosystem photosynthesis (GEP) and R over this period were 1116 ± 93 gC m−2 y−1 and 976 ± 68 gC m−2 y−1, respectively. The annual carbon sequestration ranged from 19 gC m−2 in 1996 to 281 gC m−2 in 1999. However, these estimates were sensitive to frictional velocity threshold () used for screening data associated with poor turbulent mixing at night. Increasing from 0.2 m s−1 (based on the inflection point in the nighttime CO2 flux vs. u* relationship) to 0.35 m s−1 (determined using a selection algorithm based on change-point detection) modified the 8-year mean NEP estimate from 140 ± 111 gC m−2 y−1 to 65 ± 120 gC m−2 y−1. Both approaches show that the Borden forest was a low to moderate sink of carbon over the 8-year period. 相似文献
17.
This study sought to assess the influence of compost and earthworms (Dendrobaena veneta) upon the level of hydrocarbon catabolism in petroleum contaminated forecourt soil (extractable petroleum hydrocarbons (EPH) 10 + 1.8 g kg−1 and total 16 United States Environment Protection Agency (USEPA) polycyclic aromatic hydrocarbons (PAH) 1.62 ± 0.5 g kg−1). The catabolic activity of the indigenous microorganisms within uncombined materials (soil and compost) and within the combined treatments (soil plus compost; either with or without earthworms) was assessed by 14C-radiorespirometry (14C-hexadecane, 14C-toluene and 14C-phenanthrene). Maximum levels of catabolic activity were observed (at the end of the incubation period; 84 d) for all three compounds in the combined contaminated soil, compost and earthworm mixtures. Significant (p < 0.05) enhancement factors (relative to the soil only control) in catabolic activity in the combined treatments (soil:compost (1:0.5)) of 3.6 times, 1.5 times and 3.5 times were observed for 14C-hexadecane, 14C-phenanthrene and 14C-toluene, respectively; with maximum levels of catabolic activity for these substrates being 68.6 ± 1.7%, 37.9 ± 5.3% and 85.9 ± 1.3%. 相似文献
18.
Pressure drops were measured in clean green gram beds at moisture content in a range of 8·36–16·65% d.b. for superficial air velocities which ranged between 0·0104 and 1·0875 m3 s−1 m−2 at bed depths of 0·2 to 0·6 m with bulk density ranging from 760 to 855 kg m−3. The airflow resistance of green gram increased with the increase in airflow rate, bulk density, bed depth and decreased moisture content. Results indicated that 1% increase in moisture content decreased the pressure drop by 2·43% whereas, 1% increase in bulk density increased the pressure drop by 6·6%. Modified Shedd's equation, Hukill and Ives equation and modified Ergun equation all with two parameters were examined. Airflow resistance was accurately described by modified Shedd's equation and an empirical equation, composed of airflow rate, moisture content and bulk density. 相似文献
19.
The physical properties of okra seed were evaluated as a function of moisture content (m.c.). The average length, breadth and thickness of the seed varied from 5·92 to 7·30, 4·71 to 5·40 and 4·59 to 5·36 mm, respectively, as the moisture content increased from 8·16 to 87·57% d.b. The roundness and sphericity increased from 77·76 to 79·35% and 74·48 to 76·52%, respectively, with increase in moisture content from 8·16 to 19·56% d.b. and then decreased to 72·39 and 70·63%, respectively, with further increase of moisture content. In the moisture range of 8·16–87·57%, the seed volume increased from 0·067 to 0·124 cm3, 1000 seed weight, W1000 from 65·78 to 129·75 g and the angle of repose from 27·60 to 39·47°. The bulk density, true density and porosity decreased from 0·592 to 0·558 g cm−3, 1·107 to 0·986 g cm−3 and 46·34 to 43·20%, respectively, in the moisture range from 8·16 to 87·57% d.b. The static coefficient of friction increased on four structural surfaces namely, aluminium (0·390–0·484), bakelite (0·345–0·480), galvanised iron (0·368–0·493) and mild steel (0·389–0·480) as the moisture content increased from 8·16 to 87·57% d.b. 相似文献
20.
Erosion rates and nutrient losses affected by composted cattle manure application in vineyard soils of NE Spain 总被引：4，自引：0，他引：4
Land preparation for mechanisation in vineyards of the Anoia–Alt Penedès region, NE Spain, has required major soil movements, which has enormous environmental implications not only due to changes in the landscape morphology but also due to soil degradation. The resulting cultivated soils are very poor in organic matter and highly susceptible to erosion, which reduces the possibilities of water intake as most of the rain is lost as runoff. In order to improve soil conditions, the application of organic wastes has been generalised in the area, not only before plantation but also every 3–4 years at rates of 30–50 Mg ha− 1 mixed in the upper 30 cm.These organic materials are important sources of nutrients (N and P) and other elements, which could reduce further fertilisation cost. However, due to the high susceptibility to sealing of these soils, erosion rates are relatively high, so a higher nutrient concentration on the soil surface increases non-point pollution sources due to runoff.The aim of this study is to analyse the influence of applied composted cattle manure on infiltration, runoff and soil losses and on nutrients transported by runoff in vineyards of the Alt Penedès–Anoia region, NE Spain. In the two plots selected for the analysis, composted cattle manure had been applied in alternate rows 1 year previous to the study. In each plot soil surface samples (0–25 cm) were taken and compared to those of plots without manure application. The study was carried out at laboratory scale using simulated rainfall. Infiltration rates were calculated from the difference between rainfall intensity and runoff rates, and the sediment and total nitrogen and phosphorus were measured for each simulation. In addition, the influence of compost was investigated in the field under natural rainfall conditions by analysing the nutrient concentration in runoff samples collected in the field (in the same plots) after seven rainfall events, which amount different total precipitation and had different erosive character.Compost application increases infiltration rates by up to 26% and also increases the time when runoff starts. Sediment concentration in runoff was lower in treated (13.4 on average mg L− 1) than in untreated soils (ranging from 16.8 to 23.4 mg L− 1). However, the higher nutrient concentration in soils produces a higher mobilisation of N (7–17 mg L− 1 in untreated soils and 20–26 mg L− 1 in treated soils) and P (6–7 mg L− 1 in untreated soils and 13–19 mg L− 1 in treated soils). A major part of the P mobilised was attached to soil particles (about 90% on average) and only 10% was dissolved. Under natural conditions, higher nutrient concentrations were always recorded in treated vs. untreated soils in both plots, and the total amount of N and P mobilised by runoff was higher in treated soils, although without significant differences. Nutrient concentrations in runoff depend on rainfall erosivity but the average value in treated soils was twice that in untreated soils for both plots. 相似文献