Physical carbon‐sequestration mechanisms under special consideration of soil wettability     

Jrg Bachmann  Georg Guggenberger  Thomas Baumgartl  Ruth H. Ellerbrock  Emilia Urbanek  Marc‐O. Goebel  Klaus Kaiser  Rainer Horn  Walter R. Fischer 《植物养料与土壤学杂志》2008,171(1):14-26

The protective impact of aggregation on microbial degradation through separation has been described frequently, especially for biotically formed aggregates. However, to date little information exists on the effects of organic‐matter (OM) quantity and OM quality on physical protection, i.e., reduced degradability by microorganisms caused by physical factors. In the present paper, we hypothesize that soil wettability, which is significantly influenced by OM, may act as a key factor for OM stabilization as it controls the microbial accessibility for water, nutrients, and oxygen in three‐phase systems like soil. Based on this hypothesis, the first objective is to evaluate new findings on the organization of organo‐mineral complexes at the nanoscale as one of the processes creating water‐repellent coatings on mineral surfaces. The second objective is to quantify the degree of alteration of coated surfaces with regard to water repellence. We introduce a recently developed trial that combines FTIR spectra with contact‐angle data as the link between chemical composition of OM and the physical wetting behavior of soil particles. In addition to characterizing the wetting properties of OM coatings, we discuss the implications of water‐repellent surfaces for different physical protection mechanisms of OM. For typical minerals, the OM loading on mineral surfaces is patchy, whereas OM forms nanoscaled micro‐aggregates together with metal oxides and hydroxides and with layered clay minerals. Such small aggregates may efficiently stabilize OM against microbial decomposition. However, despite the patchy structure of OM coating, we observed a relation between the chemical composition of OM and wettability. A higher hydrophobicity of the OM appears to stabilize the organic C in soil, either caused by a specific reduced biodegradability of OM or indirectly caused by increased aggregate stability. In partly saturated nonaggregated soil, the specific distribution of the pore water appears to further affect the mineralization of OM as a function of wettability. We conclude that the wettability of OM, quantified by the contact angle, links the chemical structure of OM with a bundle of physical soil properties and that reduced wettability results in the stabilization of OM in soils.  相似文献   

Prognose der mechanischen Belastbarkeit und der auflastabhängigen Änderung des Lufthaushaltes in Ackerböden anhand von Bodenkarten     

Rainer Horn  Catalin Simota  Heiner Fleige  Anthony Dexter  Kalman Rajkai  Diego de la Rosa 《植物养料与土壤学杂志》2002,165(2):235-239

Prediction of soil strength of arable soils and stress dependent changes in ecological properties based on soil maps Based on a database of at present 160 mechanical soil profile datasets, the site and horizon dependent mechanical soil strength expressed as precompression stress can be predicted by multiple regression analysis and used for documentation in maps at different scales. Stress dependent changes in air permeability or air capacity can be derived for the virgin compression stress range as well as the effect of stress propagation in soils or stress attenuation capacity and depth dependent changes of ecological properties. Thus, areas with defined mechanical sensitivity as a function of depth can be derived and recommendations for site adjusted farming techniques can be given. In addition it allows the agricultural machine industry to develop site adjusted machines to support the ideas of good farming practice, defined by the soil protection law of Germany.  相似文献   

Age and growth of sea perch (Helicolenus percoides) from two adjacent areas off the east coast of South Island,New Zealand     

L.J. Paul  P.L. Horn 《Fisheries Research》2009,95(2-3):169-180

A validated ageing methodology using otolith thin sections is presented for sea perch (Helicolenus percoides) in two adjacent areas off the east coast of South Island, New Zealand. Oxytetracycline marking of two adult fish held in captivity for 1 year suggested that a single dark growth increment formed during winter, commencing May or June. The annual formation of growth increments was confirmed by the observed progression of year classes in comparable samples from three different years, and the progression of length modes in several consecutive years that matched the estimated growth curves. Otolith interpretation was difficult because of a central dense region and the presence of many fine bands within each growth increment, but the latter could be counted, and it is considered that a validated ageing procedure is presented. Von Bertalanffy growth parameters were calculated for east coast South Island (ECSI) and Chatham Rise males and females. In both areas the growth rate of males is slightly but significantly faster than for females. Growth is relatively slow throughout life. From the maximum observed ages for ECSI and Chatham Rise fish of 35 and 59 years, the respective natural mortality rates are estimated to be 0.12 and 0.07 year^?1, but the most plausible value for the species is likely to be at the lower end of this range. Some stock differentiation between the two areas is indicated, based primarily on differences in length-frequency distributions implying different patterns of year class strengths, but also on apparent differences in growth rates between areas. This supports the present management regime of separate commercial catch quotas.  相似文献   

Genotyping of red and white fruited strawberry (Fragaria L.) accessions and hybrids based on microsatellite markers and on the genetic diversity in the allergen genes fra a 1 and fra a 3     

René Kaiser  Vera Mageney  Konrad Schwefel  Daniela Vollmers  Aenne Krüger  Renate Horn 《Genetic Resources and Crop Evolution》2016,63(7):1203-1217

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Reference bulk density and critical degree-of-compactness for no-till crop production in subtropical highly weathered soils     

Jos Miguel Reichert  Luis Eduardo Akiyoshi Sanches Suzuki  Dalvan Jos Reinert  Rainer Horn  Inge Hkansson 《Soil & Tillage Research》2009,102(2):242

The concept of degree of compactness (DC), referred to as field bulk density (BD) as a percentage of a reference bulk density (BD_ref), was developed to characterize compactness of soil frequently disturbed, but for undisturbed soil such as under no-tillage critical degree of compactness values have not been tested. The objective of this study was to compare methods to determine BD_ref and limits of DC and BD for plant growth under no-tillage in subtropical soils. Data from the literature and other databases were used to establish relationships between BD and clay or clay plus silt content, and between DC and macroporosity and yield of crops under no-tillage in subtropical Brazil. Data of BD_ref reached by the soil Proctor test on disturbed soil samples, by uniaxial compression with loads of 200 kPa on disturbed and undisturbed soil samples, and 400, 800 and 1600 kPa on undisturbed soil samples, were used. Also, comparisons were made with critical bulk density based on the least limiting water range (BDc LLWR) and on observed root and/or yield restriction in the field (BDc Rest). Using vertical uniaxial compression with a load of 200 kPa on disturbed or undisturbed samples generates low BD_ref and high DC-values. The standard Proctor test generates higher BD_ref-values, which are similar to those in a uniaxial test with a load of 1600 kPa for soils with low clay content but lower for soils with high clay content. The BDc LLWR does not necessarily restrict root growth or crop yield under no-tillage, since field investigations led to higher BDc Rest-values. A uniaxial load greater than 800 kPa is promising to determine BD_ref for no-tillage soils. The BD_ref is highly correlated to the clay content and thus pedotransfer functions may be established to estimate the former based on the latter. Soil ecological properties are affected before compaction restricts plant growth and yield. The DC is an efficient parameter to identify soil compaction affecting crops. The effect of compaction on ecological properties must also be further considered.  相似文献   

Do dogs talk to each other? Field investigations on dog–dog acoustic communication     

Éva Szabó  Marta Borgi  Csaba Molnár  Péter Pongrácz  Ádám Miklósi 《Journal of Veterinary Behavior: Clinical Applications and Research》2009,4(2):59

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Working dogs personalities: Individual differences in learning performance     

Martin Tiefenthaler  Friederike Range  Judit Vas  Ádám Miklósi  Ludwig Huber 《Journal of Veterinary Behavior: Clinical Applications and Research》2009,4(2):87

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Dog as a model for studying conspecific and heterospecific social learning     

Enikő Kubinyi  Péter Pongrácz  Ádám Miklósi 《Journal of Veterinary Behavior: Clinical Applications and Research》2009,4(1):31-41

In human communities social learning (i.e., learning by the observation of knowledgeable individuals) plays an important role; it shapes cultures, traditions, and cognition. Dogs seem to be an ideal system for modeling human cognition from the social learning aspect. The present review offers a short overview on the relevant general theories of social learning, discusses the adaptive value of social learning, introduces dog as a model system, presents evidence for different forms of social learning in dogs and argues for practical implications that social learning might have in this species.  相似文献   

Comprehension and utilization of gestures and gazing in dog-human communication     

Márta Gácsi  Justine Philip  Ádám Miklósi 《Journal of Veterinary Behavior: Clinical Applications and Research》2009,4(2):58-59

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The seasonal activity of flea beetles in Bulgaria     

Teodora B. Toshova  Éva Csonka  Mitko A. Subchev  Miklós Tóth 《Journal of pest science》2009,82(3):295-303

Using allyl-isothiocyanate-baited traps, we recorded six species of flea beetles in cabbage and horseradish crops in the region of Sofia, Bulgaria in 2006 and 2007. The most abundant species in the traps was Ph. cruciferae (92–96%) followed by Ph. vittula, Ph. undulata and Ph. nigripes. The overwintering adults of these species emerge before the beginning of April and are active to the end of May–beginning of June. Catches of adults of the new generation occurred from the end of June–beginning of July to the second half of October–beginning of November. In 2006, air temperature and humidity strongly influenced the catches of the flea beetles. Investigations of the reproductive status of field collected females of Ph. cruciferae showed that this species develops one generation per year in the region. The results of this study can be used in integrated pest management approach to flea beetles control.  相似文献