How organic farmers view their own practice: results from the Czech Republic     

Lukas Zagata 《Agriculture and Human Values》2010,27(3):277-290

This paper addresses the development of organic agriculture in the Czech Republic, which is seen as a success story among post-communist countries. The relatively short history of organic farming and specific contextual factors raises questions about the nature and meaning of Czech organic farming. The goal of this study was to find out how farmers view their own practice, interpret its symbolic value, and construct its content. This empirical study uses Q methodology aimed at the identification of the collectively-shared perspectives belonging engaged actors. Data were gathered through semi-standardized interviews with Czech farmers registered in official organic scheme. The analysis emphasized three components, which are considered as three distinct perspectives possessed by organic farmers; that is, (1) organic farming as a way of life, (2) as an occupation, and (3) as a production of food of an alternative quality compared to conventional food. Each viewpoint entails a different understanding of what organic farming means; each then—when considered together—comprises the meaning of organic agriculture in the Czech Republic. The presented classification of the farmers holding the viewpoints contributes to the ongoing theoretical discussion regarding the nature of the current organic sector, its development and potential conventionalization.  相似文献   

Optimal Estimation Versus MCMC for $$\mathrm{{CO}}_{2}$$ Retrievals     

Jenny Brynjarsdottir  Jonathan Hobbs  Amy Braverman  Lukas Mandrake 《Journal of Agricultural, Biological & Environmental Statistics》2018,23(2):297-316

The Orbiting Carbon Observatory-2 (OCO-2) collects infrared spectra from which atmospheric properties are retrieved. OCO-2 operational data processing uses optimal estimation (OE), a state-of-the-art approach to inference of atmospheric properties from satellite measurements. One of the main advantages of the OE approach is computational efficiency, but it only characterizes the first two moments of the posterior distribution of interest. Here we obtain samples from the posterior using a Markov Chain Monte Carlo (MCMC) algorithm and compare this empirical estimate of the true posterior to the OE results. We focus on 600 simulated soundings that represent the variability of physical conditions encountered by OCO-2 between November 2014 and January 2016. We treat the two retrieval methods as ensemble and density probabilistic forecasts, where the MCMC yields an ensemble from the posterior and the OE retrieval result provide the first two moments of a normal distribution. To compare these methods, we apply both univariate and multivariate diagnostic tools and proper scoring rules. The general impression from our study is that when compared to MCMC, the OE retrieval performs reasonably well for the main quantity of interest, the column-averaged \(\mathrm{{CO}}_{2}\) concentration \(X_{\mathrm{{CO}}_{2}}\), but not for the full state vector \(\mathbf {X}\) which includes a profile of \(\mathrm{{CO}}_{2}\) concentrations over 20 pressure levels, as well as several other atmospheric properties.Supplementary materials accompanying this paper appear on-line.  相似文献   

Interaction of minerals,organic matter,and microorganisms during biogeochemical interface formation as shown by a series of artificial soil experiments     

Geertje?J.?PronkEmail author  Katja?Heister  Cordula?Vogel  Doreen?Babin  J?rg?Bachmann  Guo-Chun?Ding  Franziska?Ditterich  Martin?H.?Gerzabek  Julia?Giebler  Michael?Hemkemeyer  Ellen?Kandeler  Yamuna?Kunhi Mouvenchery  Anja?Miltner  Christian?Poll  Gabriele?E.?Schaumann  Kornelia?Smalla  Annelie?Steinbach  Irina?Tanuwidjaja  Christoph?C.?Tebbe  Lukas?Y.?Wick  Susanne?K.?Woche  Kai?U.?Totsche  Michael?Schloter  Ingrid?K?gel-Knabner 《Biology and Fertility of Soils》2017,53(1):9-22

Our understanding of the interactions between minerals, organic matter, and microorganisms at so-called biogeochemical interfaces in soil is still hampered by the inherent complexity of these systems. Artificial soil maturation experiments can help to bridge a gap in complexity between simple abiotic sorption experiments and larger-scale field experiments. By controlling other soil-forming factors, the effect of a particular variable can be identified in a simplified system. Here, we review the findings of a series of artificial soil incubation experiments with the aim of revealing general trends and conclusions. The artificial soils were designed to determine the effect of mineral composition and charcoal presence on the development of abiotic and biotic soil properties during maturation. In particular, the development of soil aggregates, organic matter (OM) composition and turnover, sorption properties, and the establishment of microbial community composition and function were considered. The main objectives of the research were to determine (1) how surface properties and sorption of chemicals modify biogeochemical interfaces; (2) how much time is required to form aggregates from mixtures of pure minerals, OM, and a microbial inoculum; and (3) how the presence of different mineral and charcoal surfaces affects aggregation, OM turnover, and the development of microbial community composition.  相似文献   

Impact of climate and lithology on soil phytolith-occluded carbon accumulation in eastern China     

Xiaodong Zhang  Zhaoliang Song  Zhiqi Zhao  Lukas Van Zwieten  Jianwu Li  Linan Liu  Song Xu  Hailong Wang 《Journal of Soils and Sediments》2017,17(2):481-490

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Sugarcane bagasse biochars impact respiration and greenhouse gas emissions from a latosol     

Wangang Deng  Lukas Van Zwieten  Zhaomu Lin  Xingyuan Liu  Ajit K Sarmah  Hailong Wang 《Journal of Soils and Sediments》2017,17(3):632-640

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Does closure of traditionally managed open woodlands threaten epigeic invertebrates? Effects of coppicing and high deer densities   总被引：1，自引：0，他引：1  

Lukas Spitzer  Martin Konvicka  Jiri Benes  Ivan H. Tuf 《Biological conservation》2008,141(3):827-837

The demise of traditional woodland management techniques, such as coppicing or woodland pasture, is causing a gradual closure of formerly sparse lowland woods across Central Europe. It is established that these processes threaten such organisms as butterflies and higher plants. Effects on other groups, such as epigeic invertebrates, are little known, hindering rational conservation decisions. We investigated the effects of stand openness on three epigeic groups, carabids (Carabidae), arachnids (Araneae + Opiliones) and myriapods-isopods (Chilopoda + Diplopoda + Oniscidea), in a lowland deciduous wood in the Czech Republic. Situating some of the traps in an intensive deer park allowed a simultaneous assessment of effects of high vs. low ungulate densities. Carabids reached the highest species richness in either sparse stands with low game or dense stands, high game. More arachnids occurred under low game and in sparse stands than under high game density and in dense stands. The highest richness of myriapods-isopods was in sparse stands with low game. Ordinations revealed that species of conservation concern (‘relic species’ according to C. European authors) tended to be associated with sparse stands and low game. A considerable proportion of epigeic woodland invertebrates, including many species of conservation concern, depends on preserving highly heterogeneous sparse canopy conditions. Restoring such conditions in selected areas will benefit these sensitive open woodland specialists while causing minimum harm to specialists of dense stands, that likely prosper in commercially managed high forests.  相似文献   

Proanthocyanidins: target compounds as antibacterial agents     

Mayer R  Stecher G  Wuerzner R  Silva RC  Sultana T  Trojer L  Feuerstein I  Krieg C  Abel G  Popp M  Bobleter O  Bonn GK 《Journal of agricultural and food chemistry》2008,56(16):6959-6966

Grape seeds accumulate in huge quantities as byproduct during wine production and are therefore a cheap source for pharmacologically active agents. However, studies prove poor antibacterial activity, and results of analyses are sometimes contradictory. The aim of this study was, thus, to determine the antibacterial activity of grape seed extracts with special focus on the chromatographic characterization of active fractions. In the course of these investigations, extraction protocols were optimized so that microwave-assisted extraction (MAE) guaranteed highest preconcentration efficiency. Proanthocyanidins, monomeric flavonoid aglycones, as well as some of their glycosides could be identified within yielded extracts via high-performance liquid chromatography-mass spectrometry (HPLC-MS). By that means the coherence number of possible isomers of procyanidins was approximated by a newly developed equation. As far as antibacterial activity determined via screening tests is concerned, the extracts generally have been found to be positively responsive toward 10 different gram-positive and gram-negative bacteria strains. After fractionation of the raw extracts, proanthocyanidins P2, P3, P4 and gallate esters P2G and P3G (P = proanthocyanidin consisting of catechin and epicatechin units, n = oligomerization degree, G = gallate ester) were determined as active antibacterial agents toward 10 different pathogens. Only moderate activity was found for monomeric flavonoid fractions.  相似文献   

Modelling the effects of alcohol ethoxylates on diffusion of pesticides in the cuticular wax of Chenopodium album leaves     

Burghardt M  Friedmann A  Schreiber L  Riederer M 《Pest management science》2006,62(2):137-147

Cuticular waxes represent the first and, in most cases, the limiting barrier for foliar uptake of pesticides from solution. Sorption of pesticides in reconstituted cuticular wax (wax/water partition coefficients) of Chenopodium album L. and in isolated cuticular membranes (cuticle/water partition coefficients) of Prunus laurocerasus L. was determined. Diffusion coefficients of pesticides in reconstituted cuticular wax of C. album leaves were size-dependent, increasing with increasing molar volume. In the presence of alcohol ethoxylates, diffusion coefficients were enhanced by up to two orders of magnitude, and size selectivity was significantly decreased. The accelerating effect and the decrease in size selectivity were attributed to plasticisation of the cuticular wax by the alcohol ethoxylates increasing the fluidity in the wax. A free volume model adopted from polymer science was successfully applied to predict diffusion coefficients of pesticides on the basis of the transport properties of the wax (size selectivity and crystallinity), the molar volume of the diffusing compound and the accelerator concentration in the wax.  相似文献   

Detection of Colchicum autumnale in drone images,using a machine-learning approach     

Petrich  Lukas  Lohrmann  Georg  Neumann  Matthias  Martin  Fabio  Frey  Andreas  Stoll  Albert  Schmidt  Volker 《Precision Agriculture》2020,21(6):1291-1303

Precision Agriculture - Colchicum autumnale are toxic autumn-blooming flowering plants, which often grow on extensive meadows and pastures. Thus, they pose a threat to farm animals especially in...  相似文献   

An effective biochar-based slow-release fertilizer for reducing nitrogen loss in paddy fields     

Dong  Da  Wang  Cheng  Van Zwieten  Lukas  Wang  Hailong  Jiang  Peikun  Zhou  Minmin  Wu  Weixiang 《Journal of Soils and Sediments》2020,20(8):3027-3040

Journal of Soils and Sediments - As a carbon sequestration material, biochar has attracted much attention due to its potential to enhance rice productivity and nitrogen retention in paddy fields....  相似文献