Organic Farming – A Research Guide

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Tractors on eBay: Differences between Internet and In-Person Auctions

Internet auction platforms are changing the face of transactions in many business sectors, including agriculture. We provide one of the first systematic examinations of the differences between internet and in-person auctions in agricultural input markets. A hedonic model estimated with used tractor transactions from Midwestern sellers pooled between eBay and in-person auctions reveals statistically distinct price surfaces for the two auction venues and predicts significantly lower prices for comparable equipment sold on eBay, though this difference is attenuated for tractors fully covered by eBay's buyer protection program and is fully absent for the most frequently traded tractor. An endogenous venue-selection model reveals that larger, more-valuable tractors are less likely to be offered on eBay, a choice that should enhance seller revenues. Furthermore, sellers in states with more valuable stocks of machinery, more frequent tractor sales, and a lower propensity to use the internet for agricultural marketing are more likely to offer tractors for sale via in-person auctions than on eBay.auctions, electronic commerce, eBay, farm equipment, hedonic models, Marketing, D44, Q13,

Elektronische und strukturelle Phasenübergänge in den stark korrelierten Systemen 1T-TaSe2 und 1T′-TaTe2 sowie der Entwicklung einer Experimentierstation zur in operando Spektroskopie der Plasma-Festkörper-Grenzfläche

Das Ziel dieser Arbeit ist die Untersuchung der elektronischen Struktur der Übergangsmetalldichalkogenide 1T-TaSe2 und 1T′-TaTe2 in unterschiedlichen Phasen im Bereich der Oberfläche. Hierfür wurde zunächst an 1T-TaSe2 die Tiefenabhängigkeit der Ladungsdichtewelle bei tiefen Temperaturen mit Hilfe von Photoelektronenspektroskopie unter Verwendung von Röntgenstrahlung untersucht. Ausgehend von einem isolierenden Zustand im Bereich der ersten Atomlage wurden anhand der Ta4f-Rumpfniveauzustände spektroskopische Parameter identifiziert, die den Übergang in die metallische Volumenphase zeigen. Des weiteren wurde mit winkelauflösender Photoelektronenspektroskopie die Struktur der Valenz- und Rumpfzustände der monoklinen 3 × 1-Hoch- und 3 × 3- Tieftemperaturphase in 1T′-TaTe2 untersucht. Die Ergebnisse zeigen, dass 1T′-TaTe2 im Gegensatz zu anderen Übergangsmetalldichalkogeniden keine klassische Ladungsdichtewelle hervorruft, die sich durch eine Energielücke im Bereich des Valenzbandes auszeichnet. Abschließend wird die Entwicklung und Inbetriebnahme einer neuartigen Experimentierstation zur Untersuchung der Plasma-Festkörper-Grenzfläche vorgestellt. Hierbei wird ein in operando Ansatz mit Hilfe von synchrotronbasierter Röntgenspektroskopie vorgestellt, der beide Seiten der Grenzfläche einer Niederdruckplasmaentladung untersuchen soll. Strukturelle und chemische Veränderungen der Elektrodenoberfläche wurden hierbei durch photonenabhängige Röntgenreflektivitätsmessungen erfasst, während plasmaspezifische Parameter im Bereich des Plasmavolumens und der Randschicht mit Hilfe des entwickelten Spektrometers erfasst werden

A scoping review of research funding for small-scale farmers in water scarce regions

Water scarcity is a global issue that disproportionately affects small-scale farmers in low- and middle-income countries (LMICs). Through geospatial analysis, we estimated that less than 37% of small-scale farms probably have irrigation in water scarce regions across LMICs, compared with 42% of non-small-scale farms. Through a literature synthesis assisted by machine learning, we then systematically mapped the existing research for on-farm interventions that improve the incomes or yields of small-scale farmers in water scarce regions. We mapped over 888 on-farm interventions used to combat water scarcity from 560 publications and showed a research bias towards yields rather than livelihoods. We found gaps in evidence for many commonly proposed solutions, including livestock management, digital technology and solutions to protect natural resources at the farm-level, such as buffer strips. Our findings can be used to set a funding agenda for research on the geographies that are most at risk of water scarcity and the interventions that most lack evidence

Soil seed bank responses to edge effects in temperate European forests

Aim The amount of forest edges is increasing globally due to forest fragmentation and land-use changes. However, edge effects on the soil seed bank of temperate forests are still poorly understood. Here, we assessed edge effects at contrasting spatial scales across Europe and quantified the extent to which edges can preserve the seeds of forest specialist plants. Location Temperate European deciduous forests along a 2,300-km latitudinal gradient. Time period 2018-2021. Major taxa studied Vascular plants. Methods Through a greenhouse germination experiment, we studied how edge effects alter the density, diversity, composition and functionality of forest soil seed banks in 90 plots along different latitudes, elevations and forest management types. We also assessed which environmental conditions drive the seed bank responses at the forest edge versus interior and looked at the relationship between the seed bank and the herb layer species richness. Results Overall, 10,108 seedlings of 250 species emerged from the soil seed bank. Seed density and species richness of generalists (species not only associated with forests) were higher at edges compared to interiors, with a negative influence of C : N ratio and litter quality. Conversely, forest specialist species richness did not decline from the interior to the edge. Also, edges were compositionally, but not functionally, different from interiors. The correlation between the seed bank and the herb layer species richness was positive and affected by microclimate. Main conclusions Our results underpin how edge effects shape species diversity and composition of soil seed banks in ancient forests, especially increasing the proportion of generalist species and thus potentially favouring a shift in community composition. However, the presence of many forest specialists suggests that soil seed banks still play a key role in understorey species persistence and could support the resilience of our fragmented forests

Author Correction: Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

A Correction to this paper has been published: https://doi.org/10.1038/s41535-021-00314-