Light availability is improved for legume species grown in moderately N-fertilized mixtures with non-legume species

Empirical evidence indicates a positive relationship between grassland phytodiversity and yield. One cause may be species’complementary use of available resources. The aim of this study was to investigate possible complementarities between grassland species with differing spatial arrangements of leaves. Mixtures of Trifolium pratense L., Phleum pratense L., Lolium perenne L., and Cichorium intybus L. or Medicago sativa L. and pure stands of all species were established in 2007 at Svalöv, Sweden, in a field experiment receiving a total input of 100 kg N ha−1. Community height, light transmission, yield, and species composition as well as species’ 813C signatures and N concentrations were measured on four mowing occasions in 2009. Species’ 813C signatures are directly affected by carbon assimilation and stomatal conductivity for water, and indirectly by light, nitrogen and water availability as well as community composition. Light transmission through the sward was greatest in pure stand non-legumes; mixed communities intercepted more light than these, albeit not generally more than pure legumes. Non-legume species had more depleted 813C signatures when grown in mixtures than in pure stands, but the opposite was true for legumes. The 813C signatures generally became enriched with increases in light transmission (grasses and legumes), but not with increases in N concentration (grasses). Community composition affected the 813C signatures of all species except C. intybus. Our results suggest that mixing species of contrasting leaf morphologies and biomass distribution contributed to (i) increased light captureby mixtures over pure stand non-legumes, and (ii) better light availability in mixed than in pure stand legumes

Plant Traits Relevant for Multi-Functionality of Grassland Swards for Free-Range Chicken Husbandry

The sward of the outdoor run serves multiple important functions in free-range chicken husbandry systems. Vegetation ground cover is crucial for soil conservation. Moreover, by providing a foraging enrichment it is relevant for animal welfare (Shimmura et al. 2008). Scientific knowledge of the plant-animal interactions of swards in outdoor chicken runs is only just emerging. An understanding of these will help to improve swards both in view of the conservation of an intact vegetation cover, and for fostering animal welfare. In the present field study, we investigated: (1) the growth of a number of grassland plant species under conditions of chicken stocking in order to identify species that provide a durable greening of run areas; and (2) the foraging behaviour of chickens on swards of different botanical composition and canopy cover. Based on these data, our aim was to determine properties of plants that are particularly suitable for greening outdoor chicken runs

Little Effect of Species Richness and Vegetation Composition on Herbage Production and Quality in a Permanent Temperate Grassland

Phytodiversity of grasslands has been shown to support production and other ecosystem services (e.g.Weigel et al. 2009, Tilman et al. 2012). However, in many of these studies, species richness was controlled by sowing and weeding and it was questionable to what extent the findings would also be applicable to permanent \u27real world\u27 grasslands where the species number is dependent on site and management conditions. In addition there is uncertainty about the effect of diversity on the herbage value for ruminants (Wrage et al. 2011). In a new approach to biodiversity experiments, we combined experimental and observational measures and modified the vegetation of a permanent grassland by the use of herbicides (Petersen et al. 2012). We measured herbage production and quality over two full harvest years

Rolle des Phosphors als Steuerungsgröße des Stickstoffertrages und der Phytodiversität ökologisch bewirtschafteter Dauergrünlandbestände

In einem konzeptionellen Projektansatz, der sowohl Felderhebungen, Feldversuche, Gefäßversuche und Laboranalysen umfasste, wurde der Frage der Bedeutung der Bodenphosphor-Trophie für die Präsenz, die Entwicklung und die Leistungsfähigkeit von Grünlandleguminosen im Ökologischen Landbau nachgegangen. Ziel der Untersuchungen war es, die Bivalenz des Phosphors, der einerseits die Leguminosen und damit den N-Ertrag fördern kann und andererseits die Phytodiversität zu reduzieren vermag, näher zu ergründen. Es zeigte sich, dass die Präsenz von Grünlandleguminosen auf heterogenem Dauergrünland weder vom Gehalt an pflanzenverfügbarem P noch den einzelnen P-Fraktionen hinreichend erklärt werden konnte. Demnach spielen erratische bzw. weitere nicht kontrollierte Umweltbedingungen eine mindestens ebenso wichtige Rolle bei der kleinräumigen Verbreitung der Leguminosen auf dem Dauergrünland. Bei überhöhten P-Gehalten war tendenziell eine Verringerung der Phytodiversität zu konstatieren, wobei diese Beziehung im Bereich moderater P-Level weniger stark ausgeprägt war als in internationalen Studien, die sich nicht auf Öko-Grünland beschränkten. Offenbar vermochte der Phosphor aufgrund der N-Co-Limitierung im System des Ökologischen Landbaus keine vergleichbar verdrängende Wirkung via Förderung konkurrenzstärkerer, aber auch Nährstoff-bedürftigerer Florenvertreter zu entfalten. Beide Befunde weisen auf die realistische Möglichkeit hin, unter hiesigen Bedingungen eine moderate P-Düngung zur Förderung der Grünlandleguminosen ohne markant negative Auswirkungen auf die Phytodiversität zu rechtfertigen und damit auch zu praktizieren. Hierfür stehen verschiedene Düngemittel zur Verfügung, von denen sich in unseren Feldversuchen der zugelassene Standarddünger ‚Physalg‘ besonders für die kurzfristige Behebung von P-Defiziten sowie für die Unterstützung der Leguminosenetablierung empfahl, wohingegen das mit elementarem Schwefel versetzte Knochenkohle- Präparat seine Stärken in der Langzeitstabilisierung der Leguminosenanteile hatte und weniger zur Bodeneutrophierung neigte, was es zum Einsatz in floristisch wertvollen, artenreichen Grünlandbeständen prädestiniert. Die potenziellen P-Alternativen, die Recycling-Präparate ‚Leachphos‘ und ‚AshDec‘, erwiesen sich in ihrer Ertragswirkung der der für den Ökolandbau zugelassenen P-Dünger als ebenbürtig. Insgesamt waren die Ertragseffekte aller geprüften P-Dünger jedoch gering und daher auch selten abzusichern. Die in einigen Aufwüchsen festgestellte Interaktion Leguminosenart x Art des P-Düngers kann mit der unterschiedlichen Wurzelmorphologie und dem damit einhergehenden unterschiedlichen P-Aneignungsvermögen auch bei geringen PDL-Werten erklärt werden

Mass Balances of a Drained and a Rewetted Peatland: on Former Losses and Recent Gains

Drained peatlands are important sources of greenhouse gases and are rewetted to curb these emissions. We study one drained and one rewetted fen in terms of losses—and, after rewetting—gains of organic matter (OM), carbon (C), and peat thickness. We determined bulk density (BD) and ash/OM (and C/OM) ratios for 0.5 cm thick contiguous slices from peat monoliths to calculate losses. Whereas one site has lost 28.5 kg OM m−2 corresponding to annual emissions of ~10 t CO2 ha−1 a−1 over 50 years of effective drainage, the other site has lost 102 kg OM m−2, corresponding to an annual loss of ~30 t CO2 ha−1 a−1 for 30 years of intensive drainage and 6 t CO2 ha−1 a−1 during ~225 years of weak drainage before that. Height losses ranged from 43 to 162 cm. In the 20 years after rewetting, 2.12 kg C m−2 was accumulated, equaling an average annual uptake of ~0.4 kg CO2 m−2 a−1. The results indicate that rewetting can lead to carbon accumulation in fens. This sink function is only small compared with the high emissions that are avoided through rewetting

Patch-Differentiation of Vegetation and Nutrient Cycling in an Extensive Pasture System

In extensive grazing systems, ‘patch-grazing’ may lead to the development of a mosaic structure consisting of short, frequently defoliated, and tall, infrequently defoliated patches. If spatial patterns of sward structure are stable over time, this may result in a long-term differentiation of botanical composition and matter fluxes between patch types within a pasture. Patch dynamics, botanical composition and topsoil nutrient concentrations of different patch types were investigated in a long-term grazing experiment in the Solling hills, Germany, where differentiated grazing intensities have been applied for 10 years. Continuously stocked beef cattle grazed to target sward heights of 6 or12 cm in a put-and-take system in replicated 1-ha paddocks. Time series of point-specific sward height measurements showed that patches were relatively stable within- and between-seasons. Botanical composition as well as soil phosphorus and potassium concentrations differed between short and tall patches. While grazing intensity influenced the frequency of short and tall patches within a pasture, differences between patch types were larger than those within the same patch type between different grazing intensities. The results highlight the importance of studying biodiversity as well as nutrient dynamics of extensive pastures in a patch-specific way. Through the development of pasture areas with different functionality, extensive grazing systems have the potential to maintain biodiversity while sustaining agricultural production

Biochar as a tool to reduce the agricultural greenhouse-gas burden–knowns, unknowns and future research needs

Agriculture and land use change has significantly increased atmospheric emissions of the non-CO2 green-house gases (GHG) nitrous oxide (N2O) and methane (CH4). Since human nutritional and bioenergy needs continue to increase, at a shrinking global land area for production, novel land management strategies are required that reduce the GHG footprint per unit of yield. Here we review the potential of biochar to reduce N2O and CH4 emissions from agricultural practices including potential mechanisms behind observed effects. Furthermore, we investigate alternative uses of biochar in agricultural land management that may significantly reduce the GHG-emissions-per-unit-of-product footprint, such as (i) pyrolysis of manures as hygienic alternative to direct soil application, (ii) using biochar as fertilizer carrier matrix for underfoot fertilization, biochar use (iii) as composting additive or (iv) as feed additive in animal husbandry or for manure treatment. We conclude that the largest future research needs lay in conducting life-cycle GHG assessments when using biochar as an on-farm management tool for nutrient-rich biomass waste streams. © 2017 The Author(s) Published by VGTU Press and Informa UK Limited, [trading as Taylor & Francis Group]

Biochar research activities and their relation to development and environmental quality. A meta-analysis

Biochar is the solid product that results from pyrolysis of organic materials. Its addition to highly weathered soils changes physico-chemical soil properties, improves soil functions and enhances crop yields. Highly weathered soils are typical of humid tropics where agricultural productivity is low and needs to be raised to reduce human hunger and poverty. However, impact of biochar research on scientists, politicians and end-users in poor tropical countries remains unknown; assessing needs and interests on biochar is essential to develop reliable knowledge transfer/translation mechanisms. The aim of this publication is to present results of a meta-analysis conducted to (1) survey global biochar research published between 2010 and 2014 to assess its relation to human development and environmental quality, and (2) deduce, based on the results of this analysis, priorities required to assess and promote the role of biochar in the development of adapted and sustainable agronomic methods. Our main findings reveal for the very first time that: (1) biochar research associated with less developed countries focused on biochar production technologies (26.5 ± 0.7%), then on biochars’ impact on chemical soil properties (18.7 ± 1.2%), and on plant productivity (17.1 ± 2.6%); (2) China dominated biochar research activities among the medium developed countries focusing on biochar production technologies (26.8 ± 0.5%) and on use of biochar as sorbent for organic and inorganic compounds (29.1 ± 0.4%); and (3) the majority of biochar research (69.0±2.9%) was associated with highly developed countries that are able to address a higher diversity of questions. Evidently, less developed countries are eager to improve soil fertility and agricultural productivity, which requires transfer and/or translation of biochar knowledge acquired in highly developed countries. Yet, improving local research capacities and encouraging synergies across scientific disciplines and countries are crucial to foster development of sustainable agronomy in less developed countries. © 2017, The Author(s)

Wissenschaftliche Grundlagen zum Strategiediskurs für einen nachhaltigen Pflanzenbau

Für den rationalen gesellschaftlichen Diskurs zur Lösung der vielfältigen Zielkonflikte auf dem Weg zu einem nachhaltigen Pflanzenbausind wissenschaftliche Fakten über die Beziehungen zwischen den Zielen unabdingbar. Daher hat die Gesellschaft für Pflanzenbauwissen-schaften wissenschaftliche Befunde zu den Themenbereichen Biodiversität, Klimarelevanz und Klimaresilienz, Nährstoffmanagement,Pflanzenschutz, Bodenschutz und Produktion nachwachsender Rohstoffe zusammengestellt und den bestehenden Forschungsbedarfidentifiziert. Nach einem Executive Summary, das die Befunde schlaglichtartig darstellt, werden die Themenbereiche im Einzelnen ausgeführt. Ziel dieses Papiers ist nicht, Empfehlungen für die politische Entscheidungsfindung abzugeben, sondern die öffentliche Diskussiondurch Bereitstellung von Sachinformationen zu unterstützen.Scientific facts about the relationships between the goals are indispensable for the rational social discourse on solving the various conflict-ing goals on the way to sustainable crop production. Therefore, the German Society for Agronomy has compiled scientific findings on thetopics of biodiversity, climate relevance and climate resilience, nutrient management, crop protection, soil protection and production ofrenewable raw materials, and identified the existing need for research. After an executive summary that highlights the findings, the subjectareas are explained in detail. The purpose of this paper is not to make recommendations for policy-making, but to support the publicdebate by providing factual information

From Understanding to Sustainable Use of Peatlands: The WETSCAPES Approach

Of all terrestrial ecosystems, peatlands store carbon most effectively in long-term scales of millennia. However, many peatlands have been drained for peat extraction or agricultural use. This converts peatlands from sinks to sources of carbon, causing approx. 5% of the anthropogenic greenhouse effect and additional negative effects on other ecosystem services. Rewetting peatlands can mitigate climate change and may be combined with management in the form of paludiculture. Rewetted peatlands, however, do not equal their pristine ancestors and their ecological functioning is not understood. This holds true especially for groundwater-fed fens. Their functioning results from manifold interactions and can only be understood following an integrative approach of many relevant fields of science, which we merge in the interdisciplinary project WETSCAPES. Here, we address interactions among water transport and chemistry, primary production, peat formation, matter transformation and transport, microbial community, and greenhouse gas exchange using state of the art methods. We record data on six study sites spread across three common fen types (Alder forest, percolation fen, and coastal fen), each in drained and rewetted states. First results revealed that indicators reflecting more long-term effects like vegetation and soil chemistry showed a stronger differentiation between drained and rewetted states than variables with a more immediate reaction to environmental change, like greenhouse gas (GHG) emissions. Variations in microbial community composition explained differences in soil chemical data as well as vegetation composition and GHG exchange. We show the importance of developing an integrative understanding of managed fen peatlands and their ecosystem functioning.