3,086 research outputs found
High Root Biomass FOR cereal crops increases carbon sequestration in organic Arable systems
In agroecosystems, soil organic carbon (C) inputs come from applied manures, plant roots and retained shoot residues. Several reasons, associated with root measurements, limit current knowledge on root C input.This study aimed at evaluating root responses to nutrient management and fertility building measures (e.g. catch crops). We made use of one inorganic fertilizer-based and two organic systems in an 11-year-old field experiment on sandy loam soil. At anthesis, soil cores (5 cm dia.) were sampled from 0-30 cm depth within and between rows of winter wheat and spring barley. Roots were separated from soil and washed with tap water, the dry matter (DM) biomass was determined. Dry matter biomass was also measured in shoots.The spring barley root DM was at least 30% higher in the organic compared to the inorganic fertilizer-based system. The organic system that included catch crops had 17% higher spring barley root DM than where catch crops were absent. In the inorganic fertilizer-based system, the biomass shoot-to-root ratio for spring barley was double that in the comparable organic system. High root DM biomass in organic compared to the inorganic fertilizer-based systems, implies higher C sequestration in the former, especially considering the slow decomposition rate of root residues
From Doubled Chern-Simons-Maxwell Lattice Gauge Theory to Extensions of the Toric Code
We regularize compact and non-compact Abelian Chern-Simons-Maxwell theories
on a spatial lattice using the Hamiltonian formulation. We consider a doubled
theory with gauge fields living on a lattice and its dual lattice. The Hilbert
space of the theory is a product of local Hilbert spaces, each associated with
a link and the corresponding dual link. The two electric field operators
associated with the link-pair do not commute. In the non-compact case with
gauge group , each local Hilbert space is analogous to the one of a
charged "particle" moving in the link-pair group space in a
constant "magnetic" background field. In the compact case, the link-pair group
space is a torus threaded by units of quantized "magnetic" flux,
with being the level of the Chern-Simons theory. The holonomies of the
torus give rise to two self-adjoint extension parameters, which form
two non-dynamical background lattice gauge fields that explicitly break the
manifest gauge symmetry from to . The local Hilbert space
of a link-pair then decomposes into representations of a magnetic translation
group. In the pure Chern-Simons limit of a large "photon" mass, this results in
a -symmetric variant of Kitaev's toric code, self-adjointly
extended by the two non-dynamical background lattice gauge fields. Electric
charges on the original lattice and on the dual lattice obey mutually anyonic
statistics with the statistics angle . Non-Abelian
Berry gauge fields that arise from the self-adjoint extension parameters may be
interesting in the context of quantum information processing.Comment: 38 pages, 4 figure
Reducing Global Warming and Adapting to Climate Change: The Potential of Organic Agriculture
Climate change mitigation is urgent and adaptation to climate change is crucial, particularly in agriculture, where food security is at stake. Agriculture, currently responsible for 20-30% of global greenhouse gas emissions counting direct and indirect agricultural emissions), can however contribute to both climate change mitigation and adaptation. The main mitigation potential lies in the capacity of agricultural soils to sequester CO2 through building organic matter. This potential can be realized by employing sustainable agricultural practices, such as those commonly found within organic farming systems. Examples of these practices are the use of organic fertilizers and crop rotations including legumes leys and cover crops. Mitigation is also achieved in organic agriculture through the avoidance of open biomass burning and the avoidance of synthetic fertilizers and the related production emissions from fossil fuels. Common organic practices also contribute to adaptation. Building soil organic matter increases water retention capacity, and creates more stabile, fertile soils, thus reducing vulnerability to drought, extreme precipitation events, floods and water logging. Adaptation is further supported by increased agro-ecosystem diversity of organic farms, due to reduced nitrogen inputs and the absence of chemical pesticides. The high diversity together with the lower input costs of organic agriculture is key in reducing production risks associated with extreme weather events. All these advantageous practices are not exclusive to organic agriculture. However, they are core parts of the organic production system, in contrast to most non-organic agriculture, where they play a minor role only.
Mitigation in agriculture cannot be restricted to the agricultural sector alone, though. Consumer behaviour strongly influences agricultural production systems, and thus their mitigation potential. Significant factors are meat consumption and food wastage. Any discussion on mitigation climate change in agriculture needs to address the entire food chain and needs to be linked to general sustainable development strategies.
The main challenges to climate change mitigation and adaptation in organic agriculture and agriculture in general concern
a)the understanding of some of the basic processes, such as the interaction of N2O emissions and soil carbon sequestration, contributions of roots to soil carbon sequestration and the life-cycle emissions of organic fertilizers such as compost;
b) approaches for emissions accounting that adequately represent agricultural production systems with multiple and diverse outputs and that also encompass ecosystem services;
c) the identification and implementation of most adequate policy frameworks for supporting mitigation and adaptation in agriculture, i.e: not putting systemic approaches at a disadvantage due to difficulties in the quantification of emissions, and in their allocation to single products;
d) how to assure that the current focus on mitigation does not lead to neglect of the other sustainability aspects of agriculture, such as pesticide loads, eutrophication, acidification or soil erosion and
e) the question how to address consumer behaviour and how to utilize the mitigation potential of changes in consumption patterns
Below-ground plant-fungus network topology is not congruent with above-ground plant-animal network topology
植物を支える「共生ネットワーク」は地上と地下で構造が違う --見えてきた地下生物圏の構造--. 京都大学プレスリリース. 2015-10-26.In nature, plants and their pollinating and/or seed-dispersing animals form complex interaction networks. The commonly observed pattern of links between specialists and generalists in these networks has been predicted to promote species coexistence. Plants also build highly species-rich mutualistic networks below ground with root-associated fungi, and the structure of these plant–fungus networks may also affect terrestrial community processes. By compiling high-throughput DNA sequencing data sets of the symbiosis of plants and their root-associated fungi from three localities along a latitudinal gradient, we uncovered the entire network architecture of these interactions under contrasting environmental conditions. Each network included more than 30 plant species and hundreds of mycorrhizal and endophytic fungi belonging to diverse phylogenetic groups. The results were consistent with the notion that processes shaping host-plant specialization of fungal species generate a unique linkage pattern that strongly contrasts with the pattern of above-ground plant–partner networks. Specifically, plant–fungus networks lacked a “nested” architecture, which has been considered to promote species coexistence in plant–partner networks. Rather, the below-ground networks had a conspicuous “antinested” topology. Our findings lead to the working hypothesis that terrestrial plant community dynamics are likely determined by the balance between above-ground and below-ground webs of interspecific interactions
Quantum corrections from a path integral over reparametrizations
We study the path integral over reparametrizations that has been proposed as
an ansatz for the Wilson loops in the large- QCD and reproduces the area law
in the classical limit of large loops. We show that a semiclassical expansion
for a rectangular loop captures the L\"uscher term associated with
dimensions and propose a modification of the ansatz which reproduces the
L\"uscher term in other dimensions, which is observed in lattice QCD. We repeat
the calculation for an outstretched ellipse advocating the emergence of an
analog of the L\"uscher term and verify this result by a direct computation of
the determinant of the Laplace operator and the conformal anomaly
Quantifying the Influence of Social Characteristics on Accident and Injuries Risk: A Comparative Study Between Motorcyclists and Car Drivers
On the integrability of Wilson loops in AdS_5 x S^5: Some periodic ansatze
Wilson loops are calculated within the AdS/CFT correspondence by finding a
classical solution to the string equations of motion in AdS_5 x S^5 and
evaluating its action. An important fact is that this sigma-model used to
evaluate the Wilson loops is integrable, a feature that has gained relevance
through the study of spinning strings carrying large quantum numbers and
spin-chains. We apply the same techniques used to solve the equations for
spinning strings to find the minimal surfaces describing a wide class of Wilson
loops. We focus on different cases with periodic boundary conditions on the
AdS_5 and S^5 factors and find a rich array of solutions. We examine the
different phases that appear in the problem and comment on the applicability of
integrability to the general problem.Comment: LaTex, 49 pages, 8 figure
Exploring Digitised Moving Image Collections: The SEMIA Project, Visual Analysis and the Turn to Abstraction
Nucleation of quark matter bubbles in neutron stars
The thermal nucleation of quark matter bubbles inside neutron stars is
examined for various temperatures which the star may realistically encounter
during its lifetime. It is found that for a bag constant less than a critical
value, a very large part of the star will be converted into the quark phase
within a fraction of a second. Depending on the equation of state for neutron
star matter and strange quark matter, all or some of the outer parts of the
star may subsequently be converted by a slower burning or a detonation.Comment: 13 pages, REVTeX, Phys.Rev.D (in press), IFA 93-32. 5 figures (not
included) available upon request from [email protected]
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