133 research outputs found
Mapping Soil Erosion Sensitive Areas in Organic Matter Amended Soil Associations in the Ntabelanga area, Eastern Cape Province, South Africa
The study aims to map areas sensitive to erosion by water and rainfall erosivity after addition of organic matter (OM) in highly unstable soils. A soil association map was created using digital soil mapping methodology. Soil samples from six soil associations were incubated and analysed for several soil erodibility measures and inferred to the soil association map. Soil stabilization against soil erosion by use of OM was evaluated for 30 weeks under two simulated rainstorms, intermittent rainstorms (IR) and single rainstorm (SR). Rainfall erosivity (R-factor) was calculated from theduration of a rainstorm and the total amount of rainfall received under rainfall simulations. Erodibility factor (K-factor) was estimated using the soil OM content and texture. Largest area (40%) was covered by shallow soils and K-factor range of 0.0693-0.0778 t.ha.hha-1MJ-1mm-1. Largest (60.2%) area had a structural stability index of 0.8 and 42.7% of the area was covered by a dispersion ratio value range of 0.65-0.70. The area size with erosion rates of > 15 t/ha/yr was drastically reduced from 1 to 8 weeks after OM application thereafter gradually increased under both IR and SR. Soil erosion rates of < 5 t-1 ha-1 yr-1 and > 15 t-1 ha-1 yr-1 were most and least observed respectively under both storms. R-factor was higher under IR than SR and the smallest areas with soil erosion rates of > 15 t-1 ha-1 yr-1 contributed most to the lost soil. Organic matter confers soil resistance to erosion up to a certain period before losing its effectiveness. The study provided first assessment of erosion dynamics, basis for identifying conservation priorities which may be applicable in similar areas.
Keywords: Erosivity, planning, rainstorm, soil conservation, soil degradatio
Sub-MHz Linewidth at 240 GHz from an Injection-Locked Free-Electron Laser
Radiation from an ultra-stable 240 GHz solid-state source has been injected,
through an isolator, into the cavity of the University of California Santa
Barbara (UCSB) MM-wave free-electron laser (FEL). High-power FEL emission,
normally distributed among many of the cavity's longitudinal modes, is
concentrated into the single mode to which the solid state source has been
tuned. The linewidth of the FEL emission is 0.5 MHz, consistent with the
Fourier transform limit for the 2 microsecond pulses. This demonstration of
frequency-stable, ultra-narrow-band FEL emission is a critical milestone on the
road to FEL-based pulsed electron paramagnetic resonance spectroscopy.Comment: 3 pages including 3 figure
Rabi oscillations of solitons in spin-chains: a new route to quantum computation and communication
We provide the first evidence for coherence and Rabi oscillations of
spin-solitons pinned by the local breaking of translational symmetry in
isotropic Heisenberg chains (simple antiferromagnetic-N\'{e}el or
spin-Peierls).We show that these correlated spin systems made of hundreds of
coupled spin bear an overall spin S=1/2 and can be manipulated as a single
spin. This is clearly contrary to all known spin-qubits which are paramagnetic
centres, highly diluted to prevent decoherence. These results offer an
alternative approach for spin-qubits paving the way for the implementation of a
new type of quantum computer
High-frequency electron paramagnetic resonance investigation of the Fe3+ impurity center in polycrystalline PbTiO3 in its ferroelectric phase
The intrinsic iron(III) impurity center in polycrystalline lead titanate was
investigated by means of high-frequency electron paramagnetic resonance (EPR)
spectroscopy in order to determine the local-environment sensitive fine
structure parameter D. At a spectrometer frequency of 190 GHz, spectral
analysis of a powder sample was unambiguously possible. The observed mean value
D = +35.28 GHz can be rationalized if Fe3+ ions substitute for Ti4+ at the
B-site of the perovskite ABO3 lattice forming a directly coordinated iron -
oxygen vacancy defect associate. A consistent fit of the multi-frequency data
necessitated use of a distribution of D values with a variance of about 1 GHz.
This statistical distribution of values is probably related to more distant
defects and vacancies.Comment: 6 pages, 3 figures, 1 table, to appear in J. App. Phys, 96 (2004
Mapping Soil Erosion Sensitive Areas in Organic Matter Amended Soil Associations in the Ntabelanga area, Eastern Cape Province, South Africa
The study aims to map areas sensitive to erosion by water and rainfall
erosivity after addition of organic matter (OM) in highly unstable
soils. A soil association map was created using digital soil mapping
methodology. Soil samples from six soil associations were incubated and
analysed for several soil erodibility measures and inferred to the soil
association map. Soil stabilization against soil erosion by use of OM
was evaluated for 30 weeks under two simulated rainstorms, intermittent
rainstorms (IR) and single rainstorm (SR). Rainfall erosivity
(R-factor) was calculated from the duration of a rainstorm and the
total amount of rainfall received under rainfall simulations.
Erodibility factor (K-factor) was estimated using the soil OM content
and texture. Largest area (40%) was covered by shallow soils and
K-factor range of 0.0693-0.0778 t.ha.hha-1MJ-1mm-1. Largest (60.2%)
area had a structural stability index of 0.8 and 42.7% of the area was
covered by a dispersion ratio value range of 0.65-0.70. The area size
with erosion rates of > 15 t/ha/yr was drastically reduced from 1 to
8 weeks after OM application thereafter gradually increased under both
IR and SR. Soil erosion rates of < 5 t-1 ha-1 yr-1 and > 15 t-1
ha-1 yr-1 were most and least observed respectively under both storms.
R-factor was higher under IR than SR and the smallest areas with soil
erosion rates of > 15 t-1 ha-1 yr-1 contributed most to the lost
soil. Organic matter confers soil resistance to erosion up to a certain
period before losing its effectiveness. The study provided first
assessment of erosion dynamics, basis for identifying conservation
priorities which may be applicable in similar areas
Africa’s First Alpine and Transboundary Long-Term Socioecological Research Platform
The austrotemperate alpine system of southern Africa's Maloti–Drakensberg is the only alpine system south of Mount Kilimanjaro, making it unique on the continent. With a difference in elevation of only 300–600 m and characterized by an undulating Gondwanan mature erosional land surface plateau around 2865–3500 masl, it is threatened by unsustainable land uses and climate change. To better understand these challenges, the Afromontane Research Unit of the University of the Free State, South Africa, is setting up the 1200 km2 Mont-Aux-Sources Long-Term Socio-Ecological Research (LTSER) platform. It is the first alpine-focused, long-term monitoring protocol implemented in the Maloti–Drakensberg. Straddling the border between South Africa and Lesotho, it is also the only alpine and transboundary LTSER area in Africa
Spatial soil information in South Africa : situational analysis, limitations and challenges
CITATION: Paterson, G. et al. 2015. Spatial soil information in South Africa : situational analysis, limitations and challenges. South African Journal of Science, 111(5/6),
Art. #2014-0178, doi:10.17159/sajs.2015/20140178.The original publication is available at http://sajs.co.zaSoil information is vital for a range of purposes; however, soils vary greatly over short distances, making
accurate soil data difficult to obtain. Soil surveys were first carried out in the 1920s, and the first national soil
map was produced in 1940. Several regional studies were done in the 1960s, with the national Land Type
Survey completed in 2002. Subsequently, the transfer of soil data to digital format has allowed a wide range
of interpretations, but many data are still not freely available as they are held by a number of different bodies.
The need for soil data is rapidly expanding to a range of fields, including health, food security, hydrological
modelling and climate change. Fortunately, advances have been made in fields such as digital soil mapping,
which enables the soil surveyors to address the need. The South African Soil Science fraternity will have
to adapt to the changing environment in order to comply with the growing demands for data. At a recent
Soil Information Workshop, soil scientists from government, academia and industry met to concentrate
efforts in meeting the current and future soil data needs. The priorities identified included: interdisciplinary
collaboration; expansion of the current national soil database with advanced data acquisition, manipulation,
interpretation and countrywide dissemination facilities; and policy and human capital development in newly
emerging soil science and environmental fields. It is hoped that soil information can play a critical role in the
establishment of a national Natural Agricultural Information System.http://sajs.co.za/spatial-soil-information-south-africa-situational-analysis-limitations-and-challenges/garry-paterson-dave-turner-liesl-wiese-george-van-zijl-cathy-clarke-johan-van-tolPublisher's versio
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