211,595 research outputs found
Effect of clay amendments on nitrogen leaching and forms in a sandy soil
No full textNitrogen (N) leaching in sandy soil decreases fertiliser use efficiency and may depress plant production. Application of high cation exchange capacity (CEC) materials (e.g. high activity clay minerals) is hypothesized to reduce N leaching and increase plant N uptake in sandy soils. However, the mechanism of leaching in sands with clay amendment is not understood. A column experiment was conducted to determine N leaching and N concentration in soil solution in a sandy soil (1.4 % clay) with three soil amendments (nil, clay soil and bentonite clay) and three fertiliser rates (0, 28 N 17 P 22 K kg/ha and 56 N 34 P 44 K kg/ha). Soil amendments were applied at the rate of 50 Mg/ha. The soil columns were leached with de-ionised water equivalent to 50 mm rainfall every 4 days. Concentrations of soil solution extracted by Rhizon samplers indicated that NH4 leaching was decreased 38-43 % by bentonite addition but little of the soil solution N was in NO3 form and bentonite had no effect on mobility of this form of N. The application of bentonite was able to hold NH4 in soil solution of top soil. Leaching of NH4 was delayed to 15 day after fertiliser application in bentonite-amended sand
Sandy soils in south central coastal Vietnam: their origin, constraints and management
No full textIn Vietnam, sandy soils are distributed mainly in the coastal central provinces where they occupy 337,768 ha comprising 63 % of the nation’s sandy soils, and they are also important to regional economic growth where more than 10 million people are living i.e.14 % of the Vietnamese population. The sandy materials in the central coastal Vietnam originate from mostly in situ weathering of granite although aeolian sediments are parent materials for sandy soils also. Sandy soils have a wide range of limiting factors for agricultural production, including nutrient deficiencies, acidity, low water holding capacity and wind erosion risk (on coastal dunal sands). Although there are soil fertility constraints to the use of sandy soils in Vietnam, 79,076 ha has been utilized in agriculture. Developing integrated nutrient management practices are needed to improve soil physical, chemical and biological fertilities of sandy soils. For example, systematic use of farmyard manures, crop residues, green manures, and alley cropping need to be considered. Developing integrated nutrient management practices also need to address environmental considerations by matching nutrient applications to crop needs and amending soils to minimise nutrient losses to water. Developing new soil management technologies (such as use of biochar, slow release fertilisers and minimum tillage) is also important for sustainable management of sandy soils in Vietnam
Low faunal diversity on Maltese sandy beaches : fact or artefact?
No full textEight sandy beaches on Malta and two on Gozo were sampled for macrofauna to test the hypothesis that Maltese beaches have
an intrinsically low diversity. Stations distributed in the supralittoral (dry zone), mediolittoral (wet zone) and upper infralittoral
(submerged zone to 1m water depth) were sampled by sieving core samples and standardised searching during daytime, and pitfall
trapping and standardised sweeping of the water column using a hand-net at night, as appropriate. Physical parameters of the
sediment were measured and human occupancy of the beaches was estimated.
From the supralittoral and mediolittoral, 39 species represented by 1584 individuals were collected by the combined techniques of
pitfall trapping, sieving and standard searching. For Ramla beach, which had the highest diversity, 267 individuals representing 25
infaunal species were collected by sieving from a combined volume of 1.175m3 of sand, and 149 individuals representing 28
epifaunal species were collected by standardised searching from a combined area of 700m2 of sand during two winter and two
summer sampling sessions between 1992 and 1993. For nine other beaches sampled during the summer of 2000, only six
macrofaunal species were collected from core samples, with overall population densities ranging from 4.13 to 45.45 individualsm 2.
Only 92 individuals belonging to 12 species were collected by hand-net from the uppermost infralittoral of five beaches sampled
using this method during the summer of 2000. Taxa of gastropods, bivalves, decapods, mysids and staphylinid beetles generally
abundant on Mediterranean sandy beaches, were entirely absent from the beaches sampled.
Few correlations that could explain the impoverishment of Maltese sandy beaches were found between physical parameters and
faunal abundances, and other factors such as inadequate sampling effort, human disturbance and marine pollution were also
excluded; however, seasonally biased sampling may partly explain the results obtained. One factor that may explain why certain
species are missing could be lack of recruitment, due to Malta’s geographical isolation from the European and African mainlands.
2003 Elsevier Ltd. All rights reserved.peer-reviewe
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A letter from Sandy Speed to Dr. Hector P. Garcia.
No full textA letter from Sandy Speed, General Chairman of Corpus Christi State University and Leadership Corpus Christi, to Dr. Hector P. Garcia, inviting him to serve on the Advisory Committee
Code to compare model outputs and pollen-based reconstructions
No full textProvides code used to generate Figure 8 in Harrison, S.P., Gaillard, M-J., Stocker, B., Vander Linden, M., Klein Goldewijk, K., Boles, O., Braconnot, P., Dawson, A., Fluet-Chouinard, E., Kaplan, J.O., Kastner, T., Pausata, F.S.R., Robinson, E., Whitehouse, N., Madella, M., Morrison, K.D., 2019. Development and testing of scenarios for implementing Holocene LULC in Earth System Model Experiments. Geoscientific Model Development Discussions, https://doi.org/10.5194/gmd-2019-125 7</p
The influence of coastal upwelling on the biodiversity of sandy beaches in South Africa
No full textSandy beaches are often highly allochthonous, depending on external subsidies of carbon and nutrients. Despite this, sandy beach macrofaunal assemblages have received little attention regarding their response to enhanced primary productivity generated from coastal upwelling. This thesis investigates the influence of upwelling on macrofaunal assemblages over a variety of spatial and temporal scales. Spatially, four regions were examined across two biogeographic provinces to remove temperature as a confounding factor, and limit biogeography-specific effects. A nested hierarchical design enabled both large and small scales to be examined and generalities about upwelling effects across multiple areas to be considered. Sampling was conducted in two seasons, and over two years, to test the persistence of any effects. Biogeography and region had the strongest influences on macrofaunal biodiversity. Upwelling influenced macrofaunal assemblages in every region when analyses were conducted at the species level. However, the particular effect, positive or negative, differed among regions depending on local factors, and between the response variables, abundance and biomass. Coarser scales of taxonomy, feeding guild and developmental mode were investigated; however, the influence of upwelling generally became weaker and more varied, and occasionally disappeared. Seasonality was greater on the South Coast but was still important in some analyses on the West Coast. At the small-scale, variation within-beaches was lower than between beaches, assemblage structure remained stable over time, and consistent zonation was not present. The influence of temperature on filtration rate and oxygen consumption of Donax serra was investigated to test a driving mechanism for assemblage responses to upwelling. Feeding ability was significantly reduced at colder temperatures indicating an important factor which may be involved in determining assemblage structure. These results suggest that alterations to upwelling regimes predicted under climate change scenarios will impact sandy beach macrofauna, however the specific outcome will depend on multiple contextual factors
Sandy Cairncross, Maggie Black and Girish Menon - 28 Mar 2008
No full textIn this edition of Audio News, presented by Peter Goodwin, Sandy Cairncross, Maggie Black (Earthscan), and Girish Menon (Water Aid) talk about:
The Last Taboo: Opening The Door On The Global Sanitation Crisis
a book by Maggie Black and Ben Fawcett, published by Earthscan with UNICEF.
A massive improvement in health and wealth in developing countries could be achieved by providing systems to dispose of human excreta safely. A new book: "The Last Taboo" was launched at the London School of Hygiene and Tropical Medicine by the Professor of Environmental Health, Sandy Cairncross
Non-discursive knowledge and the construction of identity. Potters, potting and performance at the bronze age tell of Százhalombatta, Hungary
No full textThis article explores the relationship between the making of things and the making of people at the Bronze Age tell at Százhalombatta, Hungary. Focusing on potters and potting, we explore how the performance of non-discursive knowledge was critical to the construction of social categories. Potters literally came into being as potters through repeated bodily enactment of potting skills. Potters also gained their identity in the social sphere through the connection between their potting performance and their audience. We trace degrees of skill in the ceramic record to reveal the material articulation of non-discursive knowledge and consider the ramifications of the differential acquisition of non-discursive knowledge for the expression of different kinds of potter's identities. The creation of potters as a social category was essential to the ongoing creation of specific forms of material culture. We examine the implications of altered potters' performances and the role of non-discursive knowledge in the construction of social models of the Bronze Ag
Sandy coastlines under threat of erosion
No full textSandy beaches occupy more than one-third of the global coastline1 and have high socioeconomic value related to recreation, tourism and ecosystem services2. Beaches are the interface between land and ocean, providing coastal protection from marine storms and cyclones3. However the presence of sandy beaches cannot be taken for granted, as they are under constant change, driven by meteorological4,5, geological6 and anthropogenic factors1,7. A substantial proportion of the world’s sandy coastline is already eroding1,7, a situation that could be exacerbated by climate change8,9. Here, we show that ambient trends in shoreline dynamics, combined with coastal recession driven by sea level rise, could result in the near extinction of almost half of the world’s sandy beaches by the end of the century. Moderate GHG emission mitigation could prevent 40% of shoreline retreat. Projected shoreline dynamics are dominated by sea level rise for the majority of sandy beaches, but in certain regions the erosive trend is counteracted by accretive ambient shoreline changes; for example, in the Amazon, East and Southeast Asia and the north tropical Pacific. A substantial proportion of the threatened sandy shorelines are in densely populated areas, underlining the need for the design and implementation of effective adaptive measures.Accepted Author ManuscriptCoastal Engineerin
Crushed rock and clay amelioration of a nutrient decifient, sandy soil of Maputaland
No full textBibliography: leaves 57-62.Various studies have suggested the possibility that food derived through subsistence agriculture in the Mseleni region of Maputaland contributes to malnutrition within the local community, particularfy within the high proportion of the population which suffers from a severe, disabling form of osteoarthritis. This study was conducted to determine if the application of local crushed rock or black clay to these nutrient deficient, sandy soils would increase available nutrient concentrations and improve the growth of plants in the ameliorated soil
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