Spelling suggestions: "subject:"aphosphorus content"" "subject:"diphosphorus content""
71 |
Effect of ammonium and phosphorous fertilizers on soil ogranic [sic] matter and reactionMyers, Roger Gene. January 1984 (has links)
Call number: LD2668 .T4 1984 M93 / Master of Science
|
72 |
Zinc content and yield of corn as influenced by methods and rates of application of zinc and phosphorusNewton, David Wayne,1940- January 1966 (has links)
Call number: LD2668 .T4 1966 N562 / Master of Science
|
73 |
The modeling of lake response to phosphorus loadings : empirical, chemical, and hydrodynamic aspects.Yeasted, Joseph Gerard January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Civil Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / Ph.D.
|
74 |
Soil Phosphorus Characterization and Vulnerability to Release in Urban Stormwater Bioretention FacilitiesShetterly, Benjamin James 26 March 2018 (has links)
Modern urban stormwater infrastructure includes vegetated bioretention facilities (BRFs) that are designed to detain water and pollutants. Phosphorus (P) is a pollutant in stormwater which can be retained in BRF soils in mineral, plant, and microbial pools. We explored soil properties and phosphorus forms in the soils of 16 operational BRFs in Portland, OR. Since soil hydrology can significantly impact P retention, we selected BRFs along an infiltration rate (IR) gradient. We conducted sequential fractionation and tests of P pools and measured P release in a subset of soils after drying and flooding samples for ten days. We hypothesized that mineral or organic soil P forms would be correlated with IR, and that vulnerability to P release would depend on the interaction of drying and flooding treatments with P forms and pools. IR did not significantly explain differences in P forms. Soil TP was elevated across all sites, compared with TP in agriculturally-impacted wetlands and was substantially composed of soil organic matter (OM)-associated P. Phosphorus sorbed to mineral Fe and Al oxides- was variable but positively correlated with water-extractable P. The concentration gradient of water-extractable P was primarily controlled by overall P pools. Experimentally induced P releases were seen in 5 of 6 soils exposed to drying conditions, presumably released through microbial mineralization of OM. Only one site showed significant P release following the flooding treatment. Our measurements supported the idea that Fe and Al oxides provide P sorption capacity in these BRF soils. Variable inputs of P to BRFs through stormwater and litterfall may contribute to variability in P profiles and P release vulnerability across sites. Design specifications and management decisions relating to bioretention soils (e.g. establishment of acceptable soil test P levels, focusing on P forms known to influence vulnerability of P release) may benefit from detailed biogeochemical investigations.
|
75 |
Site-specific environmental risk assessment for phosphorus runoffLukhele, Nomagugu Precious January 2014 (has links)
Thesis (MSc. Agriculture (Soil Science)) -- University of Limpopo, 2014 / Phosphorus (P) runoff from agricultural sites and the subsequent loading into surface water
bodies contribute to eutrophication. Environmental concerns associated with P loading in
soil have motivated the need for the development of a proper tool that will allow farmers to
identify agricultural areas or management practices that have the greatest potential to
accelerate eutrophication. The objective of the study was to determine the spatial variability
of soil test P, soil loss potential of the farm, P application rate and methods, and map P runoff
risk across the field. This study was conducted in Vierfontein Boerdery in Kriel,
Mpumalanga province, South Africa (longitude 29.11258833 and latitude -26.27104340). The
field was under dryland cultivation and planted to yellow maize that was rotated with
soybeans. Soil samples were taken at georeferenced locations in a 100 x 100 m grid for soil
analysis. Spatial layers of soil P distribution, soil loss potential as well as application rate and
method were created in ArcGIS software. These layers were used as input factors in a P
index model to identify areas in the farm that are vulnerable to P runoff. Results indicated a
variation in soil test P. Although soil test P variation was not statistically different at P≤0.05,
variation had both agronomic and environmental implications. This variation could be
attributed to differences in site-specific conditions and management practices. Furthermore,
soil loss potential across the study site predicted by the Revised Universal Soil Loss
Equation (RUSLE) showed variation with a range of 3-15 tons/ha/yr. This variation was
attributed to differences in topographic variations in the study site. There is a need for best
management practices that control soil erosion to minimize P runoff into water bodies.
KEYWORDS: Eutrophication, Geographic Information System, Phosphorus best
management practises, Phosphorus runoff index, Soil erosion, Site-specific management.
|
76 |
An investigation of the role of soil micro-organisms in phosphorus mobilisation : a report submitted to fulfil the requrements of the degree of Doctor of PhilosophyCoyle, Kieran. January 2001 (has links) (PDF)
"September 2001" Includes bibliographical references (leaves 206-230)
|
77 |
Phosphorus cycling in soil under wheat-pasture rotations / by Michael John McLaughlinMcLaughlin, Michael John January 1986 (has links)
2 offprints in pocket / Bibliography: leaves 184-210 / xx, 217 leaves, [1] leaf of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1987
|
78 |
An investigation of the role of soil micro-organisms in phosphorus mobilisation : a report submitted to fulfil the requirements of the degree of Doctor of Philosophy / Kieran Coyle.Coyle, Kieran January 2001 (has links)
"September 2001" / Includes bibliographical references (leaves 206-230) / xviii, 230 leaves : ill., plates ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 2002
|
79 |
Basic Concepts of Nitrogen Phosphorus and Potassium in Calcareous SoilsFuller, Wallace H., Ray, Howard E. 07 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
|
80 |
An evaluation of the use of organic amandments to ameliorate aluminium toxicity and phosphorus deficiency in an acid soil.Mokolobate, Motlogeloa Salathiel. January 2000 (has links)
The effects of the additions of some commonly-available organic residues to an acid, P-deficient soil (typical of those used by small-scale farmers in KwaZulu-Natal) on soil pH, exchangeable and soil solution AI, P availability and maize yield response was investigated in a number of
laboratory and glasshouse experiments. The organic amendments used were ground-up grassveld residues, household compost, filter cake (a waste product from a sugar mill) and layer poultry manure. The soil used was a Hutton form (Farmingham series) (Rhodic Ferrasol, FAO).
In an initial laboratory study, addition of all of the organic residues, at rates equivalent to 10 and 20 Mg ha¯¹, raised soil pH significantly and as a result there was a marked reduction in exchangeable AI concentrations. The increase in pH and decrease in exchangeable AI was more
pronounced at the higher rate of addition and followed the order: poultry manure> filter cake> household compost> grass residues. The major mechanism responsible for the increase in pH was thought to differ depending upon the type of organic residue being considered. Whilst the
relatively high content ofCaC0₃ was probably the main mechanism in the case of poultry manure and filter cake, the proton consuming ability of humic material probably predominated for household compost and decarboxylation of organic acids during decomposition was probably the
main mechanism in the case of grass residues.
Additions of organic amendments also decreased concentrations of total AI (AIT) in soil solution
but the concentration of monomeric AI (AIMono) as estimated by pyrocatechol violet 60 sec. method, was unchanged or even increased. This latter effect was attributed to the high cation content of residues (particularly that of poultry manure) which increased soil salinity and exchangeable AI³⁺ was consequently displaced into soil solution.Additions of amendments also increased the Olsen-extractable P levels in the order: poultry
manure> filter cake> household compost> grass residues and their addition also decreased theP adsorption capacity ofsoils. Concentrations of exchangeable Ca, Mg and K, and Na in the case of poultry manure, were increased by additions of organic amendments. In a glasshouse experiment, the four organic residues were applied to soils at a rate equivalent to 20 Mg ha¯¹ with or without the addition of either lime (equivalent to 0, 5 or 10 Mg ha¯¹) or P (equivalent to 0, 10 or 50 kg ha¯¹). Lime applications to the control (unamended) treatment resulted in a marked reduction in exchangeable AI, AIT AIMono and in the proportion of AIT present as AIMono in soil solution. The addition of organic amendments increased soil pH and
reduced AIT and AIMono to low concentrations regardless of whether lime was applied or not. There was no yield response in maize to applied lime in any of the amended treatments. There was a yield increase in response to applied P in the control, household compost and grass residue treatments but none for the filter cake and poultry manure treatments. In agreement with this, Olsen-extractable P values in soils followed the order: poultry manure> filter cake> household compost> grass residues > control. It was concluded that the addition of organic amendments to acid soils is a practicable way of liming them and reducing the potential for Al toxicity and that it can also reduce fertilizer P requirements. This research now needs to be extended into the field situation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.
|
Page generated in 0.0718 seconds