Presented as thesis (Ph. D.)--University of Wisconsin--Madison, 1920. / Added collective title page. Part I. reprinted from Soil science, vol. IX, no. 4 (April 1920), p. 235-251 ; Part II. reprinted from Soil science, vol. XII, no. 1 (July 1921), p. 21-41. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [83]-86).

Thesis (M.S.)--Florida State University, 1985. / Typescript. Includes bibliographical references (leaves 134-139).

No description available.

Master of Science

Phosphate is one of the essential minerals for all living organisms. It has to be supplied to the soil in order for plant growth. In Turkey, most of the soils lack phosphate mineral. Although this can be overcome by the use of phosphate fertilizers, in Turkey there are no phosphate mines being utilized / and this brings about the need to import phosphate rock and phosphate fertilizers. The estimated phosphate rock reserve of Turkey is around 300 million tons, but it cannot be utilized since no economical method of upgrading has been proved to work yet. The aim of this study has been two-fold / to determine the effects of several parameters on the cell flotation of Mardin-Mazidagi phosphate rock and to increase the grade of the product above 30% P2O5 content with a reasonable recovery rate, so that it could be used commercially. Phosphate rock upgrading was made by using flotation in a cell. There are many factors affecting the recovery and grade of the product such as, particle size, pulp pH, collector volume, acid and collector conditioning times and temperature. Phosphate rock samples used contained 14% P2O5, 43% CaCO3 and 1% SiO2 with a CaO/P2O5 ratio of 3.1. Due to the low silica content, one-stage flotation was made. In the experiments, effects of the important parameters were tested at constant pulp density (10% solids by weight). Particle sizes were between 53 m and 150 m, while the pH values were kept between 5,0 - 6,5 using amounts of acid within the range of 6 - 19 kg H3PO4/ton of rock. The collector (mixture of kerosene and oleic acid in 1:3 volumetric ratio) was used in the range of 0,6 ml (0,96 kg collector/ton rock) and 5,4 ml (8,64 kg collector/ton rock). Acid and collector conditioning times were changed between 10-110 s and 10-80 s, respectively. The temperature range was between 15-35 &deg / C. At the end of the parametric studies a grade of 36% P2O5 with a recovery of 93% could be obtained.

Today's modern agriculture is totally dependent on phosphorus to sustain their large yields. Several studies have recently expressed a concern for a future phosphorus deficiency. These studies are based on data for estimated reserves which have been increased with more than a fourfold since 2010. Some argue that these concerns are unfounded, despite the fact that only Morocco account for the bulk of these new reserves. This report provides new forecast for the world phosphorus production based on the new available reserve data. These forecasts are using bell shaped curve models to examine how individual countries' future production of phosphate rock affects a global production peak. Estimates of the size of several reserves are highly uncertain and it is therefore difficult to make an accurate forecast of future phosphorus extraction. Despite this uncertainty, a global production peak is likely to occur within this century. The global production will depend largely on China and Morocco's production as they hold a large share of the reserves and the current production. China's production will probably peak in 10-20 years at current production trend. It is uncertain if Morocco can increase production enough to replace China's production in the future. It is not likely that Morocco will be able to produce as much as would be required to meet the highest scenarios. This is mainly due to a number of bottlenecks in production such as water scarcity, increasing proportion of impurities and a decreasing concentration of phosphorus in the phosphate rock.

No description available.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1974. / Bibliography: leaves 155-164. / viii, 164 leaves ill., map

Thesis (M. Sc. Agriculture (Soil Science)) -- University of Limpopo, 2016 / This study aimed at assess phosphorus (P) solubility and bioavailability from non-reactive Phalaborwa ground phosphate rock (GPR) using thermophilic co-composting technology. Two types of organic wastes (Cattle, CM and poultry manure, PM) were used to produce different mix ratios (5:5, 7:3, 8:2 and 9:1) of phospho-composts. Control compost of both manures without GPR addition were included. Samples of each compost heap were taken at mesophilic, thermophilic, cooling and maturity stages and used for bioquality and chemical tests. Microbial counts, enzyme activity, molecular analysis, and the quatification of different P forms and fractions were carried out on all compost samples. Results showed that the concentration of P measured in the different phospho-composts differed significantly (p < 0.05). The 8:2 mix ratio gave quantitatively higher P concentration in both CM- and PM-based phospho-composts. Organic P form had the lowest concentration when compared to other P forms and fractions while water soluble-P had the highest concentration as compared to other P fractions. The content of actinomycetes showed correlated positively with EC, phosphatase β-glucosidase, fungi and bacteria but negatively correlated with organic P, Ca-P water P and pH. There was a positive and significant correlation between electrical conductivity, enzyme activity (phosphatase, dehydrogenase and β-glucosidase), fungi, actinomycete and P fractions (Bray P1, Ca-P and Pi value). Acid phosphatase activity correlated negatively with water extractable P, organic P and Ca-P contents but revealed a positively significant correlation with bacteria, fungi and actinomycete counts. Generally higher microbial counts were measured in CM- than PM-based phospho-composts but the concentrations varied with each microbial species. Highest fungi (7.27 CFU g-1) and actinomycete (6.83 CFU g-1) counts were generally recorded in the control composts, which was quantitatively higher in CM- than PM-based phospho-composts. Quantitatively higher enzyme activities were measured across compost types and mix ratios during the cooling phase phospho-compost production; but were statistically comparable to measured values at maturity phase. Acid phosphatase and β-glucosidase enzymes were predominately higher at maturity phase in all cattle manure-based phospho-compost excluding the 5:5 mix ratio. In PM-based phospho-compost, both β-glucosidase and phosphatase were higher at initial phase with PM5:5 , PM9:1 and PM10:0. Dehydrogenase activities were predominately higher at thermophilic and cooling phase from both PM- and CM-based phospho-compost. Results of molecular analysis revealed that Bacillus sp. and Acholeplasma cavigenitalium sp. were dorminant in PM-based phospho-composts while Pseudomonas sp. and Acholeplasma pleciae dorminated the CM-based phospho-composts. In conclusion, results of this study revealed that the type of manure used exerts great influence on the bioquality parameters and the amount of P released. Key words: Phospho-compost, Compost quality, Enzyme activities, Nutrient cycling, Ground phosphate rock, Phosphorus forms and fractions