In 1947 an investigation on soil genesis was initiated at Macdonald College with the objective to obtain information on the mechanism of translocation within the profiles of forested podsolic soils of elements such as iron and aluminum.

Numerous investigators have confirmed the early work of H. W. Conn (1889a), (1889b), (1903), and Conn and Esten (1904) in regard to the effects of cold storage upon bacteria in milk. In general, these workers have agreed that 40-50 F (4.4-10 C) is the maximum temperature for the storage of milk; they recognized, however, the fact that bacterial growth does occur not only at refrigeration temperatures but at and near the freezing point.

One of the chief characteristics of podsol soils is the accumulation of organic matter and sesquioxides in the B horizon of these soils. In recent years several workers have studied characteristics of soluble organic matter leaching from the overlying organic layer of these soils and passing downward through the profile. However, it has not been established that these organic materials or any part of these are deposited in the B horizon of podsol soils, or if the organic matter leached from the organic layer in aqueous solution is similar in nature to the organic matter deposited in the B horizon.

Studies on the effects of exogenous hormones have led to the accumulation of a considerable body of information on the reproductive physiology and endocrinology of birds, and of the female domestic fowl in particular. Exogenous estrogens have been shown to produce striking effects in immature pullets, both on the morphology of the secondary sex organs and on the composition of the blood and other tissues. The similarity of these changes to those which occur in the normal pullet at puberty clearly indicate the presence of an endogenous estrogen or estrogens in the bird, and crude extracts of the ovaries of hens have been shown to have estrogenic activity by bioassay in rats.

In 1943 Lochhead and Chase (97) devised a system of nutritional classification of soil microorganism which has since proved to be of considerable value as a method of characterizing the soil microflora and hence of studying changes in the distribution of the nutritional groups of organisms comprising the flora, under different soil conditions. The procedure used by these workers, which was based upon the growth response of individual soil isolates in six nutritional media, proved to be cumbersome in the laboratory, largely because of the necessity of using one hundred or more isolates from each soil sample to obtain statistically valid results.

In the development of economic thought, and particularly since the construction of Quesnay's "Tableau Economic", concern for an understanding of the processes of the economy has exerted a major influence on economic thinking. With advances in technology, expansion of industrialization, accumulation of capital, growth of population and extension of the division of labour, agriculture and the rest of the economy have become increasingly dependent upon one another. [...]

This thesis describes an investigation of the forces causing swelling of Ca-montmorillonite clay in water and salt solutions. Studies on swelling of clay can yield results which are of value to a basic understanding of the behaviour of clay under compression. While the following experiments deal primarily with montmorillonite, most of the concepts will hold for any swelling clay. Good agreement of measured swelling with swelling calculated from osmotic forces of repulsion has been obtained for montmorillonite saturated with monovalent ions, the lack of agreement when the ions are divalent raises interesting questions.

Delicate and perishable small fruits like strawberries and raspberries require extra care in handling, shipping and processing. Berry growers must put their product on the market in good condition, which requires careful handling during picking, storing and subsequent shipping to the market so that the fruits retain freshness and quality. On the other hand, the fruit preservation industries are interested in the quality of their finished product, which is largely dependent upon the quality of the raw berries.

Vermicomposting, the non-thermophilic decomposition of organic wastes by earthworms, is a popular waste management option in the Americas, Europe and the Indian sub-continent. Although the technology is inexpensive and produces an organic fertilizer as well as earthworm biomass, there are few examples of vermicomposting in sub-Saharan Africa. The objective of this thesis was to investigate the potential for vermicomposting in Accra, the capital city of Ghana, by conducting 1) an earthworm survey, 2) vermicomposting trials and 3) assessing farmers' perceptions of vermicompost as an organic fertilizer and other related issues. The earthworm Eudrilus eugeniae (Kinberg), was found in the soil-litter layer at seven locations across Accra. In a 20 d period, the E. eugeniae decomposed 99% of pineapple fibers and 87% of pineapple peels supplied, indicating that this earthworm is capable of vermicomposting. The nutrient value of the vermicompost was low, relative to other organic wastes in West Africa, probably due to the low nutrient content of pineapple wastes. Farmers were aware of the benefits to soil fertility from earthworm activity and associated the presence of earthworm castings with healthy soils. However, those involved in irrigated vegetable farming had insufficient space and time for on-farm vermicomposting and would prefer to purchase this fertilizer. Conversely, subsistence farmers lacked a reliable access to water necessary for on-farm vermicomposting. In summary, farmers were interested in the technology and were willing to adopt it, provided the vermicompost improved crop performance and was affordable and available. / Le vermicompostage est un procédé effectué par les vers de terre qui décomposent la matière organique sous des conditions non thermophile. Cette technique est populaire dans les Amériques, en Europe et aux Indes. Quoique la technique soit économique et produise un engrais organique ainsi que de la biomasse de vers, elle est rarement utilisée dans les régions au Sud du désert Sahara, en Afrique. L'objectif de cette thèse était d'étudier la possibilité d'effectuer du vermicompostage à Accra, la capitale du Ghana. Par ce projet, on a : 1) effectué un relevé des types de vers de terre retrouvés ; 2) réalisé des essais de vermicompostage, et ; 3) consulté les agriculteurs locaux pour savoir s'ils seraient intéressés à faire du vermicompostage et produire un engrais organique. Le vers de terre Eudrilus eugeniae (Kinberg), fut le plus commun, retrouvé à sept endroits dans la région d'Accra, dans la partie arable des sols. Lorsqu'offert des résidus fibreux et des pelures d'ananas, le vers E. eugeniae fut capable de les décomposer à 99% et 87%, respectivement, ce qui démontre que le vermicompostage est réalisable en Afrique. La valeur fertilisante du vermicompost était relativement faible comparativement aux autres résidus organiques disponibles en Afrique de l'Ouest, à cause de la faible teneur minéral des fibres et des pelures d'ananas. Les agriculteurs consultés étaient bien au courant des bénéfices qu'apportent les vers de terre et que leur présence signifie un sol fertile. Les agriculteurs qui cultivaient des légumes et pratiquaient l'irrigation, ne possédaient ni l'espace ni le temps nécessaire au vermicompostage ; ils préféraient acheter leurs engrais. Aussi, les agriculteurs de subsistance et les plus pauvres n'avaient pas suffisamment d'eau pour effectuer le vermicompostage sur leur ferme. Par contre, les agriculteurs étaient intéressés à la technologie du vermicompostage et son utilisation, à conditions d'ob

The wide range of optimal values reported for the physical parameters of compost mixtures suggest that their interactive relationships should be investigated. The objective of this study was to examine the microbial O2 uptake rate (OUR) in 16 sludge waste recipes, offering a range in moisture content (MC), waste/bulking agent (W/BA) ratio and BA particle size. The 3 kg samples were maintained at a constant temperature and aeration rate for 28 days, during which a respirometer recorded O2 uptake in the different sludge recipes to provide a measure of microbial activity and biodegradability. The cumulative O2 consumption after 14 and 28 days was found to be significantly influenced by MC, W/BA ratio, BA particle size and the interaction between MC and W/BA ratio (P<0.05). Using multivariate regression analysis, the experimental data were used to generate a model capable of predicting average expected cumulative O2 consumption after 28 days as a function of the significant physical variables (R2=0.84). The prediction of O2 uptake by the model depended highly on the interaction between MC and W/BA ratio. The evolution of the OUR in the samples was also investigated for any short and long-term associations in O2 uptake measures. The peak OUR recorded in the samples had a significant association with the cumulative O2 consumption after 14 (R2=0.78) and 28 days (R2=0.57). Moreover, combining peak OUR data with cumulative oxygen consumption after 14 days increased the ability of predicting cumulative O2 after 28 days of aeration (R2=0.96), implying that future studies need only run trials up to 14 days to evaluate the overall O2 consumption or biodegradability of a sludge mixt / Selon plusieurs études, les paramètres physiques ont une influence très variable sur la dégradation de la matière organique pendant le compostage, ce qui suggère un certain niveau d'interaction. L'objectif du présent projet était justement de mesurer l'effet interactif sur la décomposition du compost, de l'humidité (H), du ratio massique de boues d'usine d'épuration et d'agent structurant (B/AS), et de la granulométrie (G) de l'agent structurant composé de résidus ligneux de compostage. Seize (16) recettes de compost, de 3 kg et offrant divers taux de H, B/AS et G, furent chacune incubée à 40 °C dans un respiromètre pendant quatre (4) semaines tout en mesurant leur taux d'assimilation d'oxygène. Les résultats de cette étude ont démontré qu'après 14 et 28 jours, l'assimilation totale d'oxygène était influencée de façon significative par H, le ratio B/AS et la G, ainsi que l'interaction entre le H et le ratio B/AS (p<0.05). Les résultats furent analysés par la méthode statistique d'analyse de régression linéaire multiple afin de générer un modèle capable de prédire la consommation cumulative et moyenne d'oxygène après 14 et 28 jours en fonction des paramètres physiques significatifs citées ci-haut (R2=0.84). L'assimilation d'oxygène des mélanges, telle que prédite par le modèle, est grandement influencée par l'interaction entre le H et le ratio B/AS. L'assimilation cumulative d'oxygène des mélanges à 14 jours (R2=0.78) était plus facile à prédire que celle à 28 jours (R2=0.57). Par contre, la prédiction de l'assimilation d'oxygène devient plus précise à 28 jours lorsque les valeurs mesurées à 14 jours sont inclus