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The appearance of synthetic fertilizers on the market has increased the interest in the so-called "minor elements". Much work with water and sand cultures has proven the necessity of these elements for successful plant growth. However, the need for these elements in crop production on field soils has not been studied intensively, nor have we sufficient knowledge as to the effect of our changing fertilizer practices on the necessity for minor elements. A number of field studies to determine the necessity of boron, manganese, zinc, copper and ether minor elements, when applied singly or in combinations of two or more, have given phenomenal increases in yields under certain plant and soil conditions. Under other conditions there has been no response from their use when applied to the soil either singly or in combinations of two or more elements. It is the purpose of this study to determine under what soil conditions the need of minor elements becomes a part of our soil management problem and what part natural Chilean nitrate of soda plays in preventing and correcting this condition. Also this investigation was developed to give a comparison of yield and growth of various crops grown intensively on a number of soil types where fertilized with purified carriers of nitrogen, phosphorus and potassium and where these elements were supplied from commonly used commercial carriers. Another purpose of this study was to determine how long these soils could be cropped before minor elements would become a limiting factor in crop production as shown by yields and deficiency symptoms. / Master of Science

published_or_final_version / Botany / Master / Master of Philosophy

The emission of trace metals (TMs) into boreal forest regions of the northern hemisphere is an important environmental issue due to their potential detrimental impacts on these sensitive ecosystems. One of the foremost factors controlling metal cycling is the chemistry of the overlying organic forest floor of the forest soil. In this thesis we examine the chemistry of forest floor horizons of podzolic soils. Our goal is to improve our ability to predict the partitioning of metals between the soil solid and solution phases. / We developed a standard protocol to produce solutions that resemble lysimeter solutions from podzolic soils using air-dried samples. We hypothesized that the stabilization point of the electrical conductivity (EC) of the soil solution is indicative of the point in which soluble salts and organic material precipitated during sampling and storage are removed from the soil particle surfaces. Solutions produced by leaching the soils, once the EC of wash solutions had stabilized, were comparable to lysimeter solutions from the area where samples were collected with respect to the concentrations of divalent cations, pH, EC and dissolved organic carbon (DOC). The applicability of this procedure to trace metal partitioning in forest floors was explored. Laboratory extractions produced partition coefficients (log Kd) similar to observed lysimeter solutions ranging from 3.4 to 3.9 for Cd, 3.4 to 3.9 for Cu, 3.4 to 4.1 for Ni, 4.1 to 5.2 for Pb and 3.2 to 3.5 for Zn. According to a semi-mechanistic regression model based on observed lysimeter concentrations, the metal concentrations in solution were appropriate relative to known factors that influence metal partitioning in soils: pH, the concentrations of total metals and DOC. / While chemical characteristics of soils have been consistently observed to play important roles in the partitioning and toxicity of metals we wished to place the importance of the chemical characteristics of soil on mobility and toxicity in context. We interpreted field data that had been collected from transects established with distance from two point source emitters in Rouyn PQ, and Sudbury ON. Canada find developed equations that predict dissolved metal concentrations from total metal concentrations, soil pH, soil organic matter (SOM), and DOC contents. We integrated these equations into a simple box model that calculates changes in the concentration of metals in the organic and upper mineral horizons and includes a loop for vegetative return of metals to the forest floor.

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