Christmas tree cultivation and oxygen. Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, chlorine, manganese, molybdenum, iron, and zinc are obtained from the soil. If the necessary elements are not available in the local soil, nutritious fertilizers are used. Other important soil considerations include pH and drainage. Certain types of soil are preferable, depending on the type of tree. Pine trees are usually better adapted to a sandy or sandy loam soil, while white spruce trees and fir trees, such as the Douglas-fir, prefer fine-texture loams and clay loam soils. Some trees grow well in all types of soil, but in any case,
Fraser Filter Fraser Filter A Fraser Filter, named after Douglas Fraser, is typically used in geophysics when displaying VLF data. It is effectively the first derivative of the data. If formula_1 represents the collected data then formula_2 is the average of two values. Consider this value to be plotted between point 1 and point 2 and do the same with points 3 and 4: formula_3 If formula_4 represents the space between each station along the line then formula_5 is the Fraser Filter of those four values. Since formula_6 is constant, it can be ignored and the Fraser Filter considered to be formula_7.