Christmas tree cultivation has shifted toward the production of higher-quality trees, increasing land quality expectations as well. Indeed, some species of tree, such as the Fraser fir, are unable to grow on low-quality, marginal farmland. Flat or gently rolling land is preferred to that with steep slopes and inclines, which is prone to erosion and fluctuations in fertility. Noticeable obstructions, such as rocks, fences or significant underbrush, are also undesirable. Like all crops and plants, Christmas trees require a specific set of nutrients to thrive. There are 16 elements crucial for growth; of those, three are obtained through air and water: hydrogen, carbon,
Noble metal Noble metal In chemistry, the noble metals are metals that are resistant to corrosion and oxidation in moist air (unlike most base metals). The short list of chemically noble metals (those elements upon which almost all chemists agree) comprises ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au). More inclusive lists include one or more of mercury (Hg), rhenium (Re) and copper (Cu) as noble metals. On the other hand, titanium (Ti), niobium (Nb), and tantalum (Ta) are not included as noble metals although they are very resistant to corrosion. While the