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,
Knagenhjelm (noble family) Manor ("Kaupanger Hovedgård") in Sogn og Fjordane and are included in the Yearbook of the Danish Nobility ("Danmarks Adels Aarbog"). Before he became noble, Niels Tygesen Knag had only a tree trunk as his arms (Hans Krag. 1942). The coat of arms was received upon the ennoblement in 1721. Description without the heraldic terminology: "On a blue shield a tilted, chopped and knotty silver tree trunk beside or above which there are three golden stars in each of two bends. On the helmet is a six-pointed star between two buffalo horns divided in gold and blue, vice versa, respectively." Some