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 M15 the M400. Mounting the engine longitudinally (rather than transversely as on the M400) allowed the engine designers to increase the cooling flow to the engine, which allows the twin-turbo Ford Duratec V6 engine to develop . The engine has been designed to meet European emission standards and the new steel/aluminium space frame has been designed with a view to passing crash test regulations around the world. The M15 is planned to be the first Noble which gains European and US type approval. Like all the Noble M models, the M15 has a steel spaceframe and roll cage covered with graphite-reinforced