Construction requires both study and observation, and the process varies in different parts of the world. Landscaping varies according to different regions. Therefore, normally local natural experts are recommended if it is done for the first time. Understanding the site is one of the chief essentials for successful landscaping. Different natural features and phenomena, like the position of the Sun, terrain, topography, soil qualities, prevailing winds, depth of the frost line, and the system of native flora and fauna must be taken into account. Sometimes the land is not fit for landscaping. In order to landscape it, the land must be reshaped to direct water for appropriate drainage. This reshaping of land is called grading. Sometimes in large landscaping projects, for example, parks, sports fields, and reserves soil may need to be improved by adding nutrients for the growth of plants or turf, this process is called soil amelioration.