Why do plants need soil?

            Like any living organism, plants need, besides air and sunlight, water and nutrients for growth and survival which they take up through their roots. For land plants, the soil provides the moisture and nutrients. The soil also protects the roots from rapid fluctuations in temperature, as just below the surface the temperature scarcely changes from day to night. But more importantly, soil provides the firm support which holds the plants on the ground. Some plants, like the water hyacinth which grow in water, and orchids which grow on trees do not need soil to grow on as they can get their nutrients from water or the host                                                                                              plant.