The top surface layer of Earth capable of supporting plant life is called soil. Soil is a complex mixture, comprising of minerals (45%), organic matter (5%), water (25%), air (25%) and living organisms. It is an important resource that determines the diversity of life in an area. Plants are dependent on the soil from whre they obtain various types of minerals, water and air. All these three components are essential for the growth of plants. Animals (herbivores) depend on plants for food. Other animals (carnivores) depend on these herbivores. Hence all living organisms directly or indirectly depend on the soil.
Aquatic organisms are not entirely independent of soil as a resource. Microscopic decomposers (e.g., fungi, archaebacteria and bacteria) present in the bottom sediments of water bodies decompose dead, decaying organic matter into simple, inorganic susbtances (minerals). The later get dissolved in water and are available as nutrients for aquatic plants and then indirectly through plants to animals.
