Soil has empty spaces between them called pores. These pores contain air, which is very important for plant's life. They are composed of oxygen, carbon dioxide and nitrogen that plants absorb through their roots.
Water acts as a carrier of mineral elements and oxygen for the proper growth of plants. Water from the soil enters the plant through tiny root hairs. Along water, plants get their required minerals.
Humus consists of decaying plant and animal remains. It performs various important functions for the growth of plants. It absorbs and holds water and contains rich nutrients that are essential for plant's growth.