Plants need nutrients in the soil to grow. But where do these nutrients come from? They are what is left of Mother Nature's recycling program. When plants and animals in the forest die and fall to the ground, fungi and bacteria begin to decompose them. This process can take along time, but what is left once the recycling clue has finished is new soil, full of the nutrients that once composed the no longer living plant or animal, and ready to nourish a new generation.