Phosphorus cycles through the environment as it is released from rocks by weathering and erosion. Plants absorb phosphate from the soil and water, and it becomes incorporated into important organic molecules like ATP, DNA, and RNA. Phosphate moves up the food chain as animals consume plants. When organisms die and decay, phosphate is released back into the soil and water to be reused by other organisms, completing the cycle. However, the rate of phosphate release from rocks is very slow, so human use of phosphate fertilizers supplements the natural cycle to meet agricultural needs.