PO4, or phosphate, is a chemical compound that consists of one phosphorus atom and four oxygen atoms. It is commonly found in nature, particularly in minerals and biological systems. Phosphate plays a crucial role in energy transfer within cells, as it is a key component of ATP (adenosine triphosphate), which is essential for cellular processes. In agriculture, PO4 is important as a nutrient for plants. It is often included in fertilizers to promote healthy growth and development. Phosphate is also significant in environmental contexts, as excessive runoff can lead to eutrophication, causing harmful algal blooms in water bodies.