Chicken manure does not have a specific chemical formula because its composition varies depending on several factors such as the diet of the chicken, housing conditions, and how the manure is handled and stored. However, it can be characterized by its main components:

1. Nitrogen (N): Chicken manure is a good source of nitrogen, which is an essential nutrient for plant growth. The nitrogen content in chicken manure can range from 1% to 4%.

2. Phosphorus (P): Chicken manure also contains phosphorus, another important nutrient for plants. The phosphorus content typically ranges from 0.5% to 2%.

3. Potassium (K): Potassium is another essential nutrient found in chicken manure. Its concentration can vary from 0.5% to 1.5%.

4. Water: Chicken manure also contains a significant amount of water, typically around 75% to 85%.

5. Organic matter: The remaining portion of chicken manure is composed of organic matter, which includes bedding material, undigested food, and microbial biomass.

6. Trace Elements: Chicken manure may contain trace elements such as calcium, magnesium, sulfur, and zinc, but the concentrations of these elements vary.

Due to the inherent variability in composition, it's essential to analyze the specific batch of chicken manure you're using to get accurate information on its chemical content.