Certified Crop Advisor Practice Exam

Which of the following is an organic source of phosphorus?

1. Bone meal

2. Rock phosphate

3. Ammonium phosphate

4. Superphosphate

The correct answer is: Bone meal

Bone meal is recognized as an organic source of phosphorus because it is made from the grinding of animal bones, which naturally contain organic matter along with essential nutrients like phosphorus and calcium. Its organic origin means that it can contribute to soil fertility and support plant growth by releasing nutrients over time as it breaks down, making it a suitable amendment in organic agricultural systems. In contrast, rock phosphate, while a natural mineral source of phosphorus, is not considered organic because it has not undergone any biological processes. Ammonium phosphate and superphosphate are both synthetic fertilizers derived from chemical processes, which also disqualify them from being classified as organic sources. Hence, among the given options, bone meal stands out as the only organic source of phosphorus.