How many subsamples should a soil composite have?

• A. 2-4 subsamples
• B. 5-15 subsamples
• C. 16-25 subsamples
• D. 30-40 subsamples

Answer: (B)

The key idea is that a soil composite should reflect variability across the testing area by mixing multiple subsamples from different spots. Using about five to fifteen subsamples provides enough geographic coverage to capture differences in lead concentration without washing out hotspots or making the process unnecessarily costly. If you gather too few subsamples, you risk missing areas with higher lead. If you gather too many, you may over-represent the area and dilute localized high readings, plus increase effort and cost. Therefore, five to fifteen subsamples is the recommended range for a soil composite.