How many soil samples should be collected for one composite sample?

How many soil samples should be collected for one composite sample?

• A. one to two
• B. eleven to twenty
• C. four to six
• D. three to ten

Answer: (D)

Composite sampling relies on gathering several soil subsamples from a defined area and mixing them to form one representative sample. By collecting multiple subsamples, you capture variations in lead concentration that occur across the area and reduce the influence of unusual spots. For one composite soil sample, collect three to ten subsamples and mix them together in equal portions before sending to the lab. This range balances getting a representative picture of the area with practical work and cost. Make sure the subsamples come from the same depth (typically the top 6 inches), from the area of interest, and are thoroughly mixed and properly labeled to reflect the composite. Collecting fewer than three can miss variability, while more than ten adds effort without a proportional gain in representativeness for most sites.

Composite sampling relies on gathering several soil subsamples from a defined area and mixing them to form one representative sample. By collecting multiple subsamples, you capture variations in lead concentration that occur across the area and reduce the influence of unusual spots. For one composite soil sample, collect three to ten subsamples and mix them together in equal portions before sending to the lab. This range balances getting a representative picture of the area with practical work and cost. Make sure the subsamples come from the same depth (typically the top 6 inches), from the area of interest, and are thoroughly mixed and properly labeled to reflect the composite. Collecting fewer than three can miss variability, while more than ten adds effort without a proportional gain in representativeness for most sites.