What is the recommended number of cores to collect per sample area?

• A. 10-15 cores, increasing to 20-25 in fields with a history of banded fertilizer applications.
• B. 3-5 cores.
• C. 25-35 cores.
• D. 1-2 cores.

Answer: (A)

Representativeness in soil sampling comes from collecting enough cores across the sample area to capture how nutrient levels vary within the field. Ten to fifteen cores give enough data points to form a reliable composite sample for most fields. If the field has a history of banded fertilizer applications, nutrients are more localized, so increasing the number of cores to twenty to twenty-five helps include those patches in the sample and yields a more accurate overall reading. Taking too few cores risks sampling bias from high or low spots, which can lead to misleading fertilizer recommendations. When collecting, spread the cores across the area in a systematic pattern, mix them thoroughly to create one composite sample, and submit that to the lab.