When collecting soil samples to accurately represent a field, it is important to determine how many soil cores should be collected. The number of cores depends on factors such as soil variability, the depth of the sample, and the specific tests being conducted. Numerous studies have been conducted to determine the optimal number of soil cores for a representative sample.
Soil composition can vary greatly, even within small areas, meaning that taking too few samples may lead to inaccurate readings. For whole-field sampling, based on statistical precision, taking 15-20 cores per field can predict the true field mean within ±10% accuracy 47% to 77% of the time, depending on the field’s variability. Ideally, a sample should not represent more than approximately 10 acres, unless available information suggests that larger field areas have little variation in soil type or yield potential. Cores should be taken from a combination of locations—within the row, between the rows, and mid-way between the rows when sampling row crops.
If using a zone management sampling method, it is important to follow the procedure of taking at least one core for every 5 acres. Collecting 8-12 cores per zone is common practice to produce a representative sample.
Using GPS technology in soil sampling has now become standard practice, as it ensures accuracy and consistency. Sampling the same locations properly provides accurate data for better decision-making, which ultimately reduces over- and under-application, saves costs, and makes crop production more economically efficient and profitable.
Our agronomy team is busy this time of year performing whole-field and zone management sampling across the Canadian Prairies. Their knowledge of local agricultural practices and extensive experience make them unique specialists, helping farmers achieve their goals in the most effective way possible.