A good soil sample accurately represents the area from which it's taken, ensuring reliable soil test results and informed nutrient management decisions.
To obtain a good soil sample, consider the following:
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Representative Area: The area the sample represents should be relatively uniform and manageable. As a guide, aim for individual sample areas that are at least 50 feet in diameter. Separate areas based on differences in soil type, topography, past management practices, or obvious variations in plant growth.
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Number of Cores/Borings: Take multiple cores or borings within the defined area to create a composite sample. This helps average out minor variations within the field. Use equal diameter cores or borings to ensure that each subsample contributes equally to the final, composite sample.
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Sampling Depth: Collect all cores/borings to the same depth. A consistent depth is crucial because nutrient concentrations can vary significantly with depth. Generally, recommendations for phosphorus (P), potassium (K), and zinc (Zn) are based on soil samples collected from a 6-inch depth. Adjust sampling depth according to the specific nutrients and recommendations relevant to your region and crop.
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Proper Mixing: Thoroughly mix all the cores/borings collected from a specific area into a single composite sample. This ensures that the small amount of soil sent to the lab is representative of the entire field area.
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Sample Size: Ensure the final composite sample is of adequate size, typically at least one pint, as required by the testing laboratory.
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Proper Handling and Storage: Store the sample in a clean container or bag and label it clearly. Prevent contamination and avoid excessive heat or moisture, which can alter nutrient levels.
In summary, a good soil sample is collected from a uniform area of at least 50 feet in diameter, consists of multiple cores taken to a consistent 6-inch depth, is thoroughly mixed, and is properly handled and stored to maintain its integrity until it reaches the testing lab. This comprehensive approach ensures that the soil test results are accurate and useful for making informed nutrient management decisions.
