General Sampling Guidelines: |
It is imperative when doing any type of sampling to use clean tools. Pesticide or fertilizer residues on the sampling device, as well as the container used for mixing cores will create misleading results. A composite of 15 to 20 cores are usually required from each area or field where the soil type and topography is fairly uniform and where the field has been uniformly managed with regard to the crop grown or fertilizer applied. Differences in soil color reflect differences in texture, organic matter content or possible erosion. Limit the maximum area sampled to no more than 20 acres. Collect the samples by making a random zig-zag pattern over the entire field. Mix the cores thoroughly and then submit about a pint volume of soil from the mixture to the lab.
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Sampling Depth and Pattern: |
The soil should be sampled to the plow depth before establishment (6 or 8 inches, depending on the state) and to a depth of 3 to 4 inches after establishment of permanent pastures. This is helpful in monitoring surface soil acidification and nutrient depletion. Periodic deeper sampling to the root depth will help monitor subsoil levels of the more mobile nutrients such as potassium and prevent over-fertilization. Avoid areas of livestock (nutrient) concentration such as near watering areas and shady spots.
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Time of Sampling: |
Fields with cool season perennials should be sampled in summer or winter. Fields with warm season perennials should be sampled in winter. Fields for growing hay crops should be sampled every year and grazed pasture fields should be sampled every three years. The intensity of land use will dictate the sampling schedule. Sample the soil several months before establishing perennial pastures to allow ample time for the lime to react with the soil if the soil test report indicates that lime is required. It is important that recommended amounts of lime and phosphorus be incorporated in the soil before establishment. Lime and phosphorus are immobile in the soil and mixing within the top layer will insure better distribution in the root zone and access for plant roots.
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