The wording in the source

Timing

• Most fields should be retested at least every 4 years to monitor soil fertility levels of immobile nutrients and pH

  A2100 p. 4, How often to sample

• Exceptions include sands and loamy sands, which should be tested every 2 years.

  A2100 p. 4, How often to sample

• Take soil samples at any convenient time.

  A2100 p. 3, When to take soil samples

• To receive your recommendations early enough to enable you to apply the lime and fertilizer needed, it may be best to sample in the fall.

  A2100 p. 3, When to take soil samples

• Hayfields can be sampled after any cutting. Regardless of when you sample, it is best to be consistent from one year to the next.

  A2100 p. 3

Area per sample

• For responsive fields, as well as all fields that have not been sampled in the past 4 years, take one composite sample for every 5 acres.

  A2100 p. 3, step 3

• Table 1. Recommended sample intensity for uniform fields: fields tested more than 4 years ago OR fields testing in the responsive range, all fields, 1 sample/5 acres; nonresponsive fields tested within past 4 years, 5–10 acres 2, 11–25 acres 3, 26–40 acres 4, 41–60 acres 5, 61–80 acres 6, 81–100 acres 7

  A2100 p. 1, Table 1 (transcribed)

Method

• use a W-shaped sampling pattern (as shown in Figure 1) over the whole area the sample represents.

  A2100 p. 1

• Where there is no information about the P or K status of the field or where previous tests were in the responsive range, a 200-foot grid size should be used. This is equivalent to approximately one soil sample per acre.

  A2100 p. 2, site-specific management

• Fields that have soil test P and K levels in the nonresponsive categories should be grid-point sampled on a 300-foot grid. This is equivalent to one soil sample for every 2 to 2.5 acres.

  A2100 p. 2

• Smart (zone or directed) sampling. Another approach gaining support among researchers is smart sampling, also known as directed or management zone sampling.

  A2100 p. 3

Depth

• Insert the probe or auger into the soil to plow depth or at least 6 inches.

  A2100 p. 3, step 2

• Chisel plowing and offset disking. Take soil samples to ¾ of the tillage depth.

  A2100 p. 4, Tillage system considerations

• Sample ridges to a 6-inch depth and furrows (between rows) to a depth of 4 inches.

  A2100 p. 4, Till-plant and ridge tillage

• For fertilizer recommendations, take a separate sample to a depth of 6 to 7 inches.

  A2100 p. 4, No-till

• If an acid layer is suspected, take a separate sample to a depth of only 2 inches.

  A2100 p. 4, No-till

Cores

• Each sample should be made up of a minimum of 10 cores to ensure accurate representation of the nutrient needs of the field.

  A2100 p. 1

• Research has shown that taking 10 to 20 cores provides a more representative sample of the area than when samples are made up of fewer cores.

  A2100 p. 1

Laboratory and analysis

• These provisions currently include: following the soil sampling techniques outlined above, soil testing by a Wisconsin certified laboratory

  A2100 p. 3, How to take soil samples (590 standard)