The wording in the source

Timing

• Frequency of testing: Test soil at least once every two to three years or once per complete crop rotation.

  P3934, Soil Sampling Procedure, item 1, p. 2

• Take soil samples at the same time each year, maintaining a consistent depth of 0 to 6 inches using a soil probe or auger (see Figure 1).

  P3934, Soil Sampling Procedure, item 2, p. 2

Area per sample

• Zone sampling: Take one composite sample for every 10 acres.

  P3934, Sampling density, p. 2

• Grid sampling: Take one composite sample for every 2.5 acres. A smaller grid is better than a large grid. For new fields without prior soil testing information, it is advisable to start with a smaller grid (1 acre).

  P3934, Sampling density, p. 2

Method

• Collect subsamples in a zigzag pattern within each zone or grid.

  P3934, Soil Sampling Procedure, p. 2

• In furrow irrigation systems, sample from the top of the bed, 4 to 6 inches away from the crop row.

  P3934, Preparation for sampling, p. 2

Depth

• Take soil samples at the same time each year, maintaining a consistent depth of 0 to 6 inches using a soil probe or auger (see Figure 1).

  P3934, Soil Sampling Procedure, item 2, p. 2

Cores

• Each composite sample should include 12 to 15 subsamples (one to two per acre for zone sampling and five to six per acre for grid sampling).

  P3934, Subsample collection, p. 2

• More subsamples are required for fields with past fertilizer banding or manure spreading.

  P3934, Soil Sampling Procedure, p. 2

Laboratory and analysis

• Test soil samples in a certified soil lab, such as the LSU AgCenter Soil Testing and Plant Analysis Lab in Baton Rouge.

  P3934, Soil Testing, item 1, p. 3

• In Louisiana, fertilizer recommendations are based on the Mehlich-3 soil extraction method for samples collected from a 0- to 6-inch depth.

  P3934, Soil Testing, item 1, p. 3

• Analyze soil samples in the same lab each year to maintain a consistent historic record.

  P3934, Soil Testing, item 2, p. 3

Field identifiers

• Clearly label the bag with the farm name and location, sampling date and depth, previous crop and the expected crop to be grown.

  P3934, Sample handling, p. 2