The wording in the source

Timing

• The soil test you use to calculate a manure application rate for a particular field must be no more than 4 years old on the date that you apply manure to that field.

  IDEM CFO guidance manual, How often do I have to sample soil and manure? (See 327 IAC 19-7-5(c)), p. 25

• A different frequency may be approved in your manure management plan.

  IDEM CFO guidance manual, How often do I have to sample soil and manure?, p. 25

Area per sample

• The CFO rules specify that a soil test must be obtained that provides sufficient information about soil fertility to allow for nutrient recommendations for existing or planned crops and soil tests may not represent more than 20 acres per sample.

  IDEM CFO guidance manual, Soil Testing Topics, Can I composite soil samples… (See 327 IAC 19-7-5(c)), p. 26

Method

• Yes, you can use composite sampling techniques and average test results within areas of up to 20 acres.

  IDEM CFO guidance manual, Soil Testing Topics, p. 26

• The CFO rules require your soil testing procedures to be specified in your manure management plan.

  IDEM CFO guidance manual, Soil Testing Topics, p. 26

• Although not required, using a grid to determine the locations where you will take samples is a good practice

  IDEM CFO guidance manual, Can I use grid sampling techniques…?, p. 27

Cores

• For example, you can take multiple plugs or grab samples across a 20 acre area (12-15 samples is recommended), mix the samples in a container, and take one composite sample from the container to send to the lab.

  IDEM CFO guidance manual, Soil Testing Topics, p. 26

Who it applies to

• In Indiana, an animal feeding operation with at least 300 cattle, 600 swine or sheep, 30,000 poultry, or 500 horses in confinement is a confined feeding operation (CFO).

  IDEM CFO guidance manual, Who is subject to the Confined Feeding Regulations? (See IC 13-18-10-1)

• You need soil and manure nutrient information to determine the nitrogen and phosphorus application rates for every land application event

  IDEM CFO guidance manual, Other Topics (See 327 IAC 19-14-3(c)), p. 28

Laboratory and analysis

• phosphorus is the only element required in a soil test to comply with the CFO rules.

  IDEM CFO guidance manual, What specific elements must soil be tested for? (See 327 IAC 19-7-5(c) and 327 IAC 19-14-3), p. 26

• The soil phosphorus Bray P1/Mehlich 3 test must be used and soil phosphorus levels reported in parts per million (ppm).

  IDEM CFO guidance manual, What specific elements must soil be tested for?, p. 26

The wording in the source

Timing

• In most soils, try to sample fields once every four years.

  AY-368-W, Sample timing, p. 6

• In these circumstances, soil fertility can change rapidly and these fields should be sampled once every two years.

  AY-368-W, Sample timing (sandy or highly managed soils), p. 6

• The most convenient time to collect soil samples is when there is no standing crop in the field (i.e. in the spring prior to planting or in the fall after harvest).

  AY-368-W, Sample timing, p. 6

• Schedule soil sampling and testing prior to application of fertilizers or lime

  AY-368-W, Sample timing, p. 6

• Keep sample collection timing consistent to avoid year-to-year variability.

  AY-368-W, Sample timing, p. 6

Area per sample

• Collect at least one composite per 20 acres.

  AY-368-W, Soil sampling for whole-field management, p. 4

• Typical grid sizes range from 1 to 5 acres, with smaller grids (i.e., 2.5 acres or less) providing the best results.

  AY-368-W, Grid sampling, p. 5

• In most cases, zones are between 2 and 10 acres in size.

  AY-368-W, Zone-based sampling, p. 5

Method

• collect composite samples in a zig-zag pattern (Fig. 3).

  AY-368-W, Soil sampling for whole-field management, p. 4

• While grid sampling is preferred to whole-field sampling, it is inferior to the more informative zone-based sampling.

  AY-368-W, Grid sampling, p. 6

Depth

• 0-8 inches for pH/liming recommendations

  AY-368-W, Table 1, conventional tillage

• 0-4 inches for pH/liming

  AY-368-W, Table 1, conservation tillage (take separate samples)

• 0-8 inches for fertility analysis

  AY-368-W, Table 1, conservation tillage

Cores

• Typically, a composite sample should be comprised of between 10 and 20 subsamples.

  AY-368-W, Sample collection, step 6, p. 2

• As a rule of thumb, collect two subsamples per acre in a zone. Regardless of zone size, a minimum of five subsamples per zone should be collected.

  AY-368-W, Zone-based sampling, p. 5

• For a one-acre grid cell, collect at least five subsamples. For grid cells between 2.5 and 5 acres, collect between 8 and 10 subsamples.

  AY-368-W, Grid sampling, p. 5

Laboratory and analysis

• For this reason, it is often desirable to use the same soil-testing laboratory every year.

  AY-368-W, Soil testing laboratories, p. 3

• This will ensure that any observed change in soil-test results from year to year are attributable to true changes in soil fertility status and not due to deviations in testing practices between different laboratories.

  AY-368-W, Soil testing laboratories, p. 3

Field identifiers

• Names should contain identifiers to the field and sample number.

  AY-368-W, Sample collection, step 8, p. 3

• it is especially important that samples be labeled with the correct zone and that the location of each sample or zone is recorded.

  AY-368-W, Zone-based sampling, p. 5