Wisconsin Soil Test Summary Data


Annual soil test summary data by county are available from 1995 through 2009. Soil test summary data are provided by Wisconsin DATCP certified labs. This soil test summary represents soil samples submitted to all WIDATCP certified labs for routine farm soil analysis only; lawn and garden samples are not included.

Soil test values are dependent upon the method use to analyze the parameter. Table 1 provides a list of the official soil testing methods used in Wisconsin from 1974 to present.

It should be noted that the number of soil samples submitted in any one year varies. The frequency of sampling of any given field may vary (eg. sampled every year or sampled once every four years) and the number of samples submitted for any given field may vary over time.

Historical soil test summary data by county is available from 1974 through 2009. Historical data is summarized only on a five-year basis. Please do not ask for annual summary data prior to 1995; earlier data is not archived in a manner to facilitate web viewing at this time.

Table 1. The official soil testing methods used in Wisconsin are as follows:

Parameter Year Method
Phosphorus 1974 – present Extract with Bray-1, measure with spectrophotometer
Potassium 1974 – present Extract with Bray-1, ICP, atomic absorption or flame photometer
pH 1974 – January 2007 Prepare a 1:1.3 soil:water mixture and measure pH with a glass electrode
February 2007 – present Prepare a 1:1 soil:water mixture and measure pH with a glass electrode
Buffer pH 1974 – January 2007 Prepare a 1:1.3:2 soil:water:SMP buffer mixture and measure pH with a glass electrode
February 2007 – present Prepare a 1:1:1 soil:water:Sikora buffer mixture and measure pH with a glass electrode
Organic matter 1974 – February 1990 Digest with chromic acid
March 1990 – present Loss of weight on ignition at 360°C for 2 hours
Calcium/Magnesium 1974 – present Extract with 1 N ammonium acetate and measure by ICP or atomic absorption
Sulfur 1974 – present Extract with 500 ppm P in acetic acid, develop turbidity, and measure with a photoelectric nephelometer
Boron 1974 – present Extract with hot water, develop color, and measure with a spectrophotometer
Manganese 1974 – present Extract with 0.1 N phosphoric acid and measure by ICP or atomic absorption
Zinc 1974 – present Extract with 0.1 N hydrochloric acid and measure by ICP or atomic absorption

Query the annual soil test summary database.

Query the historical five-year soil test summary database.

Statewide five-year summary maps for the periods of 1995-1999, 2000-2004 and 2005-2009 are still available.

The USDA also has Agricultural Census Information available for 2007.

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