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:
|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|
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.