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United States Department of Agriculture
Natural Resources Conservation Service
9173 W. Barnes Dr., Suite C
Boise, Idaho 83709
 
For More Information:
Contact:  Jody Fagan, 208.685.6978

Taking Accurate Soil Samples Fact Sheet

Nutrient and Pest Management

Water Quality Begins with Soil Testing
Soil Tests from Approved Labs can Save Ag Producers Money

March 2, 2006, Boise, ID—When landowners apply fertilizer to their land without a soil test, there is an increased risk of over-application. The extra nutrients can then seep into our streams and groundwater and, eventually our drinking water.

To date, 24 aquifers in Idaho are nitrate impaired and over 2,000 miles of streams are impacted by nitrogen and phosphorus, causing algae growth and reduced aquatic habitat. According to recent State of Idaho Department of Environmental Quality studies, much of this impairment is caused by agricultural and urban pollution.

“Urban homeowners need to be as responsible as their larger country neighbors in applying less fertilizers and pesticides to their pastures and lawns,” says Dr. Dick Johnson, nutrient management specialist with the USDA Natural Resources Conservation Service (NRCS) in Boise. “Meanwhile, on our cropland, we’ve often over-applied fertilizers and then over-irrigated, washing the nutrients through the soil profile.”

Agricultural producers who soil test with approved labs can apply the precise amount of nutrients needed by the crop and, most likely, save money. Chances are producers will find they can apply less fertilizer and decrease their crop production costs.

 “A good comprehensive nutrient management plan that includes soil testing is just good business for agricultural producers,” Johnson says. “The time and care taken in proper soil sampling is one of the best investments growers can make in the production of their crops.”

An accurate soil test begins with taking a representative sample of each field. This includes mapping out areas of like soils or production levels and then taking a minimum of ten sub-samples at both 0-12 inch and 12-24 inch depths for each mapped area. The samples for each area are then mixed together and placed into a plastic soil sampling bag for transport to the laboratory.

Producers are then encouraged to take their soil sample to a laboratory participating in the North American Proficiency Testing—Performance Assessment Program (NAPT-PAP). This program, administered by the Soil Science Society of America, randomly checks laboratories to ensure their soil analyses are reliable. The NAPT-PAP approves laboratories meeting their standards and places them on their website at www.naptprogram.org/pap/.

“Without a good soil sample and a reliable laboratory analysis, a good fertilizer recommendation cannot be made,” Johnson says. “Plus, producers receiving USDA conservation funds are required to soil test using an approved lab.”

For more information or to find the nearest approved soils lab, landowners can visit the NAPT-PAP website or contact their local NRCS Service Center.

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