Since 1974, the University of Wisconsin has summarized USDA-Farm Service Agency (FSA) approved lab data from over 3 million samples.
	The average soil test P level 25 years ago was 38 PPM, 50 PPM in 1990-1994, and 52 PPM in 1995-1999.  Since 1990, excess phosphorus applications have been reduced to where 26 of 72 counties had either no increase or showed decreases up to 7 PPM in soil test P.  In most Wisconsin soils 8 pounds of phosphorus would need to be removed by the crop to lower soil test P levels by 1 PPM.
	Using the 650,000 soil samples tested in the last 4 years, we can determine that 72% (6.5 million acres) of Wisconsin’s 9 million acres of cropland are being soil tested every 4 years.  This totals about 18% (1.6 million acres) annually, assuming the average sample covers 10 acres.  Using these assumptions, approximately 2.5 million acres of Wisconsin cropland is not being soil tested.