Soil testing has hopefully become standard operating procedure on most farms as a means of monitoring nutrient levels and insuring the correct amount of fertilizer is applied to the growing crop.  Every four years, all soil tests submitted to certified Wisconsin laboratories are summarized to provide a snapshot of the current soil nutrient status.  Recently the results from tests run during 2000 through 2004 were released.       

        Going back to 1974, average soil pH in the county has not changed significantly and has always ranged between 6.9 and 7.1.  Similarly, soil organic matter has fluctuated very little.  Only in one 4-year cycle did it reach 4 percent (1977-81) and it has remained steady at 3.6 percent since 1990.  Perhaps of more interest are phosphorus (P) and potassium  (K).  Average P levels were at 31 parts per million (ppm) in 1974-77 and increased steadily to a high of 52 ppm in the 1990-94 cycle (see graph).  Since that time, P levels have declined slightly to 48 ppm.  This is still well above the level needed for optimum crop growth, but efforts to reduce soil P appear to be helping.  Of course it is P that helps to cause the late summer algae blooms in area lakes when soil is eroded and washed to groundwater bodies. 

        Average K soil test levels were at 101 ppm from 1974-77 (see graph).  This is lower than what we typically like to see today, especially if alfalfa is grown in the rotation.  Since the mid-1970’s, soil K levels increased to a high of 143 ppm in 1990-94 and have remained near that level since (140 ppm in 2000-04).