Perception On Current Soil Fertility Recommendations and the Fertility Status of Soils in Illinois.

Analysis of soil phosphorus (P), potassium (K), and pH is necessary to guide application of these inputs. To teach fertility management more effectively, two surveys were conducted to determine the general fertility of soils and to assess perception on soil fertility recommendations for Illinois. A soil fertility survey was conducted in 2007 and 2008 at 598 random fields prior to corn (Zea mays L.) harvest. Soils from the 0-8 and 8-18 cm depths were analyzed for P, K, pH, calcium (Ca), magnesium (Mg), and organic matter (OM). Perception on current soil fertility recommendations was assessed during a conference series in 2009 in which 833 responses from an audience of approximately 1100 participants was obtained using TurningPoint. The soil survey revealed that 17 and 44% of the soils were below the mean critical level (19 and 140 mg P and K kg^-1, respectively). Fifty-nine and 30% of the soils were above the mean soil test level at which no fertilization is recommended (33 and 190 mg P and K kg^-1, respectively). Mean soil pH was 6.7. Mean Ca (2235 mg Ca kg^-1) and Mg (359 mg Mg kg^-1) levels indicate no need for application of these nutrients. Mean OM was 3.3%. P, K, and OM levels were stratified with surface to subsurface ratios of 1.6:1, 1.4:1, and 1.2:1, respectively. Audience response indicated that 93% of participants conduct soil sampling for P, K, and pH analysis at least every 4 years and 58 and 54% indicated that current University recommendations are adequate for P and K, respectively. While audience response and fields sampled are not necessarily linked, these surveys illustrate the need for education on following recommendations and interpreting soil analysis. This information is being used by extension personnel as an effective tool to help improve nutrient manage in Illinois.