Re-evaluating the University of Kentucky's Soil Fertility Recommendations for Soybean Production

The land grant universities and Cooperative Extension Services developed soil fertility recommendations for crop production based on field studies that included correlation and calibration work. Soil test potassium (STK) values have decreased over time across Kentucky according to data generated from the University of Kentucky Regulatory Services Soil Test Lab. Further, the majority of soybean samples submitted to the UK Plant Diagnostic Center at Princeton diagnosed with a nutrient deficiency are related to low K. It is not known if producers are applying less K than recommended or if the recommended rate is not sufficient to build or maintain STK levels. Soil phosphorus (P) levels do not appear to be declining like K, but have come into question. It is hypothesized that higher current nutrient removal rates than the past are not being addressed with adequate fertilizer rates, K in particular. We propose to test the adequacy of current UK Cooperative Extension Recommendations in field with low soil test P and K values. Intensive tissue samples will be collected throughout the growing season. Final soybean yield will be collected to determine the effect the soil fertility programs.