Much of the historic soil test calibration and correlation data used to develop fertilizer recommendations in Maryland and Delaware has been lost. While funding for soil test correlation and calibration research has been a low priority for the last several decades, there is a renewed interest in soil test calibration and correlation research in the U.S. through the Fertilizer Recommendation Support Tool (FRST) project. The FRST project is working toward development of a soil test and crop response to fertilization searchable database and web based tool that enables consistent, transparent, and science-based decision support for nutrient recommendations for major crops across the U.S.
Dr. Nicole Fiorellino and Mr. Louis Thorne from the University of Maryland will establish K rate trials in corn at two fields in Delaware to provide potassium (K) correlation and calibration data to FRST. Small plots will be established at two locations with responsive soil test K levels (i.e., low, medium) in a randomized complete block design with five replications. Soil samples will be collected by block at two depths (0-15 cm, 0-20 cm) and analyzed for Mehlich 1 and Mehlich 3 K prior to K surface application of 0-0-60 in the spring at five rates. They are also collecting ear leaf tissue samples to monitor for nutrient deficiencies and evaluate changes in Mehlich 3 by collecting post-season soil samples. Corn yields will be evaluated in the fall to determine response to K fertilization rates. Corn residue will be sampled and analyzed for K at harvest and again after decomposition in the field. Once data is collected it will be added to the FRST database.