Speaker: Dr. Karl Guillard Nitrogen fertilization for higher-cut turfgrasses such as lawns, parks, institutional grounds, etc., typically follows long-standing practices that have not changed much in the last several decades. Fertilizer applications are generally made at predetermined rates [usually around 1 lb N per 1,000 sq. ft (49 kg N per hectare)] on or around benchmark calendar dates or events throughout the growing season, e.g., Easter, Memorial Day, Labor Day, Thanksgiving Day. Depending on turfgrass species and intended use, fertilization can occur once to four times or more during the growing season. The rates and timing are common across wide ranging geographical locations, soils, and climate conditions. From a scientific perspective, this is not logical and suggests that the current fertilization approach is subjective and essentially guessing. Sometimes the turfgrass manager will guess the appropriate rate correctly, but there is a high probability that the rate will not be optimum and either higher or lower than what the turfgrass stand needs to meet growth, performance, and/or aesthetic goals. In this talk, I will review the past and current work from my laboratory researching new soil tests, sap nitrate tests, and reflectance meters to objectively guide and improve nitrogen fertilization of higher-cut turfgrasses.
