Effect of Fertilization on Penncross Creeping Bentgrass¹

Abstract Although turfgrass fertilization influences many factors that affect turfgrass quality, little information is presently available that encompasses the interrelationships between fertilization, soil fertility, and turfgrass response and quality. A field study was conducted on Hagerstown soil (fine, mixed, mesic Typic Hapludalf) to determine the effects of N sources (Agrinite, Milorganite, ureaform, and urea), P rates (0, 0.49, 0.98, and 1.95 kg/100 m 2 ), and K rates (0, 0.76, and 1.52 kg/100 m 2 ) on soil nutrient levels and the growth, quality, and chemical composition of ‘Penncross’ creeping bentgrass ( Agrostis palustris Huds.) maintained as putting green turf. Wilting, disease, chlorosis, and annual bluegrass ( Poa annua L.) infestation were used to assess quality. Fertilization with Milorganite increased available soil P and Mg. Available P and K in the soil ranged from 11 to 94 ppm and 0.06 to 0.28 meq/100 g, respectively. Elemental content of clippings was affected by all treatments, and treatment × date of sampling interactions that occurred could limit the usefulness of tissue analyses for diagnosing the nutritional status of turfgrasses. When K was applied at 0.76 kg/100 m 2 , both tissue and available soil K increased. When the K rate was increased to 1.52 kg/100 m 2 , the additional increment of K caused a greater increase in soil K and a smaller increase in tissue K than was obtained with the first increment of added K. The greatest change in tissue P occurred with the first incremental addition of P. Tissue P was not greatly affected by soil P above 24 ppm. Phosphorus fertilization had little effect on clipping yield; however, K fertilization tended to increase growth, as well as decrease chlorosis noted in early spring. Less severe summer wilting was observed with Agrinite, Milorganite, and K treatments. Less dollar spot ( Sclerotinia homoecarpa F. T. Bennett) infection was noted with urea fertilization. Annual bluegrass invasion was favored by P and K fertilization and the effect of one was enhanced by the other. Milorganite, which increased soil P, also favored annual bluegrass. Results of this study indicated a need for more work in soil test calibration for turfgrasses.