Creeping Bentgrass Putting Green Response to Foliar Nitrogen Fertilization

Within the range of environmental conditions for which creeping bentgrass (Agrostis stolonifera L.) is adapted, cultural management significantly influences golf course putting green (PG) growth and quality. The experimental objective was to identify PG quality and growth response to rate, type, and/or timing of foliarly-applied N fertilizer. In 2009 and 2010, three independent fertility trials were conducted on a sand-based PG established to a 1:1 blend of Penn A-1 and Penn A-4 creeping bentgrass. Excepting the zero-N control, treatments were prepared using amine or salt 15-0-7 liquid fertilizer comprising wholly-soluble nutrient forms and applied at 24.5+24.5, 37, or 49 kg N ha(-1). Clipping yields were collected weekly and digested for N content. Canopy reflectance was used to calculate normalized differential vegetative (NDVI) and dark green color (DGCI) indices. Nitrogen rate directly influenced PG mean NDVI, DGCI, clipping yield, and N removal. Likewise, the amine supported greater mean PG quality than the salt fertilizer. Availability of fertilizer, estimated by PG growth and N removal rate, declined dramatically over the 6-wk experiments. Initial PG growth response to the single 49-kg N application significantly exceeded the 24.5+24.5 kg N split application. However, beneficial response to split applications, relative to the single 49 kg N treatment, was observed in latter weeks. While commercially-available liquid fertilizers vary in their suitability, managers are recommended to employ a <15-d reapplication interval in meeting the 15 to 49 kg N ha(-1) monthly creeping bentgrass PG requirement.