Influence of Nitrogen Rate and Form on Quality of Putting Greens Cohabited by Creeping Bentgrass and Annual Bluegrass

Authors: SCHLOSSBERG, M - PENN STATE UNIV; Schmidt, John

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2006
Publication Date: 1/10/2006
Citation: Schlossberg, M.J., Schmidt, J.P. 2006. Influence of Nitrogen Rate and Form on Quality of Putting Greens Cohabited by Creeping Bentgrass and Annual Bluegrass. Agronomy Journal. 99:99-106.

Interpretive Summary: Nitrogen, the nutrient that most significantly influences the quality of golf course putting greens, represents a potential environmental risk to groundwater, as nitrate, when nitrate is present in the soil and infiltration exceeds evapotranspiration. We evaluated the influence of soluble N fertilizer source and frequent application rate on qualitative and nutritional parameters of a mature, surface-drained, 'push-up' putting green cohabited by 'Penn A4' creeping bentgrass (Agrostis palustris Huds.) and annual bluegrass (Poa annua L.). Nitrogen fertilizer rates of 69.1 to 402.4 kg per ha per yr, consisting of an array of ammonium-N to nitrate-N combinations, were sprayed every 15 days, April to October, at University Park, PA. All treatments exceeding 244 kg per ha per yr fostered adequate putting green quality and tissue nutrient concentrations. However, comparison of systematic N applications (more than 244 kg per ha) containing more than 50% nitrate-N to those containing more than 50% ammonium-N showed that the latter significantly enhanced shoot growth and nitrogen uptake rates, leaf color, and Mn, P, and Mg levels in the tissue. Frequent fertilization with ammonium-N at annual rates more than 244 kg per ha maximized overall quality and most tissue nutrient levels of a mature creeping bentgrass and annual bluegrass cohabited putting greens growing on a neutral, fine-textured root zone. Applying frequent applications of nitrogen fertilizer as ammonium-N reduces the incidence of nitrate-N in the soil, minimizing environmental risks, while maximizing turf quality.

Technical Abstract: Of the essential nutrients, N fertility generally influences golf course putting green (PG) quality and growth rate most significantly. Though N fertility of PGs has been thoroughly researched for that reason, controlled environmental conditions, unrepresentative mowing height/frequency, irregular reporting of physicochemical soil properties, and/or other inherently variable yet influential factors (i.e. withdrawn cultivars, irrigation water quality, coated fertilizer prill integrity and / or mower removal, organic N fertilizer release, etc.) complicate meaningful extrapolation and interpretation of published results. This 2-yr field study initiated in 2003 evaluated the influence of soluble N fertilizer source and frequent application rate on qualitative and nutritional parameters of a mature, surface-drained, 'push-up' PG cohabited by 'Penn A4' creeping bentgrass (Agrostis palustris Huds.) and annual bluegrass (Poa annua L.). Using an array of soluble N form quotients (ammonium-N to nitrate-N), fertilizer rates of 69.1 to 402.4 kg per ha per yr were sprayed every 15 d, Apr. to Oct. at University Park, PA. Growth, color, nitrogen uptake (NUP), and leaf N, K, Ca, Mn, Cu, and Zn in the PG increased directly with N rate, regardless of N form. Likewise, all treatments exceeding 244 kg per ha per yr fostered adequate PG quality and tissue nutrient concentrations. However, comparison of systematic N applications (more than 244 kg per ha) containing more than 50% nitrate-N to those containing more than 50% ammonium-N, show the latter significantly enhanced shoot growth and NUP rates, and leaf color, Mn, P, and Mg levels. Frequent fertilization with ammonium-N at annual rates more than 244 kg per ha maximized overall quality and most tissue nutrient levels of a mature creeping bentgrass and annual bluegrass cohabited-PG growing on a neutral, fine-textured root zone.