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

Schlossberg, Maxim J., Schmidt, John P.
Agronomy journal 2007 v.99 no.1 pp. 99
Poa annua, lawns and turf, turf grasses, golf courses, nitrogen fertilizers, fertilizer rates, appearance (quality), plant growth, soil fertility, color, nutrient content, Agrostis stolonifera var. palustris, Pennsylvania
Of the essential nutrients, N fertility generally influences golf course putting green (PG) quality and growth rate most significantly. Despite considerable field research on N fertility of PGs, results interpretation and transfer to practice is complicated by various influential factors; including unrepresentative mowing heights and/or frequency, varying irrigation water quality, undeclared composition of mixed swards, withdrawn cultivars, and/or use of temperature-dependent organic fertilizer sources. A 2-yr field study was initiated in 2003 at University Park, PA, to evaluate the influence of soluble N fertilizer source and rate on qualitative and nutritional parameters of a mature, primarily surface-drained, “push-up” PG cohabited by ‘Penn A4’ creeping bentgrass (Huds.) and annual bluegrass (L.). Using an array of soluble N form quotients (NH–N/NO–N), split applications of annual N fertilizer rates ranging from 69 to 402 kg ha were sprayed every 15 ± 4 d, April to October. Putting green growth, color, N uptake (NUP), and leaf N, K, Ca, Mn, Cu, and Zn increased directly with N rate, while plots receiving N rates in excess of 244 kg ha yr demonstrated acceptable PG quality and tissue nutrient concentrations. However, N rates >244 kg ha yr containing >50% NH–N significantly enhanced shoot growth, color, NUP, leaf Mn, P, and Mg levels, when compared to equal rates containing ≥50% NO–N. Frequent fertilization with NH–N at annual rates >244 kg ha maximized canopy color and most tissue nutrient levels of a mature creeping bentgrass/annual bluegrass cohabited PG growing on a neutral, fine-textured soil.