Frank S. Rossi

Effectiveness of standard soil tests for assessing potassium availability in sand rootzones

Potassium (K) is the most abundant cation in the cytoplasm, and large amounts are needed for optimum plant growth. In sand rootzones with low cation exchange capacity (CEC), commonly used for putting greens, K availability may be limited, especially when the sands are calcareous. Tools are needed to assess K availability and to direct K management for such calcareous sands. The objectives of this study were to: (i) evaluate six extraction methods (1 N NH4OAc, Mehlich 3, Morgan, 0.01 M CaCl2, 0.01 M SrCl2, and water) for their effectiveness in quantifying soil extractable K following K fertilizer applications; and (ii) to ascertain how the extractable K was related to tissue K concentrations. Potassium was applied as K2SO4 at six rates (0, 3, 6, 13, 19, and 25 g K m−2 56 days−1) to a creeping bentgrass [Agrostis stolonifera var. palustris (Huds.) Farw.] putting green grown on a calcareous sand rootzone. The potassium was applied at 2-week intervals (4 applications within the 56-day period) and repeated during two different irrigation regimes. Soils were sampled and analyzed after the fourth application. Each extraction method detected an increase in soil extractable K following K fertilizer application. The K concentrations were lowest in the water extracts and highest in the Mehlich 3 extracts, irrespective of irrigation regime, but less K was recovered under higher irrigation intensity. Creeping bentgrass tissue K content increased with K application rate. However, maximum tissue K content was obtained at lower soil K levels under the high irrigation intensity than under the lower irrigation intensity. Our results show that each extraction method could be used to detect an increase in extractable K and to predict an increase in tissue K content. Nevertheless, factors other than soil K concentration also affected the tissue K content, which suggests that soil K concentrations may not be a reliable predictor of tissue K content in this sand rootzone.

Tree Wardens and public grounds management in North America: Overseeding athletic fields with perennial ryegrass to promote safe playing surface

Responsibilities of the municipal/urban forester, or Tree Warden as the position is known in parts of the United States, may extend to a variety of widely used community green spaces that include gardens, landscapes and athletic fields. In recent years, the application of non-chemical, cultural methods pertaining to the management of publically accessible athletic fields has garnered growing interest. This is especially true as it relates to weed control and the maintenance of desirable turfgrass cover and safe playing conditions. Based on previous research, a demonstration field study was conducted over four growing seasons (2005–2008) to determine the effectiveness of weekly, repetitive (8×), late summer – early fall overseeding with varying rates of perennial ryegrass: 0, 1, 3 and 6 lbs 1000 ft−2. Overseeding at the highest rate (6 lbs 1000 ft−2) appeared to generate the greatest increase in desirable turfgrass cover during growing seasons that received adequate, well-distributed rainfall. The relationships between amenity and sports grass management and adjacent trees are considered.

Civitas Increases Clipping Yield on a Cool-Season Putting Green

C IVITAS (Suncor Energy, Calgary, AB, Canada) is an isoparain horticultural oil marketed to enhance plant defense and is certiied by the Organic Materials Review Institute (www.omri.org). It triggers induced systemic resistance to diseases leading to reduced pesticide requirements for turfgrass (Cortes-Barco et al., 2010). To mask phytotoxicity, Civitas is mixed with a copper phlalocyanate-based pigment called Harmonizer (Suncor Energy, Calgary, AB, Canada). Civitas and Harmonizer can be mixed on site (called the Two-Pack) or premixed at the factory (called Civitas One). here are anecdotal reports of increased clipping yield and reduced ball roll distance following application of the Two-Pack to putting greens of cool-season grasses, but these claims have not been substantiated scientiically. Increased clipping yield or reduced ball roll distance may limit the use of Civitas. Our objective was to determine the efect of Civitas, Harmonizer, and their combination on the clipping yield of cool-season grasses maintained as a putting green. his study was conducted in 2011 and 2012 on a mature stand of 60% creeping bentgrass (Agrostis stolonifera Hud. ‘Penncross’) and 40% perennial biotype annual bluegrass (Poa annua var. reptans) putting green at the Cornell University Bluegrass Lane Turf and Landscape Research Center in Ithaca, NY. he green was constructed approximately 15 years ago from the on-site Arkport ine sandy loam soil with a 3-inch layer of sand from monthly topdressing applications. Plots were mowed daily at 0.12 inches with a Toro Greensmaster 1000 (Toro Co., Bloomington, MN), fertilized weekly from May until October with urea at 0.1 lbs N/1000 t, and irrigated to prevent drought stress. he experiment was a randomized complete block design with four replicates of 8 by 4 t plots. Treatments included an untreated control, the high labeled rate of Civitas oil applied alone (16 l oz/1000t), Harmonizer pigment alone (1 l oz/1000t), and Civitas and Harmonizer mixed on-site (TwoPack; 16 and 1 l oz/1000t, respectively) and Civitas One Published in Applied Turfgrass Science DOI 10.2134/ATS-2014-0012-BR