Maxim J. Schlossberg

Root and shoot performance of three creeping bentgrass cultivars as affected by nitrogen fertility

Cultivar selection and nitrogen (N) fertility significantly influence the performance of creeping bentgrass (Agrostis palustris Huds.) in warmer regions of the United States. This study was conducted to determine the effects of N on root and shoot growth of three creeping bentgrass cultivars. The effect of three N rates (195.3, 390.6, and 586.0 kg N/ha year) on the total root length density (TRLD), deep root length density (DRLD), visual shoot quality, shoot density, and root to shoot ratio (RSR) of ‘Crenshaw’, ‘L93’, and ‘Penncross’ creeping bentgrass were evaluated in the University of Georgia Rhizotron at Athens, GA. Over the 19 month study, cultivar type and N rate significantly affected root and shoot growth with slight interaction. Crenshaw and L93 showed greater TRLD, DRLD, and visual shoot quality than Penncross at the 390.6 kg N rate. RSR was significantly influenced by N rate but not cultivar type. Both L93 and Crenshaw possessed significantly higher RSR at the 195.3 kg N rate than the 586.0 kg N rate. *Contribution of the Georgia Agricultural Experiment Station, Athens, GA.

Inhibition of Pythium spp. and Suppression of Pythium Blight of Turfgrasses with Phosphonate Fungicides

Pythium aphanidermatum and other Pythium spp. cause Pythium blight of turfgrasses in the United States. Phosphonate fungicides suppress Pythium blight when applied preventatively, but efficacy may vary with product, rate and timing of application, and host species. The objectives of this study were to assess the inhibitory effects of phosphorous acid on Pythium spp. in vitro, and determine if active ingredient and formulation of phosphonate fungicides provide similar levels of Pythium blight suppression on perennial ryegrass and creeping bentgrass when applied at equivalent rates of phosphorous acid. Phosphorous acid EC50 values (effective concentration that reduces mycelial growth by 50%) for P. aphanidermatum isolates ranged from 35.6 to 171.8 μg/ml. EC50 values for isolates of six other Pythium spp. were between 38.7 and 220.8 μg/ml. In 2004 and 2005, all phosphonate treatments provided significant suppression of Pythium blight symptoms on creeping bentgrass and perennial ryegrass relative to the untreated control. No differences in percentage of blighted turf occurred among phosphonate treatments when applied at equivalent rates of phosphorous acid in either year of the study, regardless of active ingredient, formulation, or turfgrass species.

An Apparatus to Evaluate the Pace of Baseball Field Playing Surfaces

During a baseball game, the ball will strike the playing surface at a variety of speeds and angles. The speed at which the ball travels after impact with the playing surface has been referred to as the pace of the surface. Wide variations in pace can reduce the safety and playability of baseball field surfaces. Pace can be quantified by measuring the coefficient of restitution. The coefficient of restitution is defined as the ratio of two velocities; the velocity of a baseball after impact with the surface divided by the velocity of the ball prior to impact. An apparatus was developed to measure the coefficient of restitution of a baseball striking various playing surfaces. The apparatus, termed Pennbounce, uses infrared screens to measure the coefficient of restitution of baseballs propelled at varying angles and velocities. Pennbounce was used to measure the pace of traditional synthetic turf (Astroturf), infilled synthetic turf (Fieldturf), natural turfgrass, and skinned infield surfaces. Baseballs were propelled at the surfaces using two velocities and impact angles. Surface pace was highest on traditional synthetic turf, skinned infield, infilled synthetic turf, and natural turfgrass areas, respectively.

Foliar fertilization–induced injury and recovery of a creeping bentgrass putting green

ABSTRACT Two independent trials were conducted on a creeping bentgrass (Agrostis stolonifera L.) putting green (PG) to evaluate early-response of canopy quality, growth, and nutrient use to rate and/or type of foliarly-applied nitrogen (N) fertilizer. Treatments were prepared using soluble ‘Amine’ or ‘Salt’ 15N–0 phosphorus (P)–5.8potassium (K) fertilizer and applied N at 0, 24.5, 37, or 49 kg ha−1. Clipping yields were weighed and digested for N content. Normalized differential vegetative (NDVI) and dark green color (DGCI) indices were determined by canopy reflectance. Relative to the Salt fertilizer, the Amine supported greater mean growth and N offtake rates and higher mean NDVI and DGCI. Two and five days after treatment (DAT), salt-fertilizer treated plots showed lesser canopy quality relative to Amine. These differences increased with N rate, likely due to the greater solute concentration of the Salt fertilizer. Eight to 21 DAT, fewer differences were observed by fertilizer type or rate.

Amelioration of Soil Acidity with Class-C Fly Ash: A Field Study

Coal combustion products (CCP) include fly ash and bottom ash and are generated nationally at rates of 108 Mg per year. Fly ashes (FA) comprise the majority of CCP production, and can possess widely-variable physicochemical properties. Current consumption/utilization of FA in the US does not approach production levels, and results in FA stockpiling. Class-C fly ash is generated from combustion of sub-bituminous and lignite coal products. This class of FA often possesses an alkaline pH, resulting from calcium, magnesium, and potassium oxide inclusions. Some Class-C FA have been reported to contain as much as 60% calcium carbonate equivalency (CCE), prompting investigations of FA as a lime substitute in agricultural/horticultural applications. Furthermore, FA often possesses small concentrations of exchangeable micronutrients. Thus, considering availability of Class-C FA, its potential beneficial use as a liming agent, and the expansive area of low-to-medium maintenance turfgrass systems currently afflicted by suboptimal soil pH levels; our objective was to evaluate the acid-neutralizing efficacy of a Class-C FA when substituted for pulverized limestone (PL) in field application. This study was conducted on a severely-acidic bermudagrass (Cynodon spp. L.) rough of a Georgia golf course during 2001 and 2002. Following material characterization, CaCO3 equivalent was applied at a prescribed rate of 3.8 Mg CaCO3 ha−1, using either PL or Georgia-produced FA (CCE = 45.5%). Soil samples collected one year following showed FA to have neutralized significantly greater acidity in the upper 8 cm of soil than the PL. Furthermore, exchangeable P, Mg, and Zn levels in the FA-treated 0–8 cm of soil exceeded levels observed in the PL-treated or control plots. Due to the disparity in CCE, requisite FA application greatly exceeded that of PL, reducing economic advantage of FA-substitution. However, in locations where Class-C FA is plentiful, high-grade PL is costly, and soil pH suboptimal for important crops; results of this study indicate soil liming with Class-C FA to be a beneficial use of this CCP. Comprehensive characterization of CCP and proper application rate (not exceeding agronomic requirements) are essential components of beneficial use.

Use of Coal Combustion by-Products (CCBP) in Horticultural and Turfgrass Industries

Coal combustion by-products (CCBP) include fly ash, bottom ash (cinders) and various desulfurization by-products. They contain plant nutrients, have variable capacities to neutralize soil acidity, and may improve physical properties of mineral soils. They have been usefully applied in agricultural, horticultural, turfgrass and land reclamation settings. However, inherent traits of CCBP such as bulkiness, excess trace metal concentrations, inconsistent availability of P, and low content of N and K make CCBP an untenable fertilizer supplement. Likewise, utilization of municipal biosolids (sewage sludge) can be problematic due to trace metal levels and undesirable nutrient ratios. Therefore, this study was initiated in early 2000 to determine the feasibility of blended CCBP and biosolids/biosolid products for use as growth media for horticultural ornamentals and turfgrass sod. Trace element concentrations in mixes used for both soil amendment and sod media were below USEPA regulatory limits. In the sod production component, growth media were uniformly spread to heights of 2, 3, and 4 cm on compacted subsoil, sprigged with bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensisBurrtDavy var. ‘TifSport’ (formerly Tift 94)], and maintained under ideal commercial sod field conditions. Following a maturation period of 99 d, sod was harvested and installed at the Georgia Experiment Station in Griffin. Remaining sod were destructively analyzed for determination of their physicochemical attributes. Field data collected from the ornamental beds showed yield and quality of flowers grown on CCBP-amended soil to outperform the commercially-amended soil under limited fertility conditions. Post-installation evaluations of sod made in April, 2001 did not reveal significant differences in rooting strength by mixture or sod thickness. All finished CCBPcontaining sod retained significantly more volumetric water (ψm<-80 kPa), while possessing 26–39% less gross (wet) weight than the control mix sod. The finished sod grown in selected combinations of bottom ash, fly ash, and biosolids possessed significantly greater biomass than the control sod mix, while requiring less supplemental fertilization. Utilization of the described CCBP-mixes as supplemental growth media in bermudagrass sod production was successful and may be a significant advantage when compared to some SE US soils. These experimental observations, in tandem with similar published results, indicate that utilization of CCBP in horticulture and turfgrass industries is technically feasible and environmentally-sound.

Predicting Initial Tall Fescue Root Growth Response to Calcium/Aluminum Solution Concentrations

A study was conducted to quantify effects of soluble aluminum (Al) and gypsum (CaSO4) on initial root growth of three varieties of tall fescue (Festuca arundinacea). Experiments were performed in a growth chamber using hydroponic solutions containing Al from 0 to74 µM in combination with CaSO4 at 0 to10 mM. Seedlings were grown for 7 d, harvested, air dried, scanned, and weighed for treatment comparisons. Significant differences in root length existed between varieties in Al‐only solutions at low Al concentrations. All varieties showed reduced root growth at concentrations greater than 37 µM Al. Increased calcium (Ca2+) and sulfate (SO4 2−) at given concentrations of Al resulted in greater root growth. Relative root growth increased approximately 30% to >80% at 37 µM Al as CaSO4 increased from 2.5 to 10 mM. A simple logistic model adequately described the effects of Al and CaSO4 on root growth (r2 = 0.86, 0.95, and 0.96 for the three varieties).

Trace Element Transport in Putting Green Root Mixes Amended by Coal Combustion Products (CCP)

Golf course putting green (PG) construction methods rely on homogenous mixtures of coarse and medium-sized sands as primary components of the root mix. In some locations, cost of quartz sand delivery is prohibitive. Coal combustion products (CCP) have been used to amend soil in agricultural, horti-cultural, and land reclamation endeavors. A greenhouse study evaluated the hydraulic properties of PG root mixes constructed with sand-sized bottom ash (BA) and silt-sized fly ash (FA) as substitutes for mineral sand and soil components. Columns (5 cm ID × 42 cm) were packed with one of three CCP-containing root mixes or a non-amended, control root mix; all of soil textural class commonly used in putting greens. Pore volumes of leachate were collected 0, 11, 24, and 100 days after [turfgrass] sodding (DAS), and analyzed for elemental content. Compactive forces were applied to root mix surfaces throughout the 6, 12, or 18 month experimental periods, following which hydraulic parameters and particle size distribution (PSD) were measured. Root mixes and compaction treatments interactively affected Ks. The control PG mix generally demon-strated the greatest saturated hydraulic conductivity (Ks), regardless of compaction treatment. Root mixes containing FA and sand (SFA) exhibited severe reductions in Ks. Similarly, the PSD of the surface 7 cm of the CCP-root mixes became more finely-textured with cumulative compaction events. This soil textural alteration was likely responsible for impaired entry and flow of water in the CCP-amended root mixes, yet conductivity rates observed after 18 months in all but the sand-FA (SFA) root mixes mix fell within accepted ranges. Trace element concentrations in root mix leachate varied with CCP inclusion rate and cumulative pore volumes, and were highly correlated to the presence of fly ash (FA). Bottom ash may be better suited for putting green root mixes amendment than FA, yet further research is necessary to determine optimal rates of inclusion.