Nitrogen sources with different properties and release characteristics are used to meet a variety of fertility management needs in turfgrass culture. Our objective was to determine the response of turfgrass to various urea‐formaldehyde reaction products; two particle sizes of oxamide; experimental sulfur‐coated ureas (SCU); products containing combinations of N sources; and an experimental composted sewage sludge. Nitrogen sources included for comparative purposes were isobutylidene diurea (IBDU); commercial SCU products; soluble sources; and Milorganite. In this 2.5‐yr study, 25 N source treatments were evaluated on ‘Merion’ Kentucky bluegrass (Poa pratensis L.) using 196 kg N ha−1 yr−1, split into two equal applications. Turf response was measured by weekly color ratings, weekly clipping yields, and N uptake for six growth periods during 2 yr. Urea‐formaldehyde reaction products containing no water‐in‐soluble N (WIN) gave results similar to those of conventional soluble N sources, while products containing WIN caused less initial color and growth responses, but gave a slight residual effect in the third year of use. Nitrogen uptake for powdered ureaform (66% of N as WIN) and the suspension FLUF (20% of N as WIN) was 44 and 75%, respectively, of that obtained with Formolene (0% WIN). Major differences in color and growth were found for the different particle sizes of oxamide, with the fine (<0.25 mm) material providing a faster release and less residual effect than the coarse (1‐3 mm) material. Turf fertilized with coarse oxamide responded similarly to that fertilized with coarse IBDU (0.7‐2.5 mm). Commercial SCU and fine particle SCU made with curtain granulated urea (94% of particles between 1.14 and 2.38 mm; dissolution rates: 6 and 15%) had pronounced residual effects, especially in the spring prior to fertilization. The experimental composted sewage sludge was inferior to Milorganite as a source of N for use on turf. N uptake with the compost treatment was only 32% of that obtained with Milorganite. Turf response from combinations of N sources generally reflected the amount and type of N source present. All N sources except the sludge compost were effective for turfgrass fertilization. Selection of an N source or combination of sources for turf fertilization should be dependent on quickness and duration of response desired, rate and frequency of applications, and various economic factors.
This study was conducted to determine the effect of various types and rates of soil reinforcing materials on soil bulk density, soil water content, surface hardness, and turfgrass density of a high‐sand root zone exposed to three levels of simulated traffic (wear). Six soil reinforcing materials were mixed at varying rates with a high‐sand root zone. These included DuPont Shredded Carpet, Netlon, Nike Lights, Nike Heavies, Turfgrids, and Sportgrass. Three levels of wear were imposed on each treatment. The types and rates of reinforcing materials had varying effects on surface hardness, bulk density, water content, and turf density of the root zone. Surface hardness and soil bulk density were correlated during the 2‐yr test period (r = 0.63). The reinforcing treatments that lowered soil bulk density and surface hardness were DuPont Shredded Carpet, Nike Lights, and Nike Heavies. Reinforcing material treatments that increased or did not affect soil bulk density generally resulted in increased surface hardness compared with nonamended controls. These treatments included Netlon and Turfgrids. Surface hardness generally became more pronounced as the level of wear increased for Netlon, Turfgrids, and Sportgrass treatments. The Sportgrass treatment consistently measured lower in soil water content than the control and had a turfgrass density lower than the control on all rating dates in 1996 but did not differ from the control in 1997. Athletic field managers considering using reinforcing materials should be aware that the type of material and rate influence athletic field surface hardness.
Irrigation water quality is one of the most important environmental issues facing the green industry today, especially in urban areas with competing interests for limited water resources. Fifty‐eight irrigation water survey kits were sent to golf courses within the Groundwater Protected Area of southeastern Pennsylvania. A total of 35 (60%) water samples were received and grouped into one of five water source categories: domestic, lake, recycled, stream, and well. Laboratory analysis measured or calculated 26 parameters for each irrigation sample and also rain water. For all samples, 22 of 26 parameters were observed within the normal range for turfgrass, but four parameters were not: pH, bicarbonate, iron, and nitrate. All irrigation water samples, however, were considered to be of acceptable to good quality for establishing and maintaining turfgrasses in southeastern Pennsylvania. Information from this survey was used to communicate proper irrigation water quality monitoring and environmental stewardship to the golf course segment of the green industry in southeastern Pennsylvania.
New configurations of synthetic turf, infilled systems, have been introduced into the market place. These infilled systems are comprised of vertical fibers that are much longer than traditional synthetic turf and can be filled with sand and crumb rubber (infill media). The objective of this study was to evaluate the surface hardness of varying configurations of an infilled synthetic turf system called SofSport™ under wet and dry conditions. Specifically, we wanted to 1) determine the effect of underlying pad thickness and type, infill media depth, sand sizes, and sand to crumb rubber ratio, on surface hardness as measured by the F355 method and the CIST and 2) compare the F355 method with the CIST to determine if one method is preferred when testing synthetic infill systems. Surface hardness differences between pad thickness and types were small but all pad treatments had lower surface hardness values compared to the no-pad treatments. Infill media depth did not affect surface hardness under dry conditions. Under wet conditions, the 38 mm infill media depth resulted in lower surface hardness than the 25 mm depth. The mixing of sand and crumb rubber infill media resulted in lower surface hardness values than sand or crumb rubber alone. When mixed with crumb rubber, finer sands measured higher in surface hardness than coarser sands. Under the conditions of this study the relationship between the Gmax values generated by the F355 method can be compared to the values generated by the Clegg Impact Soil Tester using the regression equation F355 x 0.66-9.3 = Clegg Impact Soil Tester. The regression coefficient for this equation was 0.95 and indicates that the Clegg Impact Soil Tester would be a suitable device to measure the surface hardness of SofSport installations.
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.
banned for agricultural and turfgrass uses in the USA (Ristaino and Thomas, 1997;Unruh, 1998). Dazomet (tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione)Dazomet is a granular soil fumigant that controls is a soil fumigant labeled for turfgrass renovation. Little is known about dazomet efficacy on annual bluegrass (Poa annua L.) seedling fungi, bacteria, nematodes, and weed seeds in soils (Haremergence, particularly when it is surface-applied. The objectives of ris, 1991;Fritsch and Huber, 1995). When incorporated this field study were to determine (i) the effects of rate and plastic into moist aerated soil, dazomet is degraded into several covering of surface-applied dazomet on annual bluegrass seedling volatile intermediate products including methylisothioemergence in turf; and (ii) effective creeping bentgrass seeding intercyanate (MITC). Methylisothiocyanate is toxic to many vals following surface applications of dazomet. All treatments were soilborne organisms, including weed seeds (Fritsch and applied to established turf during late summer in 2000 and 2001. , 1995;Mappes, 1995). Huber Covering dazomet treatments with plastic sheets resulted in fewerDazomet inhibits seed germination and emergence annual bluegrass seedlings than in noncovered treatments. All plasticof numerous weed species (Eitel, 1995;Mappes, 1995). covered dazomet treatments (388, 340, 291, and 194 kg ha Ϫ1 ) provided Efficacy varies with the rate of application and the greater than 98% reduction in annual bluegrass seedlings when compared with the plastic-covered controls during 2000 and 2001. When method of preventing escape of phytotoxic gases from not covered with plastic, the 388 kg ha Ϫ1 dazomet treatment provided soil. Eitel (1995) found improved control of seedling 97% fewer annual bluegrass seedlings in 2000 and 92% fewer seedlings emergence of Cyperus esculentus L., Galinsoga parin 2001 than the noncovered controls. Results of the seeding interval viflora Cav., Portulaca oleracea L., and Richardia braexperiment revealed that creeping bentgrass (Agrostis stolonifera L.) siliensis (Moq.) as rates of dazomet increased from 98 groundcover and yields were not inhibited when seeded 3 d after a to 392 kg ha Ϫ1 following incorporation into a sandy loam surface application of dazomet at 388 kg ha Ϫ1 .soil. When dazomet was incorporated into the same soil and covered with plastic sheets for 7 d, Eitel (1995) found improved control of the same four weed species
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