Grass Surface Research Articles

The trajectory of a ball in lawn bowls

The main objective in lawn bowls is to bowl a ball along a curved trajectory on a smooth grass surface so that it stops closer to the jack (a small white ball) than the opponent’s ball. The curvature of the path is induced by shaping the ball so that one side is heavier than the other. Some of the properties of the trajectory are described to illustrate this interesting example of precessional motion.

Energy and radiation balance components for three grass surfaces near Kursk, Russia

The energy and radiation balance components were determined over three grass surfaces, representing different levels of productivity, located on the Streletskaya steppe of the Bio‐spheric Reserve near Kursk, Russia, for 21 days during July 1991. The Bowen ratio energy balance method was used to determine the sensible and latent heat flux densities using six computer controlled systems. A total of 126 variables including global, diffuse and reflected solar radiation, long wave radiation (up and down), net radiation, photosynthetically active radiation above and below the vegetation, infrared surface temperatures, soil temperature and heat flow, air temperature and vapor pressure at two levels, wind speed and direction, and precipitation were sampled at 30 s intervals and averaged for 15 min periods. The day time results from July 20, 1991 (a reasonably clear day) for Site 12 (mowed in 1990), Site 13 (mowed in 1991) and Site 14 (preserve) were: net radiation, 13.50, 12.6, and 13.3MJm−2; soil heat flow, ‐0.11, ‐0.87, and ‐0.09 MJ m−2; latent heat flux density, ‐8.79, ‐7.46 and ‐9.97 MJm−2; and for sensible heat flux density, 4.46, ‐4.26, and ‐3.28 MJm−2, respectively. The ranking of the sites from greatest to smallest for net radiation and latent heat flux density were preserve, mowed in 1990, and mowed in 1991. The ranking of the sites from greatest to smallest for sensible heat flux density were mowed in 1990, mowed in 1991, and preserve.

Atmospheric mercury deposition to grass in southern Sweden

This paper summarises the results of a 5-year investigation (1990–1994) using artificially planted rye grass in open ground as a biological monitor for air-borne mercury (Hg) in the south of Sweden. The total Hg deposition was estimated to be 14 ng m −2 h −1, of which about 70% was estimated from dry deposition on the grass surface, during the growing seasons from May to October. Hg content in grass leaves decreased from 0.076 (1990) to 0.041 μg g −1 (1994) with a rate of about 10% per year, which reflects the reduced trend of Hg deposition over this area.

Skin temperature perturbations induced by surface layer turbulence above a grass surface

High‐frequency (5 Hz) atmospheric surface layer (ASL) turbulent velocity (u′) and infrared skin temperature perturbations (T′s) were measured above a grass‐covered forest clearing and analyzed for cloud free conditions. These measurements were used to investigate mechanisms responsible for the production of large short‐lived T′s perturbations caused by rapid excursions in u′. To quantify the effects of u′ on rapid surface cooling, wavelet spectra of u′ and T′s and cospectra of u′T′s were computed. The u′ wavelet power spectra were then analyzed using Townsend's [1961, 1976] hypothesis. Townsend's hypothesis states that ASL eddy motion can be decomposed into an active component, which is a function of the ground shear stress (u*) and height (z) above the zero plane displacement, and an inactive component, which is produced in the atmospheric boundary layer (ABL) outer region. A −1 power law in the u′ power spectrum was used as a signature for inactive eddy motion. Therefore the −1 power law was used to identify wavenumber ranges (about 1.5 decades) associated with inactive eddy motion. The measured T′s wavelet spectra and u′T′s cospectra identified with this wavenumber range demonstrate that much of the T′s energy and 〈u′T′s〉 are due to inactive eddy motion, where the angle brackets indicate time averaging. Hence, in contrast to the laboratory experiments of Owen and Thomson [1963], it is argued that skin temperature perturbations at the canopy‐atmosphere interface of a grass‐covered surface (small thermal inertia) are strongly dependent on the inactive eddy motion produced in the outer layer of the ABL.

DEMONSTRATION TEST ON GREENING IN THE UNITED ARAB EMIRATES

A grass growth test using a Moisture Absorbent Textile (MAT) has been carried out in the United Arab Emirates (U. A. E.) since 1996 to confirm the suitability of MAT for greening in arid regions. Meteorological data and subsurface data were collected of a grass-covered site to provide information on the differences in heat and moisture regimes for applications in an arid region. It was found that the grass growth rate and vegetation density were increased because of the improved moisture retentivity of the resulting from presence of the MAT. As an additional benefit, air temperature over the grass surface was found to be lower, while relative humidity was higher than for the bare soil surface.Additional tests carried out in the city of Dubai, U. A. E. to confirmed this effect.

Selected Rates of Conventional and Biorational Insecticides for Early Season Sod Webworm Control, 1997

Abstract Insecticides were evaluated for control of sod webworm larvae on a Kentucky bluegrass lawn at the Gering Cemetery, in Scotts Bluff County, Nebraska. The turf (80% Kentucky bluegrass, 20% perennial rye and tall fescue) was maintained at a mowing height of 2.5 inches. Thatch accumulation (finger compressed) in the plot area was 0.5 inches. Field conditions at the study site were: soil type, silt loam; soil organic matter, 2.3%; soil pH, 8.4. Weather conditions at the time of application were as follows: soil moisture 22% by wt; air temperature 71°F; soil temperature 70°F; relative humidity : 27%; wind direction and velocity 108° at 7 mph. Plots were 6 X 10 ft and the experimental design was a RCB with 4 replications. Treatments were applied on 5 May. Liquid insecticides were applied using a CO2 sprayer with a TeeJet® 8002 nozzle at 30 psi and delivering 87 gpa finished spray. Following applications, plots were irrigated with 0.25 inches of water. No rain fell during the post-treatment period. Treatments were evaluated 3, 7, and 14 DAT (8, 12, and 19 May) by mixing 0.5 oz Lemon Dawn® per gal of water and applying 2 gal of the dilution to each of two 6 ft sampling areas per plot (12.0 ft2 total area). Larvae that moved to the grass surface after 30 minutes were collected and counted.

The effect of spreading sodium bicarbonate over the surface of grass silage on the intake of grass silages by beef cattle

Ten silages were obtained from farms in Northern Ireland. They were selected on the basis of either low pH (< 3.7) or perceived low intakes on the farms. The silages were offered to 100 Charolais cross steers, either with or without the addition of sodium bicarbonate, in a two-period changeover design experiment. The sodium bicarbonate was spread over the surface of the silage at a rate of 250 g per steer day −1. Each period was of a 2-week duration. Dry matter intakes (kg day −1 and g kg −1 liveweight (LW) 0.75) were recorded daily, with intakes on the second week of each period being used in the statistical analysis. Silage dry matter intakes with (+) and without (−) dietary addition of sodium bicarbonate were: 6.27 and 6.16 (SEM = 0.122) kg day −1; 65.8 and 64.7 (SEM = 1.29) g kg −1 LW 0.75. The lack of a significant effect of dietary addition of sodium bicarbonate on the intake of low pH silages suggests that sodium bicarbonate spread over the surface of the silage has no beneficial effect, in terms of intake, with silages of this type.

Some Characteristics and Applications of Nitrogen Dioxide Passive Samplers

Ion chromatography has been used to measure nitrite (NO2 −) and nitrate (NO3 −) concentrations in the aqueous extracts from exposed and blank (unopened) passive samplers designed for the measurement of atmospheric nitrogen dioxide (NO2). Concentrations of NO2 − increased on storage of both opened and unopened samplers, however NO3 − concentrations were dependent on sampler cleaning and preparation. Only extract NO2 − concentrations were needed to calculate atmospheric NO2 levels when using the samplers for monitoring. Analytical methods for passive samplers extracts have been compared in the laboratory with good agreement being found. Calculations of possible background contamination levels suggest that sampler results may be influenced by the solubility of NO2 in the plastic construction materials but not by permeation of NO2 through the sampler walls. Passive samplers have been used to measure NO2 in a variety of locations. Outdoor urban sites in Auckland city and rural locations the Waikato Valley, New Zealand, were compared, with the seasonal variations of concentration showing a dependence on location. Samplers were also used to measure concentrations over vegetated surfaces, water and on the outside of a tall building. Vertical concentration gradients of NO2 over grassed surfaces were detected, indicating deposition, however a similar phenomenon was not observed over water. Calculation of the deposition velocity of NO2 from these data gave an unrealistic value which was most likely caused by windspeed effects or chemical reactions.

5482726 Method for reducing contamination of shellfish

A method for controlling and/or eliminating harmful lawn grass insects is disclosed, which comprises: foaming a surfactant composition having a total content of components present of from 0.2 to 50% by weight and comprising at least one surfactant selected from an anionic sulfonate, a higher fatty acid containing from 8 to 30 carbon atoms and salts of the higher fatty acid and a thickener; and applying the foam onto the surface of lawn grass in a thickness effective for controlling and/or eliminating the harmful lawn grass insects.

Spring Application of Conventional and Biorational Insecticides for Control of Sod Webworms, 1996

Abstract Insecticides were evaluated for control of sod webworm larvae on a Kentucky bluegrass lawn at the Gering Cemetery, in Scotts Bluff County, Nebraska. The turf (80% Kentucky bluegrass, 20% perennial rye and tall fescue) was maintained at a mowing height of 2.5 inches. Thatch accumulation (finger compressed) in the plot area was 0.5 inch. Field conditions at the study site were: soil type, silt loam; soil organic matter, 2.3%; soil pH, 8.4. Weather conditions at the time of treatment were as follows: soil moisture 16% by wt; air temperature 70°F; soil temperature 62°F; relative humidity 29%; wind direction and velocity 157° at 11 mph. Plots were 7 x 7 ft and the experimental design was a RCB with 3 replications. Treatments were applied on 6 May. Liquid insecticides were applied using a CO, sprayer with a TeeJet® 8002 nozzle at 30 psi and delivering 2 gal finished spray/1000 ft2. Following applications, plots were irrigated with 0.125 inches of water. A total of 0.67 inch of rain fell during the post-treatment period. Treatments were evaluated 3,7, and 14 DAT (10, 14, and 21 May) by mixing 0.5 oz of Lemon Dawn® per gal of water and applying one gal of the dilution to each of two 6 ft sampling areas per plot (12.0 ft2 total area). Larvae that moved to the grass surface after twenty minutes, were collected and counted.

Predicting the Topographic Limits to a Gully Network Using a Digital Terrain Model and Process Thresholds

A digital terrain model is used with process thresholds to predict the extent of a stable gully network in a 5 km2 catchment of the southeastern highlands of Australia. The model, developed by Dietnch et al. [1992, 1993], predicts the topographic controls on channel networks and interprets these in terms of a critical shear stress for channel incision (τc) applied by saturation overland flow. We adapt the model slightly to compare the shear stress applied by Hortonian overland flow to that applied by saturation overland flow. The limits to gully erosion in the catchment are controlled strongly by a topographic threshold that has an inverse relationship between upslope catchment area and local gradient. The topographic threshold for channel incision is reproduced using a simple model of Hortonian overland flow and a τc appropriate for incision into a degraded grass surface (τc = 245 dyn/cm2). This is consistent with historical evidence for the timing of gully erosion. The study confirms a strong topographic control on the extent of the channel network in a catchment significantly different from the western North America catchments where the topographic threshold was first demonstrated. Despite its simplicity, the model for incision by overland flow appears capable of distinguishing the hydrological processes responsible for channel incision when these are reflected in the relationship between channel network and landscape morphology. The model requires relatively simple inputs, suggesting it may be useful for mapping gully erosion hazard in actively eroding catchments.

Salivacin 140, a novel bacteriocin from Lactobacillus salivarius subsp. salicinius T140 active against pathogenic bacteria

Fifteen of 353 environmental isolates of lactic acid bacteria consistently showed activity against Listeria monocytogenes, Streptococcus mutans, Actinomyces viscosus, and/or Propionibacterium acnes. Strain T140, isolated from the surface of Japanese pampas grass leaves and identified as Lactobacillus salivarius subsp. salicinius, also had activity against several Lactobacillus species, Staphylococcus aureus and Yersinia enterocolitica. Since the antagonistic factor(s) produced by T140 was sensitive to a proteolytic enzyme, it was concluded that a bacteriocin (named salivacin 140) was involved in the inhibition activity. Strain T140 required a high initial pH (7.5-8.5) in agar plates for bacteriocin production.

Control of Sod Webworm on A Kentucky Bluegrass Lawn in Scotts Bluff Co., Nebraska, 1995

Abstract Insecticides were evaluated for control of sod webworm larvae on a Kentucky bluegrass lawn at the Gering Cemetery, in Scotts Bluff County, Nebraska. The turf (80% Kentucky bluegrass, 20% perennial rye and tall fescue) was maintained at a mowing height of 2.5 inches. Thatch accumulation (finger compressed) in the plot area was 0.25 inches. Field conditions at the study site were: soil type, silt loam; soil organic matter, 1%; soil pH, 8.0. Weather conditions at the time of treatment were as follows: soil moisture 16%; air temperature 56°F; soil temperature 62°F; relative humidity 74%; wind direction and velocity 136° at 10 mph. Plots were 10 X 10 ft and the experimental design was a RCB with 4 replications. Treatments were applied on 11 May 1995. Liquid insecticides were applied using a CO2 sprayer with an LF–4 nozzle at 30 psi and delivering 3 gal finished spray/1000 ft2. Following applications, plots were irrigated with 0.125 inches of water. A total of 0.52 inches of rain fell during the post treatment period. Treatments were evaluated 4 and 7 DAT (15 and 18 May) by mixing 0.5 oz of Lemon Dawn® per gal of water and applying one gal of the dilution to each of two 6 ft sampling areas per plot (12.0 ft2 total area). Larvae that moved to the grass surface were collected and counted after twenty minutes.

Thermal Characteristics of Porous Pavement and Its effect On Urban Environment

The variability of surface heat flux depends strongly on the material heat absorption and rate of heat storage. Heat fluxes at the air/ground interface, the temperature in the surface and sub-surface of the various pavement were observed and analysed on summer days. It was found that the surface and subsurface temperatures of different pavement materials are significantly different from each other. Temperature at the porous and nonporous asphalt pavement at the peak hour was more than 52°C, which was 22°C higher than air temperature. Temperature of other porous and nonporous pavement such as concrete, porous concrete and porous block also reached at 50°. However temperature at the ceramic pavement is much lower than that of other surfaces and almost the same as that of the grass surface. A unidimensional model coupling with subsurface heat and moisture transfer was developed to study the thermal characteristics of porous pavement under fine meteorological conditions. Subsurface heat and moisture transfer revealed that pore volumes inside the porous pavement is very important for the transport of water vapour. Large pores inside the porous asphalt, porous concrete or porous blocks reduce the capillary pressure, consequently hinder the evaporation from the surface. Ceramic pavement materials absorb a large amount of water from the underlying soil layers due to small pores, which is turned to evaporation and released to the atmosphere.

Evaluation of Steinernematid Nematodes Against Popillia Japonica (Coleoptera: Scarabaeidae) Larvae: Species, Strains, and Rinse After Application

We evaluated the efficacy of Steinernema glaseri Steiner (strains NC, NJ-43, and a strain genetically selected for improved efficacy, SI-12), Steinernema anomali Kozodai (Ryazan strain), and Steinernema sp. (RGV strain) for the control of Japanese beetle, Popillia japonica Newman, larvae in the laboratory and field. Virulence of nematodes was assessed by the mortality of the host larvae and by the number of nematodes established per host. In laboratory tests, NJ-43 and SI-12 strains of S. glaseri were significantly more virulent to larvae than the NC strain, S. anomaly or Steinernema sp. Similar results were obtained in field tests, where the NJ-43 and 51-12 strains produced 66 and 65% reductions of Japanese beetle larval population as compared with the NC strain that produced a 44% reduction. Steinernema anomali and Steinernema sp. were as effective as the NC strain of S. glaseri . Nematodes could be successfully applied during midday, if washed from the grass surface with a rinse after application. We conclude that the choice of nematode strain and rinsing of nematodes after application are important factors in obtaining control of Japanese beetle populations in turfgrass.

Dew and guttation: formation and environmental significance

Observations were made of dew and guttation droplets on the grass Holcus lanatus L. (Yorkshire fog) at a site in rural Norfolk, UK, in 1985. The mean overnight dewfall was 0.14 ± 0.02 mm ( N = 40 nights). Guttation droplets found on grass blade tips had an average diameter of 1.49 ± 0.16 mm ( N = 1200 measurements), compared with 0.20 = 0.02 mm for true dew droplets ( N = 550 measurements). The average total volume of guttation water exuded per grass blade per night was 1.0 ± 0.3 × 10 −7 dm 3, which represents about 0.1 mm of precipitation; guttation supplied about the same amount of water as dewfall to a short grass surface. About 8% of the mean daily June–August net radiation in southern England would be needed to evaporate the average dew and guttation-derived leaf wetness, which totalled 0.25 ± 0.04 mm. Guttation amount was significantly correlated with soil temperature and moisture ( P < 0.001, r 2 = 0.874). The diameter of dew droplets was proportional to gravimetrically measured dewfall amount. The average total surface area of dewdrops on short grass was about 11 m 2 m −2 ground area. The corresponding average for guttation was about 5 m 2 m −2 ground area. The modal pH of a mixture of dewfall and guttation was 5.0–5.2. Chemical analyses of mixed samples of dew and guttation showed a ten-fold super-saturation with respect to CO 2. The equilibrium partial pressure of SO 2 in these bulked samples was very low (10 −4−10 −3 Pa), an order of magnitude lower than atmospheric concentrations. The half-life of SO 2 with respect to oxidation in the dew and guttation mixtures was a few hours.

The effect of the weather on the drying rate of cut diploid and tetraploid perennial ryegrass (Lolium perenne L.) and diploid hybrid ryegrass (Lolium perenne×L. multiflorum)

AbstractThe drying rate of cut diploid and tetraploid perennial ryegrasses (Lolium perenne L.) and a diploid hybrid ryegrass (Lolium perenne×L. multiflorum), and associated meteorological characteristics, were studied in the field for three successive years: 1988, 1989 and 1990. Meteorological elements measured were: air temperature (at 0·1 in and 1·5 in height), dew point temperature (at 1·5m height), temperature within the grass sward, grass surface temperature, global radiation and wind speed (at 2 in height).Apart from the weather, the drying depended on the grass species and the yield. Hybrid ryegrass had a lower initial moisture content at cutting in the morning than perennial ryegrass. Also, the hybrid ryegrass dried faster than the perennial ryegrass. Within the same varieties a low yield dried faster than a high yield. Frequent tedding did not influence the rate of drying. The temperature within the grass swath approached the air temperature at 1·5 m. The grass surface temperature was greatly affected by global radiation. Increasing wind speed had an adverse effect on the drying rate of grass.

Comments on “The Roughness Length for Heat and Other Vegetation Parameters for a Surface of Short Grass”

Comments on “The Roughness Length for Heat and Other Vegetation Parameters for a Surface of Short Grass”

A biomechanical analysis of the plantar surface of soccer shoes.

The incidence of severe injuries for soccer players may lead to long-term inactivity or, at worst, retirement from the game. Many of these injuries, particularly those involving the lower leg, can be attributed to adverse physical conditions at the interface between the soccer shoe and the playing support surface. This study investigated the biomechanical characteristics at this interface for a range of proprietary soccer shoes. An experimental system was designed and developed which, via a weighted pendulum arm making contact with a vertical column, provided controlled rotation of the forefoot of the soccer shoe on samples of playing surfaces. The overall rotation was found to depend on several physical and material factors. For example, the size 7 soccer shoes produced a statistically significant increase in axial rotation for the same impact energy compared to the larger sized shoes under test. In addition, flat soled shoes, designed for synthetic playing surfaces, produced consistently smaller rotations than shoes with either moulded or screw-in studs, although this finding depended on the moisture content of the playing surface. The pressure distribution within several soccer shoes was also measured using the F-Scan Gait Analysis System, for a subject walking across a grass surface. Results indicated differences in pressure distribution over the first metatarsal area of the foot, in existing shoe designs.

Charge separation associated with splashing of water drops on solid surfaces

Our laboratory experiments show that the charge separation when water drops splash on a brass surface is about an order of magnitude higher than when they splash on surfaces typical of ground surface, such as soil, silica or grass on which raindrops generally splash on the earth's surface. The change being separated has been observe to increase as the drop diameter increases from 3.6 to 7.0 mm. The size distribution of fragment droplets which result from a splash show that the total number of fragments is much larger when the splash occurs on brass surface as compared to that when it occurs on the soil, silica or grass surface. The results indicate that small drops in the range of 5.8 to 7.0 mm diameter are more efficient in changing the kinetic energy of the drop to electrical energy. Results of the experiment have been used to estimate the charge that is generated when raindrops splash on ground. Results of the experiment have been discussed in terms of the hardness of the target surface and the degree of violence of the splash.