Effects of Carbon Nanomaterials on Soil Enzyme Activity of Turfgrass

[Objectives]This study was conducted to evaluate the effects of carbon nanomaterials on soil ecosystem and explore the ecological risks of environmental exposure of carbon nanomaterials. [Methods] The effects of carbon nanomaterials on soil enzyme activity was studied by adding graphene, graphene oxide and carbon nanotubes to turfgrass soil. [Results] Compared with the control(CK), the activity of soil protease, sucrase, alkaline phosphatase and catalase was not significantly affected by carbon nanomaterials. Under the treatment of carbon nanotubes, urease activity was significantly lower than that of graphene and graphene oxide, and dehydrogenase activity was significantly lower than that of the CK, graphene and graphene oxide. [Conclusions] This study provides a theoretical basis for the safe application of carbon nanomaterials.

Seasonal Variation of Carbon and Nitrogen Emissions from Turfgrass

The role of turfgrasses in C and N cycling in the southeastern U.S. has not been well documented. The objectives of this research were to determine the characterization of chemical quality, clipping decomposition rates, and C and N release from warm- and cool-season turfgrasses. The study was conducted for 46 weeks in 2012 in Auburn, AL. Four warm season turfgrasses were used included (bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy], centipedegrass (Eremochloa ophiuroides (Munro) Hack), St. Augustinegrass (Stenotaphrum secundatum (Walter) Kuntze), zoysiagrass (Zoysia japonica Steud.), and one cool season turfgrass (tall fescue (Festuca arundinacea Schreb)). Litter was placed into nylon bags at an oven dry rate of 3.6 Mg?ha?1. Litter bags were retrieved after 0, 1, 2, 4, 8, 16, 24, 32, and 46 weeks, and analyzed for total C and N. A double exponential decay model was used to describe mass, C, and N loss. Results indicated that tall fescue decomposition occurred rapidly compared to warm season turfgrasses. Litter mass loss measured after 46 weeks was determined to be 61.7%, 73.7%, 72.2%, 86.8%, and 45.4% in bermudagrass, centipedegrass, St. Augustinegrass, tall fescue, and zoysiagrass respectively. Zoysiagrass litter had a higher lignin concentration, while tall fescue had the lowest lignin. Over 46 weeks’ release of C was in the order: zoysiagrass > bermudagrass = centipedegrass = St. Augustinegrass > tall fescue, and release of N was in the order zoysiagrass > centipedegrass > bermudagrass = St. Augustinegrass > tall fescue. Our study concluded that, zosiagrass is a better choice for home lawns.

Heavy metal accumulation of urban domestic rubbish compost in turfgrass by EDTA chelating

Seven kinds of heavy metal accumulation of rubbish compost in turfgrass by EDTA chelating were investigated. With EDTA application, heavy metal accumulation by two species of turfgrass was increased significantly. The enrichment coefficients of Lolium perenne L（L） and Festuca arundinacea L（F） to Cr reached 9.4.5 and 6.15 respectively. In the range of EDTA dosages given, heavy metal accumulation in turfgrass increased with increasing EDTA level. There were significant differences in remediation of different metals by applying EDTA. L had high ability to accumulate Cr, Cd, Ni and Zn, showing better remediation to heavy metals of rubbish compost. In contrast, F showed high ability to accumulate Cr, Ni, Cu and Zn. Low EDTA level increased aboveground net primary production （ANP） of turfgrass, but EDTA would considerably inhibit it when EDTA was higher than 20 mmol/kg. The results demonstrated that the optimum dosage of EDTA for remediating heavy metals in rubbish compost by turfgrass was between 10 mmol/kg and 20 mmol/kg.

Heavy Metal Control in Domestic Rubbish by Source Screening and Suitability of Nutrient Elements as Turfgrass Medium

This paper, probing into heavy metal control in domestic rubbish by source screening and nutrient element analysis, revealed the feasibility of source control of heavy metals and the suitability of rubbish as turfgrass medium. Heavy metals in domestic rubbish were controlled by source screening before composting. The study consisted of a control with garden soil. The contents of main mineral elements and heavy metals in rubbish compost and control were determined by the method of ICP-AES. The results showed that heavy metal concentrations in rubbish were lower than those in garden soil, and little difference occurred between rubbish and garden soil in main mineral element concentrations. Based on this, it was concluded that rubbish compost was favorable for using as turfgrass medium and heavy metal control in rubbish by source screening was effective.

Effect of Drought Stress on Growth and Water Physiological Characteris­tics of Poa sibirica

In order to develop the resources of native turfgrass,the morphological traits and drought resistance of native Siberian bluegrass(Poa sibirica,abbreviated as PS)was evaluated using the introduced Kentucky bluegrass'Midnight'(Poa pratensis,abbreviated as PP)as a control.Two water schemes were imposed to plants in this pot culture study in greenhouse.One was with drought stress persistent limiting water supply for 20 days,the other was re-hydrated until 14 days after drought.The leaf shape,turf color,water status and cell plasma membrane permeability were evaluated.Similar changing trends with these parameters were shown for both species,and there were not significant differences with most evaluations during drought and re-water periods.The values leaf width and length of PS were higher while leaf color intensity was slightly lower than that of PP,but the greenness of PS leaf was still visually acceptable.There were not significant differences with cell membrane stability between the two species.In comparison,the native wild species PS possessed the potential for to be domesticated into a new cultivar for turf industry.

Application Index of Enviromental Engineering by Using Carrier of Waste Material for Belt Seeding Establishment

According to the principle of belt seeding establishment of adhesive bonded fabric,applied indexes of belt seeding establishment effect were studied using carrier combination of several kinds of waste meterials under soil cover.The results showed that the effect depended on the coordinated characteristics of carrier combination from turfgrass and waste materials.It was testified that production of belt seeding was feasible using a certain kind of waste material carrier under given conditions.The study provided a scientific basis for applying evvironmental engineering to belt seeding establishment of waste materials and developing nwe industry of environmental protection.

Effects of Turfgrass Thatch on Water Infiltration, Surface Runoff, and Evaporation

The development of a (layer of) thatch in turfgrass causes important changes to near-surface eco-hydrological processes. In this study, we investigated the effects of turfgrass thatch, specifically Kentucky bluegrass (Poa pratensis L.) and red fescue (Festuca rubra L.) on water infiltration, surface runoff, and soil moisture evaporation. The thatches were collected from the field for controlled experiments using packed soil columns under various rainfall conditions. Results indicated that the presence of thatch delayed the onset of infiltration compared with situations without a thatch at the soil surface. Infiltration was delayed for a longer period in thicker red fescue thatch than thinner Kentucky bluegrass thatch. The presence of a thatch reduced runoff by holding more water locally during the rainfall period and allowing a longer period of time for infiltration. Additionally, evaporative water loss was reduced with the presence of thatch than that of bare soil. Our results highlight that the presence of thatch changes the near-surface hydrological processes, which may help improve turf management practices in terms of thatch control and irrigation scheduling.

Effects of Nitrogen Fertilization on Some Turfgrass Characteristics of Perennial Ryegrass (Lolium perenne L.)

The paper aimed to study the effects of nitrogen fertilization on the yield and some plant characteristics of perennial ryegrass (Lolium perenne L.). The study was conducted at Agricultural Research and Application Center of the Faculty of Agriculture in Igdir University in 2013. In the experiment, eight levels of fertilizers: 0, 10.0, 20.0, 30.0, 40.0, 50.0, 60.0 and 70.0 kg N/ha per month were applied in perennial ryegrass (Lolium perenne L.) during the sixth growing season. A randomized complete block with three replications was used as the experimental design. Nitrogen application affected plant height, green grass yield, plant covering rate, canopy color and turfgrass quality values of perennial ryegrass positively. In both monthly and as the average of nitrogen application, times of application (spring, summer and fall) caused the most uniform turfgrass quality and establishment. Results indicated that although a significant impact was on the character investigated, such as the leaf length, green grass yield, plant cover ratio, canopy color and turfgrass quality, the doses of nitrogen fertilizer have created close to each other in groups. In the stand point of view of all characters, N1, N2 and N3 were located in first group, N4 and N5 in the second group, N6 and N7 in the third group, expect for control (N0). It can be concluded that 40.0-50.0 kg N/ha per month may be more suitable to be used in ryegrass production in the landscape.

Early Nutrient Diagnosis of Kentucky Bluegrass Combining Machine Learning and Compositional Methods

Kentucky bluegrass (Poa pratensis L.) is the most common perennial turfgrass species grown on playgrounds, municipal and residential lawn areas, and golf tees, fairways and roughs. Fertilization is the most efficient way to improve and maintain turfgrass aesthetic quality. Tissue diagnosis can guide fertilization, but tissue concentration ranges are biased by not taking into consideration nutrient inter-relationships, carryover effects and other key features. The centered log-ratio transformation reflects nutrient interactions in plants and avoids statistical biases. Machine learning (ML) models relate the target variable to the key features ex ante, and can predict future events from prior knowledge. The objective of his study was to predict turfgrass quality from key features and rank nutrients in the order of their limitations. The experimental setup comprised four N, three P, and four K rates applied on permanent plots during three consecutive years. Soils were a loam and an USGA sand. Eleven elements (N, S, P, K, Ca, Mg, B, Cu, Zn, Mn, Fe) were quantified in clippings collected during spring, summer and autumn every year. Turfgrass quality was categorized as target variable by color rating. Concentrations were centered log-ratioed (clr) partitioned into four quadrants in the confusion matrix generated by the xgboost ML model. The area under curve (AUC) and model accuracy were high to predict turfgrass color from the nutrient analyses of clippings collected in the preceding season, facilitating the seasonal adjustment of the fertilization regime to sustain high turfgrass quality. We provide a computational example to run the ML model and rank nutrients in the order of their limitations.

Post-Emergence Control of Windmillgrass (<i>Chloris verticillata</i>Nutt.) Using Selected Herbicides

Windmillgrass (Chloris verticillata Nutt.) is spreading from native areas, becoming problematic in established turf in Missouri, and surrounding states. Limited information is available regarding post-emergence (POST) control options for turf. The objective of this research was to assess the visual and biomass response of windmillgrass to selected herbicides approved for use in turf. In one study, a greenhouse experiment was conducted with POST application of seven selected herbicides, including dimethylamine salt of quinclorac, fenoxaprop-P-ethyl, foramsulfuron, mesotrione, sulfentrazone, and topramezone in a tank-mixture with triclopyr, as well as a pre-packed product containing thiencarbazone-methyl, foramsulfuron, and halosulfuron-methyl. Under the same experimental conditions, five additional treatments, including mesotrione or topramezone applied at label-suggested rates alone or in combination with triclopyr, in addition to triclopyr alone, were applied to a second study on tillering windmillgrass. At 4 weeks after treatment (WAT), only fenoxaprop-p-ethyl consistently resulted in a complete control of windmillgrass. No measurable regrowth of plants was observed two weeks following the initial collection of windmillgrass aboveground biomass. In the second study, combinations of mesotrione and topramezone with triclopyr resulted in 100% visual injury of windmillgrass at 4 WAT;mesotrione and topramezone alone only resulted in up to 66% visual injury. Triclopyr alone resulted in 91% injury at 4 WAT. The greatest reduction of windmillgrass biomass and least amount of regrowth resulted from mesotrione and topramezone combinations with triclopyr. Control of windmillgrass is effective with fenoxaprop-P-ethyl alone, but use of a 4-Hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor such as mesotrione and topramezone should include the addition of triclopyr.

A New Species of Dallasiellus Berg (Hemiptera: Heteroptera: Cydnidae) from Caribbean

The genus Dallasiellus Berg (Hemiptera: Cydnidae) is revised with the description of a new species from Caribbean, Dallasiellus varaderensis nov. sp. A diagnosis of species is based on external morphology of males and genitalia examination. Dorsal view of adults and parameres are illustrated. Notes about their biology and host plants are briefly discussed.

Breeding for drought tolerance in perennial ryegrass(Lolium perenne L.)and tall fescue(Lolium arundinaceum[Schreb.]Darbysh.)by exploring genotype by environment by management interactions

Background:Drought‐tolerant turfgrass cultivars are becoming more important each year as landscape irrigation practices are becoming more restrictive.Methods:In this study,we quantified the level of drought tolerance(DT)in perennial ryegrass and tall fescue genotypes across years under different mowing(MH)and fertility(FL)rates.A total of 48 ryegrass and 38 tall fescue genotypes were planted in 2011 at NexGen,Albany,OR.The trial was divided into three subtrials:(i)DT;(ii)MH and DT;and(iii)FL and DT.Results:The results showed that there was significant genetic variance for most of the traits in both species.The genotype×year interaction was predominantly simple,indicating small changes in genotype ranking for both species.Lower MH improved DT in perennial ryegrass,whereas higher MH resulted in greater DT in tall fescue.For both species,higher MH improved the population mean for turf quality.Higher FL inputs led to higher turf quality for both species,but it did not affect the DT response.Conclusions:Using a selection index,six genotypes for perennial ryegrass and four for tall fescue were selected.

Heavy Metal Accumulation and Ecological Responses of Turfgrass to Rubbish Compost with EDTA Addition

Domestic rubbish compost is a complex-polluted system, containing multiple heavy metals, which limits its application. In the present study, Cr, Mn, Ni, Cu, Zn, Cd, and Pb accumulation and ecological responses of turfgrass to rubbish compost were investigated following the addition of EDTA. The results showed that the addition of EDTA significantly increased heavy metal accumulation in Lolium perenne L. and Festuca arundinacea L. Most heavy metal concentrations in L. perenne increased with increasing EDTA supply. The concentrations of Cr, Mn, Ni, Cu, and Cd in L. perenne were highest following the addition of 30 mmol/kg EDTA and the concentrations of Cr and Ni at this point reached concentrations of 1 914.17 and 521.25 μg/g, respectively. When the EDTA level was 〈 20 mmol/kg, the accumulation of most heavy metals in F. arundinacea increased with increasing EDTA supply, but showed a tendency to decrease at EDTA concentrations 〉20 mmol/kg. The highest concentrations of Mn, Ni, Cu, and Zn in F. arundinacea reached 268.01, 110.94, 161.52 and 1 354.97 μg/g, respectively, following the addition of 20 mmol/kg EDTA. The EDTA-induced increase in the accumulation of heavy metals in turfgrass was plantand metal-specific. L. perenne had a relatively high ability to accumulate Cr, Ni, and Zn. The highest Zn concentration was 2 979.58 μg/g and, following the addition of EDTA, the concentrations of the three metals were increased 26.23, 20.03, and 10.49-fold, respectively, compared with control. However, F. arundinacea showed a high ability to accumulate Cr, with the highest concentration （596.02 μg/g） seen following the addition of 30 mmol/kg EDTA; the concentration of Cr increased 15.51-fold compared with control. With EDTA addition, ecological responses of both turfgrass species showed that EDTA at concentrations 〈10 mmol/kg increased seed germination and aboveground net primary production （ANP） of L. perenne and slightly inhibited those of F. arundinacea, but EDTA at concentrations 〉20 mmol/kg inhibited these parameters significantly for both species. Moreover, EDTA increased the chlorophyll and proline content at all concentrations tested. On the basis of the synthetic remediation index, the optimal EDTA concentration for turfgrass remediation of heavy metals in compost is approximately 10 mmol/kg.

Quantifying golf course nitrogen use efficiency

Background:Previous studies have surveyed golf courses to determine nitrogen(N)fertilizer application rates on golf courses,but no previous studies have attempted to quantify how efficiently golf courses use nitrogen.Methods:This study tests the ability of the growth potential(GP)N Requirement model as a benchmarking tool to predict a target level of N use on 76 golf courses in 5 regions of the US(Midwest,Northeast,East Texas,Florida,Northwest)and 3 countries in Europe(Denmark,Norway,UK).Results:The ratio of the golf course-wide N application rate to the GP N requirement prediction(termed the nitrogen efficiency score or NES)was 0.27,indicating that golf courses used 73%less N than predicted by the model.As such,the GP N Requirement model needs to be recalibrated to predict N use on golf courses.This was achieved by adjusting the Nmax coefficient in the model.N rates on golf courses were widely variable both within and across regions.All regions had a coefficient of variation in N rates of 0.46 or greater.Conclusions:The high variation in N rates,which is largely unexplained by climate,economic factors,grass type,and soil type,may be indicative of inefficient N use in golf course management.