Turfgrass Fertilization Research Articles

Contribution of Grass Clippings to Turfgrass Fertilization and Soil Water Content Under Four Nitrogen Levels

Contribution of Grass Clippings to Turfgrass Fertilization and Soil Water Content Under Four Nitrogen Levels

Reducing nitrate leaching losses from turfgrass fertilization of residential lawns.

Fertilizer applications on lawns have raised environmental concerns in many Canadian municipalities. In this greenhouse study, NO3 -N leaching losses from Kentucky bluegrass (Poa pratensis L.) lawns were evaluated on two soils (a schist loam and a clay loam) and on a sand/peat moss rootzone mix (80% sand, 20% peat moss). Eight different fertilizer N sources (urea, Polyon 8 and 12-wk release, Duration 45 and 90-d release, XCU, corn gluten meal, and UFLEXX) were assessed at five application rates (25-200kg N ha-1 yr-1 ) and two application frequencies over two 8-wk trials. Average NO3 -N concentration in leachate were measured at levels of 3.5, 7.4, and 1.4mg L-1 from turf grown in loam, clay, and sand respectively, but losses from loam and clay were mostly affected by N mineralization from organic matter. Turf fertilized with rates ≥100kg N ha-1 generally resulted in acceptable visual quality on both soils, but coated-urea fertilizers were more efficient to reduce leaching. In sand, UFLEXX and urea (150 and 200kg N ha-1 ) as well as XCU (200kg N ha-1 ) resulted in higher NO3 -N losses, varying from 8.5 to 23.7mg L-1 , and losses from other N sources were consistently below 3mg L-1 . Our results show that it is possible to maintain good quality turfgrass while keeping low NO3 -N leaching losses (i.e., <4mg L-1 ) in loam, clay, and sand by selecting the ideal combination of N source, N rate, and application frequency.

Evaluation of Algae-Based Fertilizers Produced from Revolving Algal Biofilms on Kentucky Bluegrass

The revolving algal biofilm (RAB) system is a wastewater treatment method that is effective at removing nutrients from wastewater, and as a result produces algae that could be used as a sustainable fertilizer source. A two-year greenhouse study was conducted to investigate if algae-based fertilizers produced from the RAB wastewater treatment system could be used as an effective and sustainable turfgrass fertilizer. Fertilizer treatments included pure algae (PA), algae + cellulosic filler (Blended), Milorganite, urea, and a nontreated control. Overall, in terms of percent green cover (PGC), Blended and PA performed similar to Milorganite and outperformed urea and the nontreated control. At the conclusion of the study, Blended was the only treatment to have an increased PGC relative to urea, which was a 29% increase. On average throughout the duration of the study, Blended and PA resulted in similar dark green color index (DGCI) relative to Milorganite and urea, and outperformed the nontreated control. Blended, PA, and Milorganite resulted in 50% and 111% greater total root length compared to urea and the nontreated control, respectively. Furthermore, Blended and Milorganite resulted in 107% and 136% greater root surface area and root volume, respectively, compared to urea and the nontreated control. Pure algae resulted in 58% greater root surface area relative to urea and the nontreated control. Blended and Milorganite increased the longest root by 22% compared to urea. Additionally, Blended and Milorganite resulted in 114% and 110% greater root and shoot biomass relative to the nontreated control, respectively. Blended and PA had a similar longest shoot length to Milorganite and urea. Overall, Blended and PA performed similar or better compared to Milorganite and urea in terms of turfgrass shoot growth, cover, color, and rooting. Thus, algae-based fertilizers (PA and Blended) produced from the RAB system should be considered an effective, sustainable turfgrass fertilizer.

Evaluation of Humic Fertilizers Applied at Full and Reduced Nitrogen Rates on Kentucky Bluegrass Quality and Soil Health

Soil health and sustainable management practices have garnered much interest within the turfgrass industry. Among the many practices that enhance soil health and sustainability are applying soil additives to enhance soil biological activity and reducing nitrogen (N) inputs—complimentary practices. A two-year study was conducted to investigate if reduced N fertilizer rates applied with humic substances could provide comparable turfgrass quality as full N rates, and whether humic fertilizers would increase biological aspects of soil health (i.e., microbial biomass and activity). Treatments included synthetic fertilizer with black gypsum (SFBG), poly-coated humic-coated urea (PCHCU; two rates), urea + humic dispersing granules (HDG; two rates), urea, stabilized nitrogen, HDG, and a nontreated control. Reduced rates of N with humic substances maintained turfgrass quality and cover, and reduced clipping biomass compared to full N rates. There were no differences in soil physical and chemical properties besides soil sulfur (S) concentration. SFBG resulted in the highest soil S concentration. Fertilizer treatments had minimal effect on microbial biomass and other plant-available nutrients. However, PCHCU (full rate) increased potentially mineralizable carbon (PMC) and N (PMN) by 68% and 59%, respectively, compared to the nontreated control. Meanwhile SFBG and stabilized nitrogen also increased PMC and PMN by 77% and 50%, and 65% and 59%, respectively. Overall, applications of reduced N fertilizer rates with the addition of humic substances could be incorporated into a more sustainable and environmentally friendly turfgrass fertilizer program.

Optimization of turfgrass fertigation rate and frequency

The main aim of turfgrass fertilization is to maintain high turf quality and obtain proper turf colour. Fertigation has been recognized as the best fertilization method for proper turfgrass nutrition and for minimizing nitrogen leaching. The aim of this study was to determine the optimum fertilizer rate and frequency for obtaining high-quality turfgrass and minimizing nutrient losses using a fertigation system.Lysimeter experiment was conducted on perennial ryegrass and Kentucky bluegrass mixture in 2016-2018. Three different fertigation rate treatments were applied: 60, 120, and 240 kg N ha−1 (NPK). Fertigation was applied at three intervals: 2, 4 and 8 days between fertigation (DBF). A control treatment with granular fertilizers (CTR) was also applied. The following turfgrass parameters were scored: leaf texture, overall appearance, turf cover and turfgrass colour. Additionally, colour was measured using a spectrophotometer. The colour parameters were expressed using the CIELAB colour system. Leached water samples were taken every two weeks during the vegetation period. The contents of the available forms of selected macro- and microelements (N, P, K, Mg, Ca, Na, Zn, Cu, Mn and Fe) were determined.The fertigation parameters, nutrient rate and interval between fertigation, significantly affected the contents in leachate of most nutrients and metals, except those of N-NH4, Na and Zn. Fertigation resulted in significantly lower N-NO3 losses in comparison with those under CTR. Higher rates of nutrients in fertigation solution resulted in increased N-NO3 content in leachate. The same effect was observed for P, Mg, K, Ca and Cu. The fertigation interval only affected P losses. The lowest P content in leachate was observed in the 2DBF treatment, and the P content in leachate increased as the intervals increased. The fertigation interval did not affect the leaching of any other nutrient. However, a significant difference in leachate content was observed between the CTR with granular fertilizers and fertigation. This effect was observed for N-NO3, K, Ca, Mn and Cu. A significantly higher content of all these nutrients was observed in leachate from the CTR treatment than in that from the fertigation treatments.Fertigation resulted in darker grass leaves in comparison with those under CTR. Higher fertigation rates resulted in darker leaves with higher green hue content than those at lower rates. There were no differences in colour hue in turfgrass fertigated at different time intervals. Turfgrass quality was affected by the fertigation rate and interval. This effect was significant for overall appearance, turf colour and leaf texture, but not for turf cover. The highest mean quality score was obtained at 240NPK, and the lowest was obtained at 60NPK. The optimal fertigation parameters for reduced nutrient losses and high turfgrass quality were calculated to be the 60NPK fertigation level at a fertigation interval of 4.4 days.

Branched-chain Amino Acids for Use as a Nitrogen Source on Creeping Bentgrass

Amino acids have been reported to improve turfgrass growth compared with mineral nutrition; however, amino acid catabolism in plants has not been well studied. A number of turfgrass fertilizers contain amino acids; however, some amino acids may be more effective additives in fertilizers than others. Three amino acids that could be effective nitrogen sources for plant growth are the branched-chain amino acids (BCAAs). The BCAA leucine (L), isoleucine (IL), and valine (V) could be effective additives because they are nonpolar and hydrophobic, which can promote plant uptake of these compounds. Although the effect of exogenously applied BCAA on plant growth is not well known, BCAAs have been reported to increase protein synthesis in humans, and that rate of increase is related to the intake ratio of L to IL and V. The objective of this study was to evaluate the use of L, IL, and V as a nitrogen sources on creeping bentgrass (Agrostis stolonifera) and to investigate the effect of BCAAs on plant growth when all three are applied as a combination. Using specially made rooting tubes, L, IL, and V were applied in a complete factorial and compared with equal urea nitrogen at four rates, as well as an untreated control. Where all three BCAAs were applied in combination, the application ratios of 2:1:1 and 4:1:1 (L:IL:V) were tested. At 63 days after seeding, there were no differences in root length, root weight, or shoot weight; however, BCAA 2:1:1 and 4:1:1 increased creeping bentgrass shoot density by 24% and 32%, respectively, compared with equal urea nitrogen. Where shoot density was increased, nitrogen application rate had no effect. On the basis of these results, BCAAs applied in a complete combination using ratios of 2:1:1 or 4:1:1 (3.03 lb/acre N) will provide a greater creeping bentgrass shoot density compared with equal urea nitrogen.

Predicting Cool‐Season Turfgrass Response with Solvita Soil Tests, Part 2: CO2–Burst Carbon Concentrations

Current turfgrass fertilizer recommendations do not account for plant‐available soil N mineralized from labile C fractions. The Solvita Soil CO2–Burst (SSCB) test can measure mineralizable C via soil CO2 respiration. This study was conducted across 3 yr (2014–2016) in Connecticut to determine: (i) if SSCB–C concentrations are correlated to responses from predominately Kentucky bluegrass (Poa pratensis L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] lawns, and (ii) the probability of turfgrass responses being equal to or greater than responses from common urea rates in relation to SSCB–C concentrations. Randomized complete block design field experiments were set out with 23 rates of organic fertilizer (0–2000 kg N ha−1 yr−1) and four different rates of urea (50, 100, 150, and 200 kg N ha−1 yr−1). Yearly spring soil samples were analyzed for SSCB–C concentrations and correlated with turfgrass responses. Growth and quality responded positively and linearly (P &lt; 0.001) to SSCB–C concentrations, but variability was high and correlations were relatively weak. When spring soil SSCB–C concentrations were ≥91, 113, 166, and 211 mg kg−1, there was a ≥90% probability that overall combined responses across species and variables would be equal to or greater than responses obtained from urea rates of 50, 100, 150, and 200 kg N ha−1 yr−1, respectively. The SSCB test has promise for predicting the probability of soils supporting turfgrass whose performance equals or exceeds benchmark values. This would be helpful in guiding N fertilization, but high variability within the test may limit its predictive ability.

Predicting Cool‐Season Turfgrass Response with Solvita Soil Tests, Part 1: Labile Amino‐Nitrogen Concentrations

ABSTRACTCurrent turfgrass fertilizer recommendations do not account for potential mineralizable N in the soil. The Solvita Soil Labile Amino‐Nitrogen (SLAN) test measures a labile fraction of soil N. This study was conducted across 9 yr (2008–2016) in Connecticut to determine if responses from predominately Kentucky bluegrass (Poa pratensis L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] lawns are correlated to SLAN–N concentrations, and to determine the probability of turfgrass responses equaling or exceeding the response from benchmark urea rates in relation to SLAN–N concentrations. Randomized complete block design field experiments were set out with 23 rates of an organic fertilizer (0–2000 kg N ha−1 yr−1) and four different rates of urea (50, 100, 150, and 200 kg N ha−1 yr−1). Yearly spring soil samples were analyzed for SLAN–N concentrations, and turfgrass growth and quality responses were collected during the growing seasons. Turfgrass responded positively and linearly (P &lt; 0.001) to SLAN–N concentrations, but correlations were relatively weak to moderate. When spring soil SLAN–N concentrations were ≥158, 165, 198, and 217 mg kg−1, there was a ≥90% probability that overall combined responses across species and measured variables would be equal to or greater than responses obtained from 50, 100, 150, and 200 kg urea N ha−1 yr−1, respectively. The SLAN test has promise as an objective soil test to categorize the N fertilization response potential of turfgrass soils, and this would be helpful in guiding N fertilization.

Turfgrass Nutrient Management and Regulatory Issues in the Chesapeake Bay Watershed

Water quality in the Chesapeake Bay has been impaired for decades from excess N, P, and sediment. As a result, the Chesapeake Bay Total Maximum Daily Load (CBTMDL) program was established by the USEPA in 2010. This program requires each of the six Chesapeake Bay watershed states and the District of Columbia to develop watershed implementation plans to limit N, P, and sediment loading. Watershed implementation plans include sections on stormwater management and improving turfgrass fertilization practices in developed areas. As a consequence, legislation restricting use of fertilizer on home lawns, sports turf, and golf courses was recently passed in Maryland, Virginia, and New York, and a similar bill has been introduced in the Pennsylvania legislature. Depending on the state, turfgrass nutrient management legislation requires government agencies to establish certification programs for professional fertilizer applicators, restrictions on P fertilizer, limits on N fertilizer rates, and restrictions on dates and location of applications. Although most turf managers are adapting to current regulations, proposed plans for monitoring nutrient use and additional restrictions are creating concern in the turfgrass industry. Increased focus on the environmental impact of turfgrass fertilization practices has led to a renewed emphasis on research to determine if N and P inputs can be reduced without a significant sacrifice in turfgrass quality and performance.

Sustainable Urban Landscaping: Consumer Preferences and Willingness to Pay for Turfgrass Fertilizers

Residential lawns provide diverse benefits, including social (e.g., enhancing humans’ physical and psychological well‐being), economic (e.g., increasing real estate values), and environmental (e.g., supporting local ecosystems) benefits. However, improper lawn fertilizer applications can cause adverse environmental consequences, such as excessive chemical runoff into adjoining watersheds leading to water contamination. Currently, the importance of eco‐friendly fertilizers to homeowners has not been assessed. This study uses a discrete choice experiment to test whether eco‐friendly fertilizer attributes influence homeowners’ preferences for sustainable landscape management. The findings show that eco‐friendly fertilizer attributes positively influence homeowners’ preferences and willingness to pay, supporting the premise that the promotion of eco‐friendly fertilizer features could improve local ecosystems through increased adaptation. Furthermore, this study tests whether certain fertilizer attributes influence homeowners’ preferences in states with and without fertilizer restrictions. Since the regulatory environment affects homeowners’ preferences for sustainable landscaping, this study compares the results between regulated and unregulated states. The findings reveal that homeowners are more likely to use and are willing to pay higher premiums for sustainable fertilizers in states with residential fertilization regulations. This suggests that with strict fertilizer ordinances, homeowners are more geared toward eco‐friendly landscaping options and that related educational programs should be made available.Les pelouses résidentielles offrent divers avantages, incluant les avantages sociaux (comme la valorisation du bien‐être physique et psychologique humain), économiques (comme la valeur immobilière), et environnementaux (comme l'appui des écosystèmes locaux). La mauvaise application des fertilisants a parfois des conséquences environnementales négatives comme le ruissellement chimique excessif dans les bassins hydrographiques attenants menant à la contamination des sources d'eau. En raison de l'importance des fertilisants respectueux de l'environnement pour la protection de ce dernier, cette étude emploie une expérience avec choix discrets pour évaluer si les attributs écologiques des fertilisants influencent les préférences des consommateurs et leur volonté de payer pour une gestion durable de l'aménagement. Les résultats indiquent que les attributs écologiques des fertilisants influencent positivement les préférences des consommateurs et leur volonté de payer, appuyant ainsi la prémisse selon laquelle la promotion des attributs écologiques des fertilisants de gazon pourrait améliorer les écosystèmes locaux. De plus, cette étude évalue l'influence des attributs de certains fertilisants sur les préférences des propriétaires résidentiels dans les états avec et sans restrictions sur l'application des fertilisants. Puisque le cadre règlementaire peut avoir un impact sur les préférences des consommateurs pour une gestion durable de l'aménagement paysager, cette étude compare les prévisions des états avec et sans cadre règlementaire. Les résultats démontrent que les consommateurs sont plus aptes à utiliser, et sont disposés à payer un surplus pour les fertilisants durables dans les états où des règlements concernant l'utilisation de fertilisants résidentiels sont en vigueur, portant donc à croire que les programmes éducatifs concernant l'aménagement paysager respectueux de l'environnement devraient être accompagnés d'ordonnances strictes en matière de fertilisants.

General Recommendations for Fertilization of Turfgrasses on Florida Soils

In many neighborhoods, people envy the individual with the most beautiful lawn and think they cannot grow a lawn of equal quality. That is not necessarily true. A well-maintained lawn only requires some knowledge about fertilization, watering, pest control, and mowing. This publication provides basic information about fertilization. By far, the best approach to a proper fertilization program is to start with a soil test, but, if a soil test is not available, these guidelines can be used for a general turfgrass fertilization program. Original publication date May 1991. Revised August 2013 and August 2015.&#x0D; SL21/LH014: General Recommendations for Fertilization of Turfgrasses on Florida Soils (ufl.edu)

Suburban groundwater quality as influenced by turfgrass and septic sources, delmarva peninsula, USA.

Suburban land use is expanding in many parts of the United States and there is a need to better understand the potential water-quality impacts of this change. This study characterized groundwater quality in a sandy, water-table aquifer influenced by suburban development and compared the results to known patterns in water chemistry associated with natural, background conditions and agricultural effects. Samples for nutrients, major ions, and isotopes of N and O in NO were collected in 2011 beneath turfgrass from 29 shallow wells (median depth 3.7 m) and from 18 deeper wells (median depth 16.9 m) in a long-term suburban development. Nitrate (as N) concentrations in groundwater beneath turfgrass were highly variable (0.02-22.3 mg L) with a median of 2.7 mg L, which is higher than natural water chemistry (>0.4 mg L; Na-Cl-HCO water type), but significantly lower than concentrations beneath a nearby agricultural area (median 16.9 mg L; < .0001). Dissolved Fe concentrations in shallow suburban groundwater, attributed to chelated Fe in turfgrass fertilizers, were significantly higher ( < .005) than concentrations from the agricultural site, although a Ca-Mg-Cl-NO water type was dominant in both areas. A Na-Cl-NO water type indicated a septic-system source for nitrate in deep suburban groundwater (0.06-6.0 mg L; median 1.5 mg L). Isotopic data indicated denitrification; however, geochemical techniques were more helpful in identifying nitrate sources. Results indicate that suburban expansion into agricultural areas may significantly decrease overall nitrate concentrations in groundwater, but excessive turfgrass fertilization could result in localized contamination.

잔디 비료 제형의 엽면 살포가 가을철 한지형 잔디의 생장 증대

Four preparations of liquid turfgrass fertilizers were tested cool season turfgrasses during fall season. The preparations of PS-A, PS-B, PH-C and PH-D for commercial products were contained with essential nutrient elements, seaweed extract, amino acids, and humus substance. Growth and quality of creeping bentgrass (Agrostis palustris Huds cv. Penn-A1) and Kentucky bluegrass (Poa pratensis L.) mixture (Midnight 33%, Moonlight 33%, Prosperity 33%) were evaluated by normalized difference vegetation index (NDVI), root length and fresh weight, shoot density, turf color, and chlorophyll content. Three foliar sprays of 4 preparations with an interval of 7 days were made in the fall of 2013 in the sod production field at Hapchun, Korea. No significant difference among 3 preparations was found in NDVI of creeping bentgrass. However, PS-A was significantly increased NDVI of Kentucky bluegrass. Two to three applications of PS-A significantly increased chlorophyll content and turf color. Three foliar sprays of PS-A and PS-B were significantly increased the shoot density of Kentucky bluegrass on 20 days after final application. These results may indicate that the use of some preparation is beneficial in producing higher quality turfgrass sod with better color and chlorophyll content during fall season.

Why “Feed the Lawn”? Exploring the Influences on Residential Turf Grass Fertilization in the Minneapolis−Saint Paul Metropolitan Area

We contribute to scholarly understanding of lawn fertilization behavior by formulating and testing models of fertilization and fertilization frequency that incorporate a wide range of human and structural influences. Specifically, we explore the impact of (a) structural/environmental aspects, (b) sociodemographics, and (c) attitudes and beliefs (informal norms, knowledge, environmental concerns, yard motivations, perceived ability regarding fertilization practices). We use survey data from a sample of 942 residents within the Minneapolis/Saint Paul, Minnesota metropolitan area. Our results indicate that fertilization is not driven by one overriding factor but by a combination of factors. Specifically, we show significant effects from a range of structural aspects (lot size, location, use of a professional lawn service), sociodemographics (home value), norms (perceived neighbor effects), knowledge (perceived positive/negative aspects of fertilization), and perceived ability. We also explore the urban/suburban divide and show higher fertilization stemming from suburban households.

A Review of Turfgrass Fertilizer Management Practices: Implications for Urban Water Quality

Urban watersheds include extensive turfgrass plantings that are associated with anthropocentric attitudes toward landscapes. Native and construction-disturbed urban soils often cannot supply adequate amounts of nitrogen (N) and phosphorus (P) for the growth and beauty of landscape plants. Hence, fertilization of landscape plants is practiced. Mismanaged fertilization and irrigation practices represent a potential source of nutrients that may contribute to water quality impairment. This review focuses on turfgrass fertilization practices and their impacts on urban water quality. Research results show that fertilization during active growth periods enhances turfgrass nutrient uptake efficiencies. The major concern regarding the fertilization of turfgrass and landscape plants in urban watersheds, therefore, is selecting the proper combination of fertilizer rate, timing, and placement that maximizes nutrient utilization efficiency and reduces the risk for nutrient loss to water bodies. Encouraging individuals to adopt best management practices (BMPs) is a priority for watershed managers. Research has found that educational programs are an important part of changing fertilization habits and that education needs to be thorough and comprehensive, which is beyond the scope of many seminars and fact sheets currently in use.

Effects of Fertilizer Type on Quality and Nutrient Content of Established Landscape Plants in Florida

In a series of three experiments, st. augustinegrass (Stenotaphrum secundatum ‘Floratam’), areca palm (Dypsis lutescens), canna (Canna × generalis ‘Richard Wallace’), pentas (Pentas lanceolata), allamanda (Allamanda cathartica ‘Hendersoni’), and nandina (Nandina domestica) were grown on highly leached sand soils in two locations in Florida. They were fertilized with typical turfgrass fertilizers having high nitrogen (N)-to-potassium (K) ratios and no magnesium (Mg), or several types of landscape palm fertilizers having low N:K ratios and 100% of their N, K, and Mg in controlled release form. St. augustinegrass, pentas, nandina, and allamanda visual quality were similar for all fertilizer types tested. However, cannas and areca palms had higher visual qualities when fertilized with an 8N–0.9P–10.0K–4Mg palm fertilizer than with higher N:K ratio turf fertilizers. High N:K turf fertilizers resulted in K deficiency severity equivalent to that of unfertilized controls and Mg deficiency that was more severe than unfertilized areca palms.

Effect of Fertilizer Source on Nitrate Leaching and St. Augustinegrass Turfgrass Quality

As a result of the coexistence of turfgrass and ornamentals in traditional landscapes, it is often impractical to separate fertilization and irrigation management among species. Furthermore, limited information is available on effects of turfgrass fertilizer on ornamental plants and vice versa. This research studied effects of two quick-release fertilizers (QRF) and one slow-release fertilizer (SRF) on quality and growth of turfgrass and ornamental plants and nutrient leaching. ‘Floratam’ St. Augustinegrass (Stenotaphrum secundatum Walt. Kuntze) was compared with a mix of common Florida ornamentals, including canna (Canna generalis L.H. Bailey), nandina (Nandina domestica Thunb.), ligustrum (Ligustrum japonicum Thunb.), and allamanda (Allamanda cathartica L.). All plants were grown in 300-L plastic pots in Arredondo fine sand. Less nitrate (NO3 −) was leached from turfgrass than from ornamentals and more NO3 − leached from QRF 16N–1.7P–6.6K than from SRF 8N–1.7P–9.9K. Quick-release fertilizers produced higher plant quality. This controlled environment research provides preliminary data on which in situ research may be modeled. Further research is required to verify how nutrient release rate affects turfgrass and ornamental quality and nitrate leaching in an urban landscape.

Use of Vermicomposted Waste Materials as a Turfgrass Fertilizer

Vermicomposting is the process of fragmenting organic wastes with certain species of earthworms. A variety of vermicomposts are being marketed as fertilizer materials for turfgrass management, particularly in the golf course industry. In 2002 and 2003, field trials were conducted on established kentucky bluegrass (Poa pratensis) in Columbus, Ohio, to evaluate the use of vermicomposted animal, food, paper, and turfgrass clipping waste materials as a turfgrass fertilizer under home lawn maintenance conditions. Visual quality of the plots was significantly higher for 2 weeks after application of paper vermicompost, regardless of application rate. Few other differences in either turfgrass visual quality of clipping yields were observed during a 6-week period after application, regardless of application rate or source of vermicompost. Based on the results of these studies, the use of vermicompost as a fertilizer material on established turfgrass is not warranted.

In situ Turfgrass Establishment: I. Responses to Arbuscular Mycorrhizae and Fertilization

ABSTRACT A two-year field study was conducted to evaluate the impact of fertilization and arbuscular mycorrhizae on the in situ establishment of turfgrasses in low and high phosphorus content experimental sites. Organic or chemical fertilizers were applied on Kentucky Blue-grass and Creeping Bentgrass plots inoculated with either Glomus mosseae, G. aggregatum or G. intraradices. The arbuscular mycorrhizal control was made from original soils with their respective indigenous fungal populations. Soil surveys for indigenous Glomales populations revealed the predominance of Gigaspora margarita and Scutellospora calospora species at the high and low P sites, respectively. Both turfgrass species showed higher root colonization levels, up to 60%, at the low phosphorus soil site. Root colonization levels of Creeping Bentgrass were found to be almost twice those of Kentucky Bluegrass for all mycorrhizal treatments. The average growth rates of aerial parts were not affected by either mycorrhizal or fertilization treatments. Statistical analyses showed a significant interaction (P ≤ 0.05) between high and low phosphorus sites for Creeping Bentgrass, and root colonization levels, especially with G. intraradices treatment. For both turfgrass species, fertilization and site effects were predominant. As turfgrass is highly dependent on soil quality and as arbuscular mycorrhizal benefits vary with plant species, special care in the development of turfgrass management practices should be taken into account to optimize the arbuscular mycorrhizal turfgrass establishment process.

Nitrogen/Potassium Fertilization Ratios for Bermudagrass Turf

Turfgrass fertilizers often contain approximately one‐half as much potassium (K) as nitrogen (N), on a weight basis. Since K fertilization has been shown to be very beneficial for turfgrass appearance and growth, higher rates of K fertilization, relative to N, have been suggested. The effect of K/N fertilization ratios on `Tifgreen' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] growth and quality was studied over a 3‐yr period in south Florida for three rates of N fertilization. Severe K deficiencies were observed in the absence of K fertilization. However, increasing K fertilization beyond a K/N fertilization ratio of 0.5 to 1 had virtually no effect on turfgrass appearance, growth, on resistance to bermudagrass decline, or on root weight. Increasing K fertilization relative to N fertilization did not provide commensurate increases in tissue K.