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Soil greenhouse gas emissions from Australian sports fields
Journal Pre-proof Soil greenhouse gas emissions from Australian sports fields
David Riches, Ian Porter, Greg Dingle, Anthony Gendall, Samantha Grover PII:
S0048-9697(19)34411-0
DOI:
https://doi.org/10.1016/j.scitotenv.2019.134420
Reference:
STOTEN 134420
To appear in:
Science of the Total Environment
Received date:
22 March 2019
Revised date:
11 September 2019
Accepted date:
11 September 2019
Please cite this article as: D. Riches, I. Porter, G. Dingle, et al., Soil greenhouse gas emissions from Australian sports fields, Science of the Total Environment (2019), https://doi.org/10.1016/j.scitotenv.2019.134420
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© 2019 Published by Elsevier.
Journal Pre-proof Soil Greenhouse Gas Emissions from Australian Sports Fields David Riches1, Ian Porter1, Greg Dingle2, Anthony Gendall1, Samantha Grover3 1
Department of Animal Plant and Soil Sciences, La Trobe University, Bundoora, Vic, Australia
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Department of Management, Sport and Tourism, La Trobe University, Bundoora, Vic, Australia
3
Applied Chemistry and Environmental Science, School of Science, RMIT University, Melbourne, Vic, Australia
Corresponding Author:
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David Riches, Biological Sciences 1, Department of Animal Plant and Soil Science, La Trobe University, Bundoora,
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Abbreviation list
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Vic 3086, Australia. [email protected]
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GHG, greenhouse gas; GWP, Global warming potential; ODS, ozone depleting substance; PCU polymer coated
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urea; NI, nitrification inhibitor; CO2-e, carbon dioxide equivalents; MAP, mono ammonium phosphate
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Keywords: Nitrous oxide, turf, nitrogen, methane
Journal Pre-proof Abstract Managed turf is a potential net source of greenhouse gas (GHG) emissions. While most studies to date have focused on non-sports turf, sports turf may pose an even greater risk of high GHG emissions due to the generally more intensive fertiliser, irrigation and mowing regimes. This study used manual and automated chambers to measure nitrous oxide (N2O) and methane (CH4) emissions from three sports fields and an area of non-sports turf in southern Australia. Over 213 days (autumn to late spring), the average daily N2O emission was 37.6 g N ha-1day1
at a sports field monitored at least weekly and cumulative N2O emission was 2.5 times higher than the adjacent
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non-sports turf. Less frequent seasonal sampling at two other sports fields showed average N2O daily emission
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ranging from 26-90 g N ha-1 day-1. Management practices associated with periods of relatively high N2O emissions were surface renovation and herbicide application. CH4 emissions at all of the sports fields were generally
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negligible with the exception of brief periods when soil was waterlogged following heavy rainfall where emissions
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of up to 1.3 kg C ha-1 day-1 were recorded. Controlled release and nitrification inhibitor containing fertilisers didn’t
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reduce N2O, CH4 or CO2 emissions relative to urea in a short term experiment. The N2O emissions from the sports fields, and even the lower emissions from the non-sports turf, were relatively high compared to other land uses in
1. Introduction
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mitigation practices.
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Australia highlighting the importance of accounting for these emissions at a national level and investigating
Climate change driven by anthropogenic increases in GHG concentrations has been widely recognised as posing a major global threat. In addition to CO2, CH4 and N2O are the two most important GHGs with global warming potential (GWP) values of 28-36 and 265-295 respectively on a 100 year timescale relative to CO2 (IPCC, 2014). N2O is also the major ozone depleting substance (ODS) in terms of current emissions (Ravishankara et al., 2009) after the phase out of other CFCs and other major ODS under the Montreal Protocol. Considerable work has been conducted to measure GHG emissions from soils in agricultural and natural systems, however, fewer studies have examined other land uses such as urban turf. Due to the high aesthetic standards required for turf, management is often intensive with large inputs of fertiliser and frequent irrigation and mowing, the latter adding labile organic matter to soil through the return of clippings. These factors together with elevated soil temperatures caused by
Journal Pre-proof close mowing result in a high potential for emissions of N2O (Horgan et. al., 2002; Mancino et al., 1988; Townsend-Small, 2011). Studies on non-sports turf have shown N2O emissions can be higher than from natural and agricultural systems with up to 3 kg N ha-1 annual emissions (i.e. 8.2 g N ha-1 day-1) observed (Braun and Bremer, 2018; Bremer, 2006; Groffman et al., 2009; Kaye et al., 2004; Livesley et al., 2010). Less GHG emission data is currently available for sports fields. This may be at least partially due to the difficulty in collecting GHG emission data from sports fields because gas sampling equipment cannot be left in situ for extended periods due to disruption to sporting and ground management activities. Another potential reason is that the magnitude of
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GHG emissions from sports fields and other intensively managed turf relative to other land uses has been largely under appreciated. Studies of sports field GHG emissions conducted in the northern hemisphere have also shown
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high N2O emissions relative to other land uses (Gillette et al., 2016; Townsend-Small and Czimczik, 2010;
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Townsend-Small et al., 2011). The magnitude of N2O emissions from turf is generally related to N fertilisation and
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precipitation/irrigation (Braun and Bremer, 2018; Bremer, 2006; Livesley et al., 2010; Mancino et al., 1988;
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Maggiotto et al., 2000).
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Owing to the relatively few studies globally, the aim of this study was to collect N2O and CH4 emissions data for
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sports fields under typical management programs in Australia in order to benchmark their magnitude in comparison to other land uses and to identify potential strategies for mitigation of GHG emissions. At one site different fertiliser treatments were evaluated for their effects on GHG emissions to determine if emissions could be effectively mitigated by improving the fertiliser management. 2. Materials and Methods 2.1 Study sites Three sports fields and an area of non-sports turf bordering one field, located in Bundoora in metropolitan Melbourne, Australia were used in this study (Table 1). The management practices at these fields were representative of well managed sports fields in the local area. The region has a mean annual precipitation of 659 mm and mean annual maximum and minimum temperatures of 20.0 ˚C and 9.6 ˚C, respectively (20 year average). Two of the sports fields (Field 1 and Field 3) were used for cricket and Australian Rules football for the summer
Journal Pre-proof and winter seasons respectively, and represent the most common type of sports field in the region. The soil at all sites is highly altered, with an imported upper sand layer, classified as Anthrosol (IUSS 2015). Field 2 was a baseball field, a less common type of sports field in the region. Fields 1 and 2 and the non-sports turf (Lawn) were located on La Trobe University’s Melbourne, Australia campus (latitude -37.722 S, longitude 145.042 E, 74 m above sea level) while Field 3 was located on the campus of a school, Parade College (latitude -37.689 S, longitude 145.067 E, 102 m above sea level), approximately 5 km away from the other two fields. Field 1 had a couch grass (Cynodon dactylon) playing surface while Field 2’s surface was composed of ryegrass (Lolium Perenne) and annual
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bluegrass (Poa annua). The Lawn was an area of kikuyu (Pennisetum clandestinum) lawn immediately adjacent to the Field 1. Field 3’s surface was couch/kikuyu grass, over-sown with ryegrass (Lolium Perenne) for the winter
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season.
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Field 1 was monitored regularly (generally at least weekly) for the emission of N2O and CH4 over a period of 7
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months (April 21 - November 20, 2017) while the adjacent Lawn site was monitored on a subset of these sampling
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days. Fields 2 and 3 were sampled for N2O and CH4 emissions less frequently than Field 1. At these two sites, gas sampling was conducted alternate days three times a week over two week sampling events with three seasonal
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(Insert Table 1)
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sampling events (winter, spring and summer) conducted at each site during the trial.
2.2. Ground management (GHG Benchmarking study) The existing management programs for fertiliser, irrigation and weed control were used at all sites. The approximate annual N fertiliser application rates were 200, 200 and 180 kg ha-1 for Fields 1, 2 and 3 respectively. At Fields 1 and 2 the fertiliser used was a polymer coated urea (PCU) formulated to slowly release N over a period of up to 16 weeks, (Best Cascade K® 21-1-17, Simplot) while the Field 3 fertiliser programme included a urea blend fertiliser, (Paton 20-0-16+Fe®, Amgrow) and mono ammonium phosphate (MAP). The fertiliser applications during the study were application of PCU at a rate of 49.4 kg N ha-1 on April 24, 2017 and October 20, 2017 at field 1 and on October 24, 2017 at field 2. Field 1 was sprayed with glyphosate (Roundup Powermax®, Monsanto) on May 11, 2017 to control winter grass (Poa Annua). Field 3 was fertilised with Paton® 20-0-16+Fe at 50 kg N ha-1 on June 5, 2017 and November 12, 2017 and with MAP at 15 kg N ha-1 on September 20, 2017.
Journal Pre-proof At all of the sporting fields the turf was mown as required (once or twice weekly depending on growth) to a height of 20-32 mm height. Irrigation frequency varied throughout the year to meet the water demand of the turf taking into account precipitation and climatic conditions. During the summer months, irrigation was generally performed every second day, while over winter there was usually no irrigation applied. Spring irrigation was at a lower frequency than the summer period due to the higher rainfall at this time of year except at the Field 1 which was not irrigated over spring due to an impending redevelopment at the site. At Field 3, a turf renovation programme began on September 19, 2017 where the field was mechanically aerated, fertilised with MAP and re-
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seeded. Over the following 3 week period, daily short irrigations were applied, depending on precipitation, to facilitate establishment of the re-seeded grass. Surface renovation is a common practice for fields used for
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football to alleviate compaction and drainage problems caused by heavy foot traffic under the higher soil
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moisture conditions that occur for winter sports. The Lawn site was unfertilised and unirrigated throughout the
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sampling period.
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2.3 Gas sampling (GHG Benchmarking study)
N2O and CH4 fluxes were measured using either manual or automated static chambers consisting of acrylic walled
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boxes covered with reflective insulation, placed on top of flanged stainless steel bases driven into the soil to a depth of 15 cm with a square footprint of 0.5 x 0.5 m. Initially, vented manual chambers (Gibson Engineering) with a headspace height of 0.25 were used and samples were manually collected with a syringe through a sampling port in the lid. On each sampling day, three gas samples of 20 mL were extracted from chambers at fixed intervals (0, 30 and 60 mins) and transferred into 12 mL evacuated vials (Exetainer, Labco) with sampling taking place between 11:00-13:00 Australian Eastern Standard Time. Previous work had shown this sampling time was a reasonable approximation of the average daily emission (unpublished data). Gas samples were subsequently analysed for GHG concentrations with a gas chromatograph (8610C, SRI Instruments) using a Hayes Sep D column (SRI Instruments) fitted with electron capture and flame ionisation detectors for N2O and CH4 respectively. From June 28, 2017, the manual chambers were replaced at Field 1 with an eight chamber system where chamber closure, sample collection and N2O and CH4 analysis was automated as described in Scheer et al. (2014). The eight
Journal Pre-proof chambers were arranged in two sets of four chambers that shared common pneumatic lines for control of chamber opening and closing. Two chambers in each set were installed in Field 1 and the other two the Lawn site bordering the sporting field. Each set of four chambers closed for 1 h during a sampling cycle with four gas samples taken at 15 minute intervals during this time. The automated system was operated for 1 or 2 cycles per sampling day at approximately the same time of day as the previous manual sample collection. Emission fluxes were determined from the linear increase in concentration of the gas over the closure period correcting for air temperature and atmospheric pressure (Scheer et al., 2014). Flux data was discarded if the regression coefficient
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(r2) for the linear increase was <0.8. Cumulative N2O fluxes at the Field 1 and Lawn sites were calculated by using
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trapezoidal integration.
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2.4. Effect of fertiliser type on GHG emissions
Sports activities at Field 1 ceased on October 20, 2017 which allowed a number of fertiliser treatments to be
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applied to small plots followed by continuous automated GHG emission monitoring. Fertiliser treatments were
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PCU (Best Cascade K® 21-1-17, Simplot), urea (Urea), urea with the nitrification inhibitor (NI) 3, 4-dimethyl pyrazole phosphate (ENTEC® urea, Incitec Pivot) and a non-fertilised control (Control). Fertilisers were applied at
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49.4 kg N ha-1 (PCU, Urea and NI) on October 20, 2017 and each of the four fertiliser treatment was replicated
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three times in 2 m2 plots in a complete randomized block design (12 plots in total) and immediately watered in with the equivalent of 32 mm of irrigation using a watering can. GHG emissions were measured with the automated system as previously described with the addition of another set of four chambers to the sampling unit to give a total of 12 chambers. In addition to N2O and CH4 measurement, the automated system also continuously measured CO2 concentration with a Li820 infrared analyser (LI-COR) sampling at 1 Hz. CO2 fluxes were calculated from six concentration measurements conducted during the first two sampling intervals as described in Scheer et al. (2014). As the measurement cycle for each set of four chambers took 1 h to complete, sampling the 12 plots of the experiment took 3 h. Continuous operation of the automated GHG system resulted in eight GHG flux measurements per day from each experimental plot. Emissions were measured for a period of 31 days up until November 20, 2017 when the experiment had to be
Journal Pre-proof concluded due to redevelopment works at the sporting complex. Cumulative GHG emissions over the experimental period were calculated by summing average daily emissions. 2.5 Soil nitrogen measurement Soil samples were collected periodically to measure soil nitrate and ammonium concentrations. At Field 1 soil samples were taken at approximately 2 week intervals while at Fields 2 and 3 soil samples were collected once, if no fertiliser was applied, or twice if fertiliser was applied (before and after application) during each seasonal sampling campaign. Four soil cores of 25 mm diameter were taken from 0-10 cm depth immediately adjacent to
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each chamber and pooled to form a single composite soil sample for each of the four replicate chambers. Soil was
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sieved to 2 mm to remove plant and root material and fresh soil was shaken for 1 h with either deionised or 2 M
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KCl for nitrate or ammonium determination respectively at a ratio of 3 mL extractant to 1 g of soil. Nitrate was measured using a nitrate test strip reader (RQflex10, Merck) according to the manufacturer’s directions (Maggini
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et al., 2010). Ammonium was measured using the colorimetric procedure of Baethgen and Alley (1989).
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2.6 Ancillary Measurements
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On each day that gas samples were collected, air temperatures in chambers during the closure time was recorded by placing a temperature data logger (Tinytag, Gemini loggers) inside one chamber and soil volumetric water
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content (VWC) in the upper 12 cm of the profile was measured with a Hydrosense II moisture probe (Campbell Scientific). Air temperature and rainfall during the study period from La Trobe University (Australian Bureau of Meteorology, Bundoora, station #86351) are shown in figure 1. (insert Fig 1) 2.7 Data Analysis Data distribution was tested for normality using the Shapiro-Wilk test. The effects of the different fertilisers on cumulative N2O, CH4 and CO2 emissions and on soil mineral N concentrations, over the period October 20 – November 20, 2017, were compared statistically by one way analysis of variance (ANOVA) where normally distributed, and by the Kruskal-Wallis test where non-normally distributed. All analysis was done in the R statistical environment (R Core team 2013).
Journal Pre-proof 3. Results 3.1 Benchmarking N2O emissions The average daily N2O emissions were 38, 26 and 97g N ha-1 day-1 for the Fields 1, 2 and 3, respectively (Fig. 2). There was a more than 3-fold difference in average daily N2O emission between the highest and lowest emitting sites. At the more intensively monitored Field 1, N2O emission increased briefly to 78 g N ha-1 day-1 following the first fertiliser application but dropped again approximately to 35 g N ha-1 day-1 within 2 days. Another brief emission increase to 160 g N ha-1 day-1 occurred approximately 20 days after a herbicide application on May 11,
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2017. After this high emission period emissions were generally lower (1-20 g N ha-1 day-1) although two brief
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periods of high emissions occurred during the winter. In the spring period following the fertiliser application
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emissions were relatively low and constant and soil moisture during this time was low (4-20 % VWC) relative to the earlier sampling days where soil moisture remained between 16-38 % VWC (Fig. 1). N2O Emissions from the
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Lawn site were lower, averaging 9.3 g N ha-1 day-1, and generally remained below 20 g N ha-1 day-1 throughout the
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assessment period. Spikes in emission did not occur for the Lawn when spikes in emission were observed at the
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nearby Field 1. (Insert Fig 2)
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Daily N2O emissions were relatively low (<50 g N ha-1 day-1) from the Field 2 for all sampling occasions and increased emissions were not observed following fertiliser application (Fig. 2). During a period of waterlogging following heavy rainfall over December 2 and 3, 2017, N2O emission dropped to 7 g N ha-1 day-1 but later increased to approximately 30 g N ha-1 day-1 in the following days. Higher emissions were observed at Field 3 with daily N2O emissions ranging from 17-220 g N ha-1 day-1. The highest emissions from Field 3 (62-222 g N ha-1 day-1) occurred in the period immediately following surface restoration works in September where fertiliser and frequent irrigation was applied. Relatively high emissions (57-151 g N ha-1 day-1) were also observed during the summer sampling period which began three days after a heavy rainfall event in early December and 25 days after the last fertiliser application. 3.2 Benchmarking CH4 emissions
Journal Pre-proof CH4 emission were generally very low or negative (CH4 uptake) for most sampling occasions for all of the sites sampled (Fig. 3). However, periods of higher CH4 emission were recorded at two of the sports fields (Fields 1 and 2), both occurring after large rainfall events. At the Field 1 the maximum CH4 emission was 35 g C ha-1 day-1 which occurred on May 1, 2017 following 75 mm of rain in the preceding 6 days (Fig 1b). A period of higher CH4 emission (up to 1.3 kg C ha-1 day-1) was observed at Field 2 from December 5-15, 2017 following >70 mm of rainfall over December 2-3, 2017 which resulted in a prolonged period of soil waterlogging. There was high variability in CH4 emissions between replicates which reflected the localised nature of the waterlogging (chambers in areas with
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the highest soil moisture readings had the highest CH4 fluxes). High CH4 emissions were not observed at Field 3 over the same period, and no measurements were taken at Field 1 due to redevelopment works making the site
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no longer accessible.
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3.3 Soil mineral N
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Soil mineral N concentrations were relatively low for most sampling occasions for all three sports fields and the
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lawn site, with NH4+ concentration generally higher than NO3- concentration (Fig. 4 and Fig. 5). Low levels of NO3<10 mg N kg-1) were recorded for all sampling times at all locations with the exception of the Field 3 on August 9,
(insert Fig 4 and Fig 5)
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application on October 20, 2017.
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2017 which had 19 mg N kg-1. Field 1 had elevated soil NH4+ concentrations 14 and 28 days after the fertiliser
3.4 Fertiliser experiment (Site 1)
Over the course of the fertiliser experiment, N2O emissions were generally low relative to the emissions observed earlier in the benchmarking study at the same site with average daily emissions of 9.2-15.2 g N ha-1 day-1 and peak N2O emissions below 30 g N ha-1 day-1 (Fig. 6, Table 2). There were periods when the urea treatment had higher daily N2O emissions than the other treatments while the control treatment had the lowest emissions from 6 day after treatment application onwards. Emissions of CH4 and CO2 were similar for the different fertiliser treatments, but all treatments had negative cumulative CH4 emission which suggests they were slight sinks for CH4 during the experiment (Fig. 6). There were no significant differences in cumulative emissions over the experimental period for N2O, CH4 and CO2.
Journal Pre-proof (insert Table 2) (insert Fig 6) A greater proportion of the soil mineral N was in the NH4+ form relative to NO3- for all treatments and sampling times (Fig 7). There were no significant differences (P>0.05) in soil NH4+ or NO3- concentrations at any of the three sampling times (3, 14 and 28 days after fertiliser application) between fertiliser treatments. However, there was a trend towards higher soil NH4+ concentrations in the PCU and NI treatments and higher soil NO3- concentrations in the Urea treatment 14 and 28 days after fertiliser application.
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(insert Fig. 7)
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Discussion
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N2O emissions from turf
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The average daily N2O emissions from the sports fields in this study ranged from 26 to 97 g N ha-1 and are considerably higher than previously published emissions for similar types of sports fields (soccer and baseball) in
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the USA (5-8 g N ha-1 day-1) (Townsend-Small and Czimczik, 2010; Townsend-Small et al., 2011). The emissions
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from these southern Australian sports fields are comparable or higher than the 5-36 g N ha-1 day-1 emissions reported for golf course turf in the northern hemisphere where similar or higher N application rates were used
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(Bremer, 2006; Gillette et al., 2016; Guilbault and Matthias, 1998). At the most intensively sampled sports field site (Field 1) the average daily emission was estimated at 38 g N ha-1 day-1 which equates to an annual emission of 13.9 kg N year-1. As the 213 day sampling period at this site did not cover the hottest part of the year (summer and early autumn) when increased soil temperatures and more frequent irrigation would potentially stimulate higher N2O emissions (Guilbault and Matthias, 1998), this is considered a conservative estimate for the annual emission. The highest N2O emission from the sports fields were observed after herbicide application (Field 1) and following surface renovation (Field 3). Herbicide application in late autumn is a common practice for weed control at nonelite level community sports fields in southern Australia. This practice may release mineral N from the decomposition of plant material and reduce the sink for N in the plant biomass, thereby increasing soil NO3concentrations and hence increasing the potential for denitrification (Jiang et al., 2000). This may explain the
Journal Pre-proof large emissions of N2O that occurred post-herbicide application at the Field 1 especially as herbicide application was followed by rain events which created soil moisture conditions favouring denitrification. Similar increases in N2O emission have been observed in our other studies following herbicide application to leafy vegetable crops (unpublished data). Many sports fields go through surface renovation on an annual basis to relieve compaction, improve aeration and establish new grass cover. This process involves fertilisation and frequent irrigation (to allow the germination and establishment of new grass), both practices that are known to stimulate N2O emission in turf (Bremer, 2006; Gillette et al., 2016).
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Across the three sports field sites, there was not a clear effect of fertiliser applications on N2O emission. At two of
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the sites where controlled release N fertiliser was applied (Fields 1 and 2), a brief increase in N2O emission was only observed at Field 1 following the first fertiliser application. However, a major rainfall event followed this
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fertiliser application so it is not possible to determine the relative effects of fertiliser application and increased
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soil moisture. The highest N2O emissions occurred at Field 3 where non-controlled release fertilisers (MAP and
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urea) were used. However, factors other than fertiliser type may have also contributed to the higher N2O emissions at Field 3 as relatively high emissions were observed both prior to the surface renovation and 25-36
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minimal.
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days after the last fertiliser application, when the influence fertiliser application would be expected to be
The less intensively managed turf area outside the sports field (the ‘lawn’ site in our study) had a considerably lower average emission of 9 g N ha-1 day-1. This level of emission is similar to previously reported emissions from lawns in urban environments (Bremer et al 2006, Groffman et al., 2009; Hall et al., 2008; Kaye et al., 2004; Livesley et al., 2010; Townsend-Small et al., 2011; Townsend-Small and Czimczik, 2010) and considerably higher than the 0.03-3.5 g N2O N ha-1 day-1 emissions observed in long terms studies in some Australian vegetable and grain production systems (Barton et al, 2008; Scheer et al., 2012; Scheer et al., 2017; Wang et al., 2011) and from native forest (Van Delden et al., 2016). In contrast, Townsend-Small and Czimczik (2010) did not find differences in N2O emissions between sports fields and lawns in California USA. However, in the US study the lawns were regularly fertilised and irrigated whereas they were not in our current study. Our study therefore appears to confirm that the management intensity, particularly irrigation and fertiliser application, have a greater impact on N2O emission than whether turf is used for sporting or other purposes.
Journal Pre-proof The average daily N2O fluxes from intensively managed sports fields in this study are similar in magnitude to those observed in other high emitting land uses in Australia. This includes emissions in high intensity vegetable production (Porter et al., 2017, Riches et al., 2016), sugarcane growing (Allen et al., 2010; Denmead et al., 2010) and irrigated pasture (Phillips et al., 2007), and following the conversion of rural pasture to urban turf (Van Delden et al., 2016). Even the lower N2O emissions from the less intensively managed turf (i.e. ‘lawn’ site) were still considerably high that those previously observed (0.03-3.5 g of N2O N ha-1 day-1) in long terms studies in some Australian vegetable and grain production systems (Barton et al, 2008; Scheer et al., 2012; Scheer et al., 2017;
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Wang et al., 2011) and from native forest (Van Delden et al., 2016). This shows that turf N2O emissions may make
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a more important contribution to national GHG emissions than previously thought.
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CH4 emissions from turf
Soil CH4 emission was generally low and the soil regularly changed between being a weak source or sink for CH4.
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However, over the longer term, CH4 oxidation appeared to dominate CH4 emission at most sites sampled in this
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study. This is consistent with the known low capacity of turf to consume CH4 (Groffman and Pouyat, 2009; Livesley et al., 2010). While it is know that N fertiliser application can reduce CH4 uptake in grasslands (Mosier et
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al., 1991), no significant change in net CH4 exchange observed at the sports field where continuous automated gas measurements were made after nitrogen fertiliser application which is similar to the findings of Livesley et al. (2010) for urban lawn. The balance between CH4 consumption and emission is determined by environmental conditions, with the most important factor being soil moisture content, which determines the ratio of aerobic to anaerobic sites in the soil (Grover et al., 2013; van den Pol-van Dasselaar et al., 1998). An unusually intense rainfall event is likely to have created anaerobic soil conditions, favouring methanogenesis over CH4 oxidation, which explains the high CH4 emissions of up to 1.29 kg C ha-1 day-1 measured at Field 2 in December 2017. Intense CH4 emission events resulting from temporary soil waterlogging have the potential to result in sports fields being net CH4 sources rather than sinks. Livesley et al (2010) previously showed that for irrigated lawn, total non-CO2 GHG emissions was dominated by N2O, with net CH4 exchange only accounting for approximately 1.3 % of the total CO2-e (CO2 equivalents). For the sports fields in this study, CH4 exchange was also of less importance for the
Journal Pre-proof overall GHG balance than N2O emission. However it was demonstrated that if soil is subject to periodic waterlogging, CH4 emission will make a larger contribution to the overall GHG balance than under more normal (drier) soil conditions. Effect of fertiliser type on GHG emissions Previous research in agricultural (Delgado and Mosier, 1996; Porter et al., 2017; Riches et al., 2016; Scheer et al., 2014) and turf systems (Braun and Bremer, 2018; Gillette et al., 2016; LeMonte et al., 2016), has shown decreases in N2O emission with the use of fertiliser products that slow the release of NO3- relative to rapidly available urea
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or nitrate based fertilisers. As would be expected, there was a trend toward lower soil NO3- concentrations in the
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treatments were enhanced efficiency fertilisers were applied, i.e. NI and PCU treatments, relative to urea
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although the effect was not statistically significant. However, controlled release and NI containing fertiliser treatments did not result in significantly lower cumulative GHG emissions at the sports field monitored
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continuously for approximately one month. The measurement period in our study was much shorter than the
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normal interval between applications of the controlled release fertiliser product which can be up to 16 weeks. Over the monitoring period soil moisture in the turf remained low (4-20 % VWC) may have been too low to
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promote denitrification due to lower than normal rainfall (63% lower than the longer term average for the
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October to November period) and the cessation of irrigation due to the impending redevelopment of the field. While supplemental hand watering was applied, it did not increase soil moisture to the levels observed during the earlier monitoring of the field. Benefits arising from using enhanced efficiency fertilisers to reduce N2O emission in turf under Australian conditions at higher soil moistures or over longer timeframes that are representative of the normal interval between applications of a controlled release fertiliser product cannot be ruled out from this preliminary study and warrant further investigation. Relevance of sport field and other turf to national GHG emissions Reliable estimates for the total land area covered by turf sports fields and other turf both in Australia and globally are not available (Van Delden et al., 2016). Globally golf courses have been estimated to cover approximately 25,600 km2 (Bartlett and James, 2011) and the total turf area for all sports turf would be considerably higher than this. For Australia, the following conservative estimate of sports turf area has been made in order to work out the
Journal Pre-proof importance of emissions from turf to the national GHG inventory. Australia has approximately 1530 golf courses (AGIC 2009), and the number of school and local council provided sporting fields could be estimated at 9477 and 4500, respectively, assuming each of Australia’s 9477 schools (ABS 2019) on average has one sports field each, and applying local government planning guidelines for the per capita provision of sport fields to the entire Australian population of approximately 25 million. This yields a total of approximately 15,500 sports fields and golf courses combined in Australia with a total turf area of approximately 780 km2 (assuming an 18 hole golf course has an average turf area of 38.5 Ha (GCSAA 2017) and a school or council owned sports field occupies 2 ha.
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This crude estimate of the total land area of sports turf in Australia suggests that GHG emissions from sports fields alone will not have a large impact on national GHG emissions. However, if all turf is considered together (i.e.
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sporting turf, urban lawns, parks and gardens, roadside reserves, turf farms) the land areas involved, and hence
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the potential for GHG emissions, are much larger. For example, in the USA, the area occupied by turf has been
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estimated as being three times larger than any other irrigated crop, somewhere between 130,000-200,000 km2
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(Milesi et al., 2005). In Australia the total turf area could be estimated at 11,250 km2 by extrapolating the average values from Australia’s two most populous cities, Sydney and Melbourne, of 450 m2 of turf per person (Holborn,
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2014) to the entire population of approximately 25 million. Although this estimate of total turf area has a large uncertainty and is likely to be an underestimate due to lower population densities outside of these two cities, it is
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still comparable in magnitude to the 20,365 km2 used for irrigated pasture, cropping and horticulture combined in Australia (ABARES, 2016).
To determine the total GHG balance of a land use requires measuring changes in C stocks in the system but this was beyond the scope of this study. While continuous grassland accumulates C in the soil profile over time, Townsend-Small and Czimczik (2010) concluded that intensively managed sports fields subject to regular surface restoration don’t sequester C in soil profile to offset management derived and soil N2O emissions. The low C contents of the sports field soils in this study support this conclusion. For less intensively managed turf where C sequestration may occur, the rate is dependent on the time since establishment and C content reaches an equilibrium over time (Selhorst and Lal 2011). Except under minimal management regimes, the rate of C sequestration is unlikely to offset GHG emissions and turf is likely to be a net GHG source in many cases (Bartlett and James 2011, Gu et al., 2015; Kong et al., 2014; Selhorst and Lal 2011; Townsend-Small and Czimczik 2010).
Journal Pre-proof Given that N2O emissions from turf may be higher than many other land uses, a warming climate is likely to see N2O emissions from fertilised turf rise (Bijoor et al., 2008) and turf areas are increasing resulting from increased urbanisation, it is possible that turf makes an important and increasing contribution to national and global GHG emissions. Conclusions N2O emissions from sports turf were shown to be high in southern Australia relative to similar sports fields in the northern hemisphere and other land uses in Australia. CH4 emission was generally negligible for the different turf
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sites except when waterlogged after extreme rainfall events. However, even at sites where periodic high CH4
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emissions occurred, over the longer term, total non-CO2 GHG emissions were still dominated by N2O emission. In
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light of the relatively high N2O emissions observed for both sports turf and non-sports turf, and the rapid expansion of turf as a land use with increasing urbanisation, further research is needed to quantify the
Acknowledgements:
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emissions.
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contribution of turf GHG emissions at a national level and to investigate mitigation practices to minimise turf N2O
This study was funded by La Trobe University through the Sport, Exercise and Rehabilitation RFA. The authors would like to thank Parade College for providing one of the sampling sites used in this study, Dr Helen Suter from Melbourne University for the loan of some of the equipment used in this work and gratefully acknowledge the assistance of grounds staff at La Trobe University (Peter Gooch) and Parade College (Rod McDonald).
Journal Pre-proof Table 1. Characteristics of sporting fields used in the study. Soil texture (Sand, Silt and Clay %) and organic C were
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determined on a single composite sample from each site.
Journal Pre-proof Table 2. N2O, CH4 and CO2 (respiration) cumulative and average daily emissions from the Field 1 fertiliser
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experiment (October 20 – November 20, 2017) (n=3).
Journal Pre-proof Figure 1. Daily minimum, maximum air temperature and daily rainfall and soil volumetric water content (VWC)
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during the experimental period (shaded area) at Field 1 (La Trobe University campus).
Journal Pre-proof Fig.2. N2O emissions from (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3. Dotted line shows timing of herbicide application at Field 1. Arrows show timing of fertiliser applications. Error bars represent the standard error of the
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mean (n=4).
Journal Pre-proof Fig. 3. CH4 emissions from (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3. Dotted line shows timing of herbicide application at Field 1. Arrows show timing of fertiliser applications. Error bars represent the standard error of the
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mean (n=4).
Journal Pre-proof Fig. 4. Soil NO3- N concentration (dry weight) in the 0-10 cm soil layer for (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3. Dotted line shows timing of herbicide application at the Field 1. Arrows show timing of fertiliser applications
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Error bars represent the standard error of the mean (n=4).
Journal Pre-proof Fig.5. Soil NH4+ N concentration (dry weight) in the 0-10 cm soil layer for (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3 (D). Dotted line shows timing of herbicide application at Field 1. Arrows show timing of fertiliser applications.
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Error bars represent the standard error of the mean (n=4).
Journal Pre-proof Fig.6. Comparison of the daily average (A) N2O, (B) CH4, and (C) CO2 respiration emissions at Field 1 for Urea, urea with nitrification inhibitor (NI), polymer coated urea (PCU) and no added fertiliser
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(Control) treatments in Oct-Nov 2017. Error bars represent the standard error of the mean (n=3).
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Journal Pre-proof Fig.7. Soil NH4+ N and NO3- N concentrations in the 0-10 cm soil layer (dry weight) at Field 1 for Urea, urea with nitrification inhibitor (NI), polymer coated urea (PCU) and Control treatments in Oct-Nov 2017.
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Error bars represent the standard error of the mean (n=3).
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Journal Pre-proof References ABARES 2016, Land use of Australia 2010-11, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, http://data.daff.gov.au/anrdl/metadata_files/pb_luav5g9abll20160704.xml Accessed August 9, 2019 ABS 2019, Catalogue Number 4221.0 Schools, Australia, 2018. Australian Bureau of Statistics. https://www.abs.gov.au/ausstats/[email protected]/mf/4221.0 Accessed August 9, 2019
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AGIC 2009. A snapshot of the Australian Golf industry. Australian Golf Industry Council.
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Allen, D.E., Kingston, G., Rennenberg, H., Dalal, R.C., Schmidt, S., 2010. Effect of nitrogen fertilizer management and waterlogging on nitrous oxide emission from subtropical sugarcane soils.
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Baethgen, W.E., Alley, M.M., 1989. A manual colorimetric procedure for measuring ammonium nitrogen in soil and plant Kjeldahl digests. Communications in Soil Science and Plant Analysis 20, 961-969.
Bartlett, M.D., James, I.T., 2011. A model of greenhouse gas emissions from the management of turf on two golf courses. Science of The Total Environment 409, 1357-1367.
Barton, L., Kiese, R., Gatter, D., Butterbach-bahl, K., Buck, R., Hinz, C., Murphy, D.V., 2008. Nitrous oxide emissions from a cropped soil in a semi-arid climate. Global Change Biology 14, 177-192.
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Journal Pre-proof Bijoor, N.S., Czimczik, C.I., Pataki, D.E., Billings, S.A., 2008. Effects of temperature and fertilization on nitrogen cycling and community composition of an urban lawn. Global Change Biology 14, 21192131. Braun, R.C., Bremer, D.J., 2018. Nitrous Oxide Emissions from Turfgrass Receiving Different Irrigation Amounts and Nitrogen Fertilizer Forms. Crop Science 58, 1762-1775. Bremer, D.J., 2006. Nitrous Oxide Fluxes in Turfgrass. Journal of Environmental Quality 35, 1678-
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sugarcane soils. Agricultural and Forest Meteorology 150, 748-756. GCSAA 2017. Golf Course Environmental Profile. Phase II, Volume IV. Land Use Characteristics and
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Enivronmental Stewardship Programs on U.S. Golf Courses. Golf Course Superintendents Assoication
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Gillette, K., Qian, Y., Follett, R., Del Grosso, S., 2016. Nitrous Oxide Emissions from a Golf Course Fairway and Rough after Application of Different Nitrogen Fertilizers. Journal of Environment Quality 45, 1788-1795.
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Journal Pre-proof Groffman, P.M., Pouyat, R.V., 2009. Methane Uptake in Urban Forests and Lawns. Environmental Science & Technology 43, 5229-5235. Groffman, P.M., Williams, C.O., Pouyat, R.V., Band, L.E., Yesilonis, I.D., 2009. Nitrate Leaching and Nitrous Oxide Flux in Urban Forests and Grasslands. Journal of Environmental Quality 38, 1848-1860. Grover, S.P.P., Cohan, A., Chan, H.S., Livesley, S.J., Beringer, J., Daly, E., 2013. Occasional large emissions of nitrous oxide and methane observed in stormwater biofiltration systems. Science of
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Hall, S.J., Huber, D., Grimm, N.B., 2008. Soil N2O and NO emissions from an arid, urban ecosystem.
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Journal of Geophysical Research: Biogeosciences 113. Horgan, B.P., Branham, B.E., Mulvaney, R.L., 2002. Direct Measurement of Denitrification Using 15Nlabeled Fertilizer Applied to Turfgrass. Crop Science 42, 1602-1610. IPCC, 2014 Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and II to the Fifth Assessment Report of the Intergovernmental Panel On Climate Change [Core Writing Teamp, R.K. Pachauri and L.A. Meyer (eds.)] IPCC, Geneva, Switzerland, 151 pp. in IPCC AR5 Synthesis Report. IUSS Working Group WRB. 2015. World Reference Base for Soil Resources 2014, update 2015 International soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports No. 106. FAO, Rome. 27
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Jiang, Z., Bushoven, J.T., Ford, H.J., Sawyer, C.D., Amador, J.A., Hull, R.J., 2000. Mobility of Soil Nitrogen and Microbial Responses following the Sudden Death of Established Turf. Journal of Environmental Quality 29, 1625-1631 Kaye, J.P., Burke, I.C., Mosier, A.R., Pablo Guerschman, J., 2004. Methane and nitrous oxide fluxes from urban soils to the atmosphere. Ecological Applications 14, 975-981.
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Kong, L., Shi, Z., Chu, L.M., 2014. Carbon emission and sequestration of urban turfgrass systems in
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Maggini, R, Carnassu G., Incrocci, L. Pardossi, A. 2010. Evaluation of quick test kits for the determination of nitrate, ammonium and phosphate in soil and hydroponic nutrient solutions. Agrochimica. 54, 331-341.
Mancino, C.F., W.A. Torello, and D.J. Wehner. 1988. Denitrification losses from Kentucky bluegrass sod. Agronomy Journal 80, 148–153. Maggiotto, S.R., Webb, J.A., Wagner-Riddle, C., Thurtell, G.W., 2000. Nitrous and Nitrogen Oxide Emissions from Turfgrass Receiving Different Forms of Nitrogen Fertilizer. Journal of Environmental Quality 29, 621-630.
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Journal Pre-proof Milesi, C., Running, S.W., Elvidge, C.D., Dietz, J.B., Tuttle, B.T., Nemani, R.R., 2005. Mapping and Modeling the Biogeochemical Cycling of Turf Grasses in the United States. Environmental Management 36, 426-438. Mosier, A., Schimel, D., Valentine, D., Bronson, K., Parton, W., 1991. Methane and nitrous oxide fluxes in native, fertilized and cultivated grasslands. Nature 350, 330-332. Phillips, F.A., Leuning, R., Baigent, R., Kelly, K.B., Denmead, O.T., 2007. Nitrous oxide flux
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measurements from an intensively managed irrigated pasture using micrometeorological
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techniques. Agricultural and Forest Meteorology 143, 92-105.
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manures and fertilisers used in temperate vegetable crops in Australia. Soil Research 55, 534-546. R Core Team, 2013. R: a Language and Environment for Statistical Computing. R Foundation for
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Ravishankara, A.R., Daniel, J.S., Portmann, R.W. 2009. Nitrous Oxide (N2O): The dominant ozone-
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depleting substance emitted in the 21st Century. Science 326(5949), 123-125. Riches, D.A., Mattner, S.W., Davies, R., Porter, I.J., 2016. Mitigation of nitrous oxide emissions with nitrification inhibitors in temperate vegetable cropping in southern Australia. Soil Research 54, 533543.
Scheer, C., Grace, P.R., Rowlings, D.W., Payero, J., 2012. Nitrous oxide emissions from irrigated wheat in Australia: impact of irrigation management. Plant Soil 359, 351-362. Scheer, C., Rowlings, D., Firrell, M., Deuter, P., Morris, S., Riches, D., Porter, I., Grace, P., 2017. Nitrification inhibitors can increase post-harvest nitrous oxide emissions in an intensive vegetable production system. Scientific Reports 7, 43677.
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Journal Pre-proof Scheer, C., Rowlings, D.W., Firrel, M., Deuter, P., Morris, S., Grace, P.R., 2014. Impact of nitrification inhibitor (DMPP) on soil nitrous oxide emissions from an intensive broccoli production system in subtropical Australia. Soil Biology and Biochemistry 77, 243-251. Townsend-Small, A., Czimczik, C.I., 2010. Carbon sequestration and greenhouse gas emissions in urban turf. Geophysical Research Letters 37. Townsend‐Small, A., Pataki, D.E., Czimczik, C.I., Tyler, S.C., 2011. Nitrous oxide emissions and isotopic
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composition in urban and agricultural systems in southern California. Journal of Geophysical
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van Delden, L., Larsen, E., Rowlings, D., Scheer, C., Grace, P., 2016. Establishing turf grass increases
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soil greenhouse gas emissions in peri-urban environments. Urban Ecosystems 19, 749-762. van den Pol-van Dasselaar, A., van Beusichem, M.L., Oenema, O., 1998. Effects of soil moisture
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content and temperature on methane uptake by grasslands on sandy soils. Plant Soil 204, 213-222.
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Wang, W., Dalal, R.C., Reeves, S.H., Butterbach-Bahl, K., Kiese, R., 2011. Greenhouse gas fluxes from an Australian subtropical cropland under long-term contrasting management regimes. Global
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Change Biology 17, 3089-3101.
Zirkle G., Lal R., Augustin B. 2011 Modeling Carbon Sequestration in Home Lawns. Hortscience 46 (5) 808-814.
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Journal Pre-proof Table 1. Characteristics of sporting fields and lawn used in the study. Soil texture and organic C were determined on a single composite sample (sub-sampled from four locations) at each site. Usage
Field 1 Lawn Field 2 Field 3
Football/cricket Lawn Baseball Football/cricket
Organic C (%) 1.1 4.1 1.5 2.8
Sand Silt (%) (%) 94.3 3.8 67.4 15.3 98.2 1.2 87.4 7.2
Clay (%) 1.9 17.3 0.6 5.4
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Journal Pre-proof Table 2. N2O, CH4 and CO2 respiration emissions from the Field 1 fertiliser experiment over the 31 days from October 20, 2017 to November 20, 2017. SE=Standard errors of the mean (n=3).
Treatment Control
Cumulative N2O-N g ha-1 257
Cumulative CH4-C g ha-1 -42.0
Cumulative CO2-C kg ha-1 1113
Daily N2O-N g ha-1 day-1 8.3
Daily CH4-C g ha-1 day-1 -1.23
Daily CO2-C g ha-1 day-1 35.9
388
-26.1
1173
12.5
-0.77
37.8
NI
423
-42.1
1193
13.6
-0.93
38.5
Urea
426
-37.3
1097
13.8
-0.78
35.4
SE
45.3
4.7
55.0
-
-
-
P value
0.513
0.619
0.905
-
-
-
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PCU
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Journal Pre-proof Highlights Sports field N2O fluxes were high relative to other land uses
CH4 fluxes generally very low except after unusually high rainfall
Herbicide use and turf renovation were associated with high N2O emission events
Fertiliser application and soil moisture had variable effects on N2O emissions
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Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
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David Riches, Ian Porter, Greg Dingle, Anthony Gendall, Samantha Grover PII:
S0048-9697(19)34411-0
DOI:
https://doi.org/10.1016/j.scitotenv.2019.134420
Reference:
STOTEN 134420
To appear in:
Science of the Total Environment
Received date:
22 March 2019
Revised date:
11 September 2019
Accepted date:
11 September 2019
Please cite this article as: D. Riches, I. Porter, G. Dingle, et al., Soil greenhouse gas emissions from Australian sports fields, Science of the Total Environment (2019), https://doi.org/10.1016/j.scitotenv.2019.134420
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier.
Journal Pre-proof Soil Greenhouse Gas Emissions from Australian Sports Fields David Riches1, Ian Porter1, Greg Dingle2, Anthony Gendall1, Samantha Grover3 1
Department of Animal Plant and Soil Sciences, La Trobe University, Bundoora, Vic, Australia
2
Department of Management, Sport and Tourism, La Trobe University, Bundoora, Vic, Australia
3
Applied Chemistry and Environmental Science, School of Science, RMIT University, Melbourne, Vic, Australia
Corresponding Author:
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David Riches, Biological Sciences 1, Department of Animal Plant and Soil Science, La Trobe University, Bundoora,
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Abbreviation list
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Vic 3086, Australia. [email protected]
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GHG, greenhouse gas; GWP, Global warming potential; ODS, ozone depleting substance; PCU polymer coated
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urea; NI, nitrification inhibitor; CO2-e, carbon dioxide equivalents; MAP, mono ammonium phosphate
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Keywords: Nitrous oxide, turf, nitrogen, methane
Journal Pre-proof Abstract Managed turf is a potential net source of greenhouse gas (GHG) emissions. While most studies to date have focused on non-sports turf, sports turf may pose an even greater risk of high GHG emissions due to the generally more intensive fertiliser, irrigation and mowing regimes. This study used manual and automated chambers to measure nitrous oxide (N2O) and methane (CH4) emissions from three sports fields and an area of non-sports turf in southern Australia. Over 213 days (autumn to late spring), the average daily N2O emission was 37.6 g N ha-1day1
at a sports field monitored at least weekly and cumulative N2O emission was 2.5 times higher than the adjacent
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non-sports turf. Less frequent seasonal sampling at two other sports fields showed average N2O daily emission
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ranging from 26-90 g N ha-1 day-1. Management practices associated with periods of relatively high N2O emissions were surface renovation and herbicide application. CH4 emissions at all of the sports fields were generally
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negligible with the exception of brief periods when soil was waterlogged following heavy rainfall where emissions
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of up to 1.3 kg C ha-1 day-1 were recorded. Controlled release and nitrification inhibitor containing fertilisers didn’t
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reduce N2O, CH4 or CO2 emissions relative to urea in a short term experiment. The N2O emissions from the sports fields, and even the lower emissions from the non-sports turf, were relatively high compared to other land uses in
1. Introduction
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mitigation practices.
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Australia highlighting the importance of accounting for these emissions at a national level and investigating
Climate change driven by anthropogenic increases in GHG concentrations has been widely recognised as posing a major global threat. In addition to CO2, CH4 and N2O are the two most important GHGs with global warming potential (GWP) values of 28-36 and 265-295 respectively on a 100 year timescale relative to CO2 (IPCC, 2014). N2O is also the major ozone depleting substance (ODS) in terms of current emissions (Ravishankara et al., 2009) after the phase out of other CFCs and other major ODS under the Montreal Protocol. Considerable work has been conducted to measure GHG emissions from soils in agricultural and natural systems, however, fewer studies have examined other land uses such as urban turf. Due to the high aesthetic standards required for turf, management is often intensive with large inputs of fertiliser and frequent irrigation and mowing, the latter adding labile organic matter to soil through the return of clippings. These factors together with elevated soil temperatures caused by
Journal Pre-proof close mowing result in a high potential for emissions of N2O (Horgan et. al., 2002; Mancino et al., 1988; Townsend-Small, 2011). Studies on non-sports turf have shown N2O emissions can be higher than from natural and agricultural systems with up to 3 kg N ha-1 annual emissions (i.e. 8.2 g N ha-1 day-1) observed (Braun and Bremer, 2018; Bremer, 2006; Groffman et al., 2009; Kaye et al., 2004; Livesley et al., 2010). Less GHG emission data is currently available for sports fields. This may be at least partially due to the difficulty in collecting GHG emission data from sports fields because gas sampling equipment cannot be left in situ for extended periods due to disruption to sporting and ground management activities. Another potential reason is that the magnitude of
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GHG emissions from sports fields and other intensively managed turf relative to other land uses has been largely under appreciated. Studies of sports field GHG emissions conducted in the northern hemisphere have also shown
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high N2O emissions relative to other land uses (Gillette et al., 2016; Townsend-Small and Czimczik, 2010;
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Townsend-Small et al., 2011). The magnitude of N2O emissions from turf is generally related to N fertilisation and
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precipitation/irrigation (Braun and Bremer, 2018; Bremer, 2006; Livesley et al., 2010; Mancino et al., 1988;
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Maggiotto et al., 2000).
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Owing to the relatively few studies globally, the aim of this study was to collect N2O and CH4 emissions data for
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sports fields under typical management programs in Australia in order to benchmark their magnitude in comparison to other land uses and to identify potential strategies for mitigation of GHG emissions. At one site different fertiliser treatments were evaluated for their effects on GHG emissions to determine if emissions could be effectively mitigated by improving the fertiliser management. 2. Materials and Methods 2.1 Study sites Three sports fields and an area of non-sports turf bordering one field, located in Bundoora in metropolitan Melbourne, Australia were used in this study (Table 1). The management practices at these fields were representative of well managed sports fields in the local area. The region has a mean annual precipitation of 659 mm and mean annual maximum and minimum temperatures of 20.0 ˚C and 9.6 ˚C, respectively (20 year average). Two of the sports fields (Field 1 and Field 3) were used for cricket and Australian Rules football for the summer
Journal Pre-proof and winter seasons respectively, and represent the most common type of sports field in the region. The soil at all sites is highly altered, with an imported upper sand layer, classified as Anthrosol (IUSS 2015). Field 2 was a baseball field, a less common type of sports field in the region. Fields 1 and 2 and the non-sports turf (Lawn) were located on La Trobe University’s Melbourne, Australia campus (latitude -37.722 S, longitude 145.042 E, 74 m above sea level) while Field 3 was located on the campus of a school, Parade College (latitude -37.689 S, longitude 145.067 E, 102 m above sea level), approximately 5 km away from the other two fields. Field 1 had a couch grass (Cynodon dactylon) playing surface while Field 2’s surface was composed of ryegrass (Lolium Perenne) and annual
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bluegrass (Poa annua). The Lawn was an area of kikuyu (Pennisetum clandestinum) lawn immediately adjacent to the Field 1. Field 3’s surface was couch/kikuyu grass, over-sown with ryegrass (Lolium Perenne) for the winter
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season.
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Field 1 was monitored regularly (generally at least weekly) for the emission of N2O and CH4 over a period of 7
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months (April 21 - November 20, 2017) while the adjacent Lawn site was monitored on a subset of these sampling
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days. Fields 2 and 3 were sampled for N2O and CH4 emissions less frequently than Field 1. At these two sites, gas sampling was conducted alternate days three times a week over two week sampling events with three seasonal
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(Insert Table 1)
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sampling events (winter, spring and summer) conducted at each site during the trial.
2.2. Ground management (GHG Benchmarking study) The existing management programs for fertiliser, irrigation and weed control were used at all sites. The approximate annual N fertiliser application rates were 200, 200 and 180 kg ha-1 for Fields 1, 2 and 3 respectively. At Fields 1 and 2 the fertiliser used was a polymer coated urea (PCU) formulated to slowly release N over a period of up to 16 weeks, (Best Cascade K® 21-1-17, Simplot) while the Field 3 fertiliser programme included a urea blend fertiliser, (Paton 20-0-16+Fe®, Amgrow) and mono ammonium phosphate (MAP). The fertiliser applications during the study were application of PCU at a rate of 49.4 kg N ha-1 on April 24, 2017 and October 20, 2017 at field 1 and on October 24, 2017 at field 2. Field 1 was sprayed with glyphosate (Roundup Powermax®, Monsanto) on May 11, 2017 to control winter grass (Poa Annua). Field 3 was fertilised with Paton® 20-0-16+Fe at 50 kg N ha-1 on June 5, 2017 and November 12, 2017 and with MAP at 15 kg N ha-1 on September 20, 2017.
Journal Pre-proof At all of the sporting fields the turf was mown as required (once or twice weekly depending on growth) to a height of 20-32 mm height. Irrigation frequency varied throughout the year to meet the water demand of the turf taking into account precipitation and climatic conditions. During the summer months, irrigation was generally performed every second day, while over winter there was usually no irrigation applied. Spring irrigation was at a lower frequency than the summer period due to the higher rainfall at this time of year except at the Field 1 which was not irrigated over spring due to an impending redevelopment at the site. At Field 3, a turf renovation programme began on September 19, 2017 where the field was mechanically aerated, fertilised with MAP and re-
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seeded. Over the following 3 week period, daily short irrigations were applied, depending on precipitation, to facilitate establishment of the re-seeded grass. Surface renovation is a common practice for fields used for
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football to alleviate compaction and drainage problems caused by heavy foot traffic under the higher soil
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moisture conditions that occur for winter sports. The Lawn site was unfertilised and unirrigated throughout the
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sampling period.
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2.3 Gas sampling (GHG Benchmarking study)
N2O and CH4 fluxes were measured using either manual or automated static chambers consisting of acrylic walled
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boxes covered with reflective insulation, placed on top of flanged stainless steel bases driven into the soil to a depth of 15 cm with a square footprint of 0.5 x 0.5 m. Initially, vented manual chambers (Gibson Engineering) with a headspace height of 0.25 were used and samples were manually collected with a syringe through a sampling port in the lid. On each sampling day, three gas samples of 20 mL were extracted from chambers at fixed intervals (0, 30 and 60 mins) and transferred into 12 mL evacuated vials (Exetainer, Labco) with sampling taking place between 11:00-13:00 Australian Eastern Standard Time. Previous work had shown this sampling time was a reasonable approximation of the average daily emission (unpublished data). Gas samples were subsequently analysed for GHG concentrations with a gas chromatograph (8610C, SRI Instruments) using a Hayes Sep D column (SRI Instruments) fitted with electron capture and flame ionisation detectors for N2O and CH4 respectively. From June 28, 2017, the manual chambers were replaced at Field 1 with an eight chamber system where chamber closure, sample collection and N2O and CH4 analysis was automated as described in Scheer et al. (2014). The eight
Journal Pre-proof chambers were arranged in two sets of four chambers that shared common pneumatic lines for control of chamber opening and closing. Two chambers in each set were installed in Field 1 and the other two the Lawn site bordering the sporting field. Each set of four chambers closed for 1 h during a sampling cycle with four gas samples taken at 15 minute intervals during this time. The automated system was operated for 1 or 2 cycles per sampling day at approximately the same time of day as the previous manual sample collection. Emission fluxes were determined from the linear increase in concentration of the gas over the closure period correcting for air temperature and atmospheric pressure (Scheer et al., 2014). Flux data was discarded if the regression coefficient
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(r2) for the linear increase was <0.8. Cumulative N2O fluxes at the Field 1 and Lawn sites were calculated by using
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trapezoidal integration.
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2.4. Effect of fertiliser type on GHG emissions
Sports activities at Field 1 ceased on October 20, 2017 which allowed a number of fertiliser treatments to be
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applied to small plots followed by continuous automated GHG emission monitoring. Fertiliser treatments were
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PCU (Best Cascade K® 21-1-17, Simplot), urea (Urea), urea with the nitrification inhibitor (NI) 3, 4-dimethyl pyrazole phosphate (ENTEC® urea, Incitec Pivot) and a non-fertilised control (Control). Fertilisers were applied at
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49.4 kg N ha-1 (PCU, Urea and NI) on October 20, 2017 and each of the four fertiliser treatment was replicated
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three times in 2 m2 plots in a complete randomized block design (12 plots in total) and immediately watered in with the equivalent of 32 mm of irrigation using a watering can. GHG emissions were measured with the automated system as previously described with the addition of another set of four chambers to the sampling unit to give a total of 12 chambers. In addition to N2O and CH4 measurement, the automated system also continuously measured CO2 concentration with a Li820 infrared analyser (LI-COR) sampling at 1 Hz. CO2 fluxes were calculated from six concentration measurements conducted during the first two sampling intervals as described in Scheer et al. (2014). As the measurement cycle for each set of four chambers took 1 h to complete, sampling the 12 plots of the experiment took 3 h. Continuous operation of the automated GHG system resulted in eight GHG flux measurements per day from each experimental plot. Emissions were measured for a period of 31 days up until November 20, 2017 when the experiment had to be
Journal Pre-proof concluded due to redevelopment works at the sporting complex. Cumulative GHG emissions over the experimental period were calculated by summing average daily emissions. 2.5 Soil nitrogen measurement Soil samples were collected periodically to measure soil nitrate and ammonium concentrations. At Field 1 soil samples were taken at approximately 2 week intervals while at Fields 2 and 3 soil samples were collected once, if no fertiliser was applied, or twice if fertiliser was applied (before and after application) during each seasonal sampling campaign. Four soil cores of 25 mm diameter were taken from 0-10 cm depth immediately adjacent to
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each chamber and pooled to form a single composite soil sample for each of the four replicate chambers. Soil was
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sieved to 2 mm to remove plant and root material and fresh soil was shaken for 1 h with either deionised or 2 M
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KCl for nitrate or ammonium determination respectively at a ratio of 3 mL extractant to 1 g of soil. Nitrate was measured using a nitrate test strip reader (RQflex10, Merck) according to the manufacturer’s directions (Maggini
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et al., 2010). Ammonium was measured using the colorimetric procedure of Baethgen and Alley (1989).
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2.6 Ancillary Measurements
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On each day that gas samples were collected, air temperatures in chambers during the closure time was recorded by placing a temperature data logger (Tinytag, Gemini loggers) inside one chamber and soil volumetric water
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content (VWC) in the upper 12 cm of the profile was measured with a Hydrosense II moisture probe (Campbell Scientific). Air temperature and rainfall during the study period from La Trobe University (Australian Bureau of Meteorology, Bundoora, station #86351) are shown in figure 1. (insert Fig 1) 2.7 Data Analysis Data distribution was tested for normality using the Shapiro-Wilk test. The effects of the different fertilisers on cumulative N2O, CH4 and CO2 emissions and on soil mineral N concentrations, over the period October 20 – November 20, 2017, were compared statistically by one way analysis of variance (ANOVA) where normally distributed, and by the Kruskal-Wallis test where non-normally distributed. All analysis was done in the R statistical environment (R Core team 2013).
Journal Pre-proof 3. Results 3.1 Benchmarking N2O emissions The average daily N2O emissions were 38, 26 and 97g N ha-1 day-1 for the Fields 1, 2 and 3, respectively (Fig. 2). There was a more than 3-fold difference in average daily N2O emission between the highest and lowest emitting sites. At the more intensively monitored Field 1, N2O emission increased briefly to 78 g N ha-1 day-1 following the first fertiliser application but dropped again approximately to 35 g N ha-1 day-1 within 2 days. Another brief emission increase to 160 g N ha-1 day-1 occurred approximately 20 days after a herbicide application on May 11,
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2017. After this high emission period emissions were generally lower (1-20 g N ha-1 day-1) although two brief
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periods of high emissions occurred during the winter. In the spring period following the fertiliser application
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emissions were relatively low and constant and soil moisture during this time was low (4-20 % VWC) relative to the earlier sampling days where soil moisture remained between 16-38 % VWC (Fig. 1). N2O Emissions from the
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Lawn site were lower, averaging 9.3 g N ha-1 day-1, and generally remained below 20 g N ha-1 day-1 throughout the
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assessment period. Spikes in emission did not occur for the Lawn when spikes in emission were observed at the
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nearby Field 1. (Insert Fig 2)
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Daily N2O emissions were relatively low (<50 g N ha-1 day-1) from the Field 2 for all sampling occasions and increased emissions were not observed following fertiliser application (Fig. 2). During a period of waterlogging following heavy rainfall over December 2 and 3, 2017, N2O emission dropped to 7 g N ha-1 day-1 but later increased to approximately 30 g N ha-1 day-1 in the following days. Higher emissions were observed at Field 3 with daily N2O emissions ranging from 17-220 g N ha-1 day-1. The highest emissions from Field 3 (62-222 g N ha-1 day-1) occurred in the period immediately following surface restoration works in September where fertiliser and frequent irrigation was applied. Relatively high emissions (57-151 g N ha-1 day-1) were also observed during the summer sampling period which began three days after a heavy rainfall event in early December and 25 days after the last fertiliser application. 3.2 Benchmarking CH4 emissions
Journal Pre-proof CH4 emission were generally very low or negative (CH4 uptake) for most sampling occasions for all of the sites sampled (Fig. 3). However, periods of higher CH4 emission were recorded at two of the sports fields (Fields 1 and 2), both occurring after large rainfall events. At the Field 1 the maximum CH4 emission was 35 g C ha-1 day-1 which occurred on May 1, 2017 following 75 mm of rain in the preceding 6 days (Fig 1b). A period of higher CH4 emission (up to 1.3 kg C ha-1 day-1) was observed at Field 2 from December 5-15, 2017 following >70 mm of rainfall over December 2-3, 2017 which resulted in a prolonged period of soil waterlogging. There was high variability in CH4 emissions between replicates which reflected the localised nature of the waterlogging (chambers in areas with
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the highest soil moisture readings had the highest CH4 fluxes). High CH4 emissions were not observed at Field 3 over the same period, and no measurements were taken at Field 1 due to redevelopment works making the site
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no longer accessible.
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3.3 Soil mineral N
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Soil mineral N concentrations were relatively low for most sampling occasions for all three sports fields and the
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lawn site, with NH4+ concentration generally higher than NO3- concentration (Fig. 4 and Fig. 5). Low levels of NO3<10 mg N kg-1) were recorded for all sampling times at all locations with the exception of the Field 3 on August 9,
(insert Fig 4 and Fig 5)
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application on October 20, 2017.
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2017 which had 19 mg N kg-1. Field 1 had elevated soil NH4+ concentrations 14 and 28 days after the fertiliser
3.4 Fertiliser experiment (Site 1)
Over the course of the fertiliser experiment, N2O emissions were generally low relative to the emissions observed earlier in the benchmarking study at the same site with average daily emissions of 9.2-15.2 g N ha-1 day-1 and peak N2O emissions below 30 g N ha-1 day-1 (Fig. 6, Table 2). There were periods when the urea treatment had higher daily N2O emissions than the other treatments while the control treatment had the lowest emissions from 6 day after treatment application onwards. Emissions of CH4 and CO2 were similar for the different fertiliser treatments, but all treatments had negative cumulative CH4 emission which suggests they were slight sinks for CH4 during the experiment (Fig. 6). There were no significant differences in cumulative emissions over the experimental period for N2O, CH4 and CO2.
Journal Pre-proof (insert Table 2) (insert Fig 6) A greater proportion of the soil mineral N was in the NH4+ form relative to NO3- for all treatments and sampling times (Fig 7). There were no significant differences (P>0.05) in soil NH4+ or NO3- concentrations at any of the three sampling times (3, 14 and 28 days after fertiliser application) between fertiliser treatments. However, there was a trend towards higher soil NH4+ concentrations in the PCU and NI treatments and higher soil NO3- concentrations in the Urea treatment 14 and 28 days after fertiliser application.
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(insert Fig. 7)
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Discussion
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N2O emissions from turf
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The average daily N2O emissions from the sports fields in this study ranged from 26 to 97 g N ha-1 and are considerably higher than previously published emissions for similar types of sports fields (soccer and baseball) in
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the USA (5-8 g N ha-1 day-1) (Townsend-Small and Czimczik, 2010; Townsend-Small et al., 2011). The emissions
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from these southern Australian sports fields are comparable or higher than the 5-36 g N ha-1 day-1 emissions reported for golf course turf in the northern hemisphere where similar or higher N application rates were used
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(Bremer, 2006; Gillette et al., 2016; Guilbault and Matthias, 1998). At the most intensively sampled sports field site (Field 1) the average daily emission was estimated at 38 g N ha-1 day-1 which equates to an annual emission of 13.9 kg N year-1. As the 213 day sampling period at this site did not cover the hottest part of the year (summer and early autumn) when increased soil temperatures and more frequent irrigation would potentially stimulate higher N2O emissions (Guilbault and Matthias, 1998), this is considered a conservative estimate for the annual emission. The highest N2O emission from the sports fields were observed after herbicide application (Field 1) and following surface renovation (Field 3). Herbicide application in late autumn is a common practice for weed control at nonelite level community sports fields in southern Australia. This practice may release mineral N from the decomposition of plant material and reduce the sink for N in the plant biomass, thereby increasing soil NO3concentrations and hence increasing the potential for denitrification (Jiang et al., 2000). This may explain the
Journal Pre-proof large emissions of N2O that occurred post-herbicide application at the Field 1 especially as herbicide application was followed by rain events which created soil moisture conditions favouring denitrification. Similar increases in N2O emission have been observed in our other studies following herbicide application to leafy vegetable crops (unpublished data). Many sports fields go through surface renovation on an annual basis to relieve compaction, improve aeration and establish new grass cover. This process involves fertilisation and frequent irrigation (to allow the germination and establishment of new grass), both practices that are known to stimulate N2O emission in turf (Bremer, 2006; Gillette et al., 2016).
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Across the three sports field sites, there was not a clear effect of fertiliser applications on N2O emission. At two of
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the sites where controlled release N fertiliser was applied (Fields 1 and 2), a brief increase in N2O emission was only observed at Field 1 following the first fertiliser application. However, a major rainfall event followed this
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fertiliser application so it is not possible to determine the relative effects of fertiliser application and increased
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soil moisture. The highest N2O emissions occurred at Field 3 where non-controlled release fertilisers (MAP and
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urea) were used. However, factors other than fertiliser type may have also contributed to the higher N2O emissions at Field 3 as relatively high emissions were observed both prior to the surface renovation and 25-36
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minimal.
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days after the last fertiliser application, when the influence fertiliser application would be expected to be
The less intensively managed turf area outside the sports field (the ‘lawn’ site in our study) had a considerably lower average emission of 9 g N ha-1 day-1. This level of emission is similar to previously reported emissions from lawns in urban environments (Bremer et al 2006, Groffman et al., 2009; Hall et al., 2008; Kaye et al., 2004; Livesley et al., 2010; Townsend-Small et al., 2011; Townsend-Small and Czimczik, 2010) and considerably higher than the 0.03-3.5 g N2O N ha-1 day-1 emissions observed in long terms studies in some Australian vegetable and grain production systems (Barton et al, 2008; Scheer et al., 2012; Scheer et al., 2017; Wang et al., 2011) and from native forest (Van Delden et al., 2016). In contrast, Townsend-Small and Czimczik (2010) did not find differences in N2O emissions between sports fields and lawns in California USA. However, in the US study the lawns were regularly fertilised and irrigated whereas they were not in our current study. Our study therefore appears to confirm that the management intensity, particularly irrigation and fertiliser application, have a greater impact on N2O emission than whether turf is used for sporting or other purposes.
Journal Pre-proof The average daily N2O fluxes from intensively managed sports fields in this study are similar in magnitude to those observed in other high emitting land uses in Australia. This includes emissions in high intensity vegetable production (Porter et al., 2017, Riches et al., 2016), sugarcane growing (Allen et al., 2010; Denmead et al., 2010) and irrigated pasture (Phillips et al., 2007), and following the conversion of rural pasture to urban turf (Van Delden et al., 2016). Even the lower N2O emissions from the less intensively managed turf (i.e. ‘lawn’ site) were still considerably high that those previously observed (0.03-3.5 g of N2O N ha-1 day-1) in long terms studies in some Australian vegetable and grain production systems (Barton et al, 2008; Scheer et al., 2012; Scheer et al., 2017;
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Wang et al., 2011) and from native forest (Van Delden et al., 2016). This shows that turf N2O emissions may make
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a more important contribution to national GHG emissions than previously thought.
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CH4 emissions from turf
Soil CH4 emission was generally low and the soil regularly changed between being a weak source or sink for CH4.
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However, over the longer term, CH4 oxidation appeared to dominate CH4 emission at most sites sampled in this
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study. This is consistent with the known low capacity of turf to consume CH4 (Groffman and Pouyat, 2009; Livesley et al., 2010). While it is know that N fertiliser application can reduce CH4 uptake in grasslands (Mosier et
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al., 1991), no significant change in net CH4 exchange observed at the sports field where continuous automated gas measurements were made after nitrogen fertiliser application which is similar to the findings of Livesley et al. (2010) for urban lawn. The balance between CH4 consumption and emission is determined by environmental conditions, with the most important factor being soil moisture content, which determines the ratio of aerobic to anaerobic sites in the soil (Grover et al., 2013; van den Pol-van Dasselaar et al., 1998). An unusually intense rainfall event is likely to have created anaerobic soil conditions, favouring methanogenesis over CH4 oxidation, which explains the high CH4 emissions of up to 1.29 kg C ha-1 day-1 measured at Field 2 in December 2017. Intense CH4 emission events resulting from temporary soil waterlogging have the potential to result in sports fields being net CH4 sources rather than sinks. Livesley et al (2010) previously showed that for irrigated lawn, total non-CO2 GHG emissions was dominated by N2O, with net CH4 exchange only accounting for approximately 1.3 % of the total CO2-e (CO2 equivalents). For the sports fields in this study, CH4 exchange was also of less importance for the
Journal Pre-proof overall GHG balance than N2O emission. However it was demonstrated that if soil is subject to periodic waterlogging, CH4 emission will make a larger contribution to the overall GHG balance than under more normal (drier) soil conditions. Effect of fertiliser type on GHG emissions Previous research in agricultural (Delgado and Mosier, 1996; Porter et al., 2017; Riches et al., 2016; Scheer et al., 2014) and turf systems (Braun and Bremer, 2018; Gillette et al., 2016; LeMonte et al., 2016), has shown decreases in N2O emission with the use of fertiliser products that slow the release of NO3- relative to rapidly available urea
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or nitrate based fertilisers. As would be expected, there was a trend toward lower soil NO3- concentrations in the
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treatments were enhanced efficiency fertilisers were applied, i.e. NI and PCU treatments, relative to urea
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although the effect was not statistically significant. However, controlled release and NI containing fertiliser treatments did not result in significantly lower cumulative GHG emissions at the sports field monitored
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continuously for approximately one month. The measurement period in our study was much shorter than the
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normal interval between applications of the controlled release fertiliser product which can be up to 16 weeks. Over the monitoring period soil moisture in the turf remained low (4-20 % VWC) may have been too low to
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promote denitrification due to lower than normal rainfall (63% lower than the longer term average for the
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October to November period) and the cessation of irrigation due to the impending redevelopment of the field. While supplemental hand watering was applied, it did not increase soil moisture to the levels observed during the earlier monitoring of the field. Benefits arising from using enhanced efficiency fertilisers to reduce N2O emission in turf under Australian conditions at higher soil moistures or over longer timeframes that are representative of the normal interval between applications of a controlled release fertiliser product cannot be ruled out from this preliminary study and warrant further investigation. Relevance of sport field and other turf to national GHG emissions Reliable estimates for the total land area covered by turf sports fields and other turf both in Australia and globally are not available (Van Delden et al., 2016). Globally golf courses have been estimated to cover approximately 25,600 km2 (Bartlett and James, 2011) and the total turf area for all sports turf would be considerably higher than this. For Australia, the following conservative estimate of sports turf area has been made in order to work out the
Journal Pre-proof importance of emissions from turf to the national GHG inventory. Australia has approximately 1530 golf courses (AGIC 2009), and the number of school and local council provided sporting fields could be estimated at 9477 and 4500, respectively, assuming each of Australia’s 9477 schools (ABS 2019) on average has one sports field each, and applying local government planning guidelines for the per capita provision of sport fields to the entire Australian population of approximately 25 million. This yields a total of approximately 15,500 sports fields and golf courses combined in Australia with a total turf area of approximately 780 km2 (assuming an 18 hole golf course has an average turf area of 38.5 Ha (GCSAA 2017) and a school or council owned sports field occupies 2 ha.
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This crude estimate of the total land area of sports turf in Australia suggests that GHG emissions from sports fields alone will not have a large impact on national GHG emissions. However, if all turf is considered together (i.e.
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sporting turf, urban lawns, parks and gardens, roadside reserves, turf farms) the land areas involved, and hence
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the potential for GHG emissions, are much larger. For example, in the USA, the area occupied by turf has been
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estimated as being three times larger than any other irrigated crop, somewhere between 130,000-200,000 km2
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(Milesi et al., 2005). In Australia the total turf area could be estimated at 11,250 km2 by extrapolating the average values from Australia’s two most populous cities, Sydney and Melbourne, of 450 m2 of turf per person (Holborn,
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2014) to the entire population of approximately 25 million. Although this estimate of total turf area has a large uncertainty and is likely to be an underestimate due to lower population densities outside of these two cities, it is
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still comparable in magnitude to the 20,365 km2 used for irrigated pasture, cropping and horticulture combined in Australia (ABARES, 2016).
To determine the total GHG balance of a land use requires measuring changes in C stocks in the system but this was beyond the scope of this study. While continuous grassland accumulates C in the soil profile over time, Townsend-Small and Czimczik (2010) concluded that intensively managed sports fields subject to regular surface restoration don’t sequester C in soil profile to offset management derived and soil N2O emissions. The low C contents of the sports field soils in this study support this conclusion. For less intensively managed turf where C sequestration may occur, the rate is dependent on the time since establishment and C content reaches an equilibrium over time (Selhorst and Lal 2011). Except under minimal management regimes, the rate of C sequestration is unlikely to offset GHG emissions and turf is likely to be a net GHG source in many cases (Bartlett and James 2011, Gu et al., 2015; Kong et al., 2014; Selhorst and Lal 2011; Townsend-Small and Czimczik 2010).
Journal Pre-proof Given that N2O emissions from turf may be higher than many other land uses, a warming climate is likely to see N2O emissions from fertilised turf rise (Bijoor et al., 2008) and turf areas are increasing resulting from increased urbanisation, it is possible that turf makes an important and increasing contribution to national and global GHG emissions. Conclusions N2O emissions from sports turf were shown to be high in southern Australia relative to similar sports fields in the northern hemisphere and other land uses in Australia. CH4 emission was generally negligible for the different turf
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sites except when waterlogged after extreme rainfall events. However, even at sites where periodic high CH4
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emissions occurred, over the longer term, total non-CO2 GHG emissions were still dominated by N2O emission. In
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light of the relatively high N2O emissions observed for both sports turf and non-sports turf, and the rapid expansion of turf as a land use with increasing urbanisation, further research is needed to quantify the
Acknowledgements:
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emissions.
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contribution of turf GHG emissions at a national level and to investigate mitigation practices to minimise turf N2O
This study was funded by La Trobe University through the Sport, Exercise and Rehabilitation RFA. The authors would like to thank Parade College for providing one of the sampling sites used in this study, Dr Helen Suter from Melbourne University for the loan of some of the equipment used in this work and gratefully acknowledge the assistance of grounds staff at La Trobe University (Peter Gooch) and Parade College (Rod McDonald).
Journal Pre-proof Table 1. Characteristics of sporting fields used in the study. Soil texture (Sand, Silt and Clay %) and organic C were
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determined on a single composite sample from each site.
Journal Pre-proof Table 2. N2O, CH4 and CO2 (respiration) cumulative and average daily emissions from the Field 1 fertiliser
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experiment (October 20 – November 20, 2017) (n=3).
Journal Pre-proof Figure 1. Daily minimum, maximum air temperature and daily rainfall and soil volumetric water content (VWC)
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during the experimental period (shaded area) at Field 1 (La Trobe University campus).
Journal Pre-proof Fig.2. N2O emissions from (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3. Dotted line shows timing of herbicide application at Field 1. Arrows show timing of fertiliser applications. Error bars represent the standard error of the
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mean (n=4).
Journal Pre-proof Fig. 3. CH4 emissions from (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3. Dotted line shows timing of herbicide application at Field 1. Arrows show timing of fertiliser applications. Error bars represent the standard error of the
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mean (n=4).
Journal Pre-proof Fig. 4. Soil NO3- N concentration (dry weight) in the 0-10 cm soil layer for (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3. Dotted line shows timing of herbicide application at the Field 1. Arrows show timing of fertiliser applications
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Error bars represent the standard error of the mean (n=4).
Journal Pre-proof Fig.5. Soil NH4+ N concentration (dry weight) in the 0-10 cm soil layer for (A) Field 1, (B) Field 2, (C) Lawn, and (D) Field 3 (D). Dotted line shows timing of herbicide application at Field 1. Arrows show timing of fertiliser applications.
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Error bars represent the standard error of the mean (n=4).
Journal Pre-proof Fig.6. Comparison of the daily average (A) N2O, (B) CH4, and (C) CO2 respiration emissions at Field 1 for Urea, urea with nitrification inhibitor (NI), polymer coated urea (PCU) and no added fertiliser
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(Control) treatments in Oct-Nov 2017. Error bars represent the standard error of the mean (n=3).
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Journal Pre-proof Fig.7. Soil NH4+ N and NO3- N concentrations in the 0-10 cm soil layer (dry weight) at Field 1 for Urea, urea with nitrification inhibitor (NI), polymer coated urea (PCU) and Control treatments in Oct-Nov 2017.
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Error bars represent the standard error of the mean (n=3).
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Allen, D.E., Kingston, G., Rennenberg, H., Dalal, R.C., Schmidt, S., 2010. Effect of nitrogen fertilizer management and waterlogging on nitrous oxide emission from subtropical sugarcane soils.
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Baethgen, W.E., Alley, M.M., 1989. A manual colorimetric procedure for measuring ammonium nitrogen in soil and plant Kjeldahl digests. Communications in Soil Science and Plant Analysis 20, 961-969.
Bartlett, M.D., James, I.T., 2011. A model of greenhouse gas emissions from the management of turf on two golf courses. Science of The Total Environment 409, 1357-1367.
Barton, L., Kiese, R., Gatter, D., Butterbach-bahl, K., Buck, R., Hinz, C., Murphy, D.V., 2008. Nitrous oxide emissions from a cropped soil in a semi-arid climate. Global Change Biology 14, 177-192.
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Journal Pre-proof Bijoor, N.S., Czimczik, C.I., Pataki, D.E., Billings, S.A., 2008. Effects of temperature and fertilization on nitrogen cycling and community composition of an urban lawn. Global Change Biology 14, 21192131. Braun, R.C., Bremer, D.J., 2018. Nitrous Oxide Emissions from Turfgrass Receiving Different Irrigation Amounts and Nitrogen Fertilizer Forms. Crop Science 58, 1762-1775. Bremer, D.J., 2006. Nitrous Oxide Fluxes in Turfgrass. Journal of Environmental Quality 35, 1678-
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Denmead, O.T., Macdonald, B.C.T., Bryant, G., Naylor, T., Wilson, S., Griffith, D.W.T., Wang, W.J.,
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Salter, B., White, I., Moody, P.W., 2010. Emissions of methane and nitrous oxide from Australian
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sugarcane soils. Agricultural and Forest Meteorology 150, 748-756. GCSAA 2017. Golf Course Environmental Profile. Phase II, Volume IV. Land Use Characteristics and
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Enivronmental Stewardship Programs on U.S. Golf Courses. Golf Course Superintendents Assoication
https://www.gcsaa.org/docs/default-source/Environment/phase-2-energy-survey-fullreport.pdf?sfvrsn=9cedeb3e_2 Accessed August 9, 2019.
Gillette, K., Qian, Y., Follett, R., Del Grosso, S., 2016. Nitrous Oxide Emissions from a Golf Course Fairway and Rough after Application of Different Nitrogen Fertilizers. Journal of Environment Quality 45, 1788-1795.
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Journal Pre-proof Groffman, P.M., Pouyat, R.V., 2009. Methane Uptake in Urban Forests and Lawns. Environmental Science & Technology 43, 5229-5235. Groffman, P.M., Williams, C.O., Pouyat, R.V., Band, L.E., Yesilonis, I.D., 2009. Nitrate Leaching and Nitrous Oxide Flux in Urban Forests and Grasslands. Journal of Environmental Quality 38, 1848-1860. Grover, S.P.P., Cohan, A., Chan, H.S., Livesley, S.J., Beringer, J., Daly, E., 2013. Occasional large emissions of nitrous oxide and methane observed in stormwater biofiltration systems. Science of
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Gu, C., Crane, J., Hornberger, G., Carrico, A., 2015. The effects of household management practices
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Journal Pre-proof Table 1. Characteristics of sporting fields and lawn used in the study. Soil texture and organic C were determined on a single composite sample (sub-sampled from four locations) at each site. Usage
Field 1 Lawn Field 2 Field 3
Football/cricket Lawn Baseball Football/cricket
Organic C (%) 1.1 4.1 1.5 2.8
Sand Silt (%) (%) 94.3 3.8 67.4 15.3 98.2 1.2 87.4 7.2
Clay (%) 1.9 17.3 0.6 5.4
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Journal Pre-proof Table 2. N2O, CH4 and CO2 respiration emissions from the Field 1 fertiliser experiment over the 31 days from October 20, 2017 to November 20, 2017. SE=Standard errors of the mean (n=3).
Treatment Control
Cumulative N2O-N g ha-1 257
Cumulative CH4-C g ha-1 -42.0
Cumulative CO2-C kg ha-1 1113
Daily N2O-N g ha-1 day-1 8.3
Daily CH4-C g ha-1 day-1 -1.23
Daily CO2-C g ha-1 day-1 35.9
388
-26.1
1173
12.5
-0.77
37.8
NI
423
-42.1
1193
13.6
-0.93
38.5
Urea
426
-37.3
1097
13.8
-0.78
35.4
SE
45.3
4.7
55.0
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-
-
P value
0.513
0.619
0.905
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-
-
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Journal Pre-proof Highlights Sports field N2O fluxes were high relative to other land uses
CH4 fluxes generally very low except after unusually high rainfall
Herbicide use and turf renovation were associated with high N2O emission events
Fertiliser application and soil moisture had variable effects on N2O emissions
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Figure 7