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The effects of household management practices on the global warming potential of urban lawns

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Abstract

Nitrous oxide (N2O) emissions are an important component of the greenhouse gas (GHG) budget for urban turfgrasses. A biogeochemical model DNDC successfully captured the magnitudes and patterns of N2O emissions observed at an urban turfgrass system at the Richland Creek Watershed in Nashville, TN. The model was then used to study the long-term (i.e. 75 years) impacts of lawn management practice (LMP) on soil organic carbon sequestration rate (dSOC), soil N2O emissions, and net Global Warming Potentials (net GWPs). The model simulated N2O emissions and net GWP from the three management intensity levels over 75 years ranged from 0.75 to 3.57 kg Nha(-1)yr(-1) and 697 to 2443 kg CO2-eq ha(-1)yr(-1), respectively, which suggested that turfgrasses act as a net carbon emitter. Reduction of fertilization is most effective to mitigate the global warming potentials of turfgrasses. Compared to the baseline scenario, halving fertilization rate and clipping recycle as an alternative to synthetic fertilizer can reduce net GWPs by 17% and 12%, respectively. In addition, reducing irrigation and mowing are also effective in lowering net GWPs. The minimum-maintenance LMP without irrigation and fertilization can reduce annual N2O emissions and net GWPs by approximately 53% and 70%, respectively, with the price of gradual depletion of soil organic carbon, when compared to the intensive-maintenance LMP. A lawn age-dependent best management practice is recommended: a high dose fertilizer input at the initial stage of lawn establishment to enhance SOC sequestration, followed by decreasing fertilization rate when the lawn ages to minimize N2O emissions. A minimum-maintained LMP with clipping recycling, and minimum irrigation and mowing, is recommended to mitigate global warming effects from urban turfgrass systems. Among all practices, clipping recycle may be a relatively malleable behavior and, therefore, a good target for interventions seeking to reduce the environmental impacts of lawn management through public education. Our results suggest that a long-term or a chronosequence study of turfgrasses with varying ages is warranted to capture the complete dynamics of contribution of turfgrasses to global warming. Copyright © 2015. Published by Elsevier Ltd.

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... Similar to farm operations, turfgrass maintenance is comprised of energy-based inputs that have been labeled hidden carbon costs (HCC) in kilograms of carbon equivalents (CE) ha -1 yr -1 (Selhorst and Lal, 2011;Zirkle et al., 2011;Gu et al., 2015). These HCC should also include emissions from other GHG such as N 2 O (Gu et al., 2015;Zhang et al., 2013). ...
... Similar to farm operations, turfgrass maintenance is comprised of energy-based inputs that have been labeled hidden carbon costs (HCC) in kilograms of carbon equivalents (CE) ha -1 yr -1 (Selhorst and Lal, 2011;Zirkle et al., 2011;Gu et al., 2015). These HCC should also include emissions from other GHG such as N 2 O (Gu et al., 2015;Zhang et al., 2013). Although emissions of N 2 O do not directly affect C sequestration rates, these emissions should be also included in HCC for more complete accounting of the GHG impact of management practices in turf (Zhang et al., 2013;Gu et al., 2015). ...
... These HCC should also include emissions from other GHG such as N 2 O (Gu et al., 2015;Zhang et al., 2013). Although emissions of N 2 O do not directly affect C sequestration rates, these emissions should be also included in HCC for more complete accounting of the GHG impact of management practices in turf (Zhang et al., 2013;Gu et al., 2015). However, very few turf studies exist that have factored HCC estimates into soil C sequestration rates, and even fewer have included N 2 O emissions in HCC estimates, and in this current study we included N 2 O emissions in HCC estimates. ...
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Core Ideas Further research is required to evaluate and develop management practices that may sequester C in turfgrass soils. Hidden C costs, which are energy‐based inputs from turf maintenance, should be factored into soil C sequestration calculations. A higher‐input management regime in turf will not increase net C sequestration compared with a low management input regime. Zoysiagrass golf course fairway turf had an average gross C sequestration rate of 1.01 Mg C ha–1 yr–1. Carbon dioxide (CO2) is an important greenhouse gas (GHG) implicated in climate change. Turfgrass covers an estimated 12.8 to 20 million ha in the United States and has the capacity to sequester or emit significant amounts of CO2 from/into the atmosphere. Our objective was to evaluate irrigation and N fertilization management practices that may increase sequestration of atmospheric CO2 in turf soils. The rate of change in soil organic carbon (SOC) at 0 to 30 cm was investigated under two management regimes in ‘Meyer’ zoysiagrass (Zoysia japonica Steud.). A high management input (HMI) (urea + medium irrigation) and low management input regime (LMI) (unfertilized [no N fertilizer] + low irrigation) were implemented. Hidden carbon costs (HCC) of maintenance practices and nitrous oxide emissions (another GHG) were estimated to account for energy expended in Mg of carbon equivalents (CE) ha–1 yr–1. Prior to subtracting HCC, average gross C sequestration rates were not statistically different at 1.046 and 0.976 Mg C ha–1 yr–1 in HMI and LMI, respectively. Once total estimated HCC was included, the average net sequestration rate was 0.412 and 0.616 Mg C ha–1 yr–1 in HMI and LMI, respectively, with no statistical differences. Results indicate that under the conditions of this study, a higher‐input management regime will not increase net C sequestration compared with a low management input regime. Further research is required over additional turfgrass species and management regimes to develop management practices that increase C sequestration.
... A minimum lawn maintenance program without irrigation and fertilization was found to reduce annual N 2 O emissions and net GWP by approximately 53% and 70%, respectively, with the price of gradual depletion of soil organic carbon, when compared to intensive management. 21 Montalvo (2015, Mooney (2015 22 Hickman (2018), Montalvo (2015), Mooney (2015), Pierre-Louis (2018) 23 Gu et al. (2015) A similar investigation focused on southern California. 24 Soil organic carbon sequestration rates, N 2 O emissions, and CO 2 e emissions generated by fuel combustion, fertilizer production, and irrigation were studied. ...
... 29 In view of a 2014 finding that only 26% of homeowners have soil tested prior to fertilizer application, 30 the likelihood of nutrients being applied in excess of soil needs is high. Gu et al. (2015) 27 Bremer (2006) 28 When granular fertilizer is used a light sprinkling is recommended within a week to ten days following application to activate the fertilizer and break down granules. 29 Millar (2015) 30 Khachatryan et al. (2014) Related to the observation that heavy rainfall following N application promotes N 2 O emissions, is the finding that climate has a large effect on both N 2 O emissions and N leaching in lawn soils. ...
... Taking steps to reduce the area of turf grass requiring intensive management will invariably reduce the overall environmental impact of lawns. (https://extension.psu.edu/dont-over-fertilize-your-lawn-this-spring) 31 Crane (2014) 32 Gu et al. (2015) ...
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While green lawns are as American as apple pie, they contribute to a host of adverse environmental impacts if not managed with restraint. Fertilization, in particular, deserves special attention as its production is energy-intensive with its use linked to pollution of surface and ground water, emissions of potent greenhouse gases, reduction of dissolved oxygen in rivers and lakes, and promotion of algal growth in water bodies. Pesticides and herbicides used on lawns and gardens also pose risks to surface and groundwater, aquatic ecosystems, birds and beneficial insects, and soil microorganisms. Healthy growing lawns sequester carbon, and store significant quantities in soil. Carbon sequestration is an important benefit of urban lawns. Healthy lawns maintained with modest fertilization, watering, and clippings retention have relatively low impact. But moderation, as in many things, is essential in lawn management in order to minimize adverse impacts. More does not mean better. While fertilization can increase the rate of carbon capture, its use can also trigger emissions that negate that benefit. Fertilizer use should be guided by periodic soil samples, and excess avoided. Timing of fertilizer application is also important. Paying attention to a number of other simple guidelines, which vary by region, can reduce the impacts of lawn care.
... Furthermore, nitrogen (N) from fertilisers and plant residues enhances nitrification and denitrification, which may increase emissions of nitrous oxide (N2O). Intensive turfgrass management combining frequent irrigation and fertilisation can enhance N2O losses, particularly if water is applied immediately after fertilisation (Gu et al., 2015). However, soil N2O production is associated with high variability depending on soil properties and management, which poses a great challenge when estimating N2O emissions (Li et al., 2013). ...
... A number of studies have evaluated GHG emissions from public and private lawns (e.g. Small and Czimczik, 2010; Zirkle et al., 2011; Selhorst and Lal, 2013; Kong et al., 2014; Gu et al., 2015), while fewer studies are available for golf courses. Bartlett and James (2011) modelled GHG emissions from two golf courses in the UK and determined the balance between soil C sequestration and emissions from turf management. ...
... According to model simulations of N2O emissions from urban lawns, expected N2O-N losses range between 0.75-3.57 kg ha -1 year -1 for lawns fertilised with 0-89 kg N, and recycling of lawn clippings has been identified as an important source of N2O emissions (Gu et al., 2015). The proposed default emissions factor for N2O-N according to IPCC (2006) for composting in windrows with infrequent turning for mixing and aeration is 1%. ...
Article
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Turf management on golf courses entails frequent maintenance activities, such as mowing, irrigation and fertilisation, and relies on purchased inputs for optimal performance and aesthetic quality. Using life cycle assessment (LCA) methodology, this study evaluated energy use and greenhouse gas (GHG) emissions from management of two Swedish golf courses, divided into green, tee, fairway and rough, and identified options for improved management. Energy use and GHG emissions per unit area were highest for greens, followed by tees, fairways and roughs. However, when considering the entire golf course, both energy use and GHG emissions were mainly related to fairway and rough maintenance due to their larger area. Emissions of GHG for the two golf courses were 1.0 and 1.6 Mg CO2e ha⁻¹year⁻¹ as an area-weighted average, while the energy use was 14 and 19 GJ ha⁻¹year⁻¹. Mowing was the most energy-consuming activity, contributing 21 and 27% of the primary energy use for the two golf courses. In addition, irrigation and manufacturing of mineral fertiliser and machinery resulted in considerable energy use. Mowing and emissions associated with fertilisation (manufacturing of N fertiliser and soil emissions of N2O occurring after application) contributed most to GHG emissions. Including the estimated mean annual soil C sequestration rate for fairway and rough in the assessment considerably reduced the carbon footprint for fairway and turned the rough into a sink for GHG. Emissions of N2O from decomposition of grass clippings may be a potential hotspot for GHG emissions, but the high spatial and temporal variability of values reported in the literature makes it difficult to estimate these emissions for specific management regimes. Lowering the application rate of N mineral fertiliser, particularly on fairways, should be a high priority for golf courses trying to reduce their carbon footprint. However, measures must be adapted to the prevailing conditions at the specific golf course and the requirements set by golfers.
... This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/). enhance N 2 O losses, particularly if water is applied immediately after fertilisation (Gu et al., 2015). However, soil N 2 O production is associated with high variability depending on soil properties and management, which poses a great challenge when estimating N 2 O emissions (Li et al., 2013). ...
... A number of studies have evaluated GHG emissions from public and private lawns (e.g. Selhorst and Lal, 2013;Kong et al., 2014;Gu et al., 2015), while fewer studies are available for golf courses. Bartlett and James (2011) modelled GHG emissions from two golf courses in the UK and determined the balance between soil C sequestration and emissions from turf management. ...
... According to model simulations of N 2 O emissions from urban lawns, expected N 2 O N losses range between 0.75-3.57 kg ha −1 year −1 for lawns fertilised with 0-89 kg N, and recycling of lawn clippings has been identified as an important source of N 2 O emissions (Gu et al., 2015). The proposed default emissions factor for N 2 O N according to IPCC (2006) for composting in windrows with infrequent turning for mixing and aeration is 1%. ...
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The goal of this manual is to share a vision of lawns based on the results of the transdisciplinary LAWN project “Lawn as ecological and cultural phenomenon. Searching for sustainable lawns in Sweden” (2013-2016) funded by Formas. First, we present the results of this project and discuss existing lawn alternatives from Europe and North America. We then analyse and discuss experiences in Sweden, including our own experimental sites at SLU Ultuna Campus in Uppsala. We also provide practical advice on establishing and managing different types of lawn alternatives suitable for Swedish conditions.
... Robbins and Birkenholtz (2003) called the expansion of the urban lawn a critical, but overlooked, component of regional ecosystem change. Given the tremendous subsidies of plant materials, water, chemicals, labor, time, capital and energy to establish and maintain them (Robbins and Sharp 2003;Robbins 2007;Naylor 2012;Gu et al. 2015;Locke et al. 2019), lawns are a crucial case (Gerring 2004) to explore how and why people manipulate urban vegetation. ...
... I hypothesized that yard goals based on normative ideas of lawn appearance should be ranked highly, while ideas about ease of maintenance should be more variable to reflect homeowner ambivalence about lawn care labor (Robbins 2007;Harris et al. 2013). Because the full regime of actual lawn care (seasonal irrigation, fertilization, mowing, edging and herbicide application) is not well documented in the literature [but see Gu et al. (2015) for resident lawn care and Yang et al. (2019) for public park lawn care], I made no predictions about lawn care frequencies. Rather, my goal was to describe new homeowner lawn care, because new homeowners have strong incentives to protect the appearance and value of their new spaces to meet neighborhood norms (Nassauer, Wang, and Dayrell 2009;Carrico, Fraser, and Bazuin 2013;Sisser et al. 2016). ...
... The lawn care regimes of new homeowners are similar to each other and to Tennessee residents (Gu et al. 2015). Mean frequencies of fertilization (2.6 vs. 2.5/year) and mowing (21 vs. 18 times/year) were similar as were irrigation seasons (nearly everyone in summer, about 75% of households in spring, and <10% in fall). ...
Article
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Households intensively manage lawns to create uniformly green, low diversity plant communities. Because lawns occupy a large proportion of urban green space, they are a crucial case for understanding how people manipulate urban vegetation. In this study, I focused on 58 homeowners who purchased a newly constructed home and yard in the Seattle Metropolitan Statistical Area, USA, to see how preferences, lawn care regimes and new lawn floras develop within a multi-scalar urban environment. A typical homeowner watered 3 times in spring, watered 24 times in summer, applied fertilizer twice, mowed 21 times and edged 15 times. Most new lawn turfgrasses were Lolium perenne, Poa pratensis and/or Festuca spp. Mean species richness was 6.5 ± 5.3 species. The most frequent species were non-native and cosmopolitan (turfgrasses, Hypochaeris radicata, Taraxacum officinale and Trifolium repens). Five variables increased the probability of homeowners managing their lawns as turfgrass monocultures: living in a neighborhood with larger yards, summer watering frequency, fertilizer frequency, valuing space for children and valuing wildlife habitat. Valuing an easy to manage yard decreased the turfgrass monoculture probability. In polyculture yards, having a larger lawn was positively correlated with non-turfgrass species richness, but elevation was negatively correlated. Homeowners who valued space for children appeared to have more intensive lawn care regimes than those who valued wildlife habitat or easy to manage yards. Although lawn floras result from complex interactions of the environment and households, urban characteristics appeared to be weaker drivers of diversity than homeowner preferences and lawn care.
... Therefore, a standard 40pound bag of lawn fertilizer comprised of 32% nitrogen produces 31-44 kg of carbon dioxide equivalents; roughly equal to driving an average passenger vehicle in the U.S. for over 70 miles (Environmental Protection Agency., 2016). Fertilized lawns are also net contributors to climate change through the direct emission of nitrous oxide, a powerful greenhouse gas (Gu, Crane, Hornberger, & Carrico, 2015). ...
... This is particularly true of those who over-fertilize. Not only are these individuals using a carbon-intensive product; but intensely managed lawns (involving above average use of fertilizer and irrigation) have a 70% higher global warming potential from direct emissions compared to lawns that are not fertilized or irrigated (Gu et al., 2015). Furthermore, lawn management intensity has a nonlinear relationship with GHG emissions and diminishing returns on the productivity of the crop (Gu et al., 2015). ...
... Not only are these individuals using a carbon-intensive product; but intensely managed lawns (involving above average use of fertilizer and irrigation) have a 70% higher global warming potential from direct emissions compared to lawns that are not fertilized or irrigated (Gu et al., 2015). Furthermore, lawn management intensity has a nonlinear relationship with GHG emissions and diminishing returns on the productivity of the crop (Gu et al., 2015). Recognizing this, a number of government and industry outreach efforts have attempted to educate households regarding best practices in fertilizer use and other lawn management behaviors (Environmental Protection Agency., 2004;Frank, 2005;Southeast Oakland County Water Authority (SOCWA), 2011;USFWS., 2000); urging households to use the correct amount of fertilizer (USFWS, 2000), to pay close attention to package instructions (USFWS, 2000), or to hire a lawn care provider so as not to over-fertilize (University of Florida IFAS Extension, Florida-Friendly Landscaping Program, & Florida Department of Environmental Protection, 2015). ...
... Therefore, a standard 40pound bag of lawn fertilizer comprised of 32% nitrogen produces 31-44 kg of carbon dioxide equivalents; roughly equal to driving an average passenger vehicle in the U.S. for over 70 miles (Environmental Protection Agency., 2016). Fertilized lawns are also net contributors to climate change through the direct emission of nitrous oxide, a powerful greenhouse gas (Gu, Crane, Hornberger, & Carrico, 2015). ...
... This is particularly true of those who over-fertilize. Not only are these individuals using a carbon-intensive product; but intensely managed lawns (involving above average use of fertilizer and irrigation) have a 70% higher global warming potential from direct emissions compared to lawns that are not fertilized or irrigated (Gu et al., 2015). Furthermore, lawn management intensity has a nonlinear relationship with GHG emissions and diminishing returns on the productivity of the crop (Gu et al., 2015). ...
... Not only are these individuals using a carbon-intensive product; but intensely managed lawns (involving above average use of fertilizer and irrigation) have a 70% higher global warming potential from direct emissions compared to lawns that are not fertilized or irrigated (Gu et al., 2015). Furthermore, lawn management intensity has a nonlinear relationship with GHG emissions and diminishing returns on the productivity of the crop (Gu et al., 2015). Recognizing this, a number of government and industry outreach efforts have attempted to educate households regarding best practices in fertilizer use and other lawn management behaviors (Environmental Protection Agency., 2004;Frank, 2005;Southeast Oakland County Water Authority (SOCWA), 2011;USFWS., 2000); urging households to use the correct amount of fertilizer (USFWS, 2000), to pay close attention to package instructions (USFWS, 2000), or to hire a lawn care provider so as not to over-fertilize (University of Florida IFAS Extension, Florida-Friendly Landscaping Program, & Florida Department of Environmental Protection, 2015). ...
Article
Urban and suburban lawns make up a large share of land use in the US. Maintaining lawns to fulfill aesthetic norms has environmental consequences. In this analysis, we examine household decisions to apply nitrogen-containing lawn fertilizer. Using survey data of 298 households in Nashville, Tennessee, we first examine the prevalence of fertilizer use and the rate of annual nitrogen applied. We find that the resulting distribution is skewed, with the top 20% of the sample applying 56% of the total share of nitrogen. In contrast to this subset of "intensive" fertilizers, 93% of households applied at or below levels recommended by landscaping professionals, challenging the assumption that the over-application of fertilizer is widespread. We employed multi-level modeling to examine the relative importance of household-and block-level characteristics on fertilizer use and the intensity of use. Consistent with prior work, we find that the desire for a green lawn is a significant predictor of fertilizer use. However, we also find that living on a wealthy block and living near others who value a green lawn independently predict fertilizer use. In addition, we observe that intensive fertilizing households tend to be less wealthy than others on their block, suggesting the possibility of an aspirational dimension to fertilizer use. Finally, we find evidence that environmental concern is associated with less intensive fertilizer use, suggesting that households may be willing to take some steps to mitigate the impact of their lawn care on the environment.
... However, these same management activities might drive SOC outputs by changing soil temperature and moisture (Allaire et al., 2008;Byrne, Bruns, & Kim, 2008;Liu & Huang, 2003;Luo, Wan, Hui, & Wallace, 2001), two of the primary drivers of SOC turnover and soil CO 2 flux (Davidson, Belk, & Boone, 1998). Anthropogenic HCCs, which are expressed as grams of C equivalents (CE) m −2 year −1 (Zirkle, Lal, & Augustin, 2011), are associated with the energy consumed from fertilizer application (e.g., the additional HCCs associated with manufacturing and distributing the fertilizer), irrigation (e.g., energy costs associated with running the irrigation system) and emissions associated with maintaining the lawn with a gas-powered mower (Gu, Crane, Hornberger, & Carrico, 2015). ...
... Regarding mowing-related activities, previous work has largely focused on the effects of clippings management and mower height on soil C cycling (Fissore et al., 2012;Lilly et al., 2015;Ng et al., 2015;Qian et al., 2003;Song, Burgess, Han, & Huang, 2015). The few studies that have explicitly considered mowing frequency have either implemented unrealistically long intervals for residential yards (e.g., once per season, Allaire et al., 2008), compared weekly sampling to a regime based on leaf blade height (e.g., Law & Patton, 2017), or conducted a modeling exercise based on self-reported mowing activities (e.g., number of mowing events; Gu et al., 2015), and thus have not examined how more typical mowing behaviors might affect soil C losses from urban lawns or how specific lawn features (e.g., size of lawn and time spent mowing) influences the associated HCCs for maintaining these systems. To better understand how lawn mowing frequency affects biogenic and anthropogenic CO 2 emissions in lawn-dominated systems, we manipulated lawn mowing frequency in suburban yards to test the following three hypotheses: (1) mowing more frequently decreases soil moisture and increases soil temperature; (2) these changes in soil microclimate drive soil respiration rates, with higher rates in warmer soils under frequent mowing; and (3) frequent lawn mowing elevates HCC such as C emissions associated with the mower itself. ...
... Although lawn mowing frequency did not influence the amount of CO 2 released from soils, the amount of CO 2 emissions from the lawn mower did increase with more frequent mowing, highlighting an important HCC. Our weekly mowing HCC results were comparable to other studies calculating the HCCs associated with lawn mowing (e.g., Horn et al., 2015;Zirkle et al., 2011) yet differed from other studies (e.g., Gu et al., 2015), perhaps due to different methods and calculations. Studies assessing the HCCs have recommended reducing mowing frequency as a possible solution to help reduce anthropogenic emissions (Selhorst & Lal, 2013;Strohbach et al., 2012). ...
Article
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Decision makers in urban areas actively pursue strategies to decrease carbon dioxide (CO2) emissions and other greenhouse gases. Lawns dominate urban lands in the U.S. and require intensive management, including frequent mowing, which may influence CO2 emissions from both biogenic and anthropogenic sources. We tested whether different lawn mowing frequencies (every one, two or three weeks) affected soil respiration (i.e., biogenic CO2 emissions), by changing soil moisture and temperature, and the gasoline emissions associated with lawn maintenance via lawn mowing (i.e., anthropogenic CO2 emissions). Sixteen yards in Springfield, Massachusetts USA were assigned a mowing frequency for two seasons (2013–2014). We measured grass height, air and soil temperature, soil moisture, soil CO2 flux, lawn mower emissions, tree canopy coverage and precipitation. We used a mixed effects modeling approach to test how these variables interacted with each other and responded to mowing frequency. Lawn-mowing frequency did not influence soil temperature, moisture, or biogenic soil CO2 fluxes. Soil microclimate and soil respiration varied more with ambient climatic fluctuations and tree canopy cover. By contrast, anthropogenic emissions increased with more frequent mowing due to emissions associated with the mower. When scaled to the entire mowing season, biogenic CO2 fluxes far exceeded the anthropogenic fluxes, thus requiring consideration for accurate accounting of urban greenhouse gas emissions. The interplay between biogenic (e.g., increasing tree canopy in lawn-dominated yards) and anthropogenic (i.e., mowing less frequently) methods of reducing CO2 emissions in cities highlights the need for more rigorous accounting processes for cities to meet climate action goals.
... Various anthropogenic greenhouse gases (CO 2 , N 2 O, CH 4 , etc.) have been identified as one of the main contributors triggering and/or accelerating global warming which is attributed to the detrimental disturbance of our ecosystem (Amponsah et al., 2014). Among these anthropogenic contributors, carbon dioxide has drawn the most public attention due to the tremendous gener-ation of it from harnessing fossil fuels (petroleum oil and coal) as our energy feedstocks (Amponsah et al., 2014;Gu et al., 2015). Therefore, the virtuous circulation associated with the ultimate carbon management has been proposed and emphasized to abate the global environmental issues stated above: scientific and engineering efforts brought forth the concept of carbon capture and storage (CCS) (Cuellar-Franca and Azapagic, 2015;Gu et al., 2015;Lee et al., 2010;Li et al., 2015) and zero emissions (Cuellar-Franca and Azapagic, 2015). ...
... Among these anthropogenic contributors, carbon dioxide has drawn the most public attention due to the tremendous gener-ation of it from harnessing fossil fuels (petroleum oil and coal) as our energy feedstocks (Amponsah et al., 2014;Gu et al., 2015). Therefore, the virtuous circulation associated with the ultimate carbon management has been proposed and emphasized to abate the global environmental issues stated above: scientific and engineering efforts brought forth the concept of carbon capture and storage (CCS) (Cuellar-Franca and Azapagic, 2015;Gu et al., 2015;Lee et al., 2010;Li et al., 2015) and zero emissions (Cuellar-Franca and Azapagic, 2015). In parallel, various renewable energies (wind mill, photovoltaic (PV), geothermal energy, bioenergies) were proposed and developed (Chauhan and Saini, 2014;Li et al., 2015). ...
Article
Instead of anaerobic digestion of biodegradable wastes for producing methane, this work introduced the transformation of acidogenesis products (VFAs) into fatty acid methyl esters (FAMEs) to validate the feasible production of short-chained fatty alcohols via hydrogenation of FAMEs. In particular, among VFAs, this work mainly described the mechanistic explanations for transforming butyric acid into butyric acid methyl ester as a case study. Unlike the conventional esterification process (conversion efficiency of ∼94%), the newly introduced esterification under the presence of porous materials via the thermo-chemical process reached up to ∼99.5%. Furthermore, the newly introduced esterification via the thermo-chemical pathway in this work showed extremely high tolerance of impurities: the conversion efficiency under the presence of impurities reached up to ∼99±0.3%; thus, the inhibition behaviors attributed from the impurities used for the experimental work were negligible.
... The lawns occupy roughly 2% of the total land in the United States (Milesi et al., 2005). Maintaining an aesthetically appealing lawn is a common driver for lawn irrigation and fertilization (Gu et al., 2015). Almost all lawns require relatively high levels of fertility (up to 200-300 kg N ha) to maintain health and promote recovery from damage (Carey et al., 2012). ...
... Almost all lawns require relatively high levels of fertility (up to 200-300 kg N ha) to maintain health and promote recovery from damage (Carey et al., 2012). Lawn management can provide optimum conditions for N 2 O emissions, especially irrigation after fertilization, which can enhance lawn N 2 O emissions (Gu et al., 2015). Some studies have shown that fertilization equalises the N 2 O emissions from urban lawn soils with agricultural soils (Townsend-Small et al., 2011;Chen et al., 2018). ...
Article
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As nitrous oxide (N2O) is one of the most important greenhouse gases, N2O emission pathways and regulation techniques in soils with different vegetation types have become a research focus. Currently, a diverse array of research exists on the N2O emissions from soils of different vegetation types, e.g., forest, grassland, and agriculture. Few studies have investigated the microbial processes of N2O emissions from lawn soils. Fertilization levels in lawn soils are often similar to or much higher than those in agricultural ecosystems, thus fertilized lawn is an important source of atmospheric N2O. In the study, we employed the 15N-nitrate labelling method combined with the nitrification inhibition technique to distinguish microbial processes and their contribution to N2O emissions in long-term nitrogen fertilised lawns. We found that the N2O emission rate from the control treatment was 1.0 nmol g−1 h−1 over the incubation, with autotrophic nitrification contributing 60%. The N2O emission rate increased to 1.4 nmol g−1 h−1 from the soil treated with long-term N fertilization, and the contribution of autotrophic nitrification increased to 69%. N fertilization did not significantly increase the contribution of denitrification (24–26%) in the total N2O emissions. However, N fertilization substantially decreased the contribution of heterotrophic nitrification from 13 to 0.4% in the total N2O emissions. Co-denitrification to N2O was detected but the overall contribution was of minor importance (3–5%). The correlation analysis revealed that soil NO3 − levels were the main influencing factors in the N2O producing microbial processes. Our results suggest that N fertilization altered both N2O production rates and the contribution pattern of microbial processes, and indicate the autotrophic nitrification and heterotrophic nitrification are more sensitive to N fertilization than denitrification and co-denitrification.
... The researchers developed a model of turf grass yield and emissions that included inputs of the biophysical features of the turfgrass system, meteorological conditions, and a range of common lawn management behaviors derived from survey data. Their results suggested that, on average, lawns are net emitters of greenhouse gases; however, the global warming potential of lawns is highly sensitive to how they are managed (Gu, Crane, Hornberger, & Carrico, 2015). Mowing and the application of synthetic nitrogen fertilizer are the most effective behaviors to target in order to reduce lawn-related greenhouse gas emissions (Gu et al., 2015). ...
... Their results suggested that, on average, lawns are net emitters of greenhouse gases; however, the global warming potential of lawns is highly sensitive to how they are managed (Gu, Crane, Hornberger, & Carrico, 2015). Mowing and the application of synthetic nitrogen fertilizer are the most effective behaviors to target in order to reduce lawn-related greenhouse gas emissions (Gu et al., 2015). However, survey data suggested that many residents might be resistant to modifying these actions due to their personal preference of maintaining a "lush, green lawn" and a strong sense of obligation to meet the expectations of neighbors (Carrico, Fraser, & Bazuin, 2013). ...
Article
Environmental challenges, though daunting, present an important area for psychologists to apply their knowledge. Psychological theories, research methods, and interventions are essential for examining the questions about human impacts, tendencies, and capacities that are integral to constructing effective responses to these challenges. Although a great deal of relevant research has been done, there is scope for psychologists to be more extensively involved. Following a brief review of existing research, we outline some important new directions. We also highlight 2 key divergences, arguing that psychological research needs to expand beyond a traditional, theory-based and decontextualized approach to environmental issues to incorporate a contextualized or "place-based" approach and a willingness to collaborate in interdisciplinary research teams that focus on specific environmental problems. Suggestions for promoting such interdisciplinary collaborations are reviewed. We encourage psychologists to expand their engagement with important environmental issues through multiple research approaches in order to further their understanding of human behavior, contributions to human wellbeing, and relevance to other disciplines and to society. (PsycINFO Database Record (c) 2015 APA, all rights reserved).
... Urbanization could alter both biotic and abiotic ecosystem properties fundamentally within and outside urban areas (Hall et al., 2008), and urban areas have been reported to be significant contributors to global greenhouse gas (GHG) emissions, especially energy-related global greenhouse gas emissions (Hoornweg et al., 2011). Urban green areas, such as urban forest, public parks and private planted areas around buildings, play essential roles in global biogeochemical cycling (Givoni, 1991;Kaye et al., 2005), and have attracted wide scientific concern, i.e., their contributions to N 2 O emission (Groffman et al., 2009;Gu et al., 2015). However, the results vary between different studies owing to distinct land management practices and investigated regions. ...
Article
Cities are increasingly being recognized as important contributors in global warming, for example by increasing atmospheric nitrous oxide (N2O). However, urban ecosystems remain poorly understood due to their functional complexity. Further, few studies have documented the microbial processes governing the N2O emissions from urban soils. Here, a field study was performed to assess in situ N2O emissions in an urban and agricultural soil located in Xiamen, China. The mechanisms underlying the difference in N2O emission patterns in both soils were further explored in an incubation experiment. Field investigations showed that N2O emission (3.5–19.0 μg N2O-N m⁻² h⁻¹) from the urban soil was significantly lower than that from the agricultural soil (25.4–18,502.3 μg N2O-N m⁻² h⁻¹). Incubation experiments showed that the urban soil initially emitted lower denitrification-derived N2O because of the lower nirS (encoding nitrite reductases) abundances, whereas overall N2O accumulation during the incubation was mainly controlled by the initial nitrate content in soil. Nitrate addition in a short period (5 days) did not change the total bacterial and denitrifier abundances or the soil bacterial community composition, but significantly altered the relative distribution of some key genera capable of denitrification. Although the urban soil exhibited lower N2O emission than its agricultural counterpart in this study, the expanding urban green areas should be taken into account when building N2O emission reduction targets.
... The potential of SOC sequestration has been considered below ground in the first 20 cm of topsoil using data given by the LUCAS Topsoil Survey Methodology (Tóth et al., 2013) for grassland. The GHG emissions from the maintenance of turf grass have been reported by Gu et al. (2015) to vary according to maintenance scenarios: 697.2 kgCO 2 e/ha/a for minimum maintenance, 845.4 kgCO 2 e/ha/a for medium maintenance and 2442.5 kgCO 2 e/ha/a for intensive maintenance. We have used the medium maintenance scenario but apply a conservative correction factor of 0.5 to it, assuming a lesser maintenance period for a lawn in the southern Finnish climate compared to a lawn in Tennessee, USA, where the study was made. ...
Article
Plants and soil are natural regulators of atmospheric CO2. Whereas plants sequester atmospheric carbon, soils deposit it for decades. As cities become increasingly more densely built, the available land area for such ecosystem services may decrease. We studied seven different housing areas in the Finnish city of Espoo to ascertain the extent to which site efficiency affects to the ecosystem services if the full life-cycle GHG emissions of these areas are taken into account. The results show that the impact of CO2 uptake through carbon sinks in growing plants and the uptake of soil organic carbon vary greatly. Its share of all emissions varied from a marginal value of 1.2% to a more considerable value of 11.9%. The highest potential was calculated for a detached house located on a large site, while the weakest was calculated for compact apartment blocks. The study revealed that in order to quantify this potential more accurately, several knowledge gaps must first be addressed. These include impartial growth algorithms for Nordic wood species, missing accumulation factors for soil organic carbon in cold climates and statistical maintenance scenarios for gardens.
... Certain lawn care practices can provide favorable conditions for N gaseous losses as N 2 O, especially lawns receiving sufficient N and water (Horgan et al., 2002). A lawn age-dependent best management practice is recommended: a high dose fertilizer input at the initial stage of lawn establishment to enhance soil organic carbon sequestration, followed by decreasing fertilization rate when the lawn ages to minimize N 2 O emissions (Gu et al., 2015). Biological N fixation technology can play a role in substituting commercially available N fertilizer use in the turf ecosystem. ...
Article
Endophytic diazotrophic bacteria have been found within many graminaceous plants in the last decades and may contribute to nitrogen (N) nutrition through biological nitrogen fixation while promoting growth and stress tolerance to host plants. Their colonization and growth promotion were reported to be affected by plant N nutrition level. However, little is known on effects of endophytic diazotrophic bacteria and their interaction with N fertilization on turfgrass. A study was conducted to evaluate the growth and turf quality of ‘TifEagle’ bermudagrass in response to inoculation with endophytic diazotroph bacteria at different rates of N fertilization. Diazotrophic strains 7D and BM13 were previously isolated from native common bermudagrass. Bacterial colonization was applied by soaking ‘TifEagle’ bermudagrass plants for 24 h with liquids of the two diazotrophic strains respectively. Four rates of N fertilizer with urea at 0, 2, 4 and 8 g m-2 were applied to the inoculated and non-inoculated ‘TifEagle’ bermudagrass once a month after planting. Results showed that the growth rate, clipping yield, turf quality and shoot dry biomass increased with increased N fertilizer rates. Inoculation with diazotrophic strains in the absence of N fertilization resulted in growth promotion, however at 8 g m-2 of N fertilization, there was a significant decrease for root dry biomass compared to the non-inoculated plants. These results suggest that high N fertilization might inhibit the biological N fixation by endophytes in root systems. These findings could be helpful in the use of endophytic bacteria to supply bermudagrass and other turfgrass with biologically fixed N.
... Intensely managed lawns have 70% higher global warming potential from direct emissions compared to lawns that are not fertilized or irrigated. 7 To reduce the loss and negative effects of agrochemicals on the environment, coating materials for fertilisers have been developed. However, many coatings are fossil based and/or non-biodegradable such as those based on polyethylene, polysulfone, polyvinyl chloride, polystyrene, polyacrylic acid latex, polyvinyl alcohol, polyethylene, polydopamine, cellulose acetate, polyacrylonitrile, copolymers of butylene-succinate-codilinoleate and polyethylene-succinate-co-terephthalate copolymers of polyvinyl alcohol (PVA) and polyvinylpyrrolidone. 4,5,8,9 Some of these polymer-coatings decompose extremely slowly or not at all in soil, leading to undesirable accumulation of microplastics potentially posing a threat to terrestrial wildlife and food security. ...
Article
Lignosulfonate-based bioactive coatings as soil improvers for lawns were developed using laccase as a biocatalyst. Incorporation of glycerol, xylitol and sorbitol as plasticizers considerably reduced the brittleness of the synthesized coatings of marine carbonate granules while thermal enzyme inactivation at 100 °C enabled the production of stable coatings. Heat inactivation produced stable coatings with a molecular weight of 2000 kDa and a viscosity of 4.5 × 10-3 Pas. The desired plasticity for the spray coating of soil improver granules was achieved by the addition of 2.7% of xylitol. Agriculture beneficial microorganisms (four different Bacillus species) were integrated into the coatings. The stable coatings protected the marine calcium carbonate granules, maintained the viability of the microorganisms and showed no toxic effects on the germination and growth of model plants including corn, wheat, salad, and tomato despite a slight delay in germination. Moreover, the coatings reduced the dust formation of soil improvers by 70%. CO2 emission analysis showed potential for the reduction of up to 3.4 kg CO2-eq. kg-1 product, making it a viable alternative to fossil-based coatings.
... Humans have converted some 30% of the planet (about 3.8 billion hectares) to resource extraction, agriculture, urban and suburban uses. For example, turf grass and lawn coverage of the American landscape, while highly fragmented, was estimated at 164,000 km 2 , which it is suggested, represents 'the single largest irrigated 'crop' in the US, occupying a total area three times larger than the surface of irrigated corn' [8, p 3]. Conversion to lawn and turf in the US, based on urbanization rates, is increasing at an annual rate of 8000 km 2 [9], and these numbers do not take into account the agricultural areas required to produce grass seed to create lawns. The human desire for green, beautiful lawn requires considerable inputs that result in the use of scarce potable water, fertilizers that pollute potable water, and mowing produces greenhouse gases contributing to higher temperatures. ...
... Previous research from golf course management zones suggested moderate management in fairways resulted in highest soil organic carbon and microbial biomass when compared to intensively managed putting greens or minimal management in rough (Wang et al., 2014). Residential lawns experience minimal to intense management that may alter urban soil quality or health (Cheng et al., 2008, Gu et al., 2015. Figure 1 shows the status of soil erosion or land degradation in India out of which 64% of land degradation occurring due to water erosion, 11% due to acidification, 10% due to flooding, 6% due to wind erosion, 4% due salinity and 5% due other factors (Source: Central Soil Water Conservation Research and Training Institute (CSWCRTI), Dehradun) which points the finger towards the efficient management aspects need to be taken. ...
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Lawns occupy a significant proportion of green spaces in manycities worldwide. Despite of aesthetic and ornamental benefits, turfgrass also possess many inevitable functional benefits. It helps in maintaining ecological balance and reclamation of polluted environments due to profuse exploitation of nature in urban landscape. The major benefits include controlling soil erosion and improving soil quality, water purification and noise reduction, mitigating air pollution and dust. Turfgrass plays a major role in carbon sequestration which reduce the atmospheric temperature. Apart from these functional benefits, turfgrass is also used in various medical therapies as a tool for reducing mental stress and by various entrepreneurs as a billion-dollar industry with high returns per unit area.
... Lawns can carry considerable symbolic weight, and have been linked to colonial history, power, class and wealth (Ignatieva et al., 2015), good morals (Hogan, 2003), and community mindedness (Carrico et al., 2013). But these associations are often at odds with the poor environmental effects of maintaining lawn (Askew & McGuirk, 2004;Gu, Crane, Hornberger, & Carrico, 2015;Robbins & Birkenholtz, 2003). To make the well-mown lawn less normative and less the default form of the road verge, alternative viewpoints need to be seen (Reckwitz, 2002). ...
Article
Road verge gardening is a civic greening practice undertaken by residents, which can contribute to the quantity, diversity and structural complexity of the greenery within the road easement. By understanding the social drivers of verge gardening, we can potentially increase biodiversity, ecosystem function and human amenity. We surveyed residents of single occupancy dwellings in Melbourne, Australia, and recorded demographic data and beliefs regarding road verge gardening. We used structural equation modelling to test causal models of cognitive constructs underlying verge gardening. We identified cultural background, gardening enthusiasm and level of education as significant factors differentiating respondents who planted verge understorey, planted street trees or did not verge garden. Normative beliefs were the main cognitive construct affecting resident behaviour, with those who did not verge garden more likely to think that others – and in particular municipal authorities – would disapprove of them verge gardening compared to residents who did verge garden. Sense of community, beliefs regarding the benefits of verge gardening, and feelings for nature had significant, but less direct, effects. Changing normative beliefs is a significant pathway to promoting verge gardening. Municipal authorities could reorient policy to encourage verge gardening and increase plantings in the verges they maintain. Planners and urban designers may wish to develop policy to better incorporate verge gardening into urban greening strategies.
... Lawns and the values they represent persist even as more and more evidence shows that using land this way is The Next Epoch Seed Library's Lawn Lab: A Public Experiment in Collaboration with Seeds, Time, and Weeds Media+Environment actually detrimental to the social-ecological health of cities large and small. Unlike other forms of green space, conventional lawns reduce biodiversity, emit more carbon than they sequester, and, depending on treatment regimes, expose local human and nonhuman populations to toxic chemicals (Gu et al. 2015). For NESL, they also represent the ongoing violence of settler-colonial domination of so-called wilderness, and a tragic waste of resources in the face of an extinction crisis. ...
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This article and the accompanying media essay describe my experience developing and implementing the collaborative, interdisciplinary art project The Lawn (Re)Disturbance Laboratory (Lawn Lab). Combining urban ecology, socially engaged art, and multispecies pedagogy, Lawn Lab takes what I define as a critical, ecosocial approach to environmental art. As a public, socially engaged project, it provides a framework for establishing rewilding interventions in institutional and residential lawns from seeds lying dormant in the soil. Focusing on Lawn Lab’s inaugural season, I describe how the project grew out of the Next Epoch Seed Library (NESL), an artist-run organization I cofounded in 2014 to collect, store, and share the seeds of spontaneous urban plants (a.k.a. weeds). After contextualizing NESL and Lawn Lab as part of a larger community of practitioners who work with vegetal attunement and entanglement in urban and disturbed landscapes, I describe the project’s implementation and progress over its first season. I close by connecting my experience implementing the first season of Lawn Lab to Georgina Born and Andrew Barry’s concept of the public experiment, part of their framework for analyzing how knowledge is produced through public-facing, interdisciplinary projects at the intersection of art and science. I use this framework to explore how Lawn Lab provides a forum for imagining and enacting new possibilities around landscape maintenance and care, urban biodiversity, and public health, offering collaboration with weedy plants as one means of working toward ecological justice in the face of a protracted environmental crisis.
... In 2012, the U.S. home and garden sector used 27 million kg of pesticides (8). The positive effect of soil carbon sequestration on the climate footprint of intensively managed lawns was found to be negated by greenhouse gas emissions from management operations such as mowing, irrigation, and fertilization (9,10). Gasoline-powered lawn mowers emitted high amounts of carcinogenic exhaust pollutants (11). ...
... The use of lawns is currently being questioned, due to potentially negative environmental impacts caused by high inputs of chemical pesticides and fertilizers and resource-consuming management by regular mowing and irrigation (Robbins & Birkenholtz, 2003). Moreover, lawns are regarded as communities with low biodiversity and are net carbon emitters (Gu, Crane, Hornberger, & Carrico, 2015;Smith & Fellowes, 2014). It has been suggested that species diversity is of great importance for stable provisioning of ecosystem services over time (Tilman, Reich, & Knops, 2006). ...
Article
Green spaces are important refuges for biodiversity in urban areas, and lawns are one of the most widespread elements of urban green spaces globally. Chinese cities have adopted the use of lawns relatively lately and are currently experiencing a rapid increase in lawn area. In order to obtain knowledge and develop recommendations related to planning, design, and management of lawns in public parks, this study compared lawns with other three types of herbaceous vegetation in terms of plant and pollinator diversity and composition, using Xi'an City as a case study. Plants and pollinators were inventoried in 72 lawns, 12 perennial meadows, 15 Ophiopogon japonicus groundcovers, and eight Oxalis corymbosa groundcovers. Plant species diversity in lawns was positively associated with proportion of green space around lawns and lawn age, and negatively associated with frequency of use of chemical fertilizers. Proportion of native plant species in lawns was negatively associated with use frequency of chemical fertilizers and mowing frequency, and positively associated with irrigation frequency and lawn size. Pollinator species diversity is positively related to flowering plant species richness in all vegetation types. In order to enhance plant and pollinator species diversity, less mowing and chemical use on lawns are recommended. Future urban planning should also consider preserving and increasing the green area coverage within the city. Based on abundance and attractiveness to pollinators, several native herbaceous plant species have potential when creating alternative green spaces to lawns, but more studies are required to test their performance.
... Motivated by social norms and cultural perceptions of social status and personal pride in the home (Robbins, 2007), turfgrass clauses often regulate lawn height and require weed control (Sisser et al., 2016). Though turfgrass offers ecosystem services by sequestering carbon dioxide, anthropogenic CO2 emissions from frequent lawn mowing and fertilization can more than offset this (Gu, Crane, Hornberger, & Carrico, 2015;Lerman & Contosta, 2019;Lerman et al., 2012). Lawn maintenance may also require irrigation to achieve an aesthetically pleasing appearance. ...
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Homeowner’s Associations (HOAs) are an increasingly prominent form of residential governance which use codes, covenants, and restrictions (CCRs) to govern the ways that HOA homes are designed and constructed as well as homeowners’ behaviors related to landscaping and energy use. We explore whether HOA CCRs in a highly suburban Midwest county may promote or prohibit sustainable residential development. Through content analysis, our findings suggest that HOAs rarely use their CCRs to promote sustainable development and more often create barriers through clauses related to home structure, landscaping, and energy use. Structural and landscaping clauses were most common with 81% of CCRs specifying a minimum home size and 58% of CCRS including landscaping restrictions on brush piles. Energy related clauses were less common, although alternative energy production was prohibited in 32% of sampled CCRs. Few CCRs included environmentally friendly clauses; 29% had outdoor light wattage restrictions and 19% required maintaining trees. While HOA CCRs more often present barriers, we end by discussing several constraints to and opportunities for HOAs to serve as bridges to more sustainable residential development.
... Therefore, the importance of regulating waste and recycling is now bigger than ever. [26] ...
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This article aims at an in-depth analysis of the relation of certain activities and services in daily life to the growth of climate change. Climate change is one of the most characteristic occurrences of the modern world, if not the most. It is a byproduct of the greenhouse effect, which is a natural phenomenon necessary for sustaining life on the planet. However, human activities have heavily contributed to the rise of an unbalanced amount of greenhouse gases in the atmosphere, causing the anthropogenic aspect of climate change. Despite the doubts on the human influence on climate change, there is indisputable scientific proof to verify it. The consequences of climate change appear to be very severe, both for the environment and humans themselves, while they are expected to escalate in the future. It is widely known that the industrial revolution is the landmark of anthropogenic climate change. But despite the industry's influence being common knowledge, what are the everyday actions of each individual or household that are key contributors to the phenomenon? Transportation is one of the most harmful everyday activities, especially aviation due to emissions from the combustion of fossil fuels used to power the vehicles. Surprisingly, the food industry is also a sector very high in emissions, mostly due to emissions from livestock production. Another cause is deforestation stemming from multiple factors, a very important one being paper production. While trees absorb carbon dioxide, when cut, they emit it back into the atmosphere, resulting in further emissions. Especially damaging is water overuse, due to the disruption of the water cycle. Furthermore, the burning of fossil fuels for general use (e.g. heating) and specifically for electricity is a big contributor in greenhouse emissions. Certain gardening activities can also contribute in the emissions. Lastly, waste is very damaging to the atmosphere. The decomposition of waste is responsible for emitting significant quantities of CO2 and methane. The need to combat climate change is very pressuring. While individual changes in lifestyle are very vital, bigger changes
... Higher fertilization and irrigation usage compared to low-input management or natural landscapes have been shown to increase soil C sequestration rate (Huyler et al., 2014;Kopp and Guillard, 2002;Qian et al., 2003), but a more recent study comparing N and irrigation inputs on zoysiagrass (Zoysia japonica Steud.) did not provide evidence of greater C sequestration under variable fertility or irrigation management (Braun and Bremer, 2019). Fertilizers, mainly containing primary macronutrients (N, P, and K), and pesticides are applied to urban landscapes to maintain optimum aesthetic quality and reduce pest infestation (Cheng et al., 2008;Gu et al., 2015;Zirkle et al., 2011). Mowing is a common management practice applied to turfgrass within urban landscapes. ...
Article
Soil organic matter (SOM) accumulation and carbon (C) sequestration are ecosystem services (ESs) provided by urban landscapes that are dominated by continuous grass cover, such as residential lawns. Organic matter and C sequestration are expected to increase over time, but few studies have determined potential soil organic carbon (SOC) accumulation from residential lawns in semiarid climates. The objectives were to evaluate physiochemical attributes of urban soils established under turfgrass landscapes of different ages and determine soil factors that differentiate urban soils in semiarid climate of Lubbock, TX. Soil samples (0− 10 cm) were obtained from 10 residential lawns of homes built: pre-1970 (oldest), 1971− 1990 (middle), 1991− 2010 (newer), and after 2011 (newest). Soil texture, bulk density, extractable nutrients [phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe)], pH, SOM, SOC, and total nitrogen (TN) were determined. Bulk density and pH were highest in newest homes and lowest in oldest homes. Increasing years of lawn establishment increased SOM, SOC, and TN content. Linear regression determined 0.036 % annual increase in SOM for residential lawns, but SOC accumulated at 0.021 kg C m − 2 yr-1 for 53.6 yr. In principal component (PC) analysis, SOM, SOC, and TN contributed most to PC1 (36.2 %) reflecting components separating residential lawns by years of establishment, and primarily soil texture components for PC2 (22.5 %). The results of this study show that home age is a strong determinant of soil carbon content in semiarid urban turfgrass systems, with the greatest accumulation threshold in oldest homes over 50 years of age.
... Intensively managed lawns also require considerable public funds (e.g. maintenance costs, see Hedblom, Lindberg, Vogel, Wissman, & Ahrné, 2017), contribute to greenhouse gas loadings (Gu, Crane, Hornberger, & Carrico, 2015), and are often reliant on environmentally detrimental fertilizers and pesticides (Haith, 2010;Stoate et al., 2001). Alternative options such as grass-free lawns or a 'benign neglect' approach (Smith, Broyles, Larzleer, & Fellowes, 2015;Venn & Kotze, 2014) have been promoted to address these issues. ...
Article
1. Intensive management of urban lawns is globally widespread, predominantly for aesthetic reasons. However, a growing body of knowledge demonstrates negative ecological and environmental effects of this practice. 2. We present a meta-analysis of North American and European studies from 2004 to 2019, which incorporates three previously unpublished datasets from eastern Canada, to investigate how mowing intensity impacts the ecology of urban lawns. 3. The meta-analysis provides aggregated evidence that invertebrate and plant diversity is lower in urban lawns under increased mowing intensity. This decline is independent of the level of contrast between mowing ‘treatment’ and ‘control’ (e.g. height or frequency of mowing), which differed considerably between studies. Intensive mowing also increases the occurrence of pest species (e.g. herbivorous beetle larvae and allergenic plants), though studies in this group were limited to northern environments. Changes in ecosystem-level variables (soil temperature, soil moisture deficit and carbon deficit) were less evident and suggest changes in abiotic processes may take longer to become apparent. 4. An economic case study of the mowing costs in Trois-Rivières, Canada, suggests that cost savings of 36% may be possible with a modest reduction of mowing frequency. 5. Synthesis and Applications. Increasing urban biodiversity and reducing greenhouse gas emissions are strong motivators for reducing lawn management intensity. We also suggest that the benefits of reducing pest species while saving lawn management costs may provide additional social and economic incentives for decision makers to review urban greenspace management practices.
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Soil microbial communities have been used as indicators of changes in soil health agroecosystems. However, few studies have evaluated soil health under turfgrass systems especially in semiarid climates. Our study determined whether microbial biomass and composition in residential soils were controlled by home age along a turfgrass chronosequence and evaluated effects of turfgrass management in structuring soil microbial communities. Soil samples were obtained from nine locations within each home age category: oldest (1950–1970), middle (1971–1990), newer (1991–2010), and newest (2011–present) in summer 2018 and 2019. Soil microbial biomass and composition were assessed using chloroform fumigation extraction method (CFEM) and ester-linked fatty acid methyl ester (EL-FAME) analysis. Soil microbial biomass carbon (MBC) and nitrogen (MBN) were 46–52% and 65–75% higher in oldest homes when compared to newest homes, respectively. Neither total FAMEs nor fungal FAME abundance differed for home age categories, but bacterial FAME abundance increased with home age. Non-parametric analysis determined no microbial abundance differences with management practices or turfgrass species. Pearson correlations indicated soil organic matter and silt content most consistently altered the microbial community. Soil microbial communities within semiarid, urban environments shifted from high fungal to bacterial dominated as landscapes matured, potentially due to long-term effects of irrigation, fertilization, and pesticide use. Our results indicate time after establishment was more important to development of soil microbial communities in semiarid, perennial turfgrass systems than subtle differences in management, suggesting soil health and resource conservation goals in this setting may be achievable with relatively low levels of management over time.
Article
Faced with the great challenge of food demand and environmental pollution, optimizing agricultural practices can potentially balance food security and environmental protection. In this study, the DeNitrification-DeComposition (DNDC) model was applied to explore the effect of wheat-based management strategies on crop productivity and greenhouse gas emissions in the wheat−maize system. The DNDC model was tested against crop yield, daily nitrous oxide (N2O) fluxes, and cumulative N2O emissions determined from field measurements in a typical winter wheat−summer maize cropping system. Model evaluations demonstrated a good agreement between the observations and simulated crop yield (4.4%≤NRMSE≤8.0%), daily N2O fluxes (0.68 ≤ d ≤ 0.88), and cumulative N2O emissions (4.9%≤NRMSE≤11.9%). By adopting sensitivity analysis, the DNDC model then assessed the impacts on crop yield and cumulative N2O emissions of multiple management practices from the winter wheat season. Delaying the sowing date from October 7 to November 4 reduced annual yield by 1.9%, while cumulative N2O emissions were increased by 10.4%. Furthermore, postponing the supplementary irrigation date from April 1 to May 20 decreased annual yield by 2.4% without affecting cumulative N2O emissions. An N fertilizer rate of 120–150 kg N ha⁻¹ was able to reduce N usage and cumulative N2O emissions without sacrificing annual yield. Despite an improvement in the annual yield at the 0–30 cm tillage depth by 2.9%, cumulative N2O emissions increased by 11.6%. The results suggest that sowing in early October, applying supplementary irrigation in early April, an N fertilizer rate of 120–150 kg N ha⁻¹, and no-tillage from the winter wheat season can improve crop yield and mitigate N2O emissions. This is conducive to the synergism of agricultural production and environmental sustainability.
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Urbanization is becoming increasingly important in terms of climate change and ecosystem functionality worldwide. We are only beginning to understand how the processes of urbanization influence ecosystem dynamics and how peri-urban environments contribute to climate change. Brisbane in South East Queensland (SEQ) currently has the most extensive urban sprawl of all Australian cities. This leads to substantial land use changes in urban and peri-urban environments and the subsequent gaseous emissions from soils are to date neglected for IPCC climate change estimations. This research examines how land use change effects methane (CH4) and nitrous oxide (N2O) fluxes from peri-urban soils and consequently influences the Global Warming Potential (GWP) of rural ecosystems in agricultural use undergoing urbanization. Therefore, manual and fully automated static chamber measurements determined soil gas fluxes over a full year and an intensive sampling campaign of 80 days after land use change. Turf grass, as the major peri-urban land cover, increased the GWP by 415 kg CO2-e ha−1 over the first 80 days after conversion from a well-established pasture. This results principally from increased daily average N2O emissions of 0.5 g N2O ha−1 d−1 from the pasture to 18.3 g N2O ha−1 d−1 from the turf grass due to fertilizer application during conversion. Compared to the native dry sclerophyll eucalypt forest, turf grass establishment increases the GWP by another 30 kg CO2-e ha−1. The results presented in this study clearly indicate the substantial impact of urbanization on soil-atmosphere gas exchange in form of non-CO2 greenhouse gas emissions particularly after turf grass establishment.
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Vegetation sequester and store carbon in their tissue, at the same time, vegetation plantation and maintenance practice release carbon back to the atmosphere based on energy-resource consumption and labors input. However, existing studies have not yet provided an exhaustive calculation of carbon balance for China from vegetation type. Thus, accounting and understanding carbon balance of urban green space (UGS) are of great important especially in China which is facing rapid industrialization and urbanization as the biggest developing country in the world. This study seeks to determine whether UGS is a carbon sink or a carbon source. Using field surveys, interviews and model simulation over a 50-year time period, carbon sequestration and emissions of four green space in China were evaluated to determine how factors influence the carbon balance. Management practices to maximize the net carbon sequestration are discussed. The main results are as follows: 1) trees and shrubs were carbon sinks with 11,972.08 and 5758.07 MgCO2e ha⁻¹ and the lawns were carbon sources with 149.15 MgCO2e ha⁻¹ in life cycle. 2) Populus tomentosa, Fraxinus chinensis and Lonicera maackii had the most net carbon sequestration. 3) the main contributions of carbon emissions in parks were irrigation and pesticide use.
Article
Nitrous oxide (N2O) is a natural and anthropogenic by-product associated with global climate change and potentially the most ozone-depleting gas. Turfgrass covers large areas of land in the United States, and some is fertilized with N and irrigated with the potential to emit N2O at similar rates (i.e., average of 2.7 kg N2O–N ha–1 yr–1) as agricultural soils. Our objective was to review scientific literature on N2O emissions in turfgrass and identify knowledge gaps and future research needs. Few turfgrass studies exist in which fluxes were intensively measured for long enough to calculate accurate annual emissions, which have ranged from 1.01 to 7.6 kg N2O–N ha–1 yr–1 in various turf species receiving N fertilizer, and from 0.5 to 2.24 kg N2O–N ha–1 yr–1 in unfertilized turf species. Research indicates reduced irrigation and controlled-release forms of N may slow nitrification and denitrification processes, and thus, reduce N2O emissions in turfgrass. Future research should be directed toward long-term investigations of controlled-release fertilizers (e.g., investigating N application amounts, seasonal application timings, and differences between warm-and cool-season turfgrass species) combined with irrigation techniques (e.g., irrigation quantity, frequency, and application timing surrounding fertilization events) to minimize N2O emissions, maximize plant nutrient uptake, and determine more efficient application methods that reduce emissions and water use in warm-and cool-season turfgrass species. The use of model simulations (i.e., DAYCENT and DNDC) should be further developed for turfgrass systems to predict long-term impacts of different management practices on C and N cycling in turfgrass. © 2018 by the American Society of Agronomy 5585 Guilford Road, Madison, WI 53711 USA All rights reserved.
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The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat–summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, as well as changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero N (control), optimum and conventional N) and straw removal (i.e. N0, Nopt and Ncon) or return (i.e. SN0, SNopt and SNcon). Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon), with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha−1 in Ncon and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt. Straw return increased annual mean N2O emissions by 27.9%. Annual SOC sequestration was 0.40–1.44 Mg C ha−1 yr−1 in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat–summer maize double-cropping system.
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A residential lawn care survey was conducted as part of the Baltimore Ecosystem Study, a Long-term Ecological Research project funded by the National Science Foundation and collaborating agencies, to estimate the nitrogen input to urban watersheds from lawn care practices. The variability in the fertilizer N application rates and the factors affecting the application rates were examined. Results indicated that the annual input of nitrogen from fertilizer is a major component of the urban watershed nitrogen budget and it is both spatially and temporally variable. There is a wide range in the application rate of fertilizer N to residential lawns applied by homeowners and by professional lawn care companies. Survey data estimated a mean fertilizer application rate of 97.6 kg N/ha/yr with a standard deviation of 88.3 kg N/ha/yr. Analyses suggested that the fertilizer application rate is affected by social economic factors and soil characteristics to include the market value of the house, age of development, soil bulk density and soil nitrogen content.
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We evaluated the biogeochemical cycling and relative greenhouse gas (GHG) mitigation potential of proposed biofuel feedstock crops by modeling growth dynamics of Miscanthus×giganteus Greef et Deuter (miscanthus), Panicum virgatum L. (switchgrass), Zea mays L. (corn), and a mixed prairie community under identical field conditions. DAYCENT model simulations for miscanthus were parameterized with data from trial plots in Europe and Illinois, USA. Switchgrass, corn, and prairie ecosystems were simulated using parameters published in the literature. A previously unknown source of nitrogen (N) was necessary to balance the plant nutrient budget in miscanthus crops, leading us to hypothesize that miscanthus growth depends on N-fixation. We tested for nitrogenase activity by acetylene reduction of whole rhizomes and bacteria isolated from the rhizosphere and miscanthus tissue. Our results supported the hypothesis that biological N-fixation contributed to the N demand of miscanthus, a highly productive perennial grass. Corn agro-ecosystems emit 956 to 1899g CO2eqm−2y−1 greater GHGs (including CO2, N2O, CH4) to the atmosphere than the other biofuel crop alternatives because of greater N2O emissions from fertilizer additions. Of the feedstock crops evaluated in this study, miscanthus would result in the greatest GHG reduction.
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The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N2O), has been re-examined, using known global atmospheric removal rates and concentration growth of N2O as a proxy for overall emissions. The relationship, in both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production and deforestation, is consistent, showing an overall conversion factor of 3-5%. This factor is covered only in part by the ~1% of "direct" emissions from agricultural crop lands estimated by IPCC (2006), or the "indirect" emissions cited therein. This means that the extra N2O entering the atmosphere as a result of using N to produce crops for biofuels will also be correspondingly greater than that estimated just on the basis of IPCC (2006). When the extra N2O emission from biofuel production is calculated in "CO2-equivalent" global warming terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species have more favourable climate impacts. This analysis only considers the conversion of biomass to biofuel. It does not take into account the use of fossil fuel on the farms and for fertilizer and pesticide production, but it also neglects the production of useful co-products. Both factors partially compensate each other. This needs to be analyzed in a full life cycle assessment.
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Most climate change policy attention has been addressed to long-term options, such as inducing new, low-carbon energy technologies and creating cap-and-trade regimes for emissions. We use a behavioral approach to examine the reasonably achievable potential for near-term reductions by altered adoption and use of available technologies in US homes and nonbusiness travel. We estimate the plasticity of 17 household action types in 5 behaviorally distinct categories by use of data on the most effective documented interventions that do not involve new regulatory measures. These interventions vary by type of action and typically combine several policy tools and strong social marketing. National implementation could save an estimated 123 million metric tons of carbon per year in year 10, which is 20% of household direct emissions or 7.4% of US national emissions, with little or no reduction in household well-being. The potential of household action deserves increased policy attention. Future analyses of this potential should incorporate behavioral as well as economic and engineering elements.
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Urban landscapes contain a mix of land-use types with different patterns of nitrogen (N) cycling and export. We measured nitrate (NO(3)(-)) leaching and soil:atmosphere nitrous oxide (N(2)O) flux in four urban grassland and eight forested long-term study plots in the Baltimore, Maryland metropolitan area. We evaluated ancillary controls on these fluxes by measuring soil temperature, moisture, and soil:atmosphere fluxes of carbon dioxide on these plots and by sampling a larger group of forest, grass, and agricultural sites once to evaluate soil organic matter, microbial biomass, and potential net N mineralization and nitrification. Annual NO(3)(-) leaching ranged from 0.05 to 4.1 g N m(-2) yr(-1) and was higher in grass than forest plots, except in a very dry year and when a disturbed forest plot was included in the analysis. Nitrous oxide fluxes ranged from 0.05 to >0.3 g N m(-2) yr(-1), with few differences between grass and forest plots and markedly higher fluxes in wet years. Differences in NO(3)(-) leaching and N(2)O flux between forests and grasslands were not as high as expected given the higher frequency of disturbance and fertilization in the grasslands. Carbon dioxide flux, organic matter, and microbial biomass were as high or higher in urban grasslands than in forests, suggesting that active carbon cycling creates sinks for N in vegetation and soil in these ecosystems. Although urban grasslands export more N to the environment than native forests, they have considerable capacity for N retention that should be considered in evaluations of land-use change.
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The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N<sub>2</sub>O), has been re-examined, using known global atmospheric removal rates and concentration growth of N<sub>2</sub>O as a proxy for overall emissions. The relationship, in both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production and deforestation, is consistent, showing an overall conversion factor of 3–5%. This factor is covered only in part by the ~1% of "direct" emissions from agricultural crop lands estimated by IPCC (2006), or the "indirect" emissions cited therein. This means that the extra N<sub>2</sub>O entering the atmosphere as a result of using N to produce crops for biofuels will also be correspondingly greater than that estimated just on the basis of IPCC (2006). When the extra N<sub>2</sub>O emission from biofuel production is calculated in "CO<sub>2</sub>-equivalent" global warming terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO<sub>2</sub>, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), can contribute as much or more to global warming by N<sub>2</sub>O emissions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species have more favourable climate impacts. This analysis only considers the conversion of biomass to biofuel. It does not take into account the use of fossil fuel on the farms and for fertilizer and pesticide production, but it also neglects the production of useful co-products. Both factors partially compensate each other. This needs to be analyzed in a full life cycle assessment.
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The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N<sub>2</sub>O), has been re-examined, using known global atmospheric removal rates and concentration growth of N<sub>2</sub>O as a proxy for overall emissions. For both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production, we find an overall conversion factor of 3–5% from newly fixed N to N<sub>2</sub>O-N. We assume the same factor to be valid for biofuel production systems. It is covered only in part by the default conversion factor for "direct" emissions from agricultural crop lands (1%) estimated by IPCC (2006), and the default factors for the "indirect" emissions (following volatilization/deposition and leaching/runoff of N: 0.35–0.45%) cited therein. However, as we show in the paper, when additional emissions included in the IPCC methodology, e.g. those from livestock production, are included, the total may not be inconsistent with that given by our "top-down" method. When the extra N<sub>2</sub>O emission from biofuel production is calculated in "CO<sub>2</sub>-equivalent" global warming terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO<sub>2</sub>, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), depending on N fertilizer uptake efficiency by the plants, can contribute as much or more to global warming by N<sub>2</sub>O emissions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species, have more favourable climate impacts. This analysis only considers the conversion of biomass to biofuel. It does not take into account the use of fossil fuel on the farms and for fertilizer and pesticide production, but it also neglects the production of useful co-products. Both factors partially compensate each other. This needs to be analyzed in a full life cycle assessment.
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Agriculture plays a major role in the global fluxes of the greenhouse gases carbon dioxide, nitrous oxide, and methane. From 1991 to 1999, we measured gas fluxes and other sources of global warming potential (GWP) in cropped and nearby unmanaged ecosystems. Net GWP (grams of carbon dioxide equivalents per square meter per year) ranged from 110 in our conventional tillage systems to −211 in early successional communities. None of the annual cropping systems provided net mitigation, although soil carbon accumulation in no-till systems came closest to mitigating all other sources of GWP. In all but one ecosystem, nitrous oxide production was the single greatest source of GWP. In the late successional system, GWP was neutral because of significant methane oxidation. These results suggest additional opportunities for lessening the GWP of agronomic systems.
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Experiments to document the long-term effects of clipping management on N requirements, soil organic carbon (SOC), and soil organic nitrogen (SON) are difficult and costly and therefore few. The CENTURY ecosystem model offers an opportunity to study long-term effects of turfgrass clipping management on biomass production, N requirements, SOC and SON, and N leaching through computer simulation. In this study, the model was verified by comparing CENTURY-predicted Kentucky bluegrass (Poa pratensis L.) clipping yields with field-measured clipping yields. Long-term simulations were run for Kentucky bluegrass grown under home lawn conditions on a clay loam soil in Colorado. The model predicted that compared with clipping-removed management, returning clippings for 10 to 50 yr would increase soil C sequestration by 11 to 25% and nitrogen sequestration by 12 to 28% under a high (150 kg N ha(-1) yr(-1) nitrogen (N) fertilization regime, and increase soil carbon sequestration by 11 to 59% and N sequestration by 14 to 78% under a low (75 kg N ha(-1) yr(-1)) N fertilization regime. The CENTURY model was further used as a management supporting system to generate optimal N fertilization rates as a function of turfgrass age. Returning grass clippings to the turf-soil ecosystem can reduce N requirements by 25% from 1 to 10 yr after turf establishment, by 33% 11 to 25 yr after establishment, by 50% 25 to 50 yr after establishment, and by 60% thereafter. The CENTURY model shows potential for use as a decision-supporting tool for maintaining turf quality and minimizing negative environmental impacts.
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This manuscript is a synthesis of the available information on energy use in farm operations, and its conversion into carbon equivalent (CE). A principal advantage of expressing energy use in terms of carbon (C) emission as kg CE lies in its direct relation to the rate of enrichment of atmospheric concentration of CO2. Synthesis of the data shows that estimates of emissions in kg CE/ha are 2-20 for different tillage operations, 1-1.4 for spraying chemicals, 2-4 for drilling or seeding and 6-12 for combine harvesting. Similarly, estimates of C emissions in kg CE/kg for different fertilizer nutrients are 0.9-1.8 for N, 0.1-0.3 for P2O5, 0.1-0.2 for K20 and 0.03-0.23 for lime. Estimates of C emission in kg CE/kg of active ingredient (a.i.) of different pesticides are 6.3 for herbicides, 5.1 for insecticides and 3.9 for fungicides. Irrigation, lifting water from deep wells and using sprinkling systems, emits 129+/-98 kg CE for applying 25 cm of water and 258+/-195 for 50 cm of water. Emission for different tillage methods are 35.3 kg CE/ha for conventional till, 7.9 kg CE/ha for chisel till or minimum till, and 5.8 kg CE/ha for no-till method of seedbed preparation. In view of the high C costs of major inputs, sustainable management of agricultural ecosystems implies that an output/input ratio, expressed either as gross or net output of C, must be >1 and has an increasing trend over time.
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Turf grasses are ubiquitous in the urban landscape of the United States and are often associated with various types of environmental impacts, especially on water resources, yet there have been limited efforts to quantify their total surface and ecosystem functioning, such as their total impact on the continental water budget and potential net ecosystem exchange (NEE). In this study, relating turf grass area to an estimate of fractional impervious surface area, it was calculated that potentially 163,800 km2 (+/- 35,850 km2) of land are cultivated with turf grasses in the continental United States, an area three times larger than that of any irrigated crop. Using the Biome-BGC ecosystem process model, the growth of warm-season and cool-season turf grasses was modeled at a number of sites across the 48 conterminous states under different management scenarios, simulating potential carbon and water fluxes as if the entire turf surface was to be managed like a well-maintained lawn. The results indicate that well-watered and fertilized turf grasses act as a carbon sink. The potential NEE that could derive from the total surface potentially under turf (up to 17 Tg C/yr with the simulated scenarios) would require up to 695 to 900 liters of water per person per day, depending on the modeled water irrigation practices, suggesting that outdoor water conservation practices such as xeriscaping and irrigation with recycled waste-water may need to be extended as many municipalities continue to face increasing pressures on freshwater.
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We used data available from the literature and measurements from Baltimore, Maryland, to (i) assess inter-city variability of soil organic carbon (SOC) pools (1-m depth) of six cities (Atlanta, Baltimore, Boston, Chicago, Oakland, and Syracuse); (ii) calculate the net effect of urban land-use conversion on SOC pools for the same cities; (iii) use the National Land Cover Database to extrapolate total SOC pools for each of the lower 48 U.S. states; and (iv) compare these totals with aboveground totals of carbon storage by trees. Residential soils in Baltimore had SOC densities that were approximately 20 to 34% less than Moscow or Chicago. By contrast, park soils in Baltimore had more than double the SOC density of Hong Kong. Of the six cities, Atlanta and Chicago had the highest and lowest SOC densities per total area, respectively (7.83 and 5.49 kg m(-2)). On a pervious area basis, the SOC densities increased between 8.32 (Oakland) and 10.82 (Atlanta) kg m(-2). In the northeastern United States, Boston and Syracuse had 1.6-fold less SOC post- than in pre-urban development stage. By contrast, cities located in warmer and/or drier climates had slightly higher SOC pools post- than in pre-urban development stage (4 and 6% for Oakland and Chicago, respectively). For the state analysis, aboveground estimates of C density varied from a low of 0.3 (WY) to a high of 5.1 (GA) kg m(-2), while belowground estimates varied from 4.6 (NV) to 12.7 (NH) kg m(-2). The ratio of aboveground to belowground estimates of C storage varied widely with an overall ratio of 2.8. Our results suggest that urban soils have the potential to sequester large amounts of SOC, especially in residential areas where management inputs and the lack of annual soil disturbances create conditions for net increases in SOC. In addition, our analysis suggests the importance of regional variations of land-use and land-cover distributions, especially wetlands, in estimating urban SOC pools.
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Soil organic carbon (SOC) sequestration and the impact of carbon (C) cycling in urban soils are themes of increasing interest. A model was developed to investigate the potential of C sequestration in home lawns. The model contrasted gross C sequestered versus the hidden C costs (HCC) associated with typical lawn maintenance practices. The potential of SOC sequestration for U.S. home lawns was determined from SOC sequestration rates of turfgrass and grasslands. Net SOC sequestration in lawn soils was estimated using a simple mass balance model derived from typical homeowner lawn maintenance practices. The average SOC sequestration rate for U.S. lawns was 46.0 to 127.1 g C/m2/year. Additional C sequestration can result from biomass gains attributable to fertilizer and irrigation management. Hidden C costs are the amount of energy expended by typical lawn management practices in grams of carbon equivalents (CE)/m2/ year and include practices including mowing, irrigating, fertilizing, and using pesticides. The net SOC sequestration rate was assessed by subtracting the HCC from gross SOC sequestration rate. Lawn maintenance practices ranged from low to high management. Low management with minimal input (MI) included mowing only, a net SOC sequestration rate of 25.4 to 114.2 g C/m2/year. The rate of SOC sequestration for doit- yourself (DIY) management by homeowners was 80.6 to 183.0 g C/m2/year. High management, based on university and industry-standard best management recommendation practices (BMPs), had a net SOC sequestration rate of 51.7 to 204.3 g C/m2/year. Lawns can be a net sink for atmospheric CO2 under all three evaluated levels of management practices with a national technical potential ranging from 25.4 to 204.3 g C/m2/year.
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Land-use change is an important driver of soil-atmosphere gas exchange, but current greenhouse-gas budgets lack data from urban lands. Field comparisons of urban and non-urban ecosystems are required to predict the consequences of global urban-land expansion for greenhouse-gas budgets. In a rapidly urbanizing region of the U.S. Great Plains, we measured soil-atmosphere exchange of methane (CH4) and nitrous oxide (N2O) for one year in replicated (n = 3) urban lawn, native shortgrass steppe, dryland wheat-fallow, and flood-irrigated corn ecosystems. All soils were net sinks for atmospheric CH4, but uptake by urban, corn, and wheat-fallow soils was half that of native grasslands (-0.30 ± 0.04 g C·m -2·yr-1 [mean ± 1 SE]). Urban (0.24 ± 0.03 g N·m-2·yr-1) and corn (0.20 ± 0.02 g N·m-2·yr-1) soils emitted 10 times more N2O to the atmosphere than native grassland and wheat-fallow soils. Using remotely sensed land-cover data we calculated an upper bound for the contribution of lawns to regional soil-atmosphere gas fluxes. Urban lawns occupied 6.4% of a 1578-km2 study region, but contribute up to 5% and 30% of the regional soil CH4 consumption and N2O emission, respectively, from land-use types that we sampled. Lawns that cover small portions of the landscape may contribute significantly to regional soil-atmosphere gas exchange.
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Nitrous oxide (NO) emissions are an important component of the greenhouse gas budget for turfgrasses. To estimate NO emissions and global warming potential, the DAYCENT ecosystem model was parameterized and applied to turfgrass ecosystems. The annual cumulative NO emissions predicted by the DAYCENT model were close to the measured emission rates of Kentucky bluegrass ( L.) sites in Colorado (within 16% of the observed values). For the perennial ryegrass ( L.) site in Kansas, the DAYCENT model initially overestimated the NO emissions for all treatments (urea and ammonium sulfate at 250 kg N ha yr and urea at 50 kg N ha yr) by about 200%. After including the effect of biological nitrification inhibition in the root exudate of perennial ryegrass, the DAYCENT model correctly simulated the NO emissions for all treatments (within 8% of the observed values). After calibration and validation, the DAYCENT model was used to simulate NO emissions and carbon sequestration of a Kentucky bluegrass lawn under a series of management regimes. The model simulation suggested that gradually reducing fertilization as the lawn ages from 0 to 50 yr would significantly reduce long-term NO emissions by approximately 40% when compared with applying N at a constant rate of 150 kg N ha yr. Our simulation indicates that a Kentucky bluegrass lawn in Colorado could change from a sink to a weak source of greenhouse gas emissions 20 to 30 yr after establishment.
Article
This paper describes a rain-event driven, process-oriented simulation model, DNDC, for the evolution of nitrous oxide (N2O), carbon dioxide (CO2), and dinitrogen (N2) from agricultural soils. The model consists of three submodels: thermal-hydraulic, decomposition, and denitrification. Basic climate data drive the model to produce dynamic soil temperature and moisture profiles and shifts of aerobic-anaerobic conditions. Additional input data include soil texture and biochemical properties as well as agricultural practices. Between rainfall events the decomposition of organic matter and other oxidation reactions (including nitrification) dominate, and the levels of total organic carbon, soluble carbon, and nitrate change continuously. During rainfall events, denitrification dominates and produces N2O and N2. Daily emissions of N2O and N2 are computed during each rainfall event and cumulative emissions of the gases are determined by including nitrification N2O emissions as well. Sensitivity analyses reveal that rainfall patterns strongly influence N2O emissions from soils but that soluble carbon and nitrite can be limiting factors for N2O evolution during denitrification. During a year sensitivity simulation, variations in temperature, precipitation, organic C, clay content, and pH had significant effects on denitrification rates and N2O emissions. The responses of DNDC to changes of external parameters are consistent with field and experimental results reported in the literature.
Article
As global climate change (GCC) becomes an increasing societal concern, scientists are assessing soils’ capacity to sequester atmospheric CO2 to off-set anthropogenic emissions. Therefore, this study was conducted to determine C sequestration potential in golf turfgrass systems in Central Ohio, USA, and to determine the effect of management practices on the net soil C sink capacity. Ohio farmland soils converted to golf course turfgrasses sequestered C at mean rates of 3.55 ± 0.08 Mg/ha/yr in fairways and 2.64 ± 0.06 Mg/ha/yr in rough areas. Soils in both fairway and rough areas sequestered C to 15 cm depth. However, hidden C costs of golf course development and management were also significant and major C emissions were attributed to diesel fuel combustion (6,557 kg Ce(Carbon Equivalents)/yr), unleaded fuel combustion (3,618 kg Ce/yr), N fertilizer use (1,498 kg Ce/yr), fungicide application (1,377 kg Ce/yr) and irrigation (626 kg Ce/yr), for an overall C emission of 14.15 Mg Ce per course per year (0.30 Mg C/ha/yr). Analysis of sequestration and emissions data showed that a newly constructed golf course has a technical C sequestration capacity of 2,224 Mg C over a 91.4 year period or the equivalent of 0.44 Mg C/ha/yr. However, the large C emissions generated by maintenance practices render courses from sinks to sources within 30 years. To maximize the potential environmental benefits of turfgrass systems while increasing the economic efficiency of each site, management practices with low C-intensity should be utilized.
Article
Although the fate of fertilizer applied to turfgrass has been studied in the past, recovery of applied fertilizer N is typically low, and denitrification has been cited as the reason. The objectives of this research were twofold: (i) to examine the fate of 15N applied to Kentucky bluegrass (Poa pratensis L.) turf as KNO3, including direct measurement of denitrification; and (ii) to determine whether and how plants affect fertilizer-N recovery. Polyvinyl chloride (PVC) cylinders, modified to permit atmospheric sampling, were used throughout field experiments during the spring and summer 1999 and a greenhouse experiment in 2000. Potassium nitrate (98.5 atom % 15N) was applied in solution at 49 kg N ha-1 to replicated plots, and atmospheric samples were collected three times a day from 0800 to 1100, 1100 to 1400, and 1400 to 1700 h during a 6-wk period in the spring and a 4-wk period during the summer of 1999. Emission of N2 or N2O ranged from 3.3 to 21.3% and from 0.3 to 5.9% of labeled fertilizer N (LFN), respectively. Recovery of LFN in the soil or plant, plus that emitted as N2 or N2O, ranged from 57.4 to 73.2%. A 4-wk greenhouse experiment comparing LFN recovery for bare soil and turf, including gas emission and leachate, was initiated in the summer of 2000. Total emission of LFN as N2 or N2O was 19.0% for the turfgrass, as compared with 7.3% for the bare soil. Corresponding values for total recovery of LFN were 70.6 and 84.2%, respectively.
Article
Predicting impacts of climate change or alternative management on both food production and environment safety in agroecosystems is drawing great attention in the scientific community. Most of the existing agroecosystem models emphasize either crop growth or soil processes. This paper reports the latest development of an agroecosystem model (Crop-DNDC) by integrating detailed crop growth algorithms with an existing soil biogeochemical model, DNDC (Li et al., J. Geophys. Res. (1992) 9759). In the Crop-DNDC model, crop growth is simulated not only by tracking crop physiological processes (phenology, leaf area index, photosynthesis, respiration, assimilate allocation, rooting processes and nitrogen uptake), but also by calculating water stress and nitrogen stress, which were closely related to soil biogeochemical processes and hydraulic dynamics. Crop-DNDC also quantifies crop residue incorporated in the soil at the end of each growing season. Thus the model has tightly coupled crop growth algorithms with soil biogeochemical components, and simulates carbon, nitrogen and water cycles in agroecosystems with a relatively complete scope. The model was validated against field measurements, including soil moisture, leaf area index, crop biomass and nitrogen content, and the modeled results were in agreement with observations on soil carbon dynamics and trace gas emissions as well. Sensitivity tests demonstrated that the modeled results in crop yield, soil carbon dynamics and trace gas emissions were sensitive to climate conditions, atmospheric CO2 concentration and various farming practices. There are potentials of applying the model for simultaneously predicting effects of changes in climate or management on crop yield, soil carbon sequestration and trace gas emissions.
Article
Soil analyses were conducted on home lawns across diverse ecoregions of the U.S. to determine the soil organic carbon (SOC) sink capacity of turfgrass soils. Establishment of lawns sequestered SOC over time. Due to variations in ecoregions, sequestration rates varied among sites from 0.9 Mg carbon (C) ha(-1) year(-1) to 5.4 Mg C ha(-1) year(-1). Potential SOC sink capacity also varied among sites ranging from 20.8 ± 1.0-96.3 ± 6.0 Mg C ha(-1). Average sequestration rate and sink capacity for all sites sampled were 2.8 ± 0.3 Mg C ha(-1) year(-1) and 45.8 ± 3.5 Mg C ha(-1), respectively. Additionally, the hidden carbon costs (HCC) due to lawn mowing (189.7 kg Ce (carbon equivalent) ha(-1) year(-1)) and fertilizer use (63.6 kg Ce ha(-1) year(-1)) for all sites totaled 254.3 kg Ce ha(-1) year(-1). Considering home lawn SOC sink capacity and HCC, mean home lawn sequestration was completely negated 184 years post establishment. The potential SOC sink capacity of home lawns in the U.S. was estimated at 496.3 Tg C, with HCC of between 2,504.1 Gg Ce year(-1) under low management regimes and 7551.4 Gg Ce year(-1) under high management. This leads to a carbon-positive system for between 66 and 199 years in U.S. home lawns. More efficient and reduction of C-intensive maintenance practices could increase the overall sequestration longevity of home lawns and improve their climate change mitigation potential.
Article
The residential landscape constitutes a significant portion of the urban environment. With the increasing mobility of our society, many people come to reside in environments with unfamiliar plant communities and environmental conditions. In this research, 232 Phoenix, Arizona homeowners were surveyed to investigate their residential landscape preferences and to what degree these preferences were reflected in their actual behaviors in their front and backyards. Landscape preferences vary between the front and backyard residential landscapes in a manner consistent with [Goffman, E., 1959. The Presentation of Self in Everyday Life. Anchor Books, New York] about the symbolic presentation of self. When a multinomial logistic regression model was constructed to predict front yard landscape preference with the independent variables income, length of residence in the Phoenix area, degree of environmental concern and engagement in desert recreational activities, income was the only significant predictor. In the front yard, lower-income homeowners tend to prefer lawn, middle-income homeowners preferred desert landscaping and higher-income homeowners’ preferences were divided between desert and oasis landscape. While backyard landscape preferences varied among income groups, income was not a significant predictor of backyard landscape preference. Landscape preferences for the front and backyard were significantly different and 55% of respondents preferred different landscape typologies for the front and backyards. Overall, for landscape preference in the front yard, form follows class-specific fashion. For landscape preference in the backyard, form is more likely to follow individual fantasy. Landscape preferences were then compared with landscape behaviors. One-third of respondents expressed landscape preferences that were different from their landscape behaviors. However, the development industry has a significant influence on the design and construction of residential neighborhoods in Phoenix [Kirby, A., 2000. All new, improved! Cities 17(1), 1–5]. In an effort to sell homes, developers’ anticipate homeowners’ tastes and package their homes with desirable front yard ‘dreamscapes’ [Jencks, C., 1993. Heteropolis: Los Angeles, the Riots and the Strange Beauty of Hetero-Architecture, Academ Editions, London]. Therefore, we hypothesized that the macro-level influence of the developer's landscape legacy would have a greater impact on the front yard's appearance (behavior) than on the backyard's appearance. For the front yard, both the legacy and the homeowner's preference were significant predictors of landscape behavior, but in the backyard, only the homeowner's preference had a significant influence. The manifestations of the residential landscape reflect expressions of self, status, and conceptions of place that combine to create little understood ‘dreamscapes’. We must recognize the importance of the front yard as a visible symbol of self, the backyard's role as a personal pleasure ground, and the conflict that may occur when the natural landscape is relatively inhospitable to domestic behaviors.
Article
Fertilizer application has many known environmental impacts, and household use of fertilizer for lawn cultivation contributes a significant amount toward these impacts. Previous study provides a compelling narrative of the social, political, and cultural factors that drive fertilizer application; however, the psychological factors involved are not well known. This article examines factors that motivate fertilizer application using surveys among a sample of 194 residents within an urban watershed. Measures included aesthetic preferences, financial concerns, social norms, and environmental concerns. A principal components analysis (PCA) revealed four orthogonal factors. Among them, individual interests and social pressures positively predicted fertilizer application, as did the likelihood that children and pets play on a resident’s lawn. Environmental concerns were not predictive. These data contribute to an evolving storyline suggesting that households make tradeoffs between lawn aesthetics and concern for the environment and exposure to chemicals in part due to strong social pressures surrounding lawn maintenance.
Article
The impact of agricultural management on global warming potential (GWP) and greenhouse gas intensity (GHGI) is not well documented. A long-term fertilizer experiment in Chinese double rice-cropping systems initiated in 1990 was used in this study to gain an insight into a complete greenhouse gas accounting of GWP and GHGI. The six fertilizer treatments included inorganic fertilizer [nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), and balanced inorganic fertilizer (NPK)], combined inorganic/organic fertilizers at full and reduced rate (FOM and ROM), and no fertilizer application as a control. Methane (CH4) and nitrous oxide (N2O) fluxes were measured using static chamber method from November 2006 through October 2009, and the net ecosystem carbon balance was estimated by the changes in topsoil (0–20 cm) organic carbon (SOC) density over the 10-year period 1999–2009. Long-term fertilizer application significantly increased grain yields, except for no difference between the NK and control plots. Annual topsoil SOC sequestration rate was estimated to be 0.96 t C ha−1 yr−1 for the control and 1.01–1.43 t C ha−1 yr−1 for the fertilizer plots. Long-term inorganic fertilizer application tended to increase CH4 emissions during the flooded rice season and significantly increased N2O emissions from drained soils during the nonrice season. Annual mean CH4 emissions ranged from 621 kg CH4 ha−1 for the control to 1175 kg CH4 ha−1 for the FOM plots, 63–83% of which derived from the late-rice season. Annual N2O emission averaged 1.15–4.11 kg N2O–N ha−1 in the double rice-cropping systems. Compared with the control, inorganic fertilizer application slightly increased the net annual GWPs, while they were remarkably increased by combined inorganic/organic fertilizer application. The GHGI was lowest for the NP and NPK plots and highest for the FOM and ROM plots. The results of this study suggest that agricultural economic viability and GHGs mitigation can be simultaneously achieved by balanced fertilizer application.
Article
The Tualatin is the first watershed in Oregon to implement the Total Maximum Daily Load provisions of the Clean Water Act to deal with nonpoint source pollution. Local officials cite residential yard care practices as potential contributors to nonpoint source pollution in the basin. Qualitative and quantitative methods, including observation of yard maintenance styles, suggest behaviors potentially harmful to water quality and conservation. Yard maintenance is influenced by the importance of neighborhood appearance and concern for aesthetics. These concerns stimulate residents to water, fertilize, and apply weed control at more frequent intervals than yard care experts recommend. Better understanding of the effects that relations with neighbors and yard maintenance knowledge have on residential yard care practices can help improve water quality.
Article
When agricultural land is no longer used for cultivation and allowed to revert to natural vegetation or replanted to perennial vegetation, soil organic carbon can accumulate. This accumulation process essentially reverses some of the effects responsible for soil organic carbon losses from when the land was converted from perennial vegetation. We discuss the essential elements of what is known about soil organic matter dynamics that may result in enhanced soil carbon sequestration with changes in land-use and soil management. We review literature that reports changes in soil organic carbon after changes in land-use that favour carbon accumulation. This data summary provides a guide to approximate rates of SOC sequestration that are possible with management, and indicates the relative importance of some factors that influence the rates of organic carbon sequestration in soil. There is a large variation in the length of time for and the rate at which carbon may accumulate in soil, related to the productivity of the recovering vegetation, physical and biological conditions in the soil, and the past history of soil organic carbon inputs and physical disturbance. Maximum rates of C accumulation during the early aggrading stage of perennial vegetation growth, while substantial, are usually much less than 100 g C m−2 y−1. Average rates of accumulation are similar for forest or grassland establishment: 33.8 g C m−2 y−1 and 33.2 g C m−2 y−1, respectively. These observed rates of soil organic C accumulation, when combined with the small amount of land area involved, are insufficient to account for a significant fraction of the missing C in the global carbon cycle as accumulating in the soils of formerly agricultural land.
Article
Rates of soil C sequestration have previously been estimated for a number of different land management activities, and these estimates continue to improve as more data become available. The time over which active sequestration occurs may be referred to as the sequestration duration. Integrating soil C sequestration rates with durations provides estimates of potential change in soil C capacity and more accurate estimates of the potential to sequester C. In agronomic systems, changing from conventional plow tillage to no-till can increase soil C by an estimated 16±3%, whereas increasing rotation intensity can increase soil C by an estimated 6±3%. The increase in soil C following a change in rotation intensity, however, may occur over a slightly longer period (26yr) than that for tillage cessation (21yr). Sequestration strategies for grasslands have, on average, longer sequestration durations (33yr) than for croplands. Estimates for sequestration rates and durations are mean values and can differ greatly between individual sites and management practices. As the annual sequestration rate declines over the sequestration duration period, soil C approaches a new steady state. Sequestration duration is synonymous with the time to which soil C steady state is reached. However, soils could potentially sequester additional C following additional changes in management until the maximum soil C capacity, or soil C saturation, is achieved. Carbon saturation of the soil mineral fraction is not well understood, nor is it readily evident. We provide evidence of soil C saturation and we discuss how the steady state C level and the level of soil C saturation together influence the rate and duration of C sequestration associated with changes in land management.
Article
Strategies for mitigating the increasing concentration of carbon dioxide (CO2) in the atmosphere include sequestering carbon (C) in soils and vegetation of terrestrial ecosystems. Carbon and nitrogen (N) move through terrestrial ecosystems in coupled biogeochemical cycles, and increasing C stocks in soils and vegetation will have an impact on the N cycle. We conducted simulations with a biogeochemical model to evaluate the impact of different cropland management strategies on the coupled cycles of C and N, with special emphasis on C-sequestration and emission of the greenhouse gases methane (CH4) and nitrous oxide (N2O). Reduced tillage, enhanced crop residue incorporation, and farmyard manure application each increased soil C-sequestration, increased N2O emissions, and had little effect on CH4 uptake. Over 20 years, increases in N2O emissions, which were converted into CO2-equivalent emissions with 100-year global warming potential multipliers, offset 75–310% of the carbon sequestered, depending on the scenario. Quantification of these types of biogeochemical interactions must be incorporated into assessment frameworks and trading mechanisms to accurately evaluate the value of agricultural systems in strategies for climate protection.
Article
A computer simulation model was developed for predicting trace gas emissions from agricultural ecosystems. The denitrification-decomposition (DNDC) model consists of two components. The first component, consisting of the soil climate, crop growth, and decomposition submodels, predicts soil temperature, moisture, pH, Eh, and substrate concentration profiles based on ecological drivers (e.g., climate, soil, vegetation, and anthropogenic activity). The second component, consisting of the nitrification, denitrification, and fermentation submodels, predicts NH3, NO, N2O, and CH4 fluxes based on the soil environmental variables. Classical laws of physics, chemistry, or biology or empirical equations generated from laboratory observations were used in the model to parameterize each specific reaction. The entire model links trace gas emissions to basic ecological drivers. Through validation against data sets of NO, N2O, CH4, and NH3 emissions measured at four agricultural sites, the model showed its ability to capture patterns and magnitudes of trace gas emissions.
Article
This paper surveys the problems of contemporary urban ecology through the lens of lawn chemical usage, exploring the difficulty of explaining and managing urban ecological dilemmas that, though built from the disaggregated choices of individuals, aggregate into large and serious issues. Introductory discussion surveys the seriousness of lawn chemicals as urban non-point pollution sources and suggests why the issue, and problems like it, it understudied. Analysis proceeds with a case study from the United States city of Columbus, Ohio, utilizing formal survey techniques and aanlysis of county assessor's data. The results suggest lawns and lawn care chemicals are expanding with urban sprewl and that users of high-input lawn chemical systems are more likely to be wealthy, well-educated, and knowledgeable about the negative environmental impacts of the actions than non-users. Further investigation demonstrates the instrumental logics of homeowners in pursuit of property values but also points to the moral and community-oriented institutions that enforce and propel high chemical use. The conclusions point to policy options for dealing with the lawn chemical dilemma but suggest the difficulties of circumventing the deeply structured roots of the problem.
Article
The increase in atmospheric concentration of CO2 by 31% since 1750 from fossil fuel combustion and land use change necessitates identification of strategies for mitigating the threat of the attendant global warming. Since the industrial revolution, global emissions of carbon (C) are estimated at 270±30 Pg (Pg=petagram=1015 g=1 billion ton) due to fossil fuel combustion and 136±55 Pg due to land use change and soil cultivation. Emissions due to land use change include those by deforestation, biomass burning, conversion of natural to agricultural ecosystems, drainage of wetlands and soil cultivation. Depletion of soil organic C (SOC) pool have contributed 78±12 Pg of C to the atmosphere. Some cultivated soils have lost one-half to two-thirds of the original SOC pool with a cumulative loss of 30–40 Mg C/ha (Mg=megagram=106 g=1 ton). The depletion of soil C is accentuated by soil degradation and exacerbated by land misuse and soil mismanagement. Thus, adoption of a restorative land use and recommended management practices (RMPs) on agricultural soils can reduce the rate of enrichment of atmospheric CO2 while having positive impacts on food security, agro-industries, water quality and the environment. A considerable part of the depleted SOC pool can be restored through conversion of marginal lands into restorative land uses, adoption of conservation tillage with cover crops and crop residue mulch, nutrient cycling including the use of compost and manure, and other systems of sustainable management of soil and water resources. Measured rates of soil C sequestration through adoption of RMPs range from 50 to 1000 kg/ha/year. The global potential of SOC sequestration through these practices is 0.9±0.3 Pg C/year, which may offset one-fourth to one-third of the annual increase in atmospheric CO2 estimated at 3.3 Pg C/year. The cumulative potential of soil C sequestration over 25–50 years is 30–60 Pg. The soil C sequestration is a truly win–win strategy. It restores degraded soils, enhances biomass production, purifies surface and ground waters, and reduces the rate of enrichment of atmospheric CO2 by offsetting emissions due to fossil fuel.
Article
Rapid worldwide urbanization calls for a better understanding of the biogeochemical cycling of those macroelements that have large environmental impacts in cities. This study, part of the Twin Cities Household Ecosystem Project, quantified fluxes of carbon (C), nitrogen (N), and phosphorus (P) at the scale of individual households in the Minneapolis-Saint Paul metropolitan area in Minnesota, USA. We estimated input and output fluxes associated with several components of household activities including air and motor vehicle travel, food consumption, home energy use, landscape, pets, and paper and plastic use for 360 owner-occupied, stand-alone households. A few component fluxes dominated total input fluxes of elements. For instance, air and motor vehicle transportation, together with home energy use, accounted for 85% of total C consumption and emissions. All total and component fluxes were skewed to varying degrees, suggesting that policies targeting disproportionately high fluxes could be an effective and efficient way to reduce pollution. For example, 20% of households contributed 75% of air travel emissions and 40% of motor vehicle emissions. Home energy use was more nearly normally distributed. Nitrogen fluxes were dominated by human diet and lawn fertilizer applications, which together accounted for 65% of total household N inputs. The majority of P inputs were associated with human diet, use of detergents, and pet food. A large portion of the variation among household fluxes of C, N, and P was related to a few biophysical variables. A better understanding of the biophysical, demographic, and behavioral drivers of household activities that contribute to C, N, and P fluxes is pivotal for developing accurate urban biogeochemical models and for informing policies aimed at reducing sources of pollution in urban ecosystems.
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Technical Assessment of the Carbon Sequestration Potential of Managed Turfgrass in the United States
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