Nitrous oxide is released into the atmosphere from a variety of human activities. This gas is roughly 300 times as potent as carbon dioxide in trapping heat in the Earth?s atmosphere, and thus even small quantities of emissions may constitute a meaningful share of US greenhouse gas emissions. One path for nitrous oxide releases is from the application of fertilizers to lawns because a portion of these fertilizers is converted to nitrous oxide by soil bacteria. Not only are the physical factors that affect nitrous oxide emissions from households not well quantified, but social science research and research into climate change mitigation laws and policies associated with lawncare has not been a focus in the past. An integrated, interdisciplinary study is needed to answer questions related to (1) the physical processes that lead to nitrous oxide emissions from household nitrogen-containing fertilizer use, (2) the types and levels of individual and household activities that affect household nitrous oxide emissions from fertilizer use; (3) the values, beliefs and norms associated with these individual and household activities; and (4) the communities and social networks associated with these activities. This project is a study of the Richland Creek Watershed, which encompasses 28.5 square miles of primarily residential neighborhoods in Nashville, Tennessee. These neighborhoods represent a diverse range of residents in terms of race, income, education, and ownership patterns. A coordinated set of biophysical and social-science data will be collected and analyzed to address the science questions. To understand how social and economic influences affect fertilizer use in Richland Creek neighborhoods, the research team will conduct a series of surveys with 600 households grouped in 60 blocks in the watershed. We also will conduct 60 focus groups, one for each sampled block. To provide the link to the release of nitrous oxide, physical samples will be taken at locations around the watershed. Nitrous oxide fluxes from the soil will be measured using soil covers and soil moisture and temperature will be measured at the sampling sites using a wireless sensor array.
Using data derived in this research, theoretical explanations of household, sub-neighborhood, and neighborhood behaviors and their effect upon fertilization rates will be tested and, through links with measured biophysical processes, emission rates of a powerful greenhouse gas, nitrous oxide, will be included. The project will lead to knowledge of how much of nitrogen-containing fertilizer applied to lawns is converted to nitrous oxide as affected by soil and meteorological conditions; how household lawncare decisions around fertilizer use are affected by a neighborhoods? norms and characteristics; which household-level beliefs, norms, and characteristics affect fertilizer use; how neighborhood-level norms and characteristics interact with household characteristics; and how the combined knowledge of emissions and behavioral characteristics can be used to explore options to effect reductions of nitrous oxide emissions from fertilizer use. In particular, the research results may indicate that a number of policy or community-level interventions may be appropriate for reducing the household share of greenhouse gas emissions and that these interventions may be quite cost effective in comparison with more often used regulatory measures targeting industrial sources.
Normal 0 false false false EN-US X-NONE X-NONE Grasses and Gases: The Nashville Yard Project Vanderbilt Institute for Energy and Environment Background Households have major impacts, both good and bad, on the environment. While the lawns that surround many American households may look green and natural, it takes a great deal of effort for many of them to look the way they do, including mowing and application of fertilizer, pesticides, and weed killers. These actions have environmental consequences, including emission of nitrous oxide, a powerful greenhouse gas;1kg of N20 can trap as much heat in the atmosphere as 310kg of carbon dioxide. Given this context, we developed two research questions: What are the social drivers of fertilizer use in the Richland Creek Watershed? How is fertilizer linked to nitrous oxide (N20) emissions there? Study Site Our study took place in the Richland Creek Watershed (RCW), an urban watershed in Nashville, Tennessee. The RCW is interesting for several reasons, not the least of which is a significant socioeconomic diversity. Households in the south of the watershed are located in some of the most affluent areas in Nashville, while neighborhoods in the northern part are middle- and working-class. Methods We interviewed and took soil samples from 350 randomly selected households in 60 neighborhoods in the Richland Creek watershed. We also surveyed companies who provide lawn care services. We also used a small dome placed on people’s lawns to collect gas emissions from six example lawns. We then analyzed those emissions in the lab and created a model linking fertilizer use under specific conditions with emissions. Key Findings There are certain economic and social drivers of lawn fertilizer use and application rates: ·56% of the households used fertilizer (21% applied themselves, 25% used a lawn care service, and 7% supplemented a service with self-application). ·Nearly two thirds of households apply fertilizer only once or twice per year. About 10% use it six or more times per year. ·Individuals apply less than either professional (agricultural extension) or corporate (package instruction) recommendations. The median user of fertilizer put the equivalent of 52kg of nitrogen per hectare of lawn each year; University of Tennessee Extension recommends 195kg. ·Wealthier people are more likely to use fertilizer than less wealthy people, but they do not put any more fertilizer on per application and do not use it more frequently. ·People who live in neighborhoods with homeowners associations are more likely to fertilize than people who do not; they also use more fertilizer per application. ·A key driver of fertilizer use is the importance the homeowner places on having a green lawn. People who live in HOA neighborhoods value a nice looking lawn more than people who do not. Wealthier people value a nice looking lawn more. ·People cite many other reasons for using fertilizer,. Fertilizer application is related to nitrous oxide (N20) in specific ways: ·N2O emissions increase as people put more fertilizer on their lawns. ·The average fertilized lawn does not emit a great deal more N20 than non-fertilized lawns, but people who follow professional guidelines for lawn fertilization can emit as much as 645g of N2O per hectare per year, which has the same atmospheric warming potential as 200kg of carbon dioxide. ·15% of households in our sample were responsible for 60% of emissions. ·Application during periods of sustained warm temperatures leads to much higher levels of emissions. - Application of fertilizer over the summer can nearly double emissions compared to spring application. ·Emissions are higher if fertilizer is applied to a wet lawn or that lawn gets watered soon after application than if the lawn stayed dry. The same quantity of fertilizer applied can produce as much as 10% more N2O if applied to a wet lawn or if the lawn is watered or rained on soon after fertilization. Summary and Implications Our findings lead to several implications: · Generally, people are using much less fertilizer than is recommended by fertilizer producers and agricultural extension offices. · Nonetheless, lawn fertilization still contributes appreciable quantities of N2O. · N2O emissions related to fertilizer use can shrink if homeowners reduce summer fertilization and fertilization of wet lawns. · A small number of houses contribute the majority of lawn fertilizer-related emissions. · The reasons why people use fertilizer are complex, and include individual preferences, neighborhood influences, and cultural values. Changing structural influences like HOA rules may be a relatively simple way to pursue reductions in fertilizer use. · Because most people apply less than widespread guidelines suggest, general education initiatives for "responsible fertilizer use," such as soil testing or consulting a professional, could actually increase emissions and other environmental consequences by encouraging people to use fertilizer in larger quantities and more often.
