SOIL CARBON CYCLING IN COOL-SEASON TURF LAWNS IN RELATION TO MANAGEMENT PRACTICE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0226299
• Project Start Date: Oct 1, 2011
• Project End Date: Sep 30, 2016
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF CONNECTICUT
438 WHITNEY RD EXTENSION UNIT 1133
STORRS,CT 06269

Performing Department
Plant Science and Landscape Architecture

Non Technical Summary
Connecticut and southern New England is a densely populated urban/suburban corridor along the Atlantic Seaboard that contains a considerable amount of amenity turfgrasses. As a result of urbanization, considerable portions of the natural and/or agricultural vegetation in this region has been largely replaced with amenity turfgrasses as the preferred landscape, and used as lawns, parks, recreational areas, athletic fields, golf courses, and other outdoor activities on grass that is mowed on a frequent basis. This vegetation replacement is occurring in other regions as well, and is not trivial. It has been estimated that there are approximately 16 to 20 million hectares (40 to 50 million acres) of land in the continental United States managed in turfgrasses, with the most of this area managed as lawns. This is an area three times larger than any irrigated crop in the United States, and is expected to increase as urbanization follows population expansion. Even though a sizeable land area is identified as being dominated by turfgrass, this landscape vegetation has usually been overlooked or not thought of as an important sink for soil carbon sequestration. Recent research suggests that there is greater soil carbon sequestration in turf than was expected. However, information is lacking as to which turf management practice or combination of practices promote the greatest amount of soil carbon sequestration. This project will determine the changes in soil carbon occurring under different species of cool-season turfgrass lawns (Kentucky bluegrass, tall fescue, perennial ryegrass, creeping red fescue) mowed at different heights, with clippings removed or returned, and receiving varying amounts of nitrogen fertilizer. Nitrogen fertilization is a common practice that promotes green color and increased density of turfgrass. When plant-available soil nitrogen is low, adding nitrogen fertilizers should increase turf growth and density, thus leading to more soil carbon accumulation. However, applying nitrogen beyond needs of the turfgrass plant could accelerate the loss of soil carbon instead of the desired effect of increasing soil carbon sequestration rates. Soil organic matter breakdown from microbial decomposition might be accelerated by the surplus reactive nitrogen. Understanding the role of turf N fertilization, in relationship to other turf practices such as cutting heights and handling of clippings, on the carbon cycling and storage in urban/suburban landscapes will provide guidance for lawn management practices that maximize carbon sequestration potential in these landscape areas. Identifying turf management practices that increase soil carbon sequestration will have direct benefits to the environment and natural ecosystems because they will be beneficial for greenhouse gas mitigation and reducing the threat of nitrogen pollution of sensitive aquatic ecosystems. It is expected that specific practices or combination of practices will be identified by this project. Promotion of these practices to turf managers will result in more soil C accumulation, leading to a more sustainable lawn system.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0110	1070	70%
102	2130	1070	30%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
2130 - Turf; 0110 - Soil;

Field Of Science
1070 - Ecology;

Keywords

carbon sequestration

turfgrass

nitrogen fertilization

grass clippings

lawns

soil carbon

carbon cycle

mowing heights

greenhouse gas mitigation

Goals / Objectives
The overall objective of this project is to determine the changes in soil C occurring under different species of cool-season turfgrass lawns receiving varying amounts of N, mowed at different heights, with clippings removed or returned. Target Dates: Late-Summer 2011 - Establishment of turf plots and initial soil sampling. Winter 2011/2012 - Analysis of soil samples. Spring 2012 - Soil sampling; imposition of treatments; annual CRIS report. Summer 2012 -Continue treatment imposition and plot maintenance; analysis of spring soil samples; tissue sample collection; data summarization. Fall 2012 - Soil sampling; analysis of fall soil samples and tissue samples. Winter 2012/2013 - Analysis of soil and plant tissue samples; statistical analyses. This cycle of activities repeats until Fall 2016. Fall 2016 - Project ends; CRIS Termination Report; preparation and submission of manuscripts. Expected Outputs: It is expected that specific turf management practices, or combination of practices, will be identified that optimize soil C sequestration amounts or rates. This information will allow for better decisions regarding lawncare practices that result in the maximum potential for soil C sequestration in our urban/suburban landscape, leading to a more sustainable system. Expected outputs include analysis of experiment data; incorporation of results into the undergraduate and graduate teaching programs, mentoring of graduate students; presentation of results to landscape managers, governmental regulatory agencies, policy makers, environmental groups, and other scientists; turf industry field days that include the experiment site; web-based articles and information that describe and interpret results; publication of scientific peer-reviewed manuscripts.

Project Methods
Soil C sequestration will be assessed in the field with a 4 x 2 x 3 x 5 factorial experiment set out in a split-split-plot design with three replicates. 4 common turfgrass species [Kentucky bluegrass (Poa pratensis), tall fescue (Festuca arundinaceae), perennial ryegrass (Lolium perenne), and creeping red fescue (Festuca rubra)] will be main plots. Combinations of 2 clipping handling practices (removed or returned) with 3 cutting heights (5, 7.5, 10 cm) will be the sub-plot treatments, and 5 varying N rates (0, 10, 20, 30, 40 kg/ha/month during the growing season, May to November) as urea, will be the subsubplot treatments. These amounts of N will span the range of commonly applied N rates for lawns in our climate. Plot size will be 2 x 2 m. Grasses will be established on a newly-prepared seedbed so that changes in soil C storage beginning from establishment can be determined. Prior to treatment imposition at the beginning of the experiment, soil samples will be collected from two depths (0 to 10 cm and 10 to 20 cm) from each plot. Soil samples will be dried and sieved to pass a 2-mm sieve and analyzed for total soil C concentration. Following treatment imposition, soils will be sampled to the two depths at the end of the growing season (late October-early November in our climate), and at the beginning of the next growing season (mid April-early May) for a total of five growing seasons. Monthly samples of the aboveground biomass of the turf will be collected and bulked to provide a single yearly estimate, and this will be analyzed for total C content. Aboveground biomass collection will occur between 10 and 14 days after N fertilization to insure that optimum N uptake and assimilation has occurred to promote aboveground growth. Since clippings will be returned and removed, an estimate will be made of the C input from the aboveground plant parts. At the end of the growing season, thatch layer samples will be collected and analyzed for total C. With an estimate from plant tissue, thatch layer, and soil samples, a C budget will be constructed for each plot. Analysis of variance will determine differences between species, N rates, cutting heights, clipping management, and their interactions. Changes in soil C measurements with time will be determined using repeated measures analysis, with sampling date designated as the repeated measure. Information gained from the project will be distributed to and discussed with turf extension personnel and other turfgrass scientists. Identification of turfgrass practices that optimize soil C concentrations will be promoted through existing extension programs and through popular and trade industry publications or on-line sources, and through peer-reviewed scientific journals. Emphasis of these desirable turf management practices will be incorporated into the undergraduate and graduate teaching programs. Once specific practices or combination of practices have been indentified that optimize soil C, workshops for professional turf managers employing pre- and post-workshop surveys could be used to assess degree of adoption or changes in current practices that occur because of the new information.

Progress 10/01/11 to 09/30/16

Outputs
Target Audience:Results from this project will provide information to a wide constituent base: professional lawncare and landscape managers, governmental regulatory agencies, policy makers, environmental groups, other environmental scientists. Changes/Problems:Due to continual and reoccurring problems with our carbon analyzer, only a small percentage of the soil samples collected in this study have been analyzed. Our conclusions are limited based on the actual number of samples that have been analyzed. It is our intent to complete the analyses, even though this project has ended. What opportunities for training and professional development has the project provided?The graduate student working on this project received training in set up and maintenance of a field experiment, plus experience and training in running a carbon analyzer. How have the results been disseminated to communities of interest?Results have been primarly disseminated at two major field days in 2014 and 2015. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? To date, soil sampling analyses suggest that soil carbon sequestration in an urban/suburban turfgrass lawn ecosystem is affected primarily by species (greatest under creeping red fescue) and how clippings are managed: greater soil carbon when clippings are mulched into the turfgrass canopy instead of being bagged and removed from the system. Due to problems with our carbon analyzer, we were not able to complete carbon analyses for most of the soil samples collected in the study before the end of the reporting period.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Guillard, K., and D. Moore. 2016. Which Turfgrass Management Practices Maximize Soil Carbon Sequestration? p. 51-53. In J.C. Inguagiato (editor) 2016 UConn Turfgrass Field Day Program and Research Summaries. University of Connecticut College of Agriculture,Health and Natural Resources, Storrs, CT.

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Results from this project will provide information to a wide constituent base: professional lawncare and landscape managers, governmental regulatory agencies, policy makers, environmental groups, other environmental scientists. Changes/Problems:Analysis of soil samples are behind schedule due to instrumentation problems with the total carbon analyzer. Repairs and service to the instrument are an ongoing issue, but hopefully can be addressed before the next reporting period. What opportunities for training and professional development has the project provided?One graduate student and one undergraduate student were trained on conducting experimental field plot research. Students were also trained on how to prepare and analyze soil samples for total carbon concentrations. The graduate student was trained in data analysis and reporting of research data. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?The goal for the next reporting period is to finish analysis of all the soil samples collected in the experiment and to analyze all the data to determine which combination of species selection and management practices maximize the soil carbon sequestration of turfgrass lawn ecosystems in temperate climates.

Impacts
What was accomplished under these goals? To date, soil sampling analyses suggest that soil carbon sequestration in a turfgrass lawn ecosystem is affected primarily by species (greatest under creeping red fescue) and how clippings are managed: greater soil carbon when clippings are mulched into the turfgrass canopy instead of being bagged and removed from the system.

Publications

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Results from this project will provide information to a wide constituent base: professional lawncare and landscape managers, governmental regulatory agencies, policy makers, environmental groups, other environmental scientists. During this reporting period, the project field study was presented to professional turfgrass managers at the 2014 Biennial UConn Turfgrass Field Day. There were approximately 250 attendees at this event. The project description and objectives of the study were detailed in the Field Day booklet that was distributed at the program. Importance and implications of the study were discussed with attendees. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Implications of the project goals, and how this could affect environmental sustainability of turfgrass systems were presented and discussed at the 2014 UCONN Turfgrass Field Day. Approximately 250 people attended this event, and most of the attendees were associated with the turfgrass industry or with governmental regulatory agencies. This presented an opportunity to educate these turfgrass professionals and governmental agencies about sustainable turfgrass management practices that maximize soil carbon sequestration. How have the results been disseminated to communities of interest? To date, the project description and summary to date has been published in the 2014 UCONN Turfgrass Field Day Program and Research Summaries booklet at was distributed at the Field Day. As more results are obtained, these will be presented in other publications and media. What do you plan to do during the next reporting period to accomplish the goals? For the next reporting period, a summary of project results will be included in the UCONN Annual Turfgrass Research Report (http://www.turf.uconn.edu/reports.shtml). I also expect to present results at the New England Regional Turfgrass Conference.

Impacts
What was accomplished under these goals? 2014 soil sample analyses are currently being conducted during this reporting period.

Publications

• Type: Other Status: Published Year Published: 2014 Citation: Guillard, K., and P. McIntosh. 2014. Which turfgrass management practices maximize soil carbon sequestration? p. 47-49. In 2014 UCONN Turfgrass Field Day Program and Research Summaries. University of Connecticut, College of Agriculture, Health, and Natural Resources, Storrs, CT.

Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Results from this project will provide information to a wide constituent base: homeowners, professional lawncare and landscape managers, governmental regulatory agencies, policy makers, environmental groups, and other scientists. Since the project period for this report has only covered the first establishment year for the turfgrasses, we have not yet collected data that would be of relevance to our target audiences for this reporting period. Changes/Problems: Analysis of aboveground tissue samples for concentrations of total carbon has been eliminated from the project. Concentrations of carbon will not vary greatly in the aboveground portions of a grass plant. Changes in mass of carbon in the aboveground plant tissue will vary according to conditions for plant growth. Although this can be measured, the most important information from this project will be the changes in soil carbon, and not the aboveground plant portions. If carbon input from the aboveground portions of the plant are important to soil carbon sequestration, then it will show in the soil total carbon analyses. There is no need to conduct analysis of plant tissue carbon analyses. This will allow more time for soil carbon analyses, and will save on expenses for conducting the soil carbon analyses. What opportunities for training and professional development has the project provided? A graduate student was assigned to the project and assisted with plot maintenance, data collection, and laboratory analyses. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? All treatments (cutting heights, clipping management, and varying nitrogen rates) will be applied beginning in 2014. Analysis for total carbon in the 2013 soil samples will be completed. New soil samples will be collected from each plot at the end of the growing season in 2014. These samples will be analyzed for concentrations of total carbon.

Impacts
What was accomplished under these goals? The initial plots of this experiment were destroyed by hurricane Irene in 2011. The entire experimental area had to be completely renovated in 2012, with new seeding of turfgrasses in fall of 2012. The first establishment year for the grasses was 2013. Only partial treatment imposition occurred during the growing season in 2013 (cutting heights and clippings management - removed or returned). Nitrogen rate treatments were not applied in 2013 because the grass density was too low to support adequate growth under low or no nitrogen. Therefore, all plots received the same rates of nitrogen so that stand density would reach adequate levels in all plots. By the end of the growing season in 2013, all plots have reached acceptable stand densities. Soil samples were collected from each plot at two different depths (0-10 and 10-20 cm) at the end of the growing season in 2013. These samples are currently being analyzed for concentrations of total carbon. All treatments (cutting heights, clipping management, and varying nitrogen rates) will be applied beginning in 2014.

Publications

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Initial experiment set out in 2011 was destroyed by Hurricane Irene. Entire experimental area was killed with glyphosate in spring 2012 and any escape volunteer plants were killed during the summer. Plots were reestablished in late August 2012. Soil samples were collected from each plot prior to grass seeding so that a baseline soil C concentration could be established. These soil samples are currently being analyzed for concentrations of total C. PARTICIPANTS: Karl Guillard is the project PI. He designed the experiment and set out the field plots for this project, and directed the soil sampling and turfgrass seeding and post-establishment maintenance. Xingyuan Geng is a PhD candidate that assisted Guillard with all aspects of the project, and was responsible for soil sample preparation for total C analysis. Geng is currently responsible for conducting the soil C analysis in the PI's laboratory. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Initial experiment that was set out in the last summer of 2011 was destroyed by Hurricane Irene. Subsequently, the experimental area was sprayed with a non-selective herbicide (glyphosate) and any volunteer plants that emerged after spraying were controlled with the same herbicide until plots could be reestablished in late summer 2012. Project objectives and approaches will not change, but results will be delayed by one year.

Impacts
None to report at this time since experiment had to be reestablished in the last summer of 2012. Soil samples are currently being analyzed for baseline concentrations of C.

Publications

• No publications reported this period