- Agronomic: corn
- Crop Production: fertilizers, no-till, nutrient management
- Education and Training: workshop
- Natural Resources/Environment: carbon sequestration
- Soil Management: organic matter
Minimum and no tillage practices have tremendous potential to reduce farmer expenses and the potentially negative impacts of intensive agriculture on soil quality and the environment. An important co-benefit of these tillage practices may be reducing regional to national greenhouse gas (GHG) emissions by storing carbon in the soil and reducing emissions of carbon dioxide, methane, and nitrous oxide. In minimum tillage systems, however, a persistent problem is how to apply and retain nutrients stored in manure: without incorporation, more than 50% of manure nitrogen may be lost through runoff and volatilization (Jokela et al. 2004).
We propose to study the benefits and/or drawbacks different tillage and manure application methods in the ongoing Manure Injection No Till (MINT) farm trial. We will examine four tillage practices (vertical-till, strip-till, no-till, conventional till) under two manure treatments (broadcast, injected). Our objective is to determine the manure and soil management practices best suited for reducing GHG emissions, increasing carbon storage, and preventing nitrogen losses. This objective will be met by taking in field GHG, soil carbon and nitrogen samples. Our results will be used in conjunction with ongoing UVM Extension measurements (e.g., crop productivity and quality), which will allow for a more complete understanding of the benefits and disadvantages of different management practices.
We will share our data and results through posters and extension and academic publications, as well as through outreach events (such as UVM Extension Field Days), where the public, policy makers, and farmers will be present to discuss results.
Project objectives from proposal:
What combination of tillage and manure application methods will maximize the ability of agriculture to increase soil quality and reduce GHG emissions? Our primary objective is determining which combination of tillage and manure practices is best suited for reducing soil CO2, N2O, and CH4 emissions, increasing soil C storage, and retaining soil N.
To meet this objective we will utilize an ongoing farm trial examining tillage and manure application practices. Specifically, we will examine GHG and soil C and N in all combinations of four tillage practices (conventional, vertical, strip and no till) and two manure application methods (injection and broadcast). We will use this data to assess the potential for each practice to enhance soil C storage and reduce GHG emissions.
Results from this study will be shared broadly as part of the Vermont Agricultural Resilience in a Changing Climate Participatory Action Research project, which has already served to share agricultural research results with the public, policy makers, and farmers through publications and outreach events, allowing the research to have a meaningful impact. We will also work closely with Dr. Heather Darby (UVM Extension) to disseminate results to Vermont farmers and service providers (e.g., Field Day events and demonstrations).
Our proposed research will be conducted within the on-going Manure Injection No Till (MINT) farm trial on Borderview Farm in Alburgh, VT. This trial is in a continuous corn system. There are three tillage treatment plots (vertical till, strip till, no till) that are 40 feet wide by 192 feet long, with 40 feet buffers between them. Within each tillage plot there are two manure application methods: broadcast and injected. Each tillage and manure treatment combination is replicated four times (i.e., each manure treatment is replicated four times within each tillage plot). We will compare measurements taken from these treatments to measurements taken in conventional agricultural management plots: conventional tillage with broadcast manure (four replicates).
Within each treatment combination we will measure soil C and N (no funding is requested for this), mineral N, soil moisture, temperature and GHG emissions (CO2, N2O and CH4). GHG measurements will be taken using a stratified vented chamber design (Figure 1), following the specifications of the USDA’s Greenhouse gas Reduction through Agricultural Carbon Enhancement network (GRACEnet) protocol. This protocol was developed to identify and further develop agricultural practices that enhance C sequestration in soils, promote sustainability, and provide a sound scientific basis for policy decision making (Parking and Ventera 2010). Treatments will be sampled a minimum of two times per month between March and October, but more intensively after management practices (e.g., manure application), snow melt, and extreme rainfall events, in order to collect data that will shed light on soil processes during these critical times. On each sampling date we will measure CO2, CH4 and N2O fluxes in one location per treatment combination using the vented closed chamber method (Hutchinson and Mosier 1981): gas concentration within the chamber is measured by withdrawing samples from the chamber by syringe at four time intervals and analyzing gas concentrations by gas chromatography at the University of Vermont (UVM; Shimadzu GC-17A equipped with a Flame Ionization Detector for quantifying CH4 and with an Electron Capture Detector for quantifying CO2 and N2O). Due to the chambers’ closed nature, measured GHG concentrations normally increase with each time increment, allowing us to calculate emission rates.
Inorganic soil N, soil temperature, and soil moisture will be measured as covariates for GHG fluxes. Soil temperatures will be taken next to the gas collecting chambers so as not to disturb the soil within the chamber. Air temperatures will also be taken once at the beginning and once more at the end of gas sampling and then coupled with the nearest NOAA weather monitoring station data in order to have a complete profile of the day’s temperature, winds, and rain accumulations. Water content of soil will also be measured using a soil moisture probe, which has already been calibrated using concurrent gravimetric soil moisture measurements. Two soil cores (0-20 cm) per plot will be composited and subsampled for 2 M KCl extraction. These extracts will be analyzed for inorganic soil N at UVM’s Agricultural and Environmental Testing Lab (Lachat QuickChem FIA).
As a part of ongoing, separately funded project, Adair and Goeschel will measure total soil C and N in each treatment (by dry combustion elemental analysis at UVM’s Agricultural and Environmental Testing Lab). Additional ongoing work by Heather Darby (UVM Extension) will measure soil nitrates (weekly until V6 leaf stage), soil aggregation, soil organic matter, soil active carbon, plant populations, corn silage yield, and corn quality. This information will be used to compliment and/or extend the data we propose to collect on mineral soil N and GHG emissions.
We will analyze collected soil C and N and GHG emissions data using an Analysis of Covariance (ANCOVA), structural equation modeling, and/or time series analysis (R; R Core Team, 2013) to determine average annual and episodic significant differences between combinations of tillage & manure application methods. This analysis will show whether differences in GHG emissions are significant, and if the differences between management practices are the cause. Results will also be used to parameterize and/or validate regional models of terrestrial and agricultural nutrient cycling (funded separately).
Dr. Carol Adair (UVM Rubenstein School of the Environment and Natural Resources, RSENR) and Tyler Goeschel (UVM RSENR MS student) will work with Dr. Heather Darby (UVM Extension) and Roger Rainville (Borderview Farm) to maintain the experimental design and make sure that it is compatible with the farm operations. Adair and Goeschel will be responsible for data collection, data analysis and results dissemination. Roger Rainville will manage the planting, cultivation, manure application, and plot maintenance. Adair and Goeschel will continue working with Darby and other service providers to disseminate results to interested farmers.
The proposed work will begin in March of 2015 and continue through February of 2016. Ideally, GHG samples collection will begin at the time the soil thaws out from its winter freeze. GHG measurements will continue at least bi-weekly after the start, with additional GHG collection times during special events, such as prior to and after planting of the corn, prior to and after manure/fertilizer application, extreme rain events, etc. A more detailed schedule for our activities is listed in the chart below – please see the project timetable under the Attachments section.
Our target audience will be production farmers interested in meshing conservation tillage practices with practical methods of manure application in the Northeastern US. We will share our results through outreach events including the annual “Crops and Soils Field Day” – an event we have participated in for the past two years – hosted by Borderview Farm, This outreach event attracts farmers from all over the Northeast. Results from this study also will be shared broadly as part of the Vermont Agricultural Resilience in a Changing Climate Participatory Action Research project, which has already served to share agricultural research results with the public, policy makers, and farmers through publications and outreach events, allowing the research to have a meaningful impact.
The practical results arising from our research will be written up in an extension publication (as well as in appropriate scientific journals), and disseminated electronically and through eOrganic, UVM Extension, NOFA-VT. We will also utilize our ongoing collaborations with UVM Extension and UVM Center for Sustainable Agriculture to further disseminate our results. Finally, this work will be a part of Goeschel’s Master’s Thesis work, which will be made public online through UVM once completed.