TGAS-Harvest Moon Origins
The long-term agricultural research field site Trace Gas Manitoba (TGAS-MAN) was established by Dr. Tenuta in 2005 and has been acquiring continuous field-scale fluxes of both N2O and CO2 using a flux-gradient micrometeorological technique ever since. The site has contributed greatly to our understanding of greenhouse gas emissions and mitigation from agricultural fields, but it is located on poorly-draining clay soils in the Red River Valley and is not representative of all soils on the Canadian Prairies.
To address the need for a similar research site, but one located on lighter well-draining soils more typical of the Canadian Prairies, Dr. Tenuta, with support of the 4R Nutrient Management Industrial Research Chair, established the Trace Gas Harvest Moon (TGAS-HM) long-term agricultural research field site in 2022.
The well-draining soils at TGAS-HM allow for an important avenue of research not available at TGAS-MAN and one that has gone largely unaddressed in Canada: studying indirect losses of N together with whole-season estimates of direct N2O emissions. TGAS-HM will address this significant knowledge gap by determining the relative importance of N loss via leaching to direct N2O emissions.
In concert with its predecessar, TGAS-HM will be used to test farming practices and their impact on greenhouse gas emissions, with the goal of providing empirical data to guide best management practices to lower emissions. Additionally, it will be used to compare emissions from well-draining light with poorly-draining clay soils under the same management practices.
Curious about the site’s name? Dr. Tenuta is an avid music enthusiast, and named it after the annual Harvest Moon Festival which occurrs nearby in Clearwater, Manitoba.
Site & Infrastructure
TGAS-HM is located approximately 6 km south of Clearwater, MB, Canada. The area is a glaciofluvial plain with nearly-level topography (0-2% slope), extreme humid-continental climate, and moderately fine clay loam soils predominantly of the Kudson (Orthic Black Chernozem), Joyale (Gleyed Rego Black Chernozem) and Melland (Gleyed Rego Black Chernozem) series. The soil is well-drained, with low organic matter content compared to TGAS-MAN.
The field site is located in a 60-ha farmed field and consists of two 200m x 200m (4-ha) experimental plots.
At the epicenter of TGAS-HM is the Tunable Diode Laser absorption specrophotometer (Campbell TGAS200A) trace gas analyzer. Housed in an insulated trailer located at the junction of the four experimental plots, the trace gas analyzer continuously measures direct emissions from the TGAS-HM plots for flux-gradient estimation of N2O and CO2 from soil.
The flux (F) of N2O and CO2 between the crop system and lower atmosphere is determined as:
Like TGAS-MAN, each plot is outfitted with its own micrometeorology station, which monitors environmental conditions such as wind speed and direction, air temperature, and soil moisture and temperature. The station’s sonic anemometer-thermometer measures temperature and 3-D wind velocities, and these data are used to estimate the turbulent transfer coefficient, K.
Gas intakes separated by a vertical height difference (Δz) on each micrometeorological station alternately provide air samples to the analyzer, switching every 15 seconds. These data are used to determine the vertical concentration gradient (ΔC) of N2O and CO2. Only one plot is sampled at a time, for 30 minutes, yielding a maximum of 12 half-hourly flux-gradient estimates of N2O and CO2 from soil each day.
Unlike the clay soil at TGAS-MAN, the loam soils at TGAS-HM are light enough for leaching to result in nutrient loss. In order to study this phenomenon, two clusters of three lysimeters (Drain Gauge G3) were installed below the root zone (depth of 60 cm) in both experimental plots at TGAS-HM. Leachate samples will be collected and analyzed for ammonia (NH3), nitrate (NO3), and phosphate (PO4).
A fully-equipped weather station is located within the vicinity of the trailer, which measures wind speed and direction, air temperature and relative humidity, precipitation, barometric pressure, snow depth, soil temperature and moisture content at various depths, incoming solar radiation, and photosynthetically active photon flux density.
As with TGAS-MAN, short-term projects will be conducted at TGAS-HM, where each plot will experience different experimental manipulation of farming practices. Data collected during these experiments will be used to address additional research objects as well as contribute to a larger nitrous oxide dataset.
The table below summarizes the crops and experimental manipulation of each year (i.e. growing season), as well as the corresponding project number.
|YEAR||North Plot||South Plot||Experimental|
|2023||Corn||Corn||1) Nitrification Inhibitors|
Phase 1: 2023-
Prior to establishment of the experimental plots, the field site was under annual crop production and field management typical of the region. Set-up of TGAS-HM began in the summer of 2022 and measurement of fluxes began on April 10, 2023. The first leachate samples were collected on May 9, 2023.
1) Nitrification Inhibitors of Granular Urea (2023-)
The first project taking place at TGAS-HM is a study of the effect of nitrification inhibition on whole-year direct and indirect N2O emissions. In 2023, both plots were planted with corn and fertilized in spring with anhydrous ammonia, but only the south plot received a nitrification inhibitor (Centuro®, KOCH Agronomic Services).
A similar study is being conducted at TGAS-MAN, allowing for a comparison of the effects of nitrification inhibitors on direct N2O emissions from light vs clay soils.
TGAS-HM Support and Funding Sources
Past and present support and funding for the operation and maintenance of TGAS-HM and research conducted at the field site has come from the following sources:
- Fertilizer Canada
- NSERC Discovery Grant Program
- NSERC Industrial Research Chair
- Western Grains Research Foundation
A special thanks to Lanny Gardiner, who has graciously provided the land and conducts agronomic activities for TGAS-HM.