Location: Agroecosystem Management Research
Project Number: 3042-21600-001-011-I
Project Type: Interagency Reimbursable Agreement
Start Date: Mar 22, 2024
End Date: Aug 31, 2031
Objective:
The proposed research will facilitate the quantification of greenhouse gas (GHG) emissions from practices that address multiple Natural Resource Conservation Service (NRCS) Conservation Practice Standards (CPS) and support the national inventory. Plains Area is charged with quantifying 4Rs of nitrogen management strategies (CPS 590), use of cover crops (CPS 340), reduced tillage (CPS 345), crop residue management (CPS 329) techniques, and land converted to grassland (CPS 550). Quantifying GHG emissions from these practices compared to prevailing agricultural methods in semi-arid to arid environments will provide data for improving model estimates for mitigation outcomes for NRCS and for the national inventory. At Lincoln, data collection will focus on GHG emissions from row crops under rotational and N management conservation practices, and in beef production grazing systems. We plan to work closely with Action Area #3: Data Management Infrastructure & Capacity and Action Area #4: Models and Tools for Assessing Outcomes to ensure relevant and useful data contributions for modeling outcomes.
Approach:
Greenhouse gas emissions are collected from 11 experimental sites using the static chamber methods (3 perennial based systems; 4 irrigated cropland sites, 4 rainfed cropland sites). Soil fluxes of CO2, CH4, and N2O are b measured and calculated using sampling designs and data processing protocols standardized by the USDA-ARS’s Greenhouse Reduction through Agricultural Carbon Enhancement Network (GRACEnet). Static chambers are used to measure GHG fluxes from the soil surface. Each base covers an area of 1707 cm2 (52.7 cm x 32.4 cm) and is installed to a soil depth of 5–7 cm, resulting in a base height of 5–7 cm above ground. Bases are removed and re-installed throughout the growing season to accommodate for field management operations (e.g., tillage, planting, fertilization, harvest). After any reinstallation, bases are allowed to equilibrate for at least 24 h (but usually 2– 4 days) before gas sampling to minimize immediate soil disturbance effects. Gas measurements are collected using a stratified sampling design in which gases are sampled with syringes and injected into evacuated glass vials at four evenly spaced time-points over 30 minutes (0, 10, 20, and 30 minutes). Sample collections are conducted every 7-10 days during the growing season (June through November), with increased sampling frequency occurring after introduction of grazing, organic, and inorganic N application. Monthly sampling occurs during the non-growing season. Collected samples are measured within 10 days of collection using a gas chromatograph. Cumulative annual gas fluxes are calculated by linear interpolation among the individual measurements. Air temperature, soil temperature, and soil volumetric moisture content from the 0-10 cm depth is recorded at the time of gas sampling. Site management records are maintained, and metadata is meticulously updated to facilitate interpretation of collected data. All data will undergo local QA/QC checks prior to submitting to the PA project data manager. In addition to chamber measurements, eddy flux measurements will be monitored year-round at Long-Term Agroecosystem Research (LTAR) sites by our University of Nebraska (UNL) collaborators.
