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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Research Project #443435

Research Project: Optimizing Soil Carbon Sequestration in Oregon Seed Production Systems

Location: Forage Seed and Cereal Research Unit

Project Number: 2072-21600-001-011-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2023
End Date: Mar 31, 2026

We have three research objectives and two educational objectives: Research Objectives: 1. Quantify soil carbon (C) stocks for the grass seed industry in the Willamette Valley (WV), OR with an emphasis on systems differing in subsurface drainage, residue, and tillage management practices. 2. Calibrate and validate the DayCent model(a biogeochemical model used to predict carbon sequestration and greenhouse gas fluxes in agricultural systems) using data generated in Objective 1. 3. Identify which management practices support the greatest C sequestration potential using sensitivity analysis from a suite of DayCent simulations across the WV region. Education Objectives: 1. Translate C results into a decision support tool to help growers understand how management impacts C storage on their farms; and, 2. Increase industry wide growers’ knowledge of the factors that affect soil C sequestration potential in WV grass seed systems.

To obtain a more accurate interpretation of management shifts, relying solely on surveying fields is not adequate due to the length of time for C stocks to respond to management and high field-to-field variability particularly in the Willamette Valley (WV) (80 to 180 Mg ha-1, figure 2). This variability is, in part, due to the complex crop management histories in the WV that vary in the length of time of perennial and annual cropping systems, integration of livestock, crop rotation diversity, and tillage frequency and intensity. Ideally, long-term field plots would exist to reduce some of these variabilities, however, these are not available in grass seed production systems in our area. To begin to tackle these challenges, we propose coupling key benchmark field sites that will serve as monitoring locations to assess changes over time as well as a suite of field measurements to be used for the calibration and validation of DayCent, a biogeochemical process-based model, to better predict site-specific impacts that can be scaled across space and time. DayCent will compliment site C measurements to test scenarios and estimate impacts of management implementation on C sequestration potential and GHG emissions. Our initial push is to focus on C sequestration potential but intend to build a flexible platform to include other soil health measures over time. Identifying the management practices and their impact will provide information for growers to make decisions on. In collaboration with an active grower panel and support from the seed industry, we will leverage previous work in the area to establish a network of farmer-led field sites to monitor soil C under three management practice categories: artificial subsurface drainage, residue management, and tillage management. Soil and root samples will be collected and analyzed for a suite of measurements targeting soil C dynamics will be conducted. Soil C stock results from field sampling efforts will be synthesized and reported in WV Soil Organic Carbon Inventory (WV SOC Inventory), described further in Educational Goal 1. Objectives 2 and 3: Using empirical observations collected in Objective 1 along with management history information, we will calibrate and validate the DayCent model. Once calibrated, the DayCent model will be used to run simulations to estimate the impact of the three management systems described above on expanded acreage across the valley. To ensure that the findings for the C inventory and modeling estimates are accessible to growers, we will develop a novel, semi-quantitative soil health management index (SHMI) that integrates all the soil health principles and relates those values to soil C sequestration and GHG emission reduction potentials. The decision support tool will be a free, web-based tool specific for the Willamette Valley seed producers to visualize and estimate the climate benefits of implementing a variety of conservation practices on grass seed production systems. The outreach efforts of this project will span a range of scales and use a variety of formats, including in-person workshops website context, field tours and extension publications.