Current Research Projects
Here is a list of current research projects that are funded by WOCS.
Soil Acidity and Base Saturation Thresholds for Canola Yield in Dryland Pacific Northwest Systems
Co-PI: Rachel Wieme, Cooperator: Rich Koenig
Soil acidification and aluminum (Al) toxicity are increasingly constraining canola production in the dryland inland Pacific Northwest (iPNW). Current recommendations rely mainly on soil pH, yet recent work shows that canola yield may respond more strongly to base saturation (BS%) and exchangeable Al, and that optimum BS% can occur at pH values lower than those considered ideal for other crops. Our hypothesis is that BS%, exchangeable Al, and sampling depth (0–6″ vs. 0–12″) provide more accurate and actionable indicators of acidity stress and canola yield response than pH alone, and that BS% calculated using reserve acidity from the Modified Mehlich buffer will outperform BS% based on direct CEC.
This project directly addresses WOCS research priorities in Nutrient Management, Crop Management & Agronomics, and Site-Specific Management. By developing calibrated acidity thresholds and sampling recommendations specific to canola, the project improves soil testing interpretation, supports decisions on lime and fertilizer inputs, and enhances yield stability in acidifying landscapes. By integrating geo-referenced soil measurements with yield-monitor data, the project advances precision management strategies that reduce input costs and improve profitability across diverse dryland systems.
Work will include a two-year, on-farm survey across winter and spring canola fields in the Palouse and surrounding dryland regions. We will measure soil pH, exchangeable cations, exchangeable Al, direct CEC, and reserve acidity using the Modified Mehlich buffer, the calibrated method for Palouse soils. BS% will be calculated using both direct and indirect CEC and compared to yield patterns derived from cleaned combine data. Outcomes will include acidity thresholds, BS% recommendations, depth-specific sampling guidance, and spatial maps to guide economical, site-specific lime management for canola growers.
Predicting Cabbage Seedpod Activity from Site-Specific Weather Data
Co-PI: Diego Rincon
The cabbage seedpod weevil is a damaging canola pest in North America, and populations are growing in Washington fields as acreage expands. Damage is mainly caused by larvae, which hatch in canola pods and are protected from insecticides as they feed on seeds. Adults, which are a target for management, invade canola crops in the spring by flying in from outside crops as temperatures increase. Adult migration is timed with flowering and podding of most canola crops, because the cabbage seedpod weevil has one generation per year and can only complete its development on a handful of annual canola-like plants.
Most growers apply control tactics to kill seedpod weevil adults before they lay eggs into growing canola pods, as the larvae are hard to target. However, insecticide applications are often timed with crop flowering but not based on cabbage seedpod weevil temperature-dependent migration and peak activity patterns. This is a problem because adult activity may not align with canola phenology, depending on site-specific seeding dates and temperature, leading to sometimes unnecessary or ineffective insecticide sprays.
Most insects and plants have metabolic rates dependent on temperature, and their development can be measured in terms of heat unit accumulation. Heat unit accumulation is calculated daily in degree days from temperature records from weather stations using development thresholds. For many insect pests, the degree days required to complete phenology events relevant for management (adult emergence, egg hatch) can be quantified and used to predict phenology from weather data. Plant degree days can similarly be calculated based on planting date and temperature thresholds. Such models allow crop producers to effectively time insecticide applications.
We hypothesize that heat accumulation is a driving factor of cabbage seedpod weevil adult activity. This project aims to determine the parameters required to calculate degree days for the cabbage seedpod weevil and build a predictive model for adult activity in canola crops. This aligns with WOCS priorities by developing new strategies to improve effectiveness of control inputs for a major canola pest.
Incorporating Oilseeds in Intermediate Rainfed Crop Rotations
Growers throughout the intermediate cropping zone (13 to 18″ of annual precipitation) have been experimenting with oilseeds in their crop rotations for 25 plus years with mixed success. During this time numerous studies have been carried out looking at multiple aspects of production individually with these crops in research plot settings. Starting in 2012, spring oilseed crops have been incorporated into the crop rotation at the WSU Wilke Research and Extension Farm near Davenport, WA. The justification is it to “put its money where its mouth is at”and use the research data collected to demonstrate the value of these crops in rotation with cereal grains and summer fallow to show farmers and their business partners (landlords, bankers, etc) how and where these crops fit into a profitable crop rotation over a duration of time. This serves as a very good platform to provide Extension outreach through field day presentations, oral presentations at grower meeting and published technical bulletins.
Updating Nitrogen and Sulfur Fertilization Requirements for Dryland Spring and Winter Canola in Eastern Washington
Co-PI: Shikha Singh
Canola (Brassica napus L.) acreage in Washington has expanded from 10,500 acres in 2011 to 145,000 acres in 2025, stabilizing at 130,000–165,000 acres since 2021 (USDA NASS, 2025). Over a 5-year period from 2020-2024, fertilizer costs for Washington farmers rose 54% compared to 2015–2019 averages (USDA ERS, 2025), contributing to total Washington farm losses of $295 million in 2025 which ranked last among U.S. states (Weaver, 2025). Because fertilizer is a major proportion of total crop production cost, rising fertilizer prices put pressure on farmers to maximize their fertilizer investments. Canola is increasingly integrated into dryland cereal rotations for agronomic and economic benefits, yet nitrogen (N) and sulfur (S) fertilization guidelines remain outdated or extrapolated from other regions. We hypothesize that region-specific N and S recommendations will improve yield, oil quality, and profitability while reducing soil health risks such as soil acidification and salt buildup related to over-fertilization. This project aligns with WOCS priorities by advancing nutrient management for canola in the Pacific Northwest (PNW). Over two years, multi-site trials will evaluate N and S fertilization rates for spring and winter canola. Data collected will include yield, oil and protein content, N use efficiency, and soil/tissue diagnostics. Outcomes will refine unit N requirement (UNR), establish localized S fertility guidelines, and develop decision tools for growers. Delivering science-based, region-specific recommendations will enhance profitability, sustainability, and resilience of dryland cropping systems in eastern Washington.
Winter and Spring Canola Variety Testing
The primary objective of the Winter and Spring Canola Variety Testing proposal is to provide growers and the agribusiness industry with information on the adaptation and performance of winter and spring canola varieties across the different climatic regions of eastern Washington. An additional objective is to deliver an Extension education program to communicate production techniques and benefits of canola to growers and the agribusiness industry. One of the key elements to continued increases in production and profitability is identifying appropriate varieties, and then extending that information rapidly to growers and agribusiness personnel. The project is envisioned as an integral part of the Washington Oilseed Cropping Systems research and extension program at Washington State University, and each variety trial will likely be the subject of an extension field day.
Synthetic Nodules for Sustainable Oilseed Production
Co-PI: Vincent James, graduate student
Crop productivity depends heavily on nitrogen (N), a vital plant nutrient. N gas makes up 78% of the atmosphere, but plants cannot use this form. The industrial Haber-Bosch process is used to make synthetic N fertilizer, accounting for 3% of global carbon emissions. Drawbacks to the use of this N source include price volatility due to fossil fuel reliance, soil acidification that limits yields, and runoff of unabsorbed N causing waterway pollution. Biological N fixation is carried out by specialized N-fixing bacteria that convert atmospheric N into plant-useable forms. Legumes house specialized N-fixing bacteria in nodules, where they are fed carbon compounds in exchange for fixed N. Most plants cannot form these structures, relying instead on free-living nitrogen fixers (FLNF) who colonize their rhizosphere where they experience intense competition and adverse oxygen conditions. There has been interest in the production of commercial biofertilizers consisting of bacteria that can fix N. Success has been variable as plant inoculation is inconsistent and native strains may outcompete them. There is also concern about microbial invasions by foreign or lab-altered strains.
To address these challenges, we will develop a synthetic nodule system, consisting of biodegradable materials to house local nitrogen-fixing bacteria. We hypothesize that the nitrogen fixed by these bacteria will create a nutrient hotspot that will attract root growth and that roots will grow into and feed the bacteria housed in the structure. Synthetic nodules will be tested with canola. This project will lay the foundation for a possible commercial product that could have great benefit towards enhancing agricultural sustainability within the state of Washington. WOCS prioritizes the identification of optimum fertilizer management practices with respect to yield and return on investment. As only ~50% of applied N fertilizer is taken up by plants, the development of a sustained community of N fixers in synthetic nodules can improve the efficiency of fertilization.
Optimizing Winter Canola Seeding Rates and Plant Stands for Winter Survival, Yield, and Quality Across
Precipitation Zones
Stand establishment remains a major challenge to winter canola production in the low-precipitation regions of eastern Washington. One option is for growers to increase seeding rates to compensate for poor emergence; however, seed costs are significant and yield responses to higher seeding rates are often inconsistent. Although winter canola exhibits substantial plasticity, its ability to compensate for low plant populations declines as water availability decreases. Precipitation-specific guidance for seeding rates and plant populations is lacking for Washington’s dryland systems. This 2-year project will address a high research priority for the 2026–2027 biennium by identifying precipitation-specific relationships among seeding rate, plant population, winter survival, yield, and seed quality in winter canola. Objectives in this study will use on-farm trials along the Highway 2 precipitation gradient under realistic management conditions. Our first objective will assess how soil properties and management practices, including seeding rate, interact to impact plant stands across at least 50 fields. Our second objective will assess how decreasing plant populations impact winter survival, yield, yield components, and quality. Precipitation will be analyzed as a continuous variable for precipitation-specific recommendations of seeding rates and to identify thresholds at which plant populations become a significant driver of yield and quality. Long-term expected outcomes include improved understanding of management effects on crop establishment and guidance to reduce risk and improve profitability of winter canola across eastern Washington state.
Advancement of Oilseed Seed Quality Evaluation via Acquisition of NIRS Analyzer
Co-PI: Wilson Craine
Near infrared spectroscopy (NIRS) provides rapid, nondestructive measurement of key oilseed traits, including oil and protein contents, fatty acid (FA) profile, and amino acid (AA) composition. Modern instruments such as the Perten DA 7250 offer the high throughput analytical capacity required to evaluate these quality traits that determine the value of canola, camelina, and other oilseeds. This capability is increasingly important as demand grows for renewable fuels, plant-based proteins, and healthier edible oils.
End-use value in oilseeds is not only driven by oil and protein contents, but also FA profile, and AA composition. High oleic canola earns premiums in food and renewable fuel markets, while low erucic camelina is required for access to edible oil markets. AA composition further defines the nutritional and economic value of oilseed meals. Yet analytical capacity at WSU is currently limited to oil and protein measurement, with no high throughput, cost effective method to evaluate FA or AA composition. High throughput compositional analysis is essential for interpreting existing WOCS research datasets and
for understanding how genotype, environment, and management influence oil, protein, FA profile, and AA composition. The DA 7250 provides the analytical capacity needed to unlock the full value of seed samples already collected, support ongoing breeding and agronomy efforts, and strengthen the foundation for future research and competitive external funding.
Acquiring this NIRS instrument will fill a critical analytical gap, enabling comprehensive evaluation of FA and AA profiles alongside oil and protein. This expanded capacity will accelerate breeding progress, enhance agronomic research, expand end use market opportunities, and improve the profitability and sustainability of oilseed production in WA.
Peaola in Rotation: System-Level Impacts of Pea-Canola Intercropping on Weeds, Soil Moisture, Rotational Crop Performance, and Soil Health
Co-PI: Aaron Esser and Rui Liu
Canola–pea intercropping (“peaola”) offers multiple agronomic and ecological benefits related to weed suppression, reduced N inputs, and resource use efficiency. Although peaola systems have been extensively researched outside the USA and shown to be highly profitable for growers, there is limited information on how this affects the weed seed banks, weed counts, and yields and grain quality of next wheat crop, especially for intermediate precipitation zone of PNW. Additionally, during various grower-interactions, raised common questions focusing on “how peaola performs within wheat-based rotations?”. Therefore, primarily study will quantify how different peaola seeding ratios and N rates affect in-season weed suppression, weed seedbank dynamics, and yield performance of next wheat crop. Additionally, this study will study peaola productivity, biological N-fixation, soil water use, and soil health. This proposal directly addresses multiple Washington Oilseed Cropping Systems (WOCS) priorities, including identification of practices for producing stable yield, and quantification of system intensification effects. In addition to the ongoing peaola trial, a new set of field trial will be established at the Wilke Research Farm, Davenport, WA, where multiple peaola seeding ratios will be tested across a gradient of nitrogen application rates followed by planting wheat and assessing teffects of different seeding ratios and N rates on weeds and next wheat crop yields and quality. We want to continue this project for another cycle of the rotation (two more year in addition to these two years). The project will support the training of a graduate student, with data generated forming the core of the student’s thesis research. Findings from this study will provide the foundation for securing additional funding to investigate long-term impacts of peaola intercropping and to conduct on-farm validation trials, particularly focusing on weed seedbank dynamics and productivity of subsequent crops in dryland rotations.
Long-Term Influences of Canola Integration into Wheat-Fallow Systems in Dryland Region
Co-PI: Tim Paulitz, Jeremy Hansen, and Daniel Schlatter
This proposal requests funding to continue and build upon two ongoing cropping systems trials with canola in the rotation near Ritzville, WA. These two trials have been the part of multi-components research activities while providing continued research-based information to regional growers since 1997. In these trials, canola is grown as part of 3-yr (winter canola – spring wheat – no till fallow) and 4-yr (winter canola – no till fallow – winter wheat – no till fallow) rotations to study the agronomic, economic, soils, and microbial components under canola integration in the cropping system. Research conducted in these studies align very well with multiple WOCS research priorities including but not limited to crop establishment, management, agronomics, economics, microbiome, and overall soil health. In this proposal, we will continue to collect detailed data from these field trials regarding complete crop and fallow soil water dynamics, microbial community, foliar and root diseases, weed ecology, and grain yields. Soil microbial activity has been, and will continue to be, assessed in rotations using both DNA sequencing and PLFA methods on bulk and rhizosphere soil. We will continue to quantify arbuscular mycorrhizal fungi (AMF). Maintaining and continuing these trials will be crucial in order to collect such data that can only be obtained through long-term cropping systems experiments. Previously, several publications and presentations have been completed and we will continue to fully explore canola integration in wheat-based cropping systems of dryland region.
Schlatter, D.C., C. Yin, J.C. Hansen, W.F. Schillinger, and T.C. Paulitz. 2026. Canola Alters Rhizosphere and Root Microbiomes of Following Wheat Crops. Applied Soil Ecology 218 (2026) 106694.