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Research Project: Cultural Practices and Cropping Systems for Economically Viable and Environmentally Sound Oilseed Production in Dryland of Columbia Plateau

Location: Columbia Plateau Conservation Research Center

Project Number: 2074-21610-002-000-D
Project Type: In-House Appropriated

Start Date: Oct 21, 2013
End Date: Sep 5, 2018

This project plan describes cropping systems research conducted jointly by the Soil and Water Conservation Research Unit (Pendleton, Oregon) and the Land Management and Water Conservation Research Unit (Pullman, Washington). The purpose of this project is to advance oilseed production reliably into drier areas in the Columbia Plateau of the interior Pacific Northwest (PNW). Specific objectives are listed below. Objective 1: Identify cultural practices for expanding oilseed production in the drier acreage portions of Columbia Plateau (Pullman, all of Obj 1). Sub-objective 1A: Assess the effectiveness of crop residues and the stripper header for maintaining soil moisture for tillage-based and chemical fallow systems. Sub-objective 1B: Identify best varieties and crop management practices for optimizing seed yield and quality attributes, and managing weeds in spring oilseeds. Objective 2: Identify and evaluate dryland cropping systems comprised of cereals and oilseeds that can be used to produce biofuels and derive environmental benefits (Pendleton, all of Obj 2). Sub-objective 2A: Evaluate the yield performance of cereal-based rotations that include oilseeds. Sub-objective 2B: Determine whether diversified wheat-oilseed rotations compared to WW-SF provide belowground benefits derived from changes in microbial communities. Sub-objective 2C: Measure dust and PM10 emissions from diversified crop rotations. Sub-objective 2D: Determine the effect of crop sequences on overwinter infiltration, rain capture, and soil water storage for spring crops. Sub-objective 2E: Calibrate and use SWAT to determine potential changes in crop productivity, hydrology, and sediment loads resulting from a shift from conventional to diverse cropping systems. Objective 3: Compare farm income from conventional winter wheat-summer fallow with diversified cropping systems (Pendleton and Pullman). Objective 4: Conduct life cycle assessments of different cultural practices and dryland cropping systems to evaluate resource use, energy efficiency, water consumption, greenhouse gas (GHG) emissions, and waste production (Pendleton and Pullman).

(Pendleton only) 2A. A field experiment consisting of 9 crop rotations will be undertaken to determine if increased oilseed production is met by cropping intensification, which replaces summer fallow. Annual crops include winter wheat, winter triticale, winter oilseed, spring wheat, spring triticale and spring oilseed. Using winter wheat-summer fallow as a control, various crop sequences, comprised of spring and winter-types of cereals and oilseeds, will be assessed for agro-economic performance. Crop systems will vary in intensity from 2 to 3 phases thus providing flexibility for accommodating year-to-year differences in weather. Specific experimental data will include crop quality and yield; biomass; crop yield loss due to weeds; dates of emergence, anthesis, and maturity; and water and N balance measurements. Process-oriented modeling will be used to simulate each crop system and provide insights into biophysical factors that drive crop performance. 2B. Field measurements will be obtained to ascertain if oilseeds will increase N use efficiency by reducing the microbial soil nitrification and nitrifying populations. To test this hypothesis, microbial community diversity of rhizosphere and bulk soil, plant nutrient availability, and soil physical properties will be examined to identify the etiology of observed benefits. A variety of microbial activity assays will be conducted for organic matter decomposition and nutrient cycling. 2C. The research will also test whether diverse crop systems create soil surface conditions that emit less dust than conventional systems. A portable wind tunnel will be used to measure dust emissions in all crop sequences after tillage and planting when soil is susceptible to wind erosion. 2D. A second field study will examine if rain capture, infiltration, and soil water storage will be improved by the root systems remaining from harvested oilseeds. Volumetric soil water will be calculated from gravimetric soil water and bulk density measured to a 1.2 m depth. Water balance will be calculated as pre-tillage soil water + rainfall - post-harvest soil water. Soil aggregation, a possible indicator of infiltration, will be characterized using wet sieving of whole soil collected before spring tillage. 2E. The Soil and Water Assessment Tool will be calibrated and applied using hydrologic, sediment, terrain, soil, and weather data collected on Wildhorse Creek in NE Oregon. Sensitivity of the calibrated model will be evaluated using various statistical metrics. 3. Data from 2A will be used to determine if diversified crop systems are more profitable and less risky than conventional crop systems. Production costs, net returns, and income variability of winter wheat-summer fallow vs. mixed crop systems of cereals and oilseeds will be compared using partial budget analysis. 4. Life cycle assessment will be used to test the hypothesis that mixed cereal-oilseed systems under reduced tillage will conserve more nonrenewable energy and reduce gaseous emissions than conventional wheat-based systems under intensive tillage.