1a. Objectives (from AD-416)
Past and current farming practices in the dryland region of the Pacific Northwest (PNW, northern Idaho, north central Oregon and eastern Washington) have resulted in excessive soil erosion by wind and water, declining soil organic matter levels, poor N use efficiency and losses of biological diversity. These adverse processes are linked to regional degradation of air, water and soil resources and contribute to GHG emissions that drive climate change. This project addresses knowledge gaps associated with the capacity to understand, predict and mitigate PM10/PM2.5 and GHG emissions from dryland agricultural lands. Objective 1. Characterize key environmental and management drivers of agricultural wind-blown dust and PM10/PM2.5 emissions that will improve process-oriented models and decision aids. Sub-objective 1.a. Determine the relationship between soil wetness/crusting and emission of windblown dust and PM10/PM2.5. Sub-objective 1.b. Determine the biotic factors driving aggregate formation and stability in dryland soils and their influence on windblown dust and PM10/PM2.5 emissions. Sub-objective 1.c. Determine the effect of wind erosion and management practices on soil organic matter (SOM), soil biological communities and other soil characteristics. Objective 2. Develop techniques for identifying sources of PM10/PM2.5 to better associate management practices with PM10/PM2.5 emissions and to corroborate models. Sub-objective 2.a. Determine the efficacy of FAME and tracer methods in discerning soils contained in various mixtures. Sub-objective 2.b. Determine point source soil movement and FAME efficacy using known microbial tracers. Sub-objective 2.c. Determine the effectiveness of using FAME fingerprinting to corroborate the Columbia Plateau regional dust transport model. Objective 3. Characterize roles of environmental and management drivers on soil C and N cycling as factors regulating GHG (N2O, CO2) emissions from agricultural soils. Sub-objective 3.a. Determine soil C sequestration rates and CO2 flux as influenced by agroecosystem drivers (e.g. soil, topography, micro-climate, organisms, management). Sub-objective 3.b. Determine biogeochemical dynamics of soil C and N including N2O flux as influenced by agroecosystem drivers (e.g. soil, topography, micro-climate, organisms, management). Objective 4. Develop agricultural PM10/PM2.5 and GHG mitigation strategies and management decision aids for Pacific Northwest cropping systems. Sub-objective 4.a. Determine the effectiveness of alternative tillage and cropping practices in reducing the emission of windblown dust and PM10/PM2.5 from agricultural soils. Sub-objective 4.b. Develop precision N management practices that increase N use efficiency and decrease N2O emissions.
1b. Approach (from AD-416)
1a. Sediment and PM10/PM2.5 flux, will be evaluated as a function of soil water content/matric potential and crust type/cover/thickness for five major soil types using a portable wind tunnel. Crust type and morphology will be ascertained by microscopy and PLFA and FAME analyses 1b. Soil aggregate properties will be assessed under a range of crop and tillage systems being examined to control wind-blown dust. Soil aggregate size classes from different crop and tillage systems will be analyzed to identify microbial community composition (PLFA and FAME analyses), active SOM, C source and crushing strength 1c. Long-term cropping system studies at Lind, Pullman, and Ritzville will be used to assess impacts on soil quality over time including bulk density, soil pH, electrical conductivity, organic C and N, aggregate size distribution, N movement and soil microbial constituents 2a. Ongoing research will fingerprint soils and PM10 material from across the PNW using FAME 2b. Bacteria and fungi containing natural markers will also be evaluated as tracers that can be retrieved from soils due to their unique traits of antibiotic resistance or strain-specific molecular markers to determine point source soil movement 2c. The FAME and bacterial tracer studies will be used to aid corroboration of the Columbia Plateau regional dust transport model by: (1) determining if modeled emissions are from given fields or grid areas; and (2) characterizing the mode of transport from given regions 3a. Studies are part of GRACEnet (Greenhouse Gas Reduction through C sequestration and Carbon Enhancement Network) and REAP (Renewable Energy Assessment Project), established to assess management impacts on greenhouse gas emissions and soil C status. We will assess tillage and crop rotation affects on soil C storage across variable soil and terrain attributes of the WSU Cook Agronomy Farm (CAF) 3b. Two studies will assess management and environmental effects on soil C and N cycling and GHG emissions. The first study (CAF) was previously described in sub-objective 3a. The second study was established in 2001 at the USDA Palouse Conservation Field Station and consists of five different farming systems including no-till, perennial biofuels, organic, and native perennials. These two field studies will be used to assess soil gas (CO2, N2O) flux, N mineralization-immobilization-turnover and soil C accumulation 4a. A portable wind tunnel will be used to assess differences in windblown sediment and PM10/PM2.5 emissions among tillage and cropping systems established at various locations across the Columbia Plateau. Wind speed profiles will be measured using pitot tubes, sediment catch obtained using an isokinetic vertical slot sampler, and PM10 concentration profiles obtained using DustTrak aerosol samplers 4b. Field studies at the CAF will evaluate two N management treatments for winter and spring wheat: (1) site-specific N management based on the spatial pattern of input variables; and (2) uniform N management. N use efficiency will be evaluated to monitor cropping system N use, assess N management strategies and identify key areas for improvements. Replacing 5348-11000-005-00D(2/10)
3. Progress Report
This report documents progress for Project 5348-11000-006-00D Mitigating Agricultural Sources of Particulate Matter and Greenhouse Gas Emissions in the Pacific Northwest which started March 26, 2010 and continues research from Project 5348-11000-005-00D Quantifying and Predicting Emission of PM10 and Greenhouse Gases from Agricultural Soils. To aid in understanding processes that govern dust emissions as well as developing management strategies to control dust emissions that affect air quality, ARS scientists measured the threshold velocity of five major soil types found across the Columbia Plateau. Soil samples from the WSU Cook Agronomy Farm were analyzed for total C and N. Preliminary spatial analyses including relationships to terrain and soil variables has been completed. Preliminary results were reported in Proceedings of the 10th International Conference on Precision Agriculture, Denver, CO. Variable N rate and wheat population studies were initiated in winter wheat at the WSU Cook Agronomy Farm. Harvest of the first winter wheat crop will be in August, 2010. Data from previous studies on variable rate N applications in spring and winter wheat have been organized into a relational database and laboratory analyses are nearing completion.
5. Significant Activities that Support Special Target Populations
Mentored one high school student, identified through a limited resource program, on laboratory techniques that are used to isolate various microbial communities in soils.