1a. Objectives (from AD-416):
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-obj. 1.a. Determine the relationship between soil wetness/crusting and emission of windblown dust and PM10/PM2.5. Sub-obj. 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-obj. 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-obj. 2.a. Determine the efficacy of FAME and tracer methods in discerning soils contained in various mixtures. Sub-obj. 2.b. Determine point source soil movement and FAME efficacy using known microbial tracers. Sub-obj. 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-obj. 3.a. Determine soil C sequestration rates and CO2 flux as influenced by agroecosystem drivers (e.g. soil, topography, micro-climate, organisms, management). Sub-obj. 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-obj. 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-obj. 4.b. Develop precision N management practices that increase N use efficiency and decrease N2O emissions. Objective 5: As part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in Inland Pacific Northwest, use the R.J. Cook Agronomy Farm LTAR (CAF) to improve the observational capabilities and data accessibility of the LTAR network, to support research to sustain or enhance agricultural production and environmental quality in agroecosystems characteristic of the Inland Pacific Northwest, as per the LTAR site responsibilities and other information outlined in the 2012 USDA Long- LTAR Network Request for Information (RFI) to which the location successfully responded, and the LTAR Shared Research Strategy, a living document that serves as a roadmap for LTAR implementation. Participation in the LTAR network includes research and data management in support of the ARS GRACEnet and/or Livestock GRACEnet projects.
1b. Approach (from AD-416):
1a. Sediment and PM10/PM2.5 flux, will be evaluated as a function of soil water content/matric potential & crust type/cover/thickness for five major soil types using a portable wind tunnel. Crust type & morphology will be ascertained by microscopy & PLFA & FAME analyses. 1b. Soil aggregate properties will be assessed under a range of crop & tillage systems being examined to control wind-blown dust. Soil aggregate size classes from different crop & tillage systems will be analyzed to identify microbial community composition (PLFA & FAME analyses), active SOM, C source & crushing strength. 1c. Long-term cropping system studies at Lind, Pullman, & Ritzville will be used to assess impacts on soil quality over time including bulk density, soil pH, electrical conductivity, organic C & N, aggregate size distribution, N movement & soil microbial constituents. 2a. Ongoing research will fingerprint soils & PM10 material from across the PNW using FAME. 2b. Bacteria & 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 & 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; & (2) characterizing the mode of transport from given regions. 3a. Studies are part of GRACEnet (Greenhouse Gas Reduction through C sequestration & Carbon Enhancement Network) & REAP (Renewable Energy Assessment Project), established to assess management impacts on greenhouse gas emissions & soil C status. We will assess tillage & crop rotation affects on soil C storage across variable soil & terrain attributes of the WSU Cook Agronomy Farm (CAF). 3b. Two studies will assess management & environmental effects on soil C and N cycling & 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 & consists of five different farming systems including no-till, perennial biofuels, organic, & native perennials. These two field studies will be used to assess soil gas (CO2, N2O) flux, N mineralization-immobilization-turnover & soil C accumulation. 4a. A portable wind tunnel will be used to assess differences in windblown sediment & PM10/PM2.5 emissions among tillage & 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, & PM10 concentration profiles obtained using DustTrak aerosol samplers. 4b. Field studies at the CAF will evaluate two N management treatments for winter & spring wheat: (1) site-specific N management based on the spatial pattern of input variables; & (2) uniform N management. N use efficiency will be evaluated to monitor cropping system N use, assess N management strategies & identify key areas for improvements.
3. Progress Report:
This is the final report for this project which expired on March 5, 2015, and was replaced with bridging project 2090-11000-007-00D, "Mitigating Agricultural Sources of Particulate Mater and Greenhouse Gas Emissions in the Pacific Northwest", while the new five year research plan is written and reviewed by a peer panel under the Office of Scientific Quality Review. Please see the annual report for the bridging project for additional information. Objective 1. Soil was collected and soil quality parameters analyzed from soil and aggregates from dryland management practices. In addition, soil quality analyses of soil organic carbon, soil biology and soil quality were conducted from long-term cropping systems plots. More carbon was found in larger than smaller aggregates. Beneficial changes in soil quality occur with less tillage and moderately diverse cropping systems. Wind speed at which five major soil types in the Columbia Plateau begin to erode was measured. This wind speed, or threshold velocity, was determined inside a wind tunnel where particulate emissions from each soil was measured at progressive higher wind speeds. Threshold velocity was defined as the wind speed that first resulted in emission of particulates from the soil surface. Threshold velocity was determined under a range of water content and crust thickness for each soil type. Wind erosion and emission of fine particulates from soils managed under different tillage intensities and reduced tillage cropping systems in the Columbia Plateau was measured. A portable wind tunnel was used to measure total sediment and PM10 loss from a potato-corn rotation subject to conventional and reduced tillage, from a wheat-fallow rotation that utilized conventional or reduced tillage during summer fallow, and from a no-till spring cropping system. Objective 2. An ARS scientist characterized soil microbial communities in soil and PM10 material at locations across the western United States to understand dust emissions. The scientist also worked on improving fingerprint methodology by applying micro-organisms to soil as tracers that could provide a powerful tool for understanding dust emission source and fate. Soil containing marked strains of bacteria (tracer organisms) created a unique fingerprint that was identified and traced using microbial analyses. Microbial communities assist in identifying source of windblown dust and assessing soil quality changes with management. Objective 3. Data analysis and preliminary manuscripts were completed for field studies that assessed topography, micro-climate, crop rotation and tillage management effects on soil carbon sequestration rates and nitrogen cycling. Long-term cropping system studies were identified and monitored for carbon and nitrogen dynamics including greenhouse gas flux to understand and measure emissions of greenhouse gas from agriculture and develop improved technologies and practices to manage emissions. Soil health variables related to soil carbon and nitrogen cycling were assessed from long-term cropping system trials throughout the Northwest. Static chamber studies with automated greenhouse gas flux measurements were successfully field- deployed with different water and N treatments. These studies were linked to Eddy-Covariance field instrumentation to monitor greenhouse gases. All data were used to aid calibration and corroboration of CropSyst model. Long-Term Agroecosystem Research on the Cook Agronomy Farm was discussed with partnerships to define aspirational and business as usual scenarios to aid long-term research objective development. Objective 4. Soil quality changes with management including assessment of microbial communities are continuing to be analyzed for various dryland production scenarios. Spatial analyses of field studies at the Washington State University Wilke Farm near Davenport, Washington, the Washington State University Cook Agronomy Farm and five on-farm locations were completed or continued. In some cases these locations are under consideration for the Long-Term Agroecosystem Research effort. A new crop performance assessment based on multiple production goals was further developed and first-time evidence for “haying-off” or premature ripening was documented for winter wheat and implications for precision management evaluated.
1. Nitrogen loss by wind erosion. Wind erosion not only removes topsoil that sustains crops, but also nutrients that impact crop production and the quality of natural resources in the Pacific Northwest. Little is known, however, about the quantity of nutrients lost from soils by wind erosion in the region. In cooperation with Washington State University scientists, an ARS scientist at Pullman, Washington, found that nitrogen was lost from agricultural lands managed in summer fallow during single wind erosion events. This loss represents a significant resource to farmers and reducing wind erosion through the use of conservation tillage could curtail loss of nitrogen to the environment.
2. First bacterial bioherbicide registered by the Environmental Protoection Agency (EPA). Downy brome (cheatgrass), medusahead rye, and jointed goatgrass are invasive annual grass species that increase wildfires; reduce cereal yields; compete with native plant species; and reduce habitat for wildlife. Naturally occurring soil bacteria inhibit these annual grass weeds, but do not harm crops or natives. ARS scientists at Pullman, Washington, have isolated bacteria that reduce these three grass weeds to near zero in 5 years and reduce the weed seed bank, when used in an integrated program. The EPA registration of one bacterium and the submission of the second bacterium and its potential registration represent the first bacterial bioherbicides to be registered. They add additional tools to the grower's toolbox to fight these invasive grass weeds, while limiting the need for tillage and herbicide use for weed control.
3. Annual bluegrass bioherbicide for use in turf. Annual bluegrass and rough bluegrass are grass weeds in turf, turfgrass seed production, and golf courses. There are few tools to combat infestations of annual or rough bluegrass except to completely kill or remove the turf. ARS scientists in Pullman, Washington, filed a patent for bacterial bioherbicide strains that inhibit the growth of annual bluegrass, but do not inhibit the growth of desired grasses, such as turf, cereal crops, and native plants. The bacteria reduced these grass weeds to near zero, when desirable plants (turfgrass, natives) were present. Because of their selectivity, these bacteria can be used in management of the invasive weeds annual bluegrass or rough bluegrass in turf, sod production, and golf courses.Li, X., Feng, G.G., Sharratt, B.S., Zheng, Z., Pi, H., Gao, F. 2014. Soil wind erodibility based on dry aggregate-size distribution in the Tarim Basin. Soil Science Society of America Journal. 78:2009-2016.
Pi, H., Feng, G.G., Sharratt, B.S., Li, X., Zheng, Z. 2014. Validation of SWEEP for contrasting agricultural land use types in the Tarim Basin. Soil Science. 179:433-445.
Li, X., Feng, G.G., Sharratt, B.S., Zheng, Z. 2015. Aerodynamic properties of agricultural and natural surfaces in northwestern Tarim Basin. Agricultural and Forest Meteorology. 204:37-45. DOI: org/10.1016/j.agrformet.2015.01.005.