Location: Northwest Sustainable Agroecosystems Research
2017 Annual Report
Objectives
The overall project goal is to enhance the resilience and sustainability of cropping systems and increase their capacity to deliver multiple agroecosystem services (e.g., healthy, bio-diverse, resilient soil). During the next five years we will focus on the following objectives.
Objective 1: Improve agricultural practices to reduce soil erosion, associated particulate emissions, and losses of soil C and essential nutrients.
• Subobjective 1A: Conduct life-cycle assessment of wind erosion and associated losses of PM10 and nutrients.
• Subobjective 1B: Determine effect of irrigated and dryland management systems on wind erosion and associated emissions of PM10 and nutrients.
Objective 2: Develop precision conservation practices to enhance soil health, reduce greenhouse gas emissions, and increase carbon sequestration and nutrient-use efficiencies.
• Subobjective 2A: Conduct long-term, site-specific assessment of agroecosystem C, N, and P cycling and flows.
• Subobjective 2B: Develop and determine precision evaluation of agroecosystem performance and associated soil health metrics.
Objective 3: Develop biological control practices for weed management and enhanced soil biological functions.
• Subobjective 3A: Isolate, select, and screen for weed-suppressive bacteria that specifically inhibit annual grass weeds, do not injure crops, native or near native rangeland plants.
• Subobjective 3B: Evaluate the survival and efficacy of annual grass weed-suppressive bacteria to reduce annual grass weeds in the field.
Approach
1.a. A life-cycle assessment of wind erosion and associated losses of PM10 and nutrients will be conducted during each phase of a winter wheat – summer fallow rotation. Standard core methods will be implemented in assessing long-term wind erosion as outlined in “Standard Methods for Wind Erosion Research and Model Development.”
1.b. Effects of conventional and conservation crop and tillage systems on wind erosion and associated emissions of PM10 and nutrients will be quantified using a portable wind tunnel under both irrigated and dryland agricultural conditions.
2.a. Landscape scale, spatiotemporal variability of agroecosystem stocks and flows of C, N, and P following conversion from conventional tillage to no-tillage will be assessed at the Long-Term Agroecosystem Research (LTAR) site at the Cook Agronomy Farm. Understanding the long-term impacts of agroecosystems on stocks and flows of major elements is lacking and key to the development of sustainable agricultural systems.
2.b. Characterize spatiotemporal agroecosystem performance (e.g. productivity, nutrient-use efficiencies) and link to soil health metrics. Linking soil health metrics to agroecosystem performance is currently lacking and if achieved will foster a broader and more complete assessment of agricultural systems as well as provide science-based aids to agricultural management decisions. The LTAR site at the Cook Agronomy Farm is the setting for the experiment.
3.a. Isolate, select, and screen for weed-suppressive bacteria that specifically inhibit annual grass weeds, do not injure crops, native or near native rangeland plants. Select soil microorganisms are expected to reduce specific weeds in the field. Studies are a combination of: isolation of soil bacteria, Agar root bioassays, and growth-chamber plant/soil bioassays.
3.b. Evaluate the survival and efficacy of weed-suppressive bacteria to reduce annual grass weeds in the field. Weed-suppressive bacteria are expected to inhibit specific weed species under variable field conditions. Field studies will determine interactive effects among bacteria, herbicides, soil, residue, weed seed bank and non-weed plants on inhibition of annual grass weeds.
Progress Report
Objective 1. Significant progress was made in identifying agricultural practices that reduce soil erosion and associated particulate emissions. No-tillage cropping systems are known to reduce soil erosion and, although not yet economically viable, are of interest in the low precipitation zone of the Inland Pacific Northwest where soil particulate emissions adversely affect air quality. Comparisons of wind erosion and particulate emissions were made among no-tillage spring wheat-spring barley, no-tillage winter wheat-chemical fallow, and conventional-tillage winter wheat-summer fallow crop rotations near Ralston, Washington using a portable wind tunnel.
Objective 2. Long-term agro-ecosystem research at the Cook Agronomy Farm Long-Term Agroecosystem Research (LTAR) site continues with field scale soil sampling completed this year to assess management impacts on soil health metrics as well as soil carbon (C), nitrogen (N) and phosphorus (P) budgets. Performance metrics to evaluate the N use efficiency of winter wheat under precision management were developed. Complementary research included establishment of Eddy co-variance flux towers for monitoring greenhouse gas flux and in-field lysimeters and flumes for assessing differences in hydrologic cycles between business-as-usual and aspirational LTAR treatments. Rates of soil acidification and base cation depletion were assessed for the LTAR. At regional scales, empirical analyses were used to assess agro-ecological classes stability under future projections of climate change. Flex cropping options are under development where process-oriented modeling of different crop options are compared to fallow, the business-as-usual scenario.
Objective 3. A patent was issued (U.S. Patent No. 9,578,884) regarding isolating and using a weed-suppressive bacteria to control the growth of invasive grass weeds. Invasive weeds, like cheatgrass, threaten the quality of rangeland ecosystems and increase the severity of wildfire in the western U.S. A bacterium was isolated from soil that inhibited root growth and vitality of cheatgrass. Toxicology studies were initiated for registration of the bacterium with the U.S. Environmental Protection Agency (EPA).
Accomplishments
1. No-tillage reduces particulate emissions in the Inland Pacific Northwest. Wind erosion from the traditional tillage-based winter wheat–summer fallow dryland cropping system adversely affects air quality in the Inland Pacific Northwest United States. No-tillage systems have the potential to reduce the risk of wind erosion. ARS scientists from Pullman, Washington, measured wind erosion from tillage-based winter wheat-summer fallow and no-tillage spring cereal cropping systems near Ralston, Washington. Although not yet economically viable, no-tillage systems reduced wind erosion and particulate emissions by as much as ninety percent in this environmentally sensitive agricultural region.
2. Isolating a soil bacterium that inhibited the growth of invasive weeds. Invasive weeds, like cheatgrass, threaten the quality of rangeland ecosystems and increase the severity of wildfire in the western United States. Although herbicides can be selected for controlling invasive weeds, they are not an economically viable strategy for rangelands and can further degrade the ecosystem. An ARS scientist in Pullman, Washington, isolated a bacterium from the soil that inhibited root growth and vitality of cheatgrass. In a number of field studies, cheatgrass populations were reduced as a result of inoculating plants with the bacterium. The advantage of using this bacterium for suppressing weed growth is that it is eco-friendly and found naturally in soils.
3. Climate change predicted to negatively influence surface soil organic matter of dryland cropping systems. Soil organic matter (SOM) is a key indicator of agricultural productivity and overall soil health. An ARS scientist at Pullman, Washington, discovered a strong relationship between the climate ratio and surface soil organic carbon and total nitrogen levels found in long-term studies across the region. Soil organic carbon and total nitrogen decreased as the ratio of mean annual temperature to mean annual precipitation, called the climate ratio, increased. Future climate projections (2030 and 2070) forecast an increase of the climate ratio, thus predicting declines in surface SOM and associated soil health across the Inland Pacific Northwest.
Review Publications
Walters, C.G., Shumway, R.C., Huggins, D.R. 2017. Impacts of terrain attributes on economics and the environment: Costs of reducing potential nitrogen pollution in wheat production. American Journal of Agricultural Economics. 48:143-152.
Sharratt, B.S., Young, F.L., Feng, G.G. 2017. Sediment and PM10 flux from no-tillage cropping systems in the Pacific Northwest. Agronomy Journal. 109:1-9.
Zhang, X., Sharratt, B.S., Chen, X., Wang, Z. 2017. Dust deposition and ambient PM10 concentration in northwest China: Spatial and temporal variability. Atmospheric Chemistry and Physics. 17:1699-1711.
Ravi, S., Sharratt, B.S., Li, J., Olshevski, S., Meng, Z., Zhang, J. 2016. Particulate matter emissions from biochar-amended soils as a potential tradeoff to the negative emission potential. Scientific Reports. 6:35984. doi:10.1038/srep35984
Zheng, Z., Feng, G.G., Sharratt, B.S., Li, X., Pi, H. 2016. Wind erosion of cropland in the northwestern Tarim Basin. Soil Science Society of America Journal. doi: 10.2136/sssaj2015.07.0259.
Morrow, J.G., Huggins, D.R., Carpenter-Boggs, L., Reganold, J.P. 2016. Evaluating measures to assess soil health in long-term agroecosystem trials. Soil Science Society of America Journal. 80:450-462.
Sharratt, B.S., Tatarko, J., Abatzoglou, J., Fox, F.A., Huggins, D.R. 2015. Implications of climate change on wind erosion of agricultural lands in the Columbia Plateau. Weather and Climate Extremes. 10:10-16.
Kennedy, A.C. 2016. Pseudomonas fluorescens strains selectively suppress annual bluegrass (Poa annua L.). Biological Control. 103:210–217.
Webb, N.P., Herrick, J.E., Van Zee, J.W., Courtright, E.M., Hugenholtz, C.H., Zobeck, T.M., Okin, G., Barchyn, T.E., Billings, B.J., Boyd, R., Clingan, S., Cooper, B., Duniway, M., Derner, J.D., Fox, F.A., Havstad, K.M., Heilman, P., Laplante, V.K., Ludwig, N., Metz, L.J., Nearing, M.A., Norfleet, M., Pierson Jr, F.B., Sanderson, M.A., Sharratt, B.S., Steiner, J.L., Tatarko, J., Tedela, N., Toledo, D.N., Unnasch, R., Van Pelt, R.S., Wagner, L.E. 2016. The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management. Aeolian Research. 22:23-36.
Karimi, T., Stockle, C.O., Higgins, S.S., Nelson, R.L., Huggins, D.R. 2017. Projected dryland cropping system shifts in the Pacific Northwest in response to climate change. Frontiers in Ecology and Evolution. 5:20. doi:10.3389/fevo.2017.00020.
Stubbs, T.L., Kennedy, A.C. 2017. Prediction of canola residue characteristics using near-infrared spectroscopy. International Journal of Agronomy. doi:10.1155/2017/4813147.
Morrow, J.G., Huggins, D.R., Reganold, J.P. 2017. Climate change predicted to negatively influence surface soil organic matter of dryland cropping systems in the Inland Pacific Northwest, USA. Frontiers in Ecology and Evolution. 5:10. doi:10.3389/fevo.2017.00010.
Robichaud, P.R., Jennewein, J., Sharratt, B.S., Lewis, S., Brown, B. 2017. Evaluating the effectiveness of agricultural mulches for reducing post-wildfire wind erosion. Aeolian Research. 27:13-21.
Pi, H., Sharratt, B.S., Feng, G.G., Lei, J. 2017. Evaluation of two empirical wind erosion models in arid and semi-arid regions of China and the USA. Environmental Modelling & Software. 91:28-46.
Sharratt, B.S., Schillinger, W. 2016. Soil characteristics and wind erosion potential of wheat-oilseed-fallow cropping systems. Soil Science Society of America Journal. doi: 10.2136/sssaj2015.12.0427.
Pi, H., Sharratt, B.S. 2017. Evaluation of the RWEQ and SWEEP in simulating soil and PM10 loss from a portable wind tunnel. Soil and Tillage Research. 170:94-103.
