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ARS Home » Pacific West Area » Pullman, Washington » Northwest Sustainable Agroecosystems Research » Research » Research Project #430915

Research Project: Improving Air Quality, Soil Health and Nutrient Use Efficiency to Increase Northwest Agroecosystem Performance

Location: Northwest Sustainable Agroecosystems Research

2020 Annual Report

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. Objective 4: Develop integrated and economically viable cropping systems that are designed to: adapt to and mitigate climate change, reduce pest infestations, improve soil health, and provide environmental services.

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
For Objective 1, significant progress was made in manuscript preparation and publishing on crop rotation, soil amendment and tillage effects on soil aggregate stability of dryland cropping systems in the inland Pacific Northwest. Here, greater stability of soil aggregates under no-tillage decreases susceptibility to wind erosion; whereas, crop rotation and bio-solid application had relatively minor impacts. Model simulations indicated annual losses of soil and PM10 have decreased 1.18 kg m-2 and 0.05 kg m-2, respectively across the region. Developing cropping systems that maintain annual cover and increase aggregate stability are required to reduce the hazard of wind erosion. In support of Objective 2, research at the Cook Agronomy Farm Long-Term Agroecosystem Research (LTAR) site completed data analyses to assess management impacts on soil health metrics as well as soil C, N and P budgets. Long-term incubations to quantify labile soil C pools found significant stocks of labile soil organic C in the subsoil that was sensitive to soil management. Complementary research included monitoring greenhouse gas flux with Eddy co-variance flux towers and in-field lysimeters and flumes for assessing differences in hydrologic cycles between business-as-usual and aspirational LTAR treatments. Soil tests to determine lime requirements for addressing soil acidification in dryland cropping systems of the inland Pacific Northwest were evaluated and manuscript submitted for publication.

1. Long-term soil carbon sequestration under no-tillage dependent on type of seed drill used. No-tillage is a primary method used to increase soil organic carbon in many agricultural systems. Different no-till drills, however, disturb the soil to varying extents. An ARS researcher discovered that soil carbon storage can significantly decrease under no-tillage when switching from a low (double-disk) to high (hoe-type) disturbance no-till drill in dryland cropping systems of the inland Pacific Northwest. This research amplifies the need to further explore disturbance effects on soil organic matter and impacts on soil carbon sequestration. Farmers that use high soil disturbance no-till drills may not sequester soil C as typically expected, although the decrease in soil erosion is still impactful.

Review Publications
Wachter, J., Painter, K., Carpenter-Boggs, L., Huggins, D.R., Reganold, J. 2019. Productivity, economic performance, and soil quality of conventional, mixed, and organic dryland farming systems in eastern Washington State. Agriculture, Ecosystems and Environment. 286:106665.
Ortega-Pieck, A., Norby, J., Brooks, E., Strawn, D., Crump, A., Huggins, D.R. 2020. Source and subsurface transport of dissolved reactive phosphorus in a semiarid, no-till catchment with complex topography. Journal of Environmental Quality.
Pi, H., Huggins, D.R., Abatzoglou, J., Sharratt, B.S. 2019. Modeling soil wind erosion from agro-ecological classes of the Pacific Northwest in response to current climate. Journal of Geophysical Research. 125(2): e2019JD031104.
McFarland, C., Santosh, S., Carpenter-Boggs, L., Schroeder, K., Brown, T., Huggins, D.R. 2020. Evaluating buffer methods for determining lime requirement on acidified agricultural soils of the Palouse. Soil Science Society of America Journal.