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). 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 weedsuppressive 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.
This is the final report for project 2090-11000-009-000-D, “Improving Air Quality, Soil Health and Nutrient Use Efficiency to Increase Northwest Agroecosystem Performance”, which is being replaced by “Advancing Soil Health and Agricultural Performance to Promote Sustainable Intensification and Resilience of Northwest Dryland Cropping Systems”, which was certified on August 18, 2022. Warmer and drier climates forecast for the coming decades could impact agriculture and wind erosion in the Pacific Northwest. Escalation of wind erosion due to climate change could further threaten air quality in the region. In support of Objective 1, ARS scientists at Pullman, Washington, in collaboration with scientists at University of Idaho, simulated the impact of climate change on wind erosion using state-of-art climate forecasts and wind erosion technologies. While a warmer climate is projected, wind erosion and PM10 emissions are predicted to decrease by 2050 in the Pacific Northwest. The projected decrease in erosion is due to higher biomass production resulting from carbon dioxide (CO2) fertilization. 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. Agricultural Research Service (ARS) scientists 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 in this environmentally sensitive agricultural region. Carbon is influential in the formation of aggregates and sustaining biological activity in soils and therefore is the foundation for healthy soils. Substantial loss of carbon, however, can result in soil degradation and negatively impact agricultural production. ARS scientists, in cooperation with Washington State University, measured the loss of carbon from dryland agricultural soils during severe windstorms in the Inland Pacific Northwest. Loss of carbon exceeded 15 lbs/ac, or about 2% of carbon contained in the topsoil, during singular windstorms. Based upon historic accounts of wind erosion in the region, carbon loss could approach 1500 pounds (lbs)/acre (ac) during single windstorms. To protect the soil and associated carbon resource, farmers in the region must utilize conservation tillage practices to reduce wind erosion. For Objective 2, invasive weeds, like cheatgrass, threaten the quality of rangeland ecosystems and increase the severity of wildfire in the western United States. 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. In support of Objective 3, climate change can impact major soil properties such as organic matter, a key indicator of soil health and productivity. An ARS researcher in Pullman, Washington, in collaboration with university scientists, discovered that projected climatic shifts in mean annual temperature and precipitation would result in significant declines in soil organic matter for the dryland cropping systems of the inland Pacific Northwest. Furthermore, climatic drivers were more influential than either tillage regime or cropping system intensity for determining soil organic matter levels. This research amplifies the need to further explore mitigation and adaptation strategies to address climate variability and ensure food security. Climate change will impact bio-climatic drivers that control the regional location and distribution of major cropping systems in the inland Pacific Northwest. An ARS researcher in Pullman, Washington, in collaboration with university scientists discovered that super-imposing projected climatic shifts onto current cropping systems resulted in major impacts on agro-ecological classes. In the inland U.S. Pacific Northwest, the amount of annual fallow significantly increased as cropping systems became less stable, which increased the overall uncertainty of what crops, if any, would be grown. This research was the justification for a competitively funded research grant and amplifies the need to further explore mitigation and adaptation strategies to address climate variability and ensure food security. Nitrous oxide is a major greenhouse gas emitted by agricultural soils in amounts greater than natural systems due to the addition of nitrogen fertilizers. These greenhouse gas emissions are not well understood for individual farms, as emissions are difficult to measure and irregular over farm fields throughout the year. Using two different field methods, an ARS researcher in Pullman, Washington, in collaboration with university scientists found that annual nitrous oxide emissions were slightly greater than previously thought, occurred primarily during long pulses in the spring, but were highly variable. Furthermore, it was discovered that nitrous oxide emissions were significant from climate change and farmer perspectives. Farmers that increase nitrogen use efficiency will save fertilizer input costs and reduce emissions of nitrous oxide, a major greenhouse gas. 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 in Pullman, Washington, 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. Soil acidification that negatively impacts crop performance is occurring in many agricultural regions of Western states. Primarily driven by applied nitrogen fertilizers, soil acidification was thought to only occur in surface soils. An ARS researcher in Pullman, Washington, however, discovered that soil acidification is occurring at depths of at least 1.5 meters in some field locations of the Cook Agronomy Farm Long-Term Agroecosystem Research site. Long-term no-tillage was discovered to ameliorate deep soil acidification while surface soil acidification continued. This research amplifies the need to further explore factors that drive soil acidification at field scales relevant to farmers. Dangers of continued soil acidification are many including increased aluminum toxicity to most crops currently grown.
1. Long-term soil carbon sequestration under no-tillage is dependent on type of seed drill used. No-tillage is a primary method used to increase soil organic carbon (C) in many agricultural systems. Different no-till drills, however, disturb the soil to varying extents. An ARS researcher in Pullman, Washington, 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.
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