Project : USDA ARS

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Research Project: Improving Plant, Soil, and Cropping Systems Health and Productivity through Advanced Integration of Comprehensive Management Practices

Location: Forage Seed and Cereal Research Unit

2022 Annual Report

Objectives
The long-term aim of this project is to address strategic, high priority needs of grass seed growers in the Pacific Northwest (PNW) by assessing and developing management practices that simultaneously improve crop productivity and advance soil health. This aim will be met by interrogating research questions that fall into two broad objectives. The first objective is primarily focused on improving crop production by lessening the overall impact of pests, weeds, and pathogens, improving the arability of marginal lands with novel soil amendments, and assessing the impacts of management practices on soil health and fertility. Objective 2 also aims to improve crop productivity by identifying key interactions between genetics, environment, and management (G x E x M). Within this objective, tradeoffs between intensifying production and advancing ecosystem services are quantified and better understood to help farms reach and sustain their potential, including the impact of crop rotation and other management practices on increasing populations of beneficial microbes and improving soil health. Collectively, Objectives 1 and 2 advance our understanding of how G x E x M interactions impact agroecosystem productivity and resilience. For Objective 3, these data will be synthesized and developed into decision-support tools and models to provide growers with concrete strategies for improved land management and cultivation of grass seed cropping systems. Objective 1: Identify and evaluate management practices that improve crop productivity and crop health or that enhance environmental quality. - Sub-objective 1A: Identify technologies to reduce priority pests, diseases, and weeds that limit the profitability and sustainability of the cropping system. - Sub-objective 1B: Assess the environmental and production outcomes from the application of biochar on marginal soils. - Sub-objective 1C: Determine the effectiveness of crop rotation in reducing populations of weeds, diseases, and invertebrate pests. Objective 2: Identify and assess key interactions between cropping system, environmental conditions and management practices that influence cropping outcomes and agroecosystem productivity. - Sub-objective 2A: Evaluate the impact of management practices, including crop rotation, on soil health parameters. - Sub-objective 2B: Assess the impact of cruciferous crop rotations on plant growth and microbiomes. Objective 3: Develop knowledge and decision support tools that enable growers to optimize production. - Sub-objective 3A: Develop and expand decision support tools that provide information about biochar to growers. - Sub-objective 3B: Develop models and decision aids that improve soil health and improve system productivity by decreasing the yield gap. - Sub-objective 3C: Develop strategies to reduce priority pests, diseases, and weeds and improve soil health.

Approach
The overall hypothesis of the project is that improved cropping practices in grass seed cropping systems provides simultaneous benefits to soil health and crop productivity. This hypothesis is tested within three objectives and their related subobjectives. In Objective One, we explore methods to reduce the populations of weeds and pests that limit productivity. This research is conducted in laboratory, greenhouse, and field experiments that determine if practices that promote soil health and lessen environmental impacts (application of soil amendments, selective herbicide application, and precision weed management) are detrimental or beneficial to crop yield. In Objective Two, the research aims to determine if conservation practices (cover cropping and reduced tillage) improve soil health, and if soil health can be attributed to improvements in crop yield. These objectives are met with laboratory, greenhouse, and field experiments that assess soil health and identify allelopathic responses mitigated by cover crops. The aim of Objective Three is to synthesize the information gathered in Objectives One and Two, and to create decision support tools that enable growers to optimize production. These tools will be provided to growers as web-based tool kits, models, or agronomic measures used to control pests, pathogens, and weeds, and to apply soil amendments. In general, these approaches aim to identify key interactions between genetics, environment, and management that simultaneously reduce farm inputs and improve ecosystem services by identifying and quantifying tradeoffs.

Progress Report
Seedborne diseases pose a challenge to Oregon’s grass seed growers. These pathogens reduce overall seed yield and can lead to costly export rejections. Two pathogen groups are associated with recent export rejections of Oregon’s grass seed and cereal crops: Anguina seed gall nematodes and Pseudomonas syringae bacteria. In support of Sub-objectives 1A and 3C, a regional survey was initiated to optimize best practices for detection of seed gall nematodes and to identify population distribution. Early detection of these pests provides a better assessment of export rejection risk and allows growers to deploy management strategies. Understanding nematode distribution and how the population is related to detection in seed lots allows ARS researchers in Corvallis, Oregon, to optimize and improve the methods currently used by USDA Animal and Plant Health Inspection Service and export partners to ensure clean seed and keep foreign markets open to Oregon grass seed producers. P. syringae seed blight bacteria have similarly led to export rejection of oat seed. Oat seed is a critical rotation for grass seed growers, and loss of access to major markets reduces profitability. In support of Sub-objectives 1A and 3C, a seed lot evaluation and greenhouse-based treatment assessment were initiated, providing a greater understanding of infections occurring in seed lots, as well as potential pre-planting or post-harvest seed treatment options. Continued validation of these management strategies is underway. Aphid-transmitted viruses are widespread in Oregon’s grass seed production systems and have been associated with reduced yield. In support of Sub-objectives 1A and 3C, regional and statewide monitoring efforts have continued investigating the composition and distribution of the aphid and barley/cereal yellow dwarf virus (B/CYDV) complex to inform predictive modeling. In addition, a field trial evaluating three management factors (insecticide timing, nitrogen rate, and genetic background) has begun. Aphid populations, B/CYDV incidence, and yield will be compared for the different treatment groups to identify best integrated pest management (IPM) practices. Biochar-based soil amendments can improve soil structure, increase yield, and sequester Carbon (C). These impacts are especially evident on marginal and degraded soils. Progress under Sub-objective 1B indicates that biochar aids in the phytostabilization of mine lands. To test this, plots at the Formosa Mine in southern Oregon were amended with various mixtures of lime and biosolids with or without the addition of fertilizer, biochar, or locally sourced microbial inoculum (LSM). In collaboration with the U.S. Environmental Protection Agency, field plots continued to be monitored, maintained, and sampled to quantify changes in plant growth, soil function, and microbial communities. Preliminary data suggest that biochar blends increase plant survival, and LSM additions increase root weight but decrease microbial diversity. In support of Sub-objective 1A2, ARS researchers evaluated the efficacy of pyroligneous acid (PA) to control phytopathogenic microbes. PA is a byproduct of biochar production that has the potential to control soil-borne phytopathogenic fungi. Efforts to quantify the ability of PA to suppress Verticillium Wilt in mint were not successful, but efforts to overcome experimental challenges are ongoing. During these experiments, we noted that PA acted as a growth stimulant and doubled the growth of mint. Control pots with acetic acid applications did not elicit similar responses, indicating that increased growth was not attributable to changes in pH. Investigations are underway to determine if PA stimulates growth in other crops and if this response persists over time. In support of Sub-objective 2A, ARS researchers and industry collaborators established a field study to determine the effect of cover crop termination method and timing of FIXatioN balansa clover on nitrogen (N) mineralization rates and greenhouse gas (GHG) fluxes. This research will provide guidance for N fertilizer reduction potential and timing when using balansa clover under various management conditions. Additionally, we will provide a GHG accounting for growth and termination conditions. In support of Sub-objective 3C, information from this project will help predict the efficacy of weed control using balansa clover cover crops. In support of Sub-objective 2A, ARS researchers analyzed the results of greenhouse studies to understand the effects of conservation practices (CP) on soil health (SH) indicators and to understand if improvements in SH affect yield. We hypothesized that plant yield and microbial community composition are positively correlated with SH indicators. We found that the effect of CP varied according to soil texture. In silty clay loams, CP increased yield, but these increases were not associated with increases in SH metrics. In silt loams, the opposite was true; CP increased SH, but these improvements were not associated with increases in yield. In response to emerging C markets, there is a need to quantify C stocks in crop production systems. Perennial grass seed crops have potential to accumulate C due to lack of repeated tillage; however, an accounting of C stocks in these systems is lacking. Progress under Sub-objective 2A to quantify the C storage potential of grass seed crops grown in the Willamette Valley (WV). We hypothesized that CPs (no-till and full straw return) would increase C sequestration. To investigate this, researchers in Corvallis, Oregon, sampled 24 paired fields. Soils in the WV are poorly drained and rely on tile drainage systems to maintain optimal water levels so growers can have timely access to fields, extend the growing season, and maximize yields. Despite its widespread use, little is known about the consequences of tile drainage on soil C. A new project aims to address this knowledge gap. We hypothesized that tile-drained fields support increased root growth and stabilization of microbial byproducts resulting in a net increase of soil C. To test this hypothesis, we will sample 30 fields and measure soil biological, physical, and chemical properties. The results of this study will provide growers with information that informs the management practices enacted on their farms. In support of Sub-objective 2A, ARS scientists took part in a nationwide multilocation soil sampling effort to understand how management, soil types, and climatic zones influence SH indicators across the nation. Together, we will explore the complex relationships between classic and modern methods and statistical approaches to validate methodology for biological indicators of SH. Research conducted under Sub-objective 3B1, facilitated the expansion of the Pacific Northwest Biochar Atlas, an online biochar decision support toolkit. A collaboration between university, ARS, and non-profit research institutes received funding from the National Resources Conservation Service to expand the functional and geographic capabilities of the Atlas. This effort will take place over the next five years. Monitoring, reporting, and forecasting pest outbreaks is an integral part of IPM programs. In support of Sub-objective 3B, ARS scientists developed the Oregon Pest Monitoring Network (OPMN), an online hub to share real-time data on insect pest populations in seed crops across Oregon in collaboration with USDA Partnerships for Data Innovation. The OPMN aims to assist rapid dissemination of data for multiple production regions. In addition to interactive visualizations of observational data, the site will provide pest updates, scouting recommendations, historical data, and pest forecasts. Complementary research projects include predictive modeling of economic moth pests in seed crops and identifying an effective sex-pheromone lure for an emerging pest in grass seed, Noctua pronuba. In support of Sub-objective 3B, ARS researchers are investigating soil microbial biomass methodologies that could be incorporated into commercial SH assessments. The soil microbial community drives numerous critical functions important for SH, crop productivity, and environmental quality, yet it is not included in most SH assessments. This work will create a standard protocol to measure microbial biomass for commercial laboratories while assessing time, labor, and tradeoffs with the traditional, time-consuming methods that depend on the use of toxic chemicals and field-moist soil. In support of Objective 3, ARS researchers have initiated a study to quantify the amount of land needed to support cover crop plantings on 100 million acres of cropland. Through the development and distribution of surveys to seed industry personnel and other stakeholders, our report aims to identify practical considerations related to cover crop seed production, seeding rate, and available acreage in appropriate seed production regions. ARS researchers are taking an ecoinformatics approach to address complex pest issues in commercial grass seed farms in support of Sub-objective 3C. This project works with crop advisors and producers to systematically record and share georeferenced data on pest observations and management practices using a phone app. These data allow researchers to analyze regional trends from grass seed farms by linking various management practices to pest outbreaks, crop damage, and yield. In support of Sub-objectives 1A and 3C, research is being conducted to improve insecticide resistance management programs for economic pests in seed crops, as well as investigating effective biological control strategies to reduce insecticide use.

Accomplishments
1. Removal of straw does not deplete carbon stocks in grass seed cropping systems. Post-harvest management of straw residues in grass seed cropping systems has both economic and environmental consequences. Although removal of straw reduces populations of pests and pathogens, increases seed yield, and increases farm profitability, it also depletes soil nutrients and decreases soil health. Therefore, understanding the tradeoffs between straw removal and residue return is important to seed producers. There is keen interest among Oregon grass seed producers to understand how crop residue management influences the amount of carbon (C) stored in soils. However, information regarding the effect of baling on soil C is lacking. ARS researchers in Corvallis, Oregon, measured C stocks (0-100 cm) in 24 paired fields and determined that removal of straw from Tall Fescue fields does not influence C stocks. Although this research suggests that farmers can remove post-harvest residue without depleting C, the depletion of other plant macronutrients should be considered when deciding if straw should be removed or should remain in the field.

U.S. DEPARTMENT OF AGRICULTURE

Forage Seed and Cereal Research Unit: Corvallis, OR