Project : USDA ARS

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Research Project: Optimizing and Enhancing Sustainable and Profitable Dryland Wheat Production

Location: Columbia Plateau Conservation Research Center

2024 Annual Report

Objectives
Objective 1: Evaluate and seek to optimize climate-adaptive cropping system alternatives to the 2-year winter wheat-fallow system that reduce fallow periods in the dryland Pacific Northwest, increasing productivity, profitability, input-use efficiency, and sustainability. 1.A: Evaluate winter cover crops in low and intermediate precipitation regions. 1.B: Evaluate newly developed food-grade winter field peas as a rotational crop with nitrogen benefit. Objective 2: Increase resilience and profitability of the widely-used dryland wheat-fallow system by improving nutrient and weed management. 2.A: Develop liming practices to ameliorate the increasing soil acidity issues on wheat production systems in the low and intermediate regions of the PNW to increase productivity and yield. 2.B: Evaluate the effects of crop management on soil and grain nutrients. 2.C: Evaluate the impacts of integrated (chemical/mechanical) weed management and weed physiology on soil water dynamics in-field and under controlled settings. 2.D: Evaluate profitability of management strategies that ameliorate soil quality decline (e.g., soil pH) or reduce weed infestation. Objective 3: Develop tools to better assess agricultural soil microbiomes for enhancing nutrient cycling and optimizing desired biochemical degradative pathways in diverse agroecosystems. 3.A: Develop high-throughput standard protocols to assess soil biological function and diversity. 3.B: Assess the soil microbiome response to PFAS as an emerging concern in agriculture.

Approach
1.A: A dryland cover crop systems trial under low and intermediate rainfall will include fall-seeded cover crops of winter pea, winter canola, winter barley, and a mix of the three. Winter wheat-fallow will be the control. Analyses include grain yield and quality; cover crop and weed biomass, density and/or cover; soil fertility and soil biology; soil water dynamics; and economic assessments. 1.B: Studies will be established at two dryland sites under low and intermediate rainfall and an irrigated site. Treatments include food-grade green pea (MiCa), a food-grade yellow pea (Klondike), and a non-food-grade Austrian winter pea (Grainger), plus wheat and fallow. Analyses include plant phenology and growth; yield components; plant nitrogen and nitrogen fixation; soil fertility; soil moisture; and soil biology. Data will support development of the first mechanistic plant growth model for winter field peas (DSSAT CROPGRO; collaboration with University of Florida). 2.A: A lime micro-dosing method will be evaluated in dryland wheat cropping systems at sites with soil acidity constraints (pH <5.5) in the low and intermediate rainfall regions. Treatments will include a one-time application of lime using the traditional broadcast approach or micro-dosing with 10-50% lime recommendation. Analyses include soil chemistry (including exchangeable aluminum [Al3+], pH, and cation exchange capacity) and grain yield. 2.B: Archived soil samples from a long-term fertility trial at Pendleton, Oregon will be analyzed for secondary- and micro-nutrient contents and soil pH to identify historical trends in soil quality and crop yield. Separately, the effects of wheat genotype, production environment, and other variables on grain nutrient density will be assessed. 2.C: Weed management with chemical, mechanical or integrated (chemical/mechanical) practices will be assessed in dryland wheat-fallow under low and intermediate rainfall. Assessments include weed density, vegetation cover (UAV-based); grain yield; and soil water dynamics. Greenhouse and column assays will assess the potential belowground advantage of weeds on water extraction compared to wheat including permanent wilting point, rooting depth, and soil water extraction. 2.D: Standard enterprise budget analyses will be performed to determine cost-benefit relationships from lime micro-dosing and integrated weed management strategies. 3.A: A bench-scale assay for combined nutrient-cycling enzymes (carbon, nitrogen, sulfur, phosphate) will be modified for microplates with robotic-assisted liquid handling. Protocols and bioinformatic pipelines will be developed to assess archaeal and bacterial ammonia-oxidizing microbial communities based on DNA sequencing of the amoA gene (ammonia monooxygenase) using the Oxford Nanopore MinION platform. 3.B: Microbial communities from PFAS-contaminated and PFAS-naïve soils amended with PFAS will be assessed using molecular techniques to identify potential microbiota associated with PFAS degradation. PFAS compositional profiles and concentrations will be determined using liquid chromatography mass spectrometry.

Progress Report
This report documents the progress for project 2074-21600-001-000D, "Optimizing and Enhancing Sustainable and Profitable Dryland Wheat Production in the Face of Climate and Economic Challenges", which started May 2024 and continues research from project 2074-12210-002-000D, "Attaining High Quality Soft White Winter Wheat through Optimal Management of Nitrogen, Residue and Soil Microbes". Progress was made on all three objectives and their sub-objectives which fall under National Program 216, Component 1 (Improve Agricultural System Resilience) and Component 2 (Optimize agricultural systems to increase ecosystem service value to farmers and society). Advances on this project focus on Problem 1A–Resilience to changing climate trends and extreme weather, Problem Statement 1B-Resilience to supply chain shocks, and Problem 2B–Biodiversity. Significant progress was made on Objective 1 in optimizing climate-adaptive cropping system alternatives to the two-year winter wheat–fallow system. In support of Sub-objective 1.A, a two-location cover crop trial was established in fields managed under a wheat-fallow rotation in low and intermediate rainfall zones. The trial was carried out through a Congressionally-mandated Non-Assistance Cooperative Agreement with Oregon State University. Cover crop establishment was successful for winter barley and winter pea; however, issues with seeding depth contributed to the loss of the canola cover crop treatment. The plot design was modified from a two-pass plot to two single-pass plots which created challenges for sample collection and border effects. Soil samples collected in the fall prior to trial initiation were analyzed for baseline soil chemistry and soil amidase enzyme activity to assess changes in fertility and biology over the life of the project. First-year assessments were completed for cover crop biomass (e.g., measurement of cover crop plant components and weeds) and soil infiltration to evaluate performance, agronomic impacts, and soil water dynamics of the cover crop vs. traditional wheat-fallow cropping systems. Significant progress was also made for Sub-objective 1.B, in evaluating food-grade winter field peas as an alternative crop. Field trials with three pea varieties and wheat were successfully established at three sites to support the development of a Decision Support System for Agrotechnology Transfer crop growth (DSSAT CROPGRO) simulation model for field peas and provide basic scientific information on crop growth and yield of the newly developed crop. Data was collected from time-series measurements to capture changes in growth and biomass partitioning over the entire lifecycle of the crop and provided to collaborators at the University of Florida for initial model development. Progress was also made in identifying the belowground benefit of field peas compared to wheat regarding soil biology, soil water, and nitrogen availability. Soil samples collected in the fall (bulk soils, pre-seeding) and spring (root-impacted, flowering) were assessed for nitrogen-cycling enzyme activity and are in the process of soil microbiome analysis through collaboration with an ARS scientist in Pullman, Washington. Significant progress was made on Objective 2 by increasing the resilience and profitability of the dryland wheat-fallow system by improving nutrient and weed management. In support of Sub-objective 2.A, three commercial farms in the low (two sites) and intermediate (two sites) rainfall regions were identified as feasible research sites for lime micro-dosing studies based on confirmed soil acidity (pH less than 5.5) issues. A second site in the low rainfall region will be assessed in the fall for soil acidity constraints prior to initiating the trial in the fall through collaboration with researchers at Oregon State University. Significant progress was made with Sub-objective 2.B by evaluating the effects of crop management on soil and grain nutrients. Evaluation of the mineral density of grain is complete and demonstrates that contrary to previous reports, yield has no significant effect on grain mineral concentrations, but both production environment and wheat variety do. Assessment of soil nutrients (secondary [Ca, Mg, S] and micronutrients (B, Zn, Mn, Fe, Cu, Mo, Cl)] will commence on archived soil samples from a long-term fertility trial at Pendleton pending the installation of a newly acquired inductively coupled plasma-optical emissions spectroscopy (ICP-OES) instrument. Significant progress was also made on Sub-objective 2.C regarding the effects of weed management and weed physiology on soil water dynamics. Field trials were successfully implemented in the low and intermediate precipitation region to evaluate integrated (chemical/mechanical) weed management strategies in the wheat-fallow cropping system as part of a Congressionally-mandated Non-Assistance Cooperative Agreement with Oregon State University. Assessments were completed for soil water, water infiltration, and weed cover (Unpiloted Aerial Vehicle [UAV]-based imagery) in the fall and/or spring. Ground and aerial assessments of weeds were performed through collaboration with researchers at Oregon State University. In addition, work was completed to contrast the capacity of weeds compared to wheat to draw down soil moisture. This work provides important information on the permanent wilting point, rooting depth, and capacity for soil water extraction of wheat compared to the regionally common warm-season weeds Russian thistle (Salsola tragus) and kochia (Bassia scoparia). Regarding Objective 3, significant progress was made in developing the microplate method for the combined carbon-, nitrogen-, phosphorus-, and sulfur-cycling (CNPS) soil enzyme assay in Sub-objective 3.A. A robot-assisted liquid-handing protocol was developed to perform five concurrent microplate assays for individual (C, N, P, and S) and combined (CNPS) soil enzyme activities in a single run. Further protocol optimization will focus on reducing consumables (pipet tips), chemical waste, and preparation time for the assay (pipetting). In addition to the soil enzyme assay, initial optimizations are complete for a robot-assisted liquid handling protocol for potentially mineralizable nitrogen. The protocol will include analysis of soil inorganic nitrogen (nitrate, ammonium, and/or nitrite) and mineralizable nitrogen (e.g., ammonium, seven-day anaerobic method) in a single run.

Accomplishments
1. Research brings new perspective on the effect of wheat yield on grain mineral density. Staple foods, such as wheat, are often relied upon as primary sources of mineral nutrients for persons worldwide lacking diversified diets. Researchers have long sought to increase grain mineral density, but efforts have been hindered by concern that simultaneously increasing yield will “dilute” grain minerals. Recognizing that this concern may have largely stemmed from comparisons of historic and modern wheat varieties that diverged substantially in genetics beyond yield traits, ARS scientists in Pendleton, Oregon, evaluated the grain mineral density of many modern wheat varieties cultivated at diverse sites across Oregon, Idaho, and Washington. Results showed there was no significant effect of yield on grain mineral concentrations, though both production environment and the choice of wheat variety had strong effects on mineral content. Grain mineral concentrations can be increased to address human malnutrition by using variations in production environments and wheat varieties without concern for yield.

2. Grain protein concentration can indicate soil nitrogen requirements for crop yield in the following year. Grain protein concentration (GPC) can be used to indicate nitrogen (N) nutrition sufficiency for grain yield of wheat once a critical protein level has been established. ARS scientists in Pendleton, Oregon, grew four popular varieties of soft white winter wheat under a wide range in precipitation and N fertility. The critical protein level and the amount of N equivalent to a unit change in GPC were identified from relationships between GPC and grain yield or applied N. Grain protein lower than 11.7% indicated that N was likely deficient for yield, but growers could produce wheat as low as 10.5% GPC before experiencing significant yield loss. In addition, 38-75 pounds of N per acre were required to change GPC by 1% in lower rainfall areas of the region where wheat is under severe water stress during grain filling. Results of this research are highly relevant for precision N management that relies upon digital maps of grain protein and yield to identify field areas of potential N deficiency/sufficiency and to estimate the amount of N removed in harvested grain, especially now that grain quality sensors are available for combine harvesters.

3. Naturally-formed biocrust communities in agricultural systems are influenced more by environment and management than season. Biocrusts are naturally formed assemblages of microorganisms at or near the soil surface that provide ecological benefits, such as stabilizing the soil and increasing water storage and nutrient availability. Biocrusts have a strong potential to enhance crop growth through increased soil moisture and nitrogen produced from nitrogen fixation, but little is known about how crop management and climate shape the microbial composition of biocrusts in agricultural systems. ARS scientists in Pendleton, Oregon, and University of Florida collaborators evaluated the seasonal activity and composition of nitrogen-fixing communities (based on the dinitrogenase gene, nifH) in native biocrusts collected from three perennial crops in Florida or Oregon. The community composition (both total bacterial and nitrogen-fixing) of the biocrusts significantly differed between crops of citrus (Florida), grape (Florida), and apple (Oregon), but for all crops biocrusts enhanced nitrogen fixation activity compared to bare soil, albeit the effects were seasonal. Overall, this information provides fundamental knowledge to scientists on of the composition of biocrusts under different agricultural practices and climates and may guide producer decisions on the management of soils in areas with biocrusts.

U.S. DEPARTMENT OF AGRICULTURE

Columbia Plateau Conservation Research Center: Pendleton, OR