Progress 09/06/18 to 09/05/23

Outputs
PROGRESS REPORT Objectives (from AD-416): Obj. 1: Extend the N replacement approach to soft white winter wheat for guiding precision management of fertilizer N and crop residue to optimize soil microbial processes and maximize the biological potential of soil. 1A: Evaluate grain protein concentration and yield response to N under varying levels of water to define the critical protein level and fertilizer N equivalent to a unit change in protein for popular cultivars of soft white winter wheat. 1B: Determine whether uniformity of protein levels in the crop can be achieved with the precision N replacement approach. 1C: Adapt instruments and algorithms to support on-farm implementation of the N replacement approach to precision fertilizer management in dryland wheat production systems. 1D: Evaluate the effects of residue management (standing, distributed on the soil surface, or removed) on the plant-available N, precipitation capture efficiency, crop productivity, weed density, and microbial activity during the 13 months of fallow. Obj. 2: Identify whether soil microbial communities adapted to dry environments benefit plant fitness under water limited conditions. 2A: Identify the composition of microbial consortia naturally adapted to low water availability. 2B: Determine whether cultivar selection and N management can be manipulated to shift the structure and function of microbial communities to benefit plants under water stress. Obj. 3. Develop resilient cropping systems and strategies that increase resilience, improve economic returns, and enhance ecosystem services; assess their economic and environmental performance of various cropping systems in concert with their supporting components; and develop decision support systems for optimizing agronomic production in these cropping systems. 3A: Compare economic returns from the variable N replacement approach based on previous season⿿s site-specific SWW crop yield data and conventional uniform N placement based on field bulk soil sampling and laboratory testing. 3B: Increase dryland farming resilience by developing cropping systems more intensive and diverse than the conventional winter wheat-fallow system. 3C: Investigate the yields and economic returns of alternative crops following winter wheat and winter wheat following cover crops across low and intermediate precipitation zones using current and future climate scenarios. Obj. 4. Increase the sustainability resilience and tolerance of the dryland crop production system to biotic and abiotic stressors through improved understanding of developmental, environmental, and management factors that limit plant health and growth, including but not limited to stress tolerance, water use efficiency, and disease resistance. 4A: Evaluate stress indicators and yield components of wheat in alternative cropping systems compared to wheat-fallow with relation to soil water availability, disease incidence, and rotational crop morphology. 4B: Investigate crop response to water deficit, high temperature, and/or nitrogen availability. Approach (from AD-416): 1A: A winter wheat-fallow Cultivar-Fertility Study located at 2 sites in the low and intermediate precipitation zone in Eastern Oregon will include 3 soft white winter wheat cultivars fertilized with inorganic nitrogen (N) at 4 rates. The study will be repeated for 3 years. Yield and grain protein concentration (GPC) measured with near-infrared spectroscopy will define the critical GPC, an indicator of crop N deficiency or adequacy. 1B: A N-Replacement Study will follow 1A in which plots will be split and fertilized based on 1) amount of N needed to achieve target protein based on the critical GPC, and 2) university recommendations based on soil N and potential yield. Select plots will be analyzed for inorganic N, nutrient cycling capacity, microbial community composition, N leaching and gaseous N loss. 1C: The GPC measurements from the relatively inexpensive AvaSpec2048 spectrophotometer will be compared to data from dry combustion. Publicly available software will be adapted from Yield Editor software in collaboration with ARS, Columbia Missouri. 1D: Winter wheat residue in the 2 precipitation zones 1) cut high, left standing, 2) cut high, flattened, 3) cut low, spread, 4) cut low, removed. Measurements include yield, soil/air temperature, air movement, soil water content, inorganic N, and microbial nutrient-cycling activity. 2A: Rhizosphere and bulk soil microbial communities will be characterized from plots replicated in the low and intermediate precipitation zones. Soils will be analyzed for chemistry and enzymes related to carbon and N- cycling, and microbial composition. 2B: Rhizosphere soils collected from different cultivars of 1A at 2 N rates will be analyzed for nutrient cycling activity and communities sequenced from treatments promoting or inhibiting activity. Microbial communities will be evaluated for benefit to wheat in a microbial transfer potting experiment. 3: Economic benefit from replacement N management and intensified cropping systems will be evaluated. An alternative crop trial (AC) and cover crop trial (CC) will be conducted. The winter wheat (WW)-chemical fallow (CF) system will be intensified in a low precipitation (<250 mm) site as a WW-AC-CF rotation and at a high precipitation (<420-mm) site as a WW-AC rotation. The CC trial will be conducted at both sites as WW- cover crop fallow. Each trial will be initiated at a new location for three replicate years. A calibrated model will be provided within a crop simulation platform that will be useful for determining the different alternative crops and cover crops that producers are likely to consider. 4: The plant stress response and yield differences will be evaluated in the alternative and cover crop trials. Soil water availability, disease incidence, soil nutrient cycling, soil chemistry and yield traits will be quantified in each of the trials. Multiple regressions will be used to model the yield and stress variables as a function of the abiotic stressors. Results will identify benefits or detriments of alternative cropping systems to the primary wheat crop in terms of herbicide use, disease incidence, nutrient availability, soil quality, and water availability. This is the final report for project 2074-12210-001-000D, Attaining High Quality Soft White Winter Wheat through Optimal Management of Nitrogen, Residue and Soil Microbes, which will be replaced by the new project, Optimizing and Enhancing Sustainable and Profitable Dryland Wheat Production in the Face of Climate and Economic Challenges, when it completes Office of Scientific Quality Review. Substantial results were realized over the five-year project. In support of Objective 1, the critical grain protein concentration of soft white winter wheat was determined for dryland cropping systems in the low and intermediate annual precipitation regions. The critical grain protein concentration can be used to indicate areas within fields where nitrogen nutrition was inadequate for optimum wheat yield. The amount of nitrogen equivalent to a unit change in grain protein concentration was found to be similar across different cultivars of winter wheat. Together with harvest maps showing levels of grain protein in the previous season, farmers can use the nitrogen equivalent to derive the nitrogen fertilizer requirements for precision fertilizer application in the next season. The first of a two-year trial evaluating the nitrogen recommendations based on either conventional testing of soil fertility or alternative mapping of grain nitrogen levels was completed at two sites in the low and intermediate precipitation regions. Concurrent research in Objective 1 evaluated the effects of residue management (cut high, residue retained or removed) on soil moisture, soil temperature, near-surface humidity, near-surface wind speed, and grain yield at the two sites. The experiment is complete with a full dataset for analysis by the new hydrologist. Products of the research conducted in Objective 1 include the adaptation of affordable spectrophotometer for on combine grain protein analysis, development of the Yield Editor grain yield/protein mapping software (collaboration with USDA-ARS scientists in Columbia, Missouri), and the design and production of a no-till research plot drill. The drill is equipped with openers designed to cut through residue typical of our region and has the capability for variable rate nitrogen application and depth control for seed and fertilizer placement. Overall, this project⿿s work on grain protein and the development of the Yield Editor software will largely serve as a basis for new research in the National Program 212 developing on-combine grain nitrogen sensing technology for precision agriculture. Significant progress was made in evaluating the belowground effects of cultivar and fertilizer management on soil biological nutrient cycling activity for Objectives 1 and 2. Site-to-site differences in precipitation largely overshadowed differences in either cultivar or fertility for nitrogen-cycling activity, specifically arylamidase (removal of amino acids from proteins, peptides, or arylamides) and potential ammonia oxidation (nitrification step). The site with the lowest organic matter, yield and annual precipitation demonstrated the greatest biological capacity to cycle nitrogen. Soil DNA extractions and protocol optimizations for the DNA sequencing in Objective 2 are complete. The ongoing microbial community assessments will evaluate 1) temporal changes in the bacterial and fungal communities over the cropping system and 2) the community response to cultivar and nitrogen fertilizer application rates. Significant progress was made on the field-based work of Objectives 3 and 4 which were added as part of a new appropriation in fiscal year 2019. The economic analyses of the different cropping systems in this project were not completed due to the ongoing critical vacancy of the agricultural economist; however, supporting data for the analyses have been collected. Two trials on alternative crops and cover crops were completed with two full rotations through a Non-Assistance Cooperative Agreement with Oregon State University. Weed infestation, yield, and yield component measurements are being finalized for the two trial sites. Soil moisture and soil chemical measurements were not successful for the cover crop trial due to instrument failure (moisture) or omission (soil chemistry), but analyses of the soil pathogens, soil chemistry, and nutrient cycling activity in the cash crop phase are either complete or in progress. Pre-plant soil moisture for the second year cash crop demonstrated a significant loss of soil water associated with fall-seeded cover crops in the low but not intermediate precipitation region. The cover crop trials at both sites in addition to the long-term experiments at Pendleton (LTE) were assessed for wheat nitrogen assimilation and plant stress. The LTE contrasts the traditional wheat-fallow system with winter wheat cover cropped with winter pea system managed under different fertility treatments. All major components of wheat biomass (e.g., leaf, stem, grain head, and grain), physiological indicators of stress (e.g., chlorophyll fluorescence, flag leaf transpiration, and canopy temperature from jointing to maturity), and yield components were measured at different growth stages. These data will elucidate the interaction between nitrogen fertility and water use efficiency to help provide an understanding of the overall function of these intensified cropping systems. Collectively, the research demonstrates the potential for intensified crop systems in the low and intermediate regions with fall- seeded cover crops or with flax as an alternative crop in an annual (intermediate precipitation) or two-crop, three-year rotation (low precipitation). This research will bridge into the new project by further evaluating fall-seeded cover crops of field pea, barley, and canola.

Impacts
(N/A)

Publications

• Reyes-Cabrera, J., Adams, C.B., Nielsen, J., Erickson, J. 2023. Yield, nitrogen, and water-use efficiency of grain sorghum with diverse crown root angle. Field Crops Research. 294. Article 108878. https://doi.org/10. 1016/j.fcr.2023.108878.
• Manley, A., Ravelombola, W., Adams, C.B., Trostle, C., Cason, J., Pham, H., Shrestha, R., Malani, S. 2023. Evaluating USDA guar [Cyamopsis tetragonoloba (L.) Taub.] genotypes for Alternaria leaf blight resistance under field conditions. Euphytica. 219. Article 56. https://doi.org/10. 1007/s10681-023-03185-2.
• Shrestha, R., Adams, C.B. 2022. Photosynthesis in guar: Recovery from water stress, basic parameter estimates, and intrinsic variation among germplasm. Journal of Crop Improvements. 37(5):626-646. https://doi.org/10. 1080/15427528.2022.2121348.
• Boote, K., Hoogenboom, G., Ale, S., Adams, C.B., Shrestha, R., Mvuyekure, R., Himanshu, S., Grover, K., Angadi, S. 2023. Adapting the CROPGRO model to simulate growth and yield of guar, Cyamopsis tetragonoloba L, an industrial legume crop. Industrial Crops and Products. 197. Article 116596. https://doi.org/10.1016/j.indcrop.2023.116596.
• Sapkota, B.R., Adams, C.B., Kelly, B., Rajan, N., Ale, S. 2022. Plant population density in cotton: Addressing knowledge gaps in stand uniformity and lint quality under dryland and irrigated conditions. Field Crops Research. 290. Article 108762. https://doi.org/10.1016/j.fcr.2022. 108762.
• Siegfried, J., Adams, C.B., Rajan, N., Hague, S., Schnell, R., Hardin, R. 2022. Combining a cotton 'boll area index' with in-season unmanned aerial multispectral and thermal imagery for yield estimation. Field Crops Research. 291. Article 108765. https://doi.org/10.1016/j.fcr.2022.108765.
• Hinson, P.O., Pinchak, B., Adams, C.B., Jones, D., Rajan, N., Kimura, E., Somenahally, A. 2022. Forage and cattle production during organic transition in dual-purpose wheat systems. Agronomy Journal. 115(2):873-886. https://doi.org/10.1002/agj2.21284.
• Shrestha, R., Adams, C.B., Abello, F., DeLaune, P., Trostle, C., Rajan, N., Ale, S., Ravelombola, W. 2023. Intensifying dryland wheat systems by integrating guar increased production and profitability. Industrial Crops and Products. 197. Article 116608. https://doi.org/10.1016/j.indcrop.2023. 116608.

Progress 10/01/21 to 09/30/22

Outputs
PROGRESS REPORT Objectives (from AD-416): Obj. 1: Extend the N replacement approach to soft white winter wheat for guiding precision management of fertilizer N and crop residue to optimize soil microbial processes and maximize the biological potential of soil. 1A: Evaluate grain protein concentration and yield response to N under varying levels of water to define the critical protein level and fertilizer N equivalent to a unit change in protein for popular cultivars of soft white winter wheat. 1B: Determine whether uniformity of protein levels in the crop can be achieved with the precision N replacement approach. 1C: Adapt instruments and algorithms to support on-farm implementation of the N replacement approach to precision fertilizer management in dryland wheat production systems. 1D: Evaluate the effects of residue management (standing, distributed on the soil surface, or removed) on the plant-available N, precipitation capture efficiency, crop productivity, weed density, and microbial activity during the 13 months of fallow. Obj. 2: Identify whether soil microbial communities adapted to dry environments benefit plant fitness under water limited conditions. 2A: Identify the composition of microbial consortia naturally adapted to low water availability. 2B: Determine whether cultivar selection and N management can be manipulated to shift the structure and function of microbial communities to benefit plants under water stress. Obj. 3. Develop resilient cropping systems and strategies that increase resilience, improve economic returns, and enhance ecosystem services; assess their economic and environmental performance of various cropping systems in concert with their supporting components; and develop decision support systems for optimizing agronomic production in these cropping systems. 3A: Compare economic returns from the variable N replacement approach based on previous season⿿s site-specific SWW crop yield data and conventional uniform N placement based on field bulk soil sampling and laboratory testing. 3B: Increase dryland farming resilience by developing cropping systems more intensive and diverse than the conventional winter wheat-fallow system. 3C: Investigate the yields and economic returns of alternative crops following winter wheat and winter wheat following cover crops across low and intermediate precipitation zones using current and future climate scenarios. Obj. 4. Increase the sustainability resilience and tolerance of the dryland crop production system to biotic and abiotic stressors through improved understanding of developmental, environmental, and management factors that limit plant health and growth, including but not limited to stress tolerance, water use efficiency, and disease resistance. 4A: Evaluate stress indicators and yield components of wheat in alternative cropping systems compared to wheat-fallow with relation to soil water availability, disease incidence, and rotational crop morphology. 4B: Investigate crop response to water deficit, high temperature, and/or nitrogen availability. Approach (from AD-416): 1A: A winter wheat-fallow Cultivar-Fertility Study located at 2 sites in the low and intermediate precipitation zone in Eastern Oregon will include 3 soft white winter wheat cultivars fertilized with inorganic nitrogen (N) at 4 rates. The study will be repeated for 3 years. Yield and grain protein concentration (GPC) measured with near-infrared spectroscopy will define the critical GPC, an indicator of crop N deficiency or adequacy. 1B: A N-Replacement Study will follow 1A in which plots will be split and fertilized based on 1) amount of N needed to achieve target protein based on the critical GPC, and 2) university recommendations based on soil N and potential yield. Select plots will be analyzed for inorganic N, nutrient cycling capacity, microbial community composition, N leaching and gaseous N loss. 1C: The GPC measurements from the relatively inexpensive AvaSpec2048 spectrophotometer will be compared to data from dry combustion. Publicly available software will be adapted from Yield Editor software in collaboration with ARS, Columbia Missouri. 1D: Winter wheat residue in the 2 precipitation zones 1) cut high, left standing, 2) cut high, flattened, 3) cut low, spread, 4) cut low, removed. Measurements include yield, soil/air temperature, air movement, soil water content, inorganic N, and microbial nutrient-cycling activity. 2A: Rhizosphere and bulk soil microbial communities will be characterized from plots replicated in the low and intermediate precipitation zones. Soils will be analyzed for chemistry and enzymes related to carbon and N- cycling, and microbial composition. 2B: Rhizosphere soils collected from different cultivars of 1A at 2 N rates will be analyzed for nutrient cycling activity and communities sequenced from treatments promoting or inhibiting activity. Microbial communities will be evaluated for benefit to wheat in a microbial transfer potting experiment. 3: Economic benefit from replacement N management and intensified cropping systems will be evaluated. An alternative crop trial (AC) and cover crop trial (CC) will be conducted. The winter wheat (WW)-chemical fallow (CF) system will be intensified in a low precipitation (<250 mm) site as a WW-AC-CF rotation and at a high precipitation (<420-mm) site as a WW-AC rotation. The CC trial will be conducted at both sites as WW- cover crop fallow. Each trial will be initiated at a new location for three replicate years. A calibrated model will be provided within a crop simulation platform that will be useful for determining the different alternative crops and cover crops that producers are likely to consider. 4: The plant stress response and yield differences will be evaluated in the alternative and cover crop trials. Soil water availability, disease incidence, soil nutrient cycling, soil chemistry and yield traits will be quantified in each of the trials. Multiple regressions will be used to model the yield and stress variables as a function of the abiotic stressors. Results will identify benefits or detriments of alternative cropping systems to the primary wheat crop in terms of herbicide use, disease incidence, nutrient availability, soil quality, and water availability. In support of Objective 1, significant progress was made to define the critical grain protein level for soft white winter wheat and determine how applied nitrogen (N) influences microbial communities relevant to nitrogen cycling. The N equivalent to a unit change in protein was identified for four popular cultivars in the region. A region-specific algorithm based on the slope of the relationship between applied N and protein was derived to help farmers target a desired grain protein level in the next season⿿s crop. For Sub-objective 1A, the Year 2 cultivar-fertility trial was successfully harvested, and the Year 3 trial was planted. The first nitrogen-replacement trial of Sub-objective 1B was seeded in fall 2022. Challenges encountered at seeding due to new equipment and inexperience resulted in overfertilization of the trial rendering the experiment ineffective for targeting low grain protein. Although the trial will not determine whether uniformity of protein levels can be achieved with precision N placement, the results can be used to further optimize the method with protein levels obtained in a year when both N and annual precipitation were highly available for plant growth. Under Sub-objective 1B, we made significant progress analyzing measurements of nitrogen in the grain of winter wheat, nitrogen lost to the atmosphere, and nitrogen lost below the soil profile. Fertilizer use efficiency was computed for each year of the three-year experiment. Significant progress was made on Sub-objective 1C in evaluating a grain yield/protein mapping software for growers who are interested in computing tools that make use of grain yield and protein maps to create fertilizer application plans. A live video listening session was organized that provided producers from Missouri and Oregon with an opportunity to view and assess the function of a software prototype. Resulting feedback was used to improve functional components of the software. Methods to prepare the software for final packaging and release are being evaluated. Progress was made on the residue height experiment of Sub-objective 1D. Winter wheat was successfully cultivated following fallow with different residue treatments at both the low and high precipitation sites. The second trial for the study was initiated by implementation of the residue treatments and instrumentation for measurement of soil water, soil temperature, near-surface soil temperature, relative humidity, and wind speed. The second trial will be planted to winter wheat in the fall for the final yield measurement of the experiment. In support of Objective 2, significant progress was made in the collection and analysis of root-impacted soils at both the low and high precipitation regions. The study was expanded to analyze soil communities throughout the wheat-fallow rotation with timepoints of early growth (tillering), post-harvest fallow, mid-fallow (spring), and late-fallow (pre-plant) for two complete years. Significant progress was made on the development of a robot-assisted, microplate protocol that couples the analysis of anaerobic mineralization to soil nitrate, nitrite, and ammonia. In brief, a liquid handling robot will perform the transfer of soil extracts to a microplate followed by reagents for a nitroprusside- based analysis of ammonium, Griess reagents for nitrite, and Griess reagents plus vanadium for nitrate. For Sub-objectives 2A and 2B, collected soils have been analyzed for ammonia oxidation and amidase activity, and a subset analyzed for total C, N, and pH. Progress was also made on Sub-objective 2A by extraction of DNA from root-impacted soils collected during tillering at both sites and for two crop years. Additionally, progress was made in evaluating the effects of nitrogen management on the soil community composition and nutrient cycling capacity in the long-term plots in Pendleton managed under wheat-fallow with no fertilizer, urea-ammonium-nitrate or manure. Under Objective 3, progress was made on data collection. Due to challenges in Objective 1 for the N-replacement trial, production outputs for the first year analysis are not available. Significant progress was made on Sub-objectives 3B and 3C through a cooperative agreement. The alternative crop and cover crop trials at the low- and intermediate- precipitation sites were successful in generating data for plant biomass, soil water availability, weed pressure, and yield. Yield data and biomass production were evaluated and will inform the development of a Phase II trial. Datasets of weather, crop yields, soil water-related attributes and management inputs have been generated. Progress was made on Objective 4 with the analysis of wheat biomass from three different trials. For Sub-objective 4A, plants were collected from the alternative crop and cover crop trials when wheat was at physiological maturity to compare yield formation between cropping systems. This milestone was expanded to evaluate the belowground microbial factors of bacterial and fungal communities as well as soilborne pathogens following cover crops. Regarding Sub-objective 4B, progress was made on the evaluation of wheat for nitrogen assimilation, physiological indicators of stress and yield components. Supply chain issues constrained equipment procurement and negatively impacted our ability to assess transpiration and chlorophyll fluorescence as physiological indicators of stress. Sub-objective 4B was also expanded to include novel research on the nutritional quality of regional wheat in terms of mineral element densities in grain. Substantial process has been made on sample processing and data analysis, and initial progress has been made on interpretation of the results. ACCOMPLISHMENTS 01 Dryland wheat-fallow systems are more profitable than intensified rotations with oilseeds in low rainfall areas. With demand for renewable diesel and jet fuel expected to increase in the future, there is need to produce bio-feedstocks that will help the trucking and aviation industries decarbonize and reduce reliance on petroleum. ARS scientists in Pendleton, Oregon, examined profit opportunities for producing Brassica oilseed crops in rotation with winter wheat under low rainfall (less than 12 inches) in eastern Oregon. Yields of winter wheat increased and were more economically competitive after fallowing with conservation (minimum) tillage versus fallowing with conventional intensive tillage. Due to relatively low oilseed yields, three-year rotations of winter wheat-spring carinata (mustard)-fallow, winter napus (canola)-spring wheat-fallow, and spring carinata-spring wheat- fallow under conservation tillage experienced lower average profitability and greater income variability than conventional two-year rotations of winter wheat-fallow regardless of tillage intensity. Growers cannot be expected to cover total production costs at present market prices when winter canola or spring carinata are grown in low precipitation areas. Oilseed prices must double to approach the total net return of winter wheat-fallow under intensive tillage. 02 Long-term fertilization imparts stable changes to soil nutrient cycling enzymes. Soil enzymes are critical to the soil⿿s ability to release and cycle nutrients from organic matter. Because farming practices, such as nitrogen management, can impact the soil microbial communities both directly and indirectly through changes to the soil environment, it is important to understand the effects of management on the soil chemistry and overall nutrient cycling capacity. ARS scientists in Pendleton, Oregon, and Pullman, Washington, evaluated enzymes important in carbon, nitrogen, phosphorus, and sulfur supply in soils managed under wheat- fallow cultivation since 1931 that received either no fertilization, urea-ammonium nitrate (UAN), or manure. Soils receiving manure had significantly greater soil carbon, more neutral soil pH, and generally greater enzyme levels than either unfertilized or UAN-fertilized plots (with exception of pH-sensitive acid phosphatase enzyme). Comparison to historical studies showed that the treatment trends in nutrient cycling activity were mostly stable across a 32-year span although the acidification of the unfertilized and UAN-fertilized plots was reflected by the acid phosphatase enzyme. Overall, growers can expect long-term manure application to buffer a decline in soil pH, slow the loss of soil carbon and stimulate enzymes important in the release of carbon, nitrogen, phosphorous and sulfur from organic matter in dryland wheat-fallow cropping systems. 03 Biocrusts stimulate subsurface nitrogen cycling activity. Biological soil crusts (biocrusts) occur naturally across many ecosystems worldwide including deserts, polar regions, and agricultural systems. Biocrusts form in the top millimeters and are often comprised of cyanobacteria, moss, algae, fungi and archaea. ARS researchers in Pendleton, Oregon, and University of Florida collaborators, evaluated the effects of native agricultural biocrusts on the soil moisture, nitrogen-cycling capacity, and microbiome composition in the upper root zone of a sandy soil citrus orchard in Florida. The soil beneath biocrusts, compared to bare soil, had increased soil moisture during the dry season; greater soil nitrogen during citrus growth stages of high nutrient demand; and activity and relative abundance of microbes involved in nitrogen cycling. This information may guide producers to conserve naturally forming biocrusts as tools to increase soil health and influence nitrogen availability in crop production.

Impacts
(N/A)

Publications

• Nevins, C.J., Inglett, P.W., Reardon, C.L., Strauss, S.L. 2022. Seasonality drives microbiome composition and nitrogen cycling in soil below biocrusts. Soil Biology and Biochemistry. 166. Article 108551. https://doi.org/10.1016/j.soilbio.2022.108551.
• Long, D.S., Barroso, J., Painter, K.M., Reardon, C.L., Williams, J.D. 2022. Economic returns from three-year crop rotations under low precipitation in Pacific Northwest. Agrosystems, Geosciences & Environment. 5(1). Article e20251. https://doi.org/10.1002/agg2.20251.
• Reardon, C.L., Klein, A.M., Melle, C.J., Hagerty, C.H., Klarer, E.R., Machado, S., Paulitz, T.C., Pritchett, L., Schlatter, D.C., Wuest, S.B. 2022. Enzyme activities distinguish long-term fertilizer effects under different soil storage methods. Applied Soil Ecology. 177. Article 104518. https://doi.org/10.1016/j.apsoil.2022.104518.
• Hinson, P.O., Adams, C.B., Pinchak, B., Rajan, N., Kimura, E., Somenahally, A. 2022. Organic transition in dual-purpose wheat systems: Agronomic performance and soil nitrogen dynamics. Agronomy Journal. 114(4):2484-2500. https://doi.org/10.1002/agj2.21093.

Progress 10/01/20 to 09/30/21

Outputs
PROGRESS REPORT Objectives (from AD-416): Obj. 1: Extend the N replacement approach to soft white winter wheat for guiding precision management of fertilizer N and crop residue to optimize soil microbial processes and maximize the biological potential of soil. 1A: Evaluate grain protein concentration and yield response to N under varying levels of water to define the critical protein level and fertilizer N equivalent to a unit change in protein for popular cultivars of soft white winter wheat. 1B: Determine whether uniformity of protein levels in the crop can be achieved with the precision N replacement approach. 1C: Adapt instruments and algorithms to support on-farm implementation of the N replacement approach to precision fertilizer management in dryland wheat production systems. 1D: Evaluate the effects of residue management (standing, distributed on the soil surface, or removed) on the plant-available N, precipitation capture efficiency, crop productivity, weed density, and microbial activity during the 13 months of fallow. Obj. 2: Identify whether soil microbial communities adapted to dry environments benefit plant fitness under water limited conditions. 2A: Identify the composition of microbial consortia naturally adapted to low water availability. 2B: Determine whether cultivar selection and N management can be manipulated to shift the structure and function of microbial communities to benefit plants under water stress. Obj. 3. Develop resilient cropping systems and strategies that increase resilience, improve economic returns, and enhance ecosystem services; assess their economic and environmental performance of various cropping systems in concert with their supporting components; and develop decision support systems for optimizing agronomic production in these cropping systems. 3A: Compare economic returns from the variable N replacement approach based on previous season⿿s site-specific SWW crop yield data and conventional uniform N placement based on field bulk soil sampling and laboratory testing. 3B: Increase dryland farming resilience by developing cropping systems more intensive and diverse than the conventional winter wheat-fallow system. 3C: Investigate the yields and economic returns of alternative crops following winter wheat and winter wheat following cover crops across low and intermediate precipitation zones using current and future climate scenarios. Obj. 4. Increase the sustainability resilience and tolerance of the dryland crop production system to biotic and abiotic stressors through improved understanding of developmental, environmental, and management factors that limit plant health and growth, including but not limited to stress tolerance, water use efficiency, and disease resistance. 4A: Evaluate stress indicators and yield components of wheat in alternative cropping systems compared to wheat-fallow with relation to soil water availability, disease incidence, and rotational crop morphology. 4B: Investigate crop response to water deficit, high temperature, and/or nitrogen availability. Approach (from AD-416): 1A: A winter wheat-fallow Cultivar-Fertility Study located at 2 sites in the low and intermediate precipitation zone in Eastern Oregon will include 3 soft white winter wheat cultivars fertilized with inorganic nitrogen (N) at 4 rates. The study will be repeated for 3 years. Yield and grain protein concentration (GPC) measured with near-infrared spectroscopy will define the critical GPC, an indicator of crop N deficiency or adequacy. 1B: A N-Replacement Study will follow 1A in which plots will be split and fertilized based on 1) amount of N needed to achieve target protein based on the critical GPC, and 2) university recommendations based on soil N and potential yield. Select plots will be analyzed for inorganic N, nutrient cycling capacity, microbial community composition, N leaching and gaseous N loss. 1C: The GPC measurements from the relatively inexpensive AvaSpec2048 spectrophotometer will be compared to data from dry combustion. Publicly available software will be adapted from Yield Editor software in collaboration with ARS, Columbia Missouri. 1D: Winter wheat residue in the 2 precipitation zones 1) cut high, left standing, 2) cut high, flattened, 3) cut low, spread, 4) cut low, removed. Measurements include yield, soil/air temperature, air movement, soil water content, inorganic N, and microbial nutrient-cycling activity. 2A: Rhizosphere and bulk soil microbial communities will be characterized from plots replicated in the low and intermediate precipitation zones. Soils will be analyzed for chemistry and enzymes related to carbon and N- cycling, and microbial composition. 2B: Rhizosphere soils collected from different cultivars of 1A at 2 N rates will be analyzed for nutrient cycling activity and communities sequenced from treatments promoting or inhibiting activity. Microbial communities will be evaluated for benefit to wheat in a microbial transfer potting experiment. 3: Economic benefit from replacement N management and intensified cropping systems will be evaluated. An alternative crop trial (AC) and cover crop trial (CC) will be conducted. The winter wheat (WW)-chemical fallow (CF) system will be intensified in a low precipitation (<250 mm) site as a WW-AC-CF rotation and at a high precipitation (<420-mm) site as a WW-AC rotation. The CC trial will be conducted at both sites as WW- cover crop fallow. Each trial will be initiated at a new location for three replicate years. A calibrated model will be provided within a crop simulation platform that will be useful for determining the different alternative crops and cover crops that producers are likely to consider. 4: The plant stress response and yield differences will be evaluated in the alternative and cover crop trials. Soil water availability, disease incidence, soil nutrient cycling, soil chemistry and yield traits will be quantified in each of the trials. Multiple regressions will be used to model the yield and stress variables as a function of the abiotic stressors. Results will identify benefits or detriments of alternative cropping systems to the primary wheat crop in terms of herbicide use, disease incidence, nutrient availability, soil quality, and water availability. Following the unexpected loss of a land lease, suitable land was found and leased for field experiments in the high and low rainfall sites. Under Sub-objective 1B, we made significant progress toward determining how fertilizer rate and plant cultivar influence the microbial supply of nitrogen (N) to the soil. The microbial component was expanded from analyzing only in-crop to both fallow and cropped soils. Ammonia oxidation assays are complete for all samples, and substantial progress has been made for amidase. We adapted methods for the soil analyses to small-volume microplate assays and optimized the protocols for the use of automated liquid handling robots. We also optimized a robotic-enabled microplate protocol to significantly reduce labor and hazardous waste generation by coupling the measurement of soil inorganic nitrogen (nitrate/ammonium) to mineralization assays. Analysis of microbial activity data will inform the selection of nitrogen and cultivar treatments in Objective 2. Additionally, progress has been made in planning for the initiation of the first nitrogen replacement trial by quantifying the grain N removed from the first-year cultivar-fertility trial. Field research of Sub-objective 1B has been completed in determining fertilizer use efficiency with attention to nitrogen losses due to volatilization and leaching. Three years of data were compiled for grain yield, grain protein concentration, harvest index, nitrate leaching, and nitrous oxide, and ammonia emission. Progress is underway for Sub-objective 1C, with plans to hold a virtual training in August 2021 on the Yield Editor software. Challenges in cost and travel were overcome by hosting a virtual rather than in-person meeting. The training will target growers interested in computing tools that make use of grain yield and protein maps to create fertilizer application plans. Significant progress on the residue height trial of Sub-objective 1D was made at both low and high precipitation regions. Continuous near-surface, inter-row measurements were made with ultrasonic anemometers and combined temperature-humidity sensors were installed at the site. Additionally, low-cost, self-logging soil temperature arrays were constructed and installed in the inter-row soils to monitor potential differences in temperature due to shading and wind flux. Challenges associated with frequent travel to the remote sites for manual data collection were overcome by telemetry using instruments with onboard data logging and Bluetooth data collection. Game cameras and graduated staff gauges enabled the visualization and measurement of snow capture at remote sites, including an accurate collection of hourly snowfall data for one of the largest snowfall events in the last 20 years. Under Sub-objective 2A, progress was made in the collection and archiving of soils for DNA analysis. The challenge in the timing between treatment selection (based on Sub-objective 1B) and rhizosphere collection was overcome by collecting and archiving the "root-impacted" soil from all cultivars at three nitrogen rates and two precipitation regions. The advantages of root-impacted soil compared to the rhizosphere are 1) the ability to directly compare measurements of microbial composition, activity, and soil chemistry due to the larger soil volume and 2) numerous samples can be collected and composited across an experimental plot with minimal impact to yield measurements. Progress was made under Sub-objective 2B with a preliminary "microbial- transfer" experiment to develop methods for soil sterilization and inoculum, water regimes, and biomass assessments. A protocol to measure plant proline content as an indicator of plant drought stress was optimized for wheat. Additionally, progress was made to improve the efficiency of quantitative polymerase chain reaction (PCR) analysis used to assess the abundance of functional genes related to carbon and nitrogen cycling. The microbial-transfer experiments will be initiated upon selection of treatments indicated by Sub-objective 1B. Significant progress has been made under Objectives 3 and 4 on developing alternative and cover crop systems in the low and intermediate precipitation regions. The two trials were conducted by Oregon State University colleagues funded through a non-assistance cooperative agreement. The weed challenges encountered in the first-year trial were partially overcome with more aggressive and frequent control practices. Fall-seeded lentil and winter pea varieties from commercial and the ARS breeding program in Pullman, Washington, continued to show positive results for emergence and weed competition. Plant tissues from the legumes in the first-year trial have been analyzed for nitrogen-15 isotope content and will inform scientists whether legumes uptake nitrogen differently in the two rainfall zones. ACCOMPLISHMENTS 01 Automated detection of yellow flowering in canola. Monitoring the growth and development of crops is important for making crop management decisions on crop protection and fertilization. ARS scientists in Pendleton, Oregon, monitored the onset and duration of flowering of canola using a sequence of aerial images that were taken over the growing season. At the same time, the crop was characterized for changes in above-ground biomass, timing of flowering, and timing of flower shedding. A computer algorithm was developed that uses spectral indices sensitive to the amount of green biomass and the presence of yellow flowers. Contrasts between these two indices were successfully used to estimate the onset and duration of flowering. Changes between vegetative and reproductive development can be automatically detected, enabling the application of this technology for satellite- or aircraft- based detection of flowering within and between farm fields. Such information might be integrated with agrometeorological data to assess disease risk and yield prediction. 02 Value of weed maps for on-farm management. Weeds that go to seed late in the season need to be controlled before they re-infest the next crop. Oregon State University and ARS researchers in Pendleton, Oregon, used weed maps and yield monitor data to evaluate the effectiveness of crop rotations and weed control strategies over four consecutive years in a commercial wheat field. Weed and yield maps showed similar distributions indicating that much of the crop variation was associated with weed competition. Potential savings using weed maps for spot herbicide application varied from 10 to 95%. Weed maps at harvest are useful for explaining crop yield variability and directing spot spraying of weeds after harvest. Growers might implement mapping of green weeds on a combine using optical sensors that can detect chlorophyll entering the grain bin.

Impacts
(N/A)

Publications

• Long, D.S., Griffith, D.A., Kvien, C.V., Clay, D.E. 2021. Moran eigenvector filtering of multi-year yield data with application to zone development. Agronomy Journal. 4(1). Article e201404. https://doi.org/10. 1002/agg2.20140.
• Sulik, J.J., Long, D.S. 2020. Automated detection of phenological transitions for yellow flowering plants such as brassica oilseeds. Agrosystems, Geosciences & Environment. 3(1). Article e20225. https://doi. org/10.1002/agg2.20125.
• Chatterjee, A., De Jesus, A.F., Goyal, D., Sigdel, S., Cihacek, L.J., Farmaha, B., Jagadamma, S., Sharma, L., Long, D.S. 2020. Temperature sensitivity of nitrogen dynamics of agricultural soils of the United States. Open Journal of Soil Science. 10(7):298-305. https://doi.org/10. 4236/ojss.2020.107016.
• Trippe, K.M., Manning, V., Reardon, C.L., Klein, A.M., Weidman, C.S., Ducey, T.F., Novak, J.M., Watts, D.W., Rushmiller, H.C., Spokas, K.A., Ippolito, J.A., Johnson, M.G. 2021. Phytostabilization of acidic mine tailings with biochar, biosolids, lime, and locally-sourced microbial inoculum: Do amendment mixtures influence plant growth, tailing chemistry, and microbial composition? Applied Soil Ecology. 165. Article 103962. https://doi.org/10.1016/j.apsoil.2021.103962.
• Barroso, J., San Martin, C., McCallum, J.D., Long, D.S. 2021. Economic and management value of weed maps at harvest in semi-arid cropping systems of the US Pacific Northwest. Precision Agriculture. https://doi.org/10.1007/ s11119-021-09819-6.
• Wuest, S.B., Reardon, C.L. 2021. Electrostatic method to remove particulate organic matter from soil. The Journal of Visualized Experiments (JoVE). 168. Article e61915. https://doi.org/10.3791/61915.
• Yan, Z., Collins, H.P., Machado, S., Long, D.S. 2021. Residue management changes soil phosphorus availability in a long-term wheat-fallow rotation in the Pacific Northwest. Nutrient Cycling in Agroecosystems. 120(1):69-81. https://doi.org/10.1007/s10705-021-10136-7.
• Williams, J.D., Reardon, C.L., Wuest, S.B., Long, D.S. 2020. Soil water infiltration after oilseed crop introduction into a Pacific Northwest winter wheat-fallow rotation. Journal of Soil and Water Conservation. 75(6) :739-745. https://doi.org/10.2489/jswc.2020.00165.

Progress 10/01/19 to 09/30/20

Outputs
Progress Report Objectives (from AD-416): Obj. 1: Extend the N replacement approach to soft white winter wheat for guiding precision management of fertilizer N and crop residue to optimize soil microbial processes and maximize the biological potential of soil. 1A: Evaluate grain protein concentration and yield response to N under varying levels of water to define the critical protein level and fertilizer N equivalent to a unit change in protein for popular cultivars of soft white winter wheat. 1B: Determine whether uniformity of protein levels in the crop can be achieved with the precision N replacement approach. 1C: Adapt instruments and algorithms to support on-farm implementation of the N replacement approach to precision fertilizer management in dryland wheat production systems. 1D: Evaluate the effects of residue management (standing, distributed on the soil surface, or removed) on the plant-available N, precipitation capture efficiency, crop productivity, weed density, and microbial activity during the 13 months of fallow. Obj. 2: Identify whether soil microbial communities adapted to dry environments benefit plant fitness under water limited conditions. 2A: Identify the composition of microbial consortia naturally adapted to low water availability. 2B: Determine whether cultivar selection and N management can be manipulated to shift the structure and function of microbial communities to benefit plants under water stress. Obj. 3. Develop resilient cropping systems and strategies that increase resilience, improve economic returns, and enhance ecosystem services; assess their economic and environmental performance of various cropping systems in concert with their supporting components; and develop decision support systems for optimizing agronomic production in these cropping systems. 3A: Compare economic returns from the variable N replacement approach based on previous season⿿s site-specific SWW crop yield data and conventional uniform N placement based on field bulk soil sampling and laboratory testing. 3B: Increase dryland farming resilience by developing cropping systems more intensive and diverse than the conventional winter wheat-fallow system. 3C: Investigate the yields and economic returns of alternative crops following winter wheat and winter wheat following cover crops across low and intermediate precipitation zones using current and future climate scenarios. Obj. 4. Increase the sustainability resilience and tolerance of the dryland crop production system to biotic and abiotic stressors through improved understanding of developmental, environmental, and management factors that limit plant health and growth, including but not limited to stress tolerance, water use efficiency, and disease resistance. 4A: Evaluate stress indicators and yield components of wheat in alternative cropping systems compared to wheat-fallow with relation to soil water availability, disease incidence, and rotational crop morphology. 4B: Investigate crop response to water deficit, high temperature, and/or nitrogen availability. Approach (from AD-416): 1A: A winter wheat-fallow Cultivar-Fertility Study located at 2 sites in the low and intermediate precipitation zone in Eastern Oregon will include 3 soft white winter wheat cultivars fertilized with inorganic nitrogen (N) at 4 rates. The study will be repeated for 3 years. Yield and grain protein concentration (GPC) measured with near-infrared spectroscopy will define the critical GPC, an indicator of crop N deficiency or adequacy. 1B: A N-Replacement Study will follow 1A in which plots will be split and fertilized based on 1) amount of N needed to achieve target protein based on the critical GPC, and 2) university recommendations based on soil N and potential yield. Select plots will be analyzed for inorganic N, nutrient cycling capacity, microbial community composition, N leaching and gaseous N loss. 1C: The GPC measurements from the relatively inexpensive AvaSpec2048 spectrophotometer will be compared to data from dry combustion. Publicly available software will be adapted from Yield Editor software in collaboration with ARS, Columbia Missouri. 1D: Winter wheat residue in the 2 precipitation zones 1) cut high, left standing, 2) cut high, flattened, 3) cut low, spread, 4) cut low, removed. Measurements include yield, soil/air temperature, air movement, soil water content, inorganic N, and microbial nutrient-cycling activity. 2A: Rhizosphere and bulk soil microbial communities will be characterized from plots replicated in the low and intermediate precipitation zones. Soils will be analyzed for chemistry and enzymes related to carbon and N- cycling, and microbial composition. 2B: Rhizosphere soils collected from different cultivars of 1A at 2 N rates will be analyzed for nutrient cycling activity and communities sequenced from treatments promoting or inhibiting activity. Microbial communities will be evaluated for benefit to wheat in a microbial transfer potting experiment. 3: Economic benefit from replacement N management and intensified cropping systems will be evaluated. An alternative crop trial (AC) and cover crop trial (CC) will be conducted. The winter wheat (WW)-chemical fallow (CF) system will be intensified in a low precipitation (<250 mm) site as a WW-AC-CF rotation and at a high precipitation (<420-mm) site as a WW-AC rotation. The CC trial will be conducted at both sites as WW- cover crop fallow. Each trial will be initiated at a new location for three replicate years. A calibrated model will be provided within a crop simulation platform that will be useful for determining the different alternative crops and cover crops that producers are likely to consider. 4: The plant stress response and yield differences will be evaluated in the alternative and cover crop trials. Soil water availability, disease incidence, soil nutrient cycling, soil chemistry and yield traits will be quantified in each of the trials. Multiple regressions will be used to model the yield and stress variables as a function of the abiotic stressors. Results will identify benefits or detriments of alternative cropping systems to the primary wheat crop in terms of herbicide use, disease incidence, nutrient availability, soil quality, and water availability. In support of Sub-objective 1A, we made significant progress toward determining the critical protein level in soft white winter wheat below which yield is impacted by insufficient nitrogen nutrition. Suitable land was found for a field experiment with four wheat cultivars grown in combination with five nitrogen fertility regimes. Experiments were established fall 2019 at high rainfall and low rainfall sites in eastern Oregon. Under Sub-objective 1B, we made significant progress toward determining how fertilizer application impacts microbial activity associated with the soil⿿s ability to supply nitrogen. Fertility tests, including micronutrients, were performed at both sites for baseline values. Analysis of the soil microbial ammonia oxidation activity, the first step in nitrification, was completed for all cultivars at both sites in plots that were unfertilized or that received the two highest nitrogen application rates. Substantial progress was made under Sub-objective 1B3 in determining fertilizer use efficiency with attention to nitrogen losses due to volatilization and leaching. A three-year database was compiled that includes measured plot observations of grain yield, grain protein concentration, harvest index, nitrous oxide, and ammonia. Nitrate movement below the root zone was monitored in deep soil cores at the start and end of each growing season. The research supporting Sub-objective 1C1 is now complete, which involved evaluating the field precision of a relatively inexpensive spectrometer for protein analysis of wheat. An instrument costing less than $6,000 was successfully adapted for use on a combine harvester. Agricultural producers and instrument manufacturers have new information on which to modify affordable spectrometers for on-combine use, including precision nitrogen management, grain segregation/blending, and late- season weed mapping. Under Sub-objective 1C2, we made significant progress in developing and testing a grain yield/protein mapping software. The software will assist growers interested in tools for developing grain yield and protein maps to create fertilizer application plans. Under Sub-objective 1D, we made significant progress in planting a residue management trial and acquiring the farm equipment for creating residue management treatments. Wind speed, temperature, and humidity sensors were prepared for deployment in fall 2020. A relatively low-cost method for measuring in-field soil respiration was developed using an indicator that responds to carbon dioxide levels with a simple color change from pink to yellow. Significant progress was made under Sub-objective 2B in optimizing protocols for microbial community sequencing of full-length ribosomal DNA. Also, progress was made in developing a high throughput microplate method to quantify urease activity. Progress on Objectives 3 and 4 have been made in a first-year trial for the fall-seeded alternative crops. Two cropping studies, an alternative crop trial, and a cover crop trial were initiated in the low and intermediate precipitation regions by Oregon State University through a Non-Assistance Cooperative Agreement. Data were collected for emergence, soil moisture, and ground cover as a measure of weed competitiveness. Commercial fall-seeded legumes and two winter pea varieties from the Pullman ARS breeding program are showing positive results for emergence and weed competition at the two sites. Accomplishments 01 Mapping grain protein concentration on-combine with a moderately-priced spectrometer. The ability to map grain protein concentration on-combine is unachievable to many farmers based on the high cost (more than $20, 000) of the commercially-available spectrometer. ARS scientists in Pendleton, Oregon, adapted a moderately-priced reflectance spectrometer (less than $5,500) for use on a combine to measure and map the protein concentration of wheat during harvest. When placed on a combine, the calibrated instrument produced a protein map that compared well with a map derived from a more expensive instrument ($32,000). A less costly instrument may be adapted for mapping protein across fields, thereby helping promote the adoption of sensing technology for use by farmers in precision nitrogen management, grain segregation/blending, and post- harvest weed mapping. 02 Reduced sensitivity of septoria tritici blotch pathogen to SDHI fungicides following their regional adoption. Zymoseptoria (Z.) tritici, the causal agent of septoria tritici blotch disease in wheat, results in significant yield loss worldwide. Z. tritici life cycle, reproductive system, abundance, and gene flow put it at a high likelihood of developing fungicide resistance. Oregon State University and ARS researchers in Pendleton, Oregon, evaluated the sensitivity of Z. tritici isolates to four fungicides in the succinate dehydrogenase inhibitor (SDHI) group of fungicides. Z. tritici isolates were collected from fields in the Willamette Valley of Oregon at dates spanning the introduction of SDHI to the region. The sensitivity of Z. tritici to benzovindiflupyr, an active ingredient of SDHI, decreased following the fungicides' introduction to the region, and cross- sensitivity was observed with pethiopyrad, another SDHI. The results demonstrate that careful consideration is required to manage fungicide resistance and suggests that between-group, rather than within-group fungicide rotation, is necessary to prolong SDHI efficacy. 03 The wheat-fallow rotation can be intensified with spring crops under low annual precipitation. The ability to intensify the traditional winter wheat-fallow rotation in dryland cropping systems can be limited by the lack of plant-available water to support yield. ARS scientists and an Oregon State University colleague in Pendleton, Oregon, evaluated the productivity and soil water use of two-year (winter wheat- fallow) and three-year crop sequences in the Pacific Northwest (PNW) receiving approximately 11 inches of annual precipitation. Water infiltration was significantly greater in the winter wheat-fallow rotation with minimum tillage, rather than wheat-fallow with intensified tillage or three-year rotations with spring barley or spring oilseed. The greatest annualized yields and water use efficiencies were rotations in which winter wheat followed minimum tillage fallow. Rotations of minimum tillage fallow-winter wheat-spring barley or spring oilseed carinata showed the most promise of the three- year intensified rotations in which the water use efficiency and total grain productivity were similar to the two-year fallow-winter wheat rotation. Spring barley and spring carinata can be integrated into three-year dryland rotations with winter wheat under low precipitation dryland conditions in the PNW. 04 Yield maps from multiple years can identify productivity zones for site- specific crop management. Maps of crop productivity can be generated using on-combine yield monitors. ARS scientists at Pendleton, Oregon, examined whether yield maps collected over multiple years could reveal regions in the field with consistently low or high productivity to construct zones for precision agriculture. A specialized mathematical method was applied to several years of yield map data from a dryland field in east-central South Dakota (corn, soybean rotation) and an irrigated field in southwest Georgia (corn, soybean, and peanut). In both the dryland and irrigated systems, the method effectively revealed patterns of productivity in the time-series data, which appeared to be related to changes in soil type and landscape position. Results from this study may benefit farmers who practice site-specific management by identifying areas within fields that are historically more (or less) productive than others. 05 Diversifying the dryland wheat-fallow rotation with oilseeds can increase water infiltration. Rapid water infiltration into soil is important for storing water and reducing erosion. In semi-arid climates, cropping systems may include a fallow, or unplanted period, to accumulate precipitation for the following crop. Wheat production in regions of the Pacific Northwest receiving less than 14 inches of annual precipitation rely heavily on the two-year winter wheat-fallow system; however, when used with tillage, the system can have negative impacts on soil structure, soil quality, and erodibility. ARS scientists and Oregon State University colleagues in Pendleton, Oregon, evaluated whether intensification of the wheat-fallow system with canola or mustard oilseed crops would increase water infiltration based on the differences in the fibrous branching wheat roots vs. oilseed taproots. The three-year study demonstrated that water infiltration rates were increased by oilseeds compared to wheat; however, the increase in infiltration did not confer a yield benefit to the following wheat crop. This knowledge guides growers in selecting rotational crops.

Impacts
(N/A)

Publications

• Williams, J.D., Reardon, C.L., Long, D.S. 2020. Productivity and water use efficiency of intensified dryland cropping systems under low precipitation in Pacific Northwest, USA. Field Crops Research. 254.
• Hagerty, C.H., Klein, A.M., Reardon, C.L., Kroese, D.R., Graber, K.R., Melle, C.J., Mundt, C.C. 2020. Baseline and temporal changes in sensitivity of Zymoseptoria tritici isolates to benzovindiflupyr in Oregon, USA, and cross-sensitivity to other SDHI fungicides. Plant Disease. Available:
• Long, D.S., McCallum, J.D. 2020. Adapting a relatively low-cost reflectance spectrometer for on-combine sensing of grain protein concentration. Computers and Electronics in Agriculture. 174.

Progress 10/01/18 to 09/30/19

Outputs
Progress Report Objectives (from AD-416): Objective 1: Extend the N replacement approach to soft white winter wheat for guiding precision management of fertilizer N and crop residue to optimize soil microbial processes and maximize the biological potential of soil. - Sub-objective 1A: Evaluate grain protein concentration and yield response to N under varying levels of water to define the critical protein level and fertilizer N equivalent to a unit change in protein for popular cultivars of soft white winter wheat. - Sub-objective 1B: Determine whether uniformity of protein levels in the crop can be achieved with the precision N replacement approach. - Sub-objective 1C: Adapt instruments and algorithms to support on-farm implementation of the N replacement approach to precision fertilizer management in dryland wheat production systems. - Sub-objective 1D: Evaluate the effects of residue management (standing, distributed on the soil surface, or removed) on the plant-available N, precipitation capture efficiency, crop productivity, weed density, and microbial activity during the 13 months of fallow. Objective 2: Identify whether soil microbial communities adapted to dry environments benefit plant fitness under water limited conditions. - Sub-objective 2A: Identify the composition of microbial consortia naturally adapted to low water availability. - Sub-objective 2B: Determine whether cultivar selection and N management can be manipulated to shift the structure and function of microbial communities to benefit plants under water stress. Objective 3. Develop resilient cropping systems and strategies that increase resilience, improve economic returns, and enhance ecosystem services (C1, PS1a); assess their economic and environmental performance of various cropping systems in concert with their supporting components (C2, PS2a; C3, PS3b); and develop decision support systems for optimizing agronomic production in these cropping systems (C2, PS2c). Objective 4. Increase the sustainability resilience and tolerance of the dryland crop production system to biotic and abiotic stressors through improved understanding of developmental, environmental, and management factors that limit plant health and growth, including but not limited to stress tolerance, water use efficiency, and disease resistance (C3, PS3a). Approach (from AD-416): 1A: A winter wheat-fallow Cultivar-Fertility Study located at 2 sites in the low and intermediate precipitation zone in Eastern Oregon will include 3 soft white winter wheat cultivars fertilized with inorganic nitrogen (N) at 4 rates. The study will be repeated for 3 years. Yield and grain protein concentration (GPC) measured with near-infrared spectroscopy will define the critical GPC, an indicator of crop N deficiency or adequacy. 1B: A N-Replacement Study will follow 1A in which plots will be split and fertilized based on 1) amount of N needed to achieve target protein based on the critical GPC, and 2) university recommendations based on soil N and potential yield. Select plots will be analyzed for inorganic N, nutrient cycling capacity, microbial community composition, N leaching and gaseous N loss.. 1C: The GPC measurements from the relatively inexpensive AvaSpec2048 spectrophotometer will be compared to data from dry combustion. Publicly available software will be adapted from Yield Editor software in collaboration with ARS, Columbia Missouri. 1D: Winter wheat residue in the 2 precipitation zones 1) cut high, left standing, 2) cut high, flattened, 3) cut low, spread, 4) cut low, removed. Measurements include yield, soil/air temperature, air movement, soil water content, inorganic N, and microbial nutrient-cycling activity. 2A: Rhizosphere and bulk soil microbial communities will be characterized from plots replicated in the low and intermediate precipitation zones. Soils will be analyzed for chemistry and enzymes related to carbon and N-cycling, and microbial composition. Impact of water availability will be confounded by soil properties; therefore, we may use a microbial transfer experiment where soil inoculum is harvested from different precipitation zones and plants grown at two watering regimes. 2B: Rhizosphere soils collected from different cultivars of 1A at 2 N rates will be analyzed for nutrient cycling activity and communities sequenced from treatments promoting or inhibiting activity. Microbial communities will be evaluated for benefit to wheat in a microbial transfer potting experiment. This report documents progress for new project 2074-12210-001-00D, which started in September 2018 and replaces expired project 2074-21610-002-00D, "Cultural Practices and Cropping Systems for Economically Viable and Environmentally Sound Oilseed Production in Dryland of Columbia Plateau." In Sub-objective 1A, land off-station was unavailable in time to start the nitrogen-cultivar trial in fall 2018 because of the unexpected loss of the long-term lease. However, firm term leases with other landowners were established for the study to begin in fall 2019. A significant portion of this study had been established on-station in 2017 within the intermediate precipitation zone. Two years of field sampling have been completed. Parameters were measured in four cultivars of winter wheat including grain yield, protein, harvest index, and harvest nitrogen (N) index. Gas samples of nitrous oxide (N2O) were collected weekly during the growing season in selected plots of the study. Samples were analyzed in the laboratory with gas chromatography. Specialized chambers, consisting of a cylinder inserted into the soil and connected with a chamber containing a sponge soaked in acid acting as a gas trap, were used to monitor ammonia (NH3) volatilization. The potassium bromide (KBr) tracer method to monitor nitrate movement below the root zone was abandoned after the labor of sample preparation, KBr extraction, and laboratory analysis proved excessive. Instead, nitrate (NO3) movement was monitored in soil cores extracted from below the root zone at the start and end of each growing season. In Sub-objective 1C, significant progress was made to adapt an affordable spectrometer for use on a combine harvester. The subject spectrometer was modified at the factory to output the detector temperature. Thermal stability of the detector was achieved by putting the instrument inside an insulated enclosure in contact with an inexpensive thermal-electric plate. Fifty grain samples of winter wheat having a wide range in protein concentration were used to calibrate the instrument. A final model, constructed by fitting the spectra of these samples to reference protein values, predicted the protein concentration to within 0.5 percent. Effects of auger speed and sensor orientation on stability of the instrument⿿s calculated protein values were tested by mounting the instrument to an auger. Predicted protein values were consistent with reference values. Significant deviation occurred only when auger speed was low, suggesting that instrument readings depend on rate of grain flow. Three years of field testing have been completed. A manuscript reporting the project results is in preparation. Also, under Sub-objective 1C, significant progress was made to develop an easy-to-use software for data editing and mapping of on-combine yield and protein data. Collaborators met in Columbia, Missouri, to plan the software design. Algorithms and methods were exchanged to support this effort. A prototype module was constructed for translating protein data for import into the Yield Editor 2.0 software. Under Sub-objective 1D, land was unavailable to initiate the experiment in fall 2018 because of the unexpected loss of the long-term lease and the requirements to work on University ground on-station. Progress has been made by establishing leases and developing treatment maps to initiate the experiment in the fall 2019. In Objective 2, progress was made in developing methods to transfer the soil microbiome as an inoculant. A preliminary experiment demonstrated that the autoclaved soil was not appropriate as a ⿿sterile⿝ medium due to increased levels of available nitrogen and high rates of enzyme activity following a recovery period. Other media such as sterile potting soil or sand will be evaluated. Accomplishments 01 Reduced tillage and crop intensification help control downy brome in dryland winter wheat. Downy brome is a grassy weed that is difficult to control in low rainfall areas of the inland Pacific Northwest where winter wheat is often grown in a two-year rotation with summer fallow involving frequent tillage. ARS scientists and their Oregon State University colleagues in Pendleton, Oregon, investigated the effects of tillage intensity and cropping intensification on infestations of downy brome. Downy brome cover was lower and winter wheat yield was higher when tillage was reduced to a few operations. In addition, downy brome cover was lower when the two-year rotation was intensified to three- year rotations of fallow/winter wheat/spring barley or fallow/winter wheat/spring mustard. Winter wheat yield in the three-year rotation with spring barley was higher than that in fallow/winter wheat, even though weeds were more competitive in the former. Growers could control downy brome in winter wheat by reducing tillage to suppress weed seedling emergence and growth or introducing a spring crop to increase weed competition. 02 Short-term intensified tillage does not have a strong or consistent impact on the soil biology or chemistry in dryland wheat-fallow cropping under low annual precipitation. ARS scientists and an Oregon State University colleague in Pendleton, Oregon, evaluated soils managed under conventional (intensive) and minimum (conservation or sweep) tillage for differences in soil chemistry (pH, inorganic nitrogen, phosphorous, total carbon and nitrogen) and soil biology (bacterial and fungal abundance, and nutrient cycling enzyme activity related to carbon, nitrogen and phosphorous availability). Sampling phase (wheat or fallow), year and soil depth were greater factors influencing soil chemistry, biology, and activity than tillage intensity. Soil chemical and microbial properties were similar between the tillage regimes, but the amount of fungi declined in the wheat phase under conventional tillage. Producers interested in short-term intensified tillage, such as to control weeds, can expect no detriment to microbial nutrient cycling; however, the amount of soil fungi that are important to soil structure may be reduced after the cropped phase.

Impacts
(N/A)

Publications

• Schlatter, D.C., Reardon, C.L., Maynard-Johnson, J.L., Brooks, E., Kahl, K. B., Norby, J., Huggins, D.R., Paulitz, T.C. 2019. Mining the drilosphere: bacterial communities and denitrifier abundance in a no-till wheat cropping system. Frontiers in Microbiology. 10:1339.
• Gesch, R.W., Long, D.S., Palmquist, D.E., Allen, B.L., Archer, D.W., Brown, J., Davis, J.B., Hatfield, J.L., Jabro, J.D., Kiniry, J.R., Vigil, M.F., Oblath, E.A., Isbell, T. 2019. Agronomic performance of Brassicaceae oilseeds in multiple environments across the Western United States. BioEnergy Research. 12(3):509-523.
• Reardon, C.L., Wuest, S.B., Melle, C.J., Klein, A.M., Williams, J.D., McCallum, J.D., Barroso, J., Long, D.S. 2019. Soil microbial and chemical properties of a minimum and conventionally-tilled wheat-fallow system. Soil Science Society of America Journal. 83(4):1100-1110.
• San Martin, C., Long, D.S., Gourlie, J., Barroso, J. 2018. Weed responses to fallow management in Pacific Northwest dryland cropping systems. PLoS One. 13(9):1-17.
• Barth, V.P., Reardon, C.L., Coffey, T., Klein, A.M., McFarland, C., Huggins, D.R., Sullivan, T.S. 2018. Stratification of soil chemical and microbial properties under no-till management after lime amendment. Applied Soil Ecology. 130:169-177.
• Long, D.S. 2018. Site-specific nutrient management systems. In: Stafford, J., editor. Precision Agriculture for Sustainability. Cambridge, UK: Burleigh Dodds Science Publishing. p. 115-125.
• San Martin, C., Long, D.S., Gourlie, J., Barroso, J. 2019. Spring crops in three year rotations reduce weed pressure in winter wheat. Field Crops Research. 233:12-20.