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1. Enhanced Efficiency Phosphorus FertilizersPhosphorus (P) is essential for plants. However, first-year phosphorus fertilizer uptake by plants is low, resulting in economic and environmental impacts. Developments with P Enhanced Efficiency Fertilizer (EEF) sources show improved uptake efficiency and increased yield and/or crop quality, while reducing environmental risk. Research with EEFs (including organic acids, maleic itaconic copolymer, and struvite) all show these improvements, especially when: 1) soil test P concentrations are low,... B. Hopkins, S.J. Kobza, C. Seely |
2. Assessing Nutrient Uptake and Accumulation in Oregon Hop ProductionCommercial hop production practices and cultivars have changed in the past 25 years and there is a need for updated nutrient management information under cotemporary practices. Current nutrient accumulation curves are only available for nitrogen (N). Current regional nutrient management guides from Oregon State University and Washington State University date back to the 1990’s or earlier. In the meantime, market forces and breeding efforts have led to a proliferation of new varieties, many... A. Moore, D. Gent, B. Verhoeven |
3. Compost Application in California Tomato Cropping SystemsWith the implementation of California Assembly Bill (AB) 341 the availability of composts such as green waste (GW) and co-composted green waste and food waste (FW) as a soil amendment is increasing. The use of those organic amendments in agricultural production systems has been recommended as an effective strategy to make full use of organic waste and improve soil health. However, little information is available to tomato growers to reassess N inputs from using GW and FW. This study was conducted... Q. Yi, W. Horwath, S. Haas, X. Zhu-barker |
4. Effects of Lime and Micronutrient Amendments for Acidic Soils of the Inland Pacific NorthwestThe soil pH of agricultural land in the inland Pacific Northwest has dropped precipitously from native soil levels of near 7.0 pH. Changes that were becoming evident in the 1980’s have reached critical levels, leaving tens of thousands of acres of previous prairie soil at pH under 5.0 and unable to grow an increasing number of aluminum-sensitive crops. Some farmers in the region are beginning to use lime application to neutralize soil acidity. However, pH changes and liming can also... R. Wieme, L. Carpenter-boggs, P. Carter, S. Van Vleet |
5. Reuse and Reclamation of PhosphogypsumPhosphogypsum (PG) is a byproduct of phosphate fertilizer production. It is produced when phosphate rock is treated with sulphuric acid during the manufacture of phosphoric acid, and is composed primarily of gypsum (CaSO4.2H2O). It is estimated that over 3 billion tonnes of PG have been accumulated in stacks worldwide and over 150 million tonnes are produced annually. In North America, PG is stockpiled in stacks that can cover hundreds... C. Nichol |
6. Soil Health and Ecological Resilience on the PalouseHealthy soil is critical for global food security and other essential ecosystem services but is threatened by processes of soil degradation, with at least 33% of global croplands estimated to be moderately or highly degraded. Current soil health assessments provide insight into soil functional performance but often lack diagnostic criteria that assess management effects on soil function over time. We integrate soil health assessments with ecological resilience theory to better understand management... A.G. Davis, D.R. Huggins, J.P. Reganold |
7. Vineyard Soil Health: What Soil Properties are Most Important?Washington is the second leading producer of wine grapes (Vitis vinifera) in the US, with over 60,000 acres in vineyards. With such a substantial acreage, it is crucial to know how management practices may affect soil and vine health in wine grape systems. Soil health indicators and threshold values have been extensively studied in commodity crops in the Midwest and the northeastern US, but there is much less information available for specialty crops in the Pacific Northwest. Soil... M. Mcilquham, D. Griffin-lahue, K. Sarpong, L. Michel |
8. Evaluating Cover Crops for Nitrogen Management in a Walnut OrchardCover crops provide numerous benefits in agricultural systems. From increasing soil water storage to reducing fertilizer inputs, quantifying cover crops benefits is crucial in nutrient management, crop productivity, environmental sustainability, and growers' adoption. The goal of this study was to quantify nitrogen (N) and carbon (C) inputs in a walnut (Juglans regia L. 'Chandler') orchard that implemented three cover crop mixtures. The study site was a 5-year-old walnut... D. Zapata, X. Zhu-barker, K. Steenwerth, W. Horwath |
9. Manure Treatments Change Nitrogen Cycling in Soils Receiving Repeated Applications of Dairy-wastesOur objective was to assess effects of treated dairy-waste on soil N pools, nitrification, plant N availability, and yield in a silage cornfield treated with ammonium sulfate (AS), dairy-waste compost (DC) or liquid dairy-waste (LW) as N sources at two levels of application over 5 years. Increases in soil C and N, nitrate and available P and K were observed for the DC treated soils throughout the 5-year period. Soil organic C increases for the high-level DC treated soil doubled the C pool resulting... J. Norton, M. Habteselassie, J. Stark, B. Miller |
10. Remote Sensing of Corn N Status with Active SensorsDetermining in-season corn (Zea mays L.) nitrogen (N) variability has been a research focus of agronomists for quite some time. One of the methods currently available to determine N variability in corn is remote sensing. Studies have shown that remotely sensed imagery can detect N variability in corn. However, this method can have some limitations, such as the timeliness in which this imagery can be acquired. Hand-held active remote sensing devices may overcome these limitations.... D. Westfall, R. Khosla, T. Shaver |
11. Economics of Fertilization Under Site-specific Management ZonesSite-specific management of crop fields using variable rate application of inputs to manage in-field variability has now been around for over 15 years. However, the degree to which site-specific management strategies increase farm profitability is not well established. The objectives of this study were: to compare uniform and variable-rate Nitrogen (N) management strategies across productivity level site-specific management zones and to identify the most profitable N management strategy. This... R. Khosla, D. Westfall, W. Frasier, B. Koch |
12. Cover Crops for Nitrogen Management in Irrigated Cropping SystemIn perennial fruit cropping systems, the inter-row offers on opportunity to grow a cover crop that then can be used to supply nitrogen (N) to the fruit crop. We conducted research in both Concord grape and Gala apple to evaluate the potential of cover crops to supply N to the crop. Based on continuous monitoring of plant available NO3-N by using PRSTM ion exchange resin probes, we found that in Concord grape, while both hairy vetch and yellow sweet clover did not release quite as much N as... J. Davenport, K. Bair, D. Granastein |
13. Soil Respiration Tests As Predictors of Nitrogen Mineralization PotentialEstimation of seasonal N availability via a soil test has proved difficult. This information gap has lead to fertilizer recommendations based upon soil inorganic N levels found before planting and or preside dress. Complicating matters, as famers adopt new irrigation technologies, the results from older fertilizer rate trails may also be less applicable. In general, most when not all recommendations do not account for the contribution of soil N mineralization during the growing season, which has... W. Horwath |
14. Use of Biological Soil Tests to Assess Soil Health and ProductivityCrops require sufficient nitrogen (N) to attain maximum yield potential. The intrinsic N supplying potential of soils is both directly and indirectly related to soil health. Soil health can reliably be predicted with existing soil tests, however, the ability to predict soil N availability, an important proxy for soil health, remains problematic due to a lack of a robust soil tests. As a result, fertilizer recommendations are often made without an accurate assessment of the amount of N that... W. Horwath |
15. Source and Rate Interactions for Enhanced Efficiency Phosphorus FertilizersPhosphorus (P) is an essential plant nutrient and plays a major role in the health and wellbeing of ecosystems. Deficient P is detrimental to plants. Excessive P is also detrimental to plants and is potentially harmful environmentally. Soil testing is an effective tool to help growers determine if fertilizer P is needed and, if so, the rate that is needed to be applied. Rates higher than the recommended amount can be detrimental to plant health and decrease yield. In addition to applying the right... A. Norris, B. Hopkins |
16. Nitrogen Management in Small Grains After AlfalfaSmall grains are commonly grown following alfalfa in Utah and the Intermountain West, especially during drought years as small grains require less irrigation than corn. Several studies across the country have shown that corn following alfalfa rarely needs N fertilizer, yet relatively few have evaluated the N needs of small grains. Furthermore, research on the N needs of small grains grown as forage vs. grain are even more sparse. The objectives of this research are to quantify the... C. Pound, M. Yost, E. Creech, G. Cardon, K. Russell, D. Despain, J. Gale, K. Heaton, B. Kitchen, M. Pace, S. Price, C. Reid, M. Palmer, M. Nelson |
17. Improved Small Grain Nitrogen Use Efficiency with California Site-specific Decision SupportSmall grains are grown throughout the state of California (CA) on approximately 500,000 acres annually. They are generally fall-sown and grown during the winter months when most precipitation occurs. Because precipitation and irrigation patterns vary across CA and there is a strong interaction between total water and plant available nitrogen (N), determining fertilizer N application recommendations is particularly challenging in this cropping system. With recent fertilizer price volatility,... N. Clark, M. Lundy, T. Nelsen, M. Leinfelder-miles, S. Light, G. Galdi, T. Getts, K. Mathesius |
18. Stacking 4R Nutrient Management: PotatoThe 4Rs of nutrient management are research-based guidelines with the aim to improve the sustainability of major cropping systems and the environment without compromising crop yield and quality. The term “4R” represents fertilizer applied at the Right rate with the Right source, Right timing, and Right placement. The objective of this project is to evaluate the interactions of individual and combined 4R management practices. In 2020, potato (Solanum tuberosum L.) was grown... S.H. Stapley, C.C. Whitaker, N.C. Hansen, R.C. Christensen, R.R. Jensen, M.A. Yost, B.G. Hopkins |
19. Effects of Long-term Biosolids Applications in Two Dryland Agroecosystems on Physical, Biological, and Chemical Soil Health PropertiesBiosolids can be important sources of organic matter to semi-arid dryland grain systems and have the potential to mitigate some of the soil health challenges specific to these areas while providing an alternative to synthetic fertilizers. Biosolids are an important avenue for beneficially reusing and redistributing nutrients from high population urban areas to more rural agricultural areas. We explored how long-term (20+ year) applications of biosolids at two field sites affected physical, biological... M. Desjardins, A. Bary, J. Ippolito, S. Cappellazzi, D. Liptzin, D. Griffin-lahue |
20. Non-dormant Alfalfa and Small Grain Rotations- Tillage and Fertility EffectsTo study the use of non-dormant and high nitrogen fixing alfalfa cultivars as a possible source of nitrogen for spring and fall-seeded wheat and barley grown under tilled and no-tilled conditions. Hi-Nitro, a non-dormant, high-nitrogen fixing alfalfa variety, and RoundUp Ready Stratica, a traditional dormant alfalfa cultivars were clear seeded in Aberdeen in 2023 and 2024. Forage was harvested 4 times. Fall or spring tillage was done approximately 3-14 days before planting fall or spring... R. Findlay, J. Spackman, J. Hatch, T. Jacobsen, J. Gibbons, J. Sagers, D. Callister |
21. Malt Barley Yield and Quality Response to Nitrogen and Sulfur FertilityNitrogen (N) and sulfur (S) and are critical nutrients for producing high-quality malt barley but can be difficult to manage in semi-arid production systems where rainfall and, periodically, irrigation is variable. High spring precipitation or excessive irrigation events can favor N and S leaching reducing yield and grain quality. However, N fertilizer additives such as urease inhibitors, nitrification inhibitors, and controlled-release products may improve N availability. Irrigated... J. Spackman, J. Spackman, J. Hatch, J. Bevan |
22. Lime Incubation for Southern Idaho SoilsSoil acidity is a growing concern for agricultural productivity in Idaho, particularly in the eastern and northern regions where soils are trending acidic. Soil acidity below a pH 5.5 adversely affects the root development and nutrient uptake of crops like alfalfa, barley, and wheat. This study aims to determine the lime requirements for acidic soils in Idaho to optimize crop growth, specifically targeting pH levels of 5.5, 6.0, 6.5, and 7.0. Soil samples were collected from various grower fields... K. Young, J. Spackman, T. Jacobsen, J. Sagers, J. Hatch, R. Ritchie, J. Williams, K. Schroeder, A. Adjesiwor |