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1. Does Post-harvest Nitrogen Application Affect Blueberry Yield or Cold Hardiness?In central Washington, nitrogen (N) management in blueberries typically consists of all N being applied prior to harvest. For early cultivars, such as Duke, this means all fertilizer is applied before the end of June, leaving a long period of growth with no supplemental N. To evaluate the potential for splitting N fertilizer applications into pre- and post-harvest timings, we conducted an experiment in a randomized complete block design with four replicates on a commercial ‘Duke’... J.R. Davenport, G.A. Hoheisel, L.W. Devetter |
2. Dairy Manure and Fertilizer Effects on Microbial Activity of an Idaho SoilDairy manure applications that have occurred in the past can have long-term lingering effects on crop production. Understanding the cause is important for current and future management practices. This study was conducted to assess selected microbial activity among past manure application rates. In a past study (2014-2016) in Kimberly Idaho, historic manure applications have been shown to have significant positive and negative effects on sugar beet production. The manure treatment history... D.D. Tarkalson, R. Dungan, D. Bjorneberg |
3. 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 |
4. Soil Acidification: Identification, Prevention, Adaptation and RestorationLow soil pH is becoming far more common in Montana soils, with at least 23 counties having at least one field with pH less than 5.5. Soil pH levels in the top 6 inches as low as 3.8 have been measured, resulting in complete crop failure insome locations, yet the problem is highly variable across fields and within soil profiles. Nitrogen fertilizer rates applied above crop nitrogen needs are the largest cause of the acidification. Low soil pH should be verified before managementpractices... C. Jones, R. Engel, S. Ewing, P. Miller, K. Olson-rutz |
5. Soil SodicitySoil sodicity refers to the amount of sodium held on soil cation exchange sites. It is typically expressed either as the percentage of the soil cation exchange capacity filled with sodium ions (exchangeable sodium percentage or ESP), or as a ratio comparing exchangeable sodium to exchangeable calcium plus magnesium (sodium adsorption ratio or SAR). Our primary interest in soil sodium is its impact on soil structure. Sodium, like all soil cations, can flocculate clay particles if present in adequate... J. Walworth |
6. Groundwater Protection in California: Nitrogen Planning and ReportingConcern over the environmental consequences of nitrogen released into the environment from agricultural operations goes back at least to the 1970s. Through the federal Clean Water Act (1972) and various state laws dating to that same time period, government has had the power to regulate nitrogen use for decades. However, only in recent years have serious attempts to restrict agricultural N usage become widespread. In California several Regional Water Quality Control Boards have recently introduced... D. Muck, T. Hartz |
7. Nitrogen Budgeting for Tree CropsIn recent years, nitrogen (N) budgets and the 4 R’s approach (right rate, right time, right placement and right source) to N fertilizer management has been gaining more acceptance. In the N budget and 4 R’s approach, fertilizers are applied in proportion to demand and timed with periods of N uptake. As a result, demand is satisfied in a timely fashion avoiding the application in excess of uptake capacity. While N is required for all plant processes, it is the specific growth and development... S. Khalsa, S. Muhammad, P. Brown |
8. Improving Nitrogen Use Efficiency of Cool Season Vegetable Production Systems with Broccoli RotationsNitrate leaching in leafy vegetable production in the Salinas Valley, CA is a continuing problem. Increased levels of nitrate in groundwater resources affects the ability of municipalities to access drinking water that meet federal water quality standards. Regulations by the Central Coast Regional Water Quality Control Board are now requiring growers to improve nitrogen use efficiency (NUE) in production fields. In prior studies we found that above ground biomass nitrogen (N) at crop maturity... R. Smith, M. Cahn, T. Hartz |
9. Salt and Sediment Balances in an Irrigated Watershed in Southern IdahoThe quality of irrigation return flow in a 205,000 acre southern Idaho watershed has changed since 1970. Converting from furrow irrigation to sprinkler irrigation and installation of wetlands and sediment ponds have greatly reduced sediment loss. There is now more sediment in the irrigation water diverted into the watershed than returns to the Snake River (>100 lb a-1) compared to a net loss of 410 lb a-1 of sediment in 1971. There is also more soluble salt flowing into the watershed than... D. Bjorneberg, A. Koehn, J. Ippolito |
10. Soil Phosphorus Availability Differences Between Sprinkler and Furrow IrrigationWater flowing in irrigation furrows detaches and transports soil particles and subsequently nutrients such as phosphorus (P). To reduce the risk of erosion and offsite P transport, producers in south-central Idaho have been converting from furrow to sprinkler irrigation. We completed research on soil P dynamics in furrow versus sprinkler irrigated soils from four paired-fields in the region. Surface soils (0-2.5 inches) were obtained from fields in September following barley harvest. Furrow irrigated... J. Ippolito, D. Bjorneberg |
11. Emissions of Ammonia and Greenhouse Gasses from Dairy Production Facilities in Southern IdahoIdaho is one of the top three milk producing states in the United States. While this commodity group is a very valuable part of the economy, there is concern over the impact of these production facilities on the generation of ammonia (NH3) and greenhouse gases (methane, CH4 and nitrous oxide, N2O) which are linked to air quality degradation and global warming. To gain a better understanding of the on-farm emissions from these production facilities, we monitored both cattle housing and manure... A.B. Leytem, D. Bjorneberg, R.S. Dungan |
12. Irrigated Small Grain Residue Management Effects on Soil Properties and Nutrient CyclingThe effects of straw removal from irrigated wheat and barley fields on soil properties and nutrient cycling is a concern due to its potential impact on the sustainability of agricultural production. The demand for animal bedding and the potential development of cellulosic ethanol production will likely increase straw demand in the future. Previous reviews addressing changes in soil properties when crop residues are removed focused primarily on rain-fed systems. This paper reviews published research... D. Tarkalson, B. Brown, D. Bjorneberg, H. Kok |
13. Agronomic Biosolids Application Rates for Dryland Wheat Across a Range of Northwest Climate ZonesPredicting agronomic rates is important to derive optimum economic and environmental benefits from biosolids fertilizer applications. We conducted this research to 1) evaluate dryland wheat response to biosolids applications over a range of climate zones in the Pacific Northwest and 2) compare agronomic application rates predicted from yield curves with those predicted from published extension guidance. We applied a range of biosolids rates during the fallow year in ten on-farm dryland wheat experiments... A. Bary, D. Sullivan, C. Cogger |
14. The Effects of Calcium Source and Placement on Soil Factors and Wheat Performace FactorsWheat production is a critical component of U.S. Pacific Northwest agriculture, with approximately 80% of the global soft white wheat grain supply originating from this region. Ammonium-based nitrogen fertilizers are widely used on typically alkaline soils in Eastern Oregon dryland production areas by wheat growers. However the nitrification process that biologically converts ammonium to nitrate increases the soil concentration of H+. This process ultimately creates acidic soil conditions, which... S. Ellickson, A. Moore, R. Zemetra, C. Hagerty |
15. 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 |
16. How Variable is Variable for Production Fields in Southern Idaho?Idaho ranks in the top 10 in the US for dairy, potato, barley, hay, sugar beet, corn silage, and dry bean production. The highest producing areas in the state for these commodities are in Southern Idaho. Agricultural producers in this region, just like many other regions, are tasked with managing irrigation water and soil fertility on large fields with spatial heterogeneity in a way that results in homogeneous crop production. Management... L. Schott, C. Robison, E. Brooks, D. Bjorneberg, K. Nouwakpo |
17. Evaluation of Soil Sulfur Tests for MontanaThere are no sulfur (S) fertilizer rate guidelines in Montana due to inconsistent yield responses, high S soil levels in many regions, a minimal number of S fertility trials in the state, and the lack of Montana and regional data that identify the best soil S tests to use. A study was initiated in 2023 to fill this research void. Three crops (spring canola, pea, and wheat) were grown at three sites, and fertilized with 0, 7.5, 15, and 30 lb S/ac using two S sources (potassium sulfate, gypsum)... C. Jones, P. Miller, P. Carr, S. Koeshall, S. Fordyce, J. Souza, J. Vetch |
18. 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 |
19. 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 |
20. 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 |
21. Hydrothermal Carbonization of Dairy Manure for Phosphorus Recovery and Runoff Risk Mitigation: Effect of Temperature and CaO AdditionDairy manure contains a significant amount of phosphorus (P) and nitrogen (N), which are essential for soil fertility and crop productivity, but are currently underutilized due to ammonia emissions, P runoff and leaching, and manure N to P ratios do not match crop nutrient needs. Meanwhile, there is a growing concern about P depletion as a non-renewable resource. To address both the excessive use of synthetic P fertilizers and inefficiently direct use of dairy manure, a logical strategy is to... M. Islam, B. He, L. Chen |
22. Sugar Beet Lime Characteristics and Effects on High pH Soils and Crops in the Western U.S.Each year in Idaho and Oregon, 351,000 Mg of precipitated calcium carbonate (PCC) (a byproduct of sucrose extraction from sugarbeet) is produced and stockpiled at sugarbeet processing factories. Currently there are limited disposal strategies for the PCC and these stockpiles continue to grow over time. The simplest solution would be to apply the PCC directly to agricultural fields each year, however the effects of PCC on high pH soils and crop rotations in the growing area are not well understood... D. Olsen, D. Bjorneberg, D. Tarkalson |