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1. The Elasticity of Biochar Across the Farm: Nutrient Capture, Compost Feedstock, and Soil AmendmentWhen biomass is thermochemically altered through pyrolysis, what results is biochar, a solid, porous material that is high in carbon (C) (e.g. 80%). Owing to its unique physicochemical properties, biochar has been evaluated as a soil amendment, a compost feedstock, a means to mitigate nutrient loss and a way to sequester carbon. Biochar is an appealing material as a farm management tool because its potential use is varied. As part of a Western SARE grant, soil scientists at Washington... N. Stacey, D. Collins |
2. Evaluation of Lime Requirement Estimation Methods for Oregon Agricultural SoilsSoil testing labs in the Pacific Northwest are considering non-hazardous alternatives to the Shoemaker-McLean-Pratt (SMP) buffer method for lime requirement estimation (LRE). While alternative LRE methods have been adopted in other parts of the U.S., they have not been evaluated for Oregon soils. The goal of this study was to evaluate several LRE methods for agricultural soils from western and eastern Oregon, applying the lime incubation method for actual lime requirement. Twenty-four acidic... C. Evans, A. Moore, D. Sullivan |
3. Evaluating Nutrient Uptake and Partitioning for Hybrid Carrot Seed Production in Central OregonHybrid carrot seed production is prominent in Central Oregon, however plant nutrient uptake dynamics in this crop are not well understood. The aim of this research was to evaluate nutrient uptake and partitioning during the production cycle of a modern Nantes-type hybrid carrot. Trials were conducted in two commercial carrot seed production fields planted to ‘Nantes 969’. Below- and above-ground plant biomass was destructively sampled and separated into roots, tops, and umbels throughout... E. Jeliazkova, A. Moore, J. Spring, T. Wilson |
4. Refining Nitrogen Management for Organic Broccoli ProductionSpecialty organic fertilizers used in organic vegetable production are expensive. So, from environmental and economic perspectives, growers want to maximize nitrogen (N) fertilizer use efficiency by the crop. This research was conducted to (1) determine sufficient N fertilizer rates for organic broccoli, (2) evaluate the efficacy of a specialty organic fertilizer (feather meal; 12-0-0), and (3) confirm the effectiveness of midseason soil nitrate analyses (0-30 cm) in determining appropriate sidedress... D. Sullivan, R.E. Peachey, A. Donaldson |
5. Is Residue Management an Important Factor in the Soil Health of Perennial Grass Seed Production Systems?Residue management in agricultural systems is a crucial pathway of nutrient and organic matter flow and is predicted to affect soil health indices. In Western Oregon, perennial grasses for seed are a major crop, occupying roughly 150,000 ha in the Willamette Valley. Current estimates are that 80-85% of producers remove straw residue, exporting more than 650,000 US tons of straw annually. The primary objectives of this study were: i) evaluate soil health outcomes under residue retention and removal... B. Verhoeven, A. Moore, D. Sullivan, M. Gonzalez-mateu |
6. Cover Crops As A Source Of Plant-Available Nitrogen: Effect Of Residual Soil N And Cover Crop SpeciesFall-planted brassica and small grain cover crops have the potential to serve as catch crops by taking up residual soil nitrogen (N) in the soil. While plant species is often considered when estimating N release rates from cover crop residues, variation in residual soil N is rarely considered. The first objective of this study was to quantify the effect of N fertilizer application rate (to simulate varying residual soil N levels) on tissue N concentrations of several cover... J. Neuman, D. Sullivan, A. Moore |
7. Interpreting Compost AnalysesThis outreach publication is designed for wholesale buyers of compost for resale, nursery managers, public/private landscape managers, farm advisors, and farmers. The publication provides guidance on how to select a laboratory, based on intended compost end use (field application vs. potting soil). Interpretations are provided for laboratory tests available from commercial laboratories, including chemical tests (pH, soluble salt, macro- and micro-nutrients), physical tests... D. Sullivan |
8. Measuring Ammonia Loss Using Field-scale and Laboratory TechniquesFollowing the surface application of urea to soil, there is the potential for nitrogen (N) loss from ammonia (NH3) volatilization until sufficient rain or irrigation has moved it into the soil. Many studies measuring NH3 loss have used laboratory and microplot field studies. The limitation of these techniques is that they do not represent NH3 loss under natural conditions because enclosures alter air movement, humidity, and soil and air temperature inside the chambers. However, they... A. Heinrich, D. Sullivan |
9. Ammonia Volatilization from Urea Vs. Alternative Nitrogen FertilizersSubstantial ammonia (NH3) volatilization can occur from surface application of urea on sandy soils with low pH buffering capacity such as those in the semi-arid Columbia Basin. Previous studies have reported loss of up to 60% of urea-N as ammonia on these soils. The objective of this study was to quantify ammonia loss per acre for urea and for alternative N fertilizer products, including: sulfur-coated urea (SCU), urea coated with NBPT urease inhibitor (urea + Agrotain), ammonium sulfate... S. Del moro, D. Sullivan, D. Horneck |
10. Nitrogen Cycling and Fertilization in Legume Inclusive Cropping SystemsAmong other benefits, legumes contribute nitrogen (N) to subsequent crops. However, predicting the impact on yield and the timing of the N release is difficult. Regardless, adjustments in the N recommendation need to be made to avoid yield and crop quality problems, as well as negative environmental and social issues. Ideally, a reduction of pre-plant/early season N fertilizer is made based on field research. Two possible approaches are used, namely the Fertilizer Replacement Value (FRV) or the... B. Hopkins, J. Stark |
11. Chloride Effects on Nitrogen Uptake in Potato ProductionPotassium (K) can be supplied by potassium chloride (KCl) or sulfate (K2SO4) salts. Past research has shown that potatoes can take up and accumulate large amounts of chloride (Cl). Plant uptake of Cl can sometimes reduce petiole nitrate-N (NO3-N) concentration and it may have other effects on potato tuber yield and quality. In contrast, sulfate-S (SO4-S) typically does not compete strongly with NO3-N for plant uptake. This research was designed to evaluate the effect of Cl application on petiole... D. Sullivan, S. Light, D. Horneck |
12. Nitrogen Budgeting for Organic ProductionNitrogen management for high value vegetable crops under organic management is challenging. Organic systems rely on N mineralization processes in soil to deliver nitrate-N in adequate amounts with appropriate timing. The traditional nutrient management planning process (checkbook method: matching nutrient supply and demand over a production cycle) contains too many assumptions for accurate forecasting of plant-available N supply for organic systems. Organic fertilizers fall into three... D. Sullivan |
13. Development of Leaf Sampling and Interpretation Methods for Almond and Development of a Nutrient Budget Approach to Fertilizer Management in AlmondA five year research project on the use of N in orchards crops has been conducted to 1) to develop early season sampling protocols, and 2) to determine the response of Almond to various rates and sources of nitrogen (N) and potassium (K) fertilizers, 3) to develop nutrient demand curves and 4) to conduct a long term assessment of nutrient use efficiency with the goal of improving fertilizer management. Leaf and nut samples were taken at 5 stages of development throughout five seasons to determine... P.H. Brown, S. Saa, S. Muhammad, B. Sanden |
14. Nitrogen Transformations in Flooded Agroecosystems: a Case Study with Taro (Colocassia Esculenta)Wetland agriculture covers an estimated 170 million ha and contributes significantly to global food supply. Nitrogen fertilizers are subject to numerous potential transformation pathways in flooded systems. The present research was focused on improving our understanding of N transformations in a flooded agricultural system by addressing the following two broad objectives: 1) determine whether the presence of anammox bacteria and its activity contribute significantly to N losses, and 2) evaluate... J. Deenik, C. Penton, B. Popp, G. Bruland, P. Engstrom, J. Mueller, J. Tiedje |
15. Seasonal Water Distribution in a Drip-irrigated Cabernet Sauvignon VineyardSeasonal irrigation is vital to sustainable production of wine grapes in inland Washington. Without supplemental irrigation there is not enough rainfall during summer months to sustain plant health and productivity. Our 5 year project evaluates the effects of several regulated deficit irrigation treatments on soil water distribution throughout the growing season and the subsequent effects on yield and fruit quality in both Cabernet Sauvignon (CS) and Concord grapes; with a focus on wine grape... J. Davenport, J. Stout |
16. Development and Use of the OSU Organic Fertilizer and Cover Crop CalculatorFarm advisory visits in Oregon highlighted the need for decision tools to help farmers and agricultural professionals estimate nitrogen (N) mineralization from organic fertilizers and cover crops, design balanced fertilizer plans and identify the most cost effective nutrient management options. Laboratory and field research was conducted to develop N mineralization models for organic fertilizers and compost based on the total percent N. Field methods for estimating cover crop biomass and total... N. Andrews, D. Sullivan, J. Julian, K. Pool |
17. Highbush Blueberry Response to Compost and SulfurHighbush blueberry is adapted to soils with high organic matter and acidic pH, and it is often grown in Oregon with coniferous sawdust as a soil amendment or mulch. Composts could provide an alternative to sawdust, but acidification is needed to overcome high pH. Our objectives were to (i) predict the quantity of acidity needed to reduce compost pH to 4.8 (ideal for blueberry), (ii) determine compost characteristics suited for blueberry, and (iii) evaluate plant growth response and soil pH response... D. Sullivan, R. Costello, D. Bryla, B. Strik, J. Owens |
18. Choosing Your Nitrogen Fertilizers Based on Ammonia VolatilizationUntil recently we have not been able to measure ammonia volatilization without impacting the surrounding environment. In the past we have used closed chambers with acid traps. These closed chambers did not reflect surrounding weather conditions, at the minimum both temperature and wind were influenced. The use of the vertical flux method allows ammonia in the air to be monitored and modeled to reflect ammonia loss without any interference of the surrounding environment. ... D. Sullivan, D. Horneck, J. Holcomb, G. Clough |
19. Ammonia VolatilizationLittle work has been reported on the loss of ammonia from soils where fertilizers have been applied in an undisturbed environment. There are a multitude of studies that have used a chamber of some sort to estimate ammonia loss. The use of a chamber of some sort means that the environment has to be altered making the data derived suspect when translated into a loss number such as kg/ha. The advent of passive vertical flux method by Wood et al., 2000 at Aubrn University in Alabama, allows for the... J. Holcomb, D. Horneck, G. Clough, D. Sullivan |
20. K Fixation and Significance for Crop ProductionSome cultivated soils in California found on the east side of the San Joaquin Valley (SJV) and derived from granitic parent material have the capacity to fix added K, making it unavailable or less available to crops. The main soil mineral responsible for K fixation is vermiculite, which is a weathering product of mica, and which can occur in the clay, silt, and fine-sand size fractions. We have developed a model that predicts the location of K-fixing soils in the region and a practical soil test... S. Pettygrove, T. O'geen, R. Southard |
21. Predicting Plant-available Nitrogen Release from Cover Crop ResiduesImproved methods are needed to estimate the timing and amount of plant- available N (PAN) release from cover crops. The OSU Organic Fertilizer and Cover Crop Calculator, a downloadable spreadsheet tool, assists agricultural professionals in estimating N fertilizer replacement value of organic inputs. We conducted a series of laboratory incubations with cover crop biomass incorporated into soil to determine: (i) speed of PAN release, (ii) amount of PAN release, and (iii) robustness of the OSU Calculator... D. Sullivan, N. Andrews, R. Datta, K. Pool |
22. Polymer Coated Urea: Impacts on Water/air Quality with Surface Applicaton to Permanent SodNitrogen (N) is the most commonly used fertilizer and is essential to sustain the world’s populations. However, inherent inefficiencies in the soil-plant system result in losses of N to air and water, which can result in environmental quality problems. Two permanent sod turfgrass sites were fertilized with coated and uncoated urea and compared to an unfertilized control at 224 lb-N/ac. The polymer coated urea (PCU) was Duration 45 CR®. Fertilization resulted in increased growth and verdure... B. Hopkins, J. Lemonte, J. Summerhays, V. Jolley |
23. Phytosiderophore Exudation from the Roots of Iron Stressed Kentucky BluegrassSome Kentucky bluegrass (Poa pratensis L., KBG) cultivars are susceptible to iron (Fe) deficiency chlorosis when grown on calcareous soils and are routinely treated with Fe fertilizers. Aesthetics could be improved and this costly practice could potentially be eliminated with the use of cultivars resistant to Fe deficiency. Grasses are known to release phytosiderophore into the rhizosphere to dissolve Fe for plant use, and this characteristic has been used to screen for resistant... B. Hopkins, E. Buxton, V. Jolley, R. Christensen |
24. Residual Soil Nitrate and Potato Yield with Polymer Coated UreaPotato (Solanum tuberosum L.) requires steady, but not excessive nitrogen (N) supply for maximum tuber yield, size, and solids, as well as minimal internal and external defects. Although more costly and labor intensive than dry broadcast applications, growers typically apply a majority of N via fertigation. A controlled release N fertilizer, polymer coated urea (PCU), is a possible alternative to this growers’ standard practice. A newly formulated PCU may meet plant demand... B. Webb, B. Hopkins, J. Lemonte, T. Taysom, V. Jolley |
25. Elemental Sulfur with Iron: Kentucky BluegrassIron (Fe) is known to improve greenness of Kentucky bluegrass (KBG; Poa pratensis L.), although applications are relatively costly and labor intensive. A new fertilizer material, elemental sulfur impregnated with Fe (ES-Fe), may provide an alternative source of Fe for KBG. The effects of ES-Fe on KBG was evaluated comparing 55 lb-Fe ac-1 ES-Fe to ferrous sulfate (FS) at the same rate and chelated Fe as a foliar (CF) or soil applied (CS) in a glasshouse study. A separate... B. Hopkins, B. Webb, K. Marcroft, R. Christenson, V. Jolley |
26. Comparing Nutrient Availability in Low Fertility Soils Using Ion Exchange Resin Capsules and Plant Bioavailability Under Greenhouse ConditionsCommonly used soil resin analysis procedures have generally been developed to determine nutrient levels in agriculture soils. The purpose of the resin capsule procedure is to determine the amount of nutrient that correlates to that which is plant available. Desert soils contain lower levels of nutrients than agricultural soils, thus the validity of using resin capsules for desert soils is uncertain. In a previous incubation study it was determined that ion exchange resin capsules can be used as... B. Webb, B. Hopkins, M. Pletsch, D. Cook, M. Vickery, V. Jolley |
27. Phosphorus and Zinc Interactions in PotatoPotato production requires high soil phosphorus (P) application with potential negative environmental and nutrient uptake effects. Impacts of high available P on species in potato cropping rotations are not adequately understood, nor have the causes of reduced yield and quality from excess P been fully explored. Antagonistic interactions with cationic micronutrients such as zinc (Zn) are plausible explanations. Two hydroponic experiments were conducted with Burbank potato to elucidate P and Zn... B. Webb, B. Hopkins, J. Ellsworth, S. Barben, B. Nichols, V. Jolley |
28. 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 |
29. Nitrogen Cycling and Partitioning Under Alternative Organic Orchard Floor Management StrategiesOrganic orchard systems are a significant and growing component of Washington State agriculture, yet sustainable methods of nitrogen (N) fertility and weed management remain a challenge. Nutrient supply is dependent on decomposition and mineralization of organic matter, yet intensive cultivation commonly used to control weeds can disrupt biological processes and cause loss of organic matter. To address the often-competing goals of organic fertility and weed control, a number of alternative orchard... L. Carpenter-boggs, D. Granatstein, J. Reganold, L. Hoagland, M. Mazzola, F. Peryea, J. Smith |
30. Optical Sensing for Nitrogen ManagementAlthough nitrogen (N) nutrition is as or more important than other nutrients, it has been largely ignored by those applying variable rate fertilizer (VRF) due to its loss potential for VRF applications that occur many weeks prior to crop need. Applications of N are best applied as close to crop uptake as possible in order to avoid leaching, denitrification, and other losses. Spatial variability for crop N need is often considerable due to differences in yield potential and, to a lesser degree,... B. Hopkins, S. Stephens, A. Shiffler |
31. Boron Fertilization in PotatoThe high value of potato (Solanum tuberosum L.), its inefficient rooting system and the low organic matter content of sandy soils on which potatoes are cultivated result in widespread application of boron (B) and other micronutrients. However, in times of cost trimming, B may become an omitted input regardless of soil test values. Further, soil tests for B may need to be updated for higher yields, better management or improved soil test methods. Russet Burbank potato was grown at... B. Webb, B. Hopkins, J. Ellsworth, V. Jolley, R. Callahan |
32. Cool Season Mineralization of Recalcitrant Organic N in Undisturbed Cores of Manured SoilsThe objectives of this study were to (1) quantify cool season N mineralization from recalcitrant organic N in soils with a long history of manure application and (2) examine the relationship between cool season recalcitrant organic N mineralization and a fall mineralizable N index. “Cool season” was defined as October to February for fields with winter crops and October to May for fields with no winter crops. Two in situ trials were conducted with undisturbed soil... D. Moberg, D. Sullivan, R. Johnson |
33. Evaluation of N Uptake Analysis As a Tool for Determing Potato N StatusPlant tissue testing has become the primary method for evaluating nitrogen availability for potatoes during the growing season. This study was conducted to determine if plant N uptake rates referenced to absorbed solar radiation could also be used as a tool to quantitatively assess plant N status of different potato varieties. Nitrogen fertilizer, as NH4NO3 (34-0-0), was applied to Russet Burbank, Gem Russet, Bannock Russet and Summit Russet at three rates (0, 100, or 300 kg N/ha) using two... J. Stark, S. Love, C. Mcintosh |
34. Developing Extension Guidance for Management Effects on Ammonia Loss: a Computer Simulation Modeling ApproachComputer simulation models provide insight into ammonia loss processes and the sensitivity of ammonia loss predictions to environmental and management variables. As an example of how a simple computer simulation model can inform the Extension guideline development process, the ALFAM (Ammonia Volatilization from Field-Applied Animal Slurry) model was used to estimate NH3 loss from surface- applied municipal biosolids: liquid (3% dry matter) and dewatered (22% dry matter). Model output... D. Sullivan |
35. Polymer Coated Urea in Potato ProductionNitrogen (N) is the most important mineral nutrient in potato (Solanum tuberosum) production. Studies show a steady, but not excessive, supply of N is important for maximum tuber yield, size, and solids, as well as minimal internal and external defects. Although more costly and labor intensive dry broadcast applications, growers typically apply the majority of N through the irrigation water in-season in order to maximize yield components. A controlled release N fertilizer, in the form of polymer-coated... B. Hopkins, T. Taysom, A. Shiffler, S. Stephens |
36. Determining Lime Requirements for Idaho SoilsFor the past 25 years, northern Idaho soils have significantly shown a decline in soil pH, from pH 6.0 to around a pH of 5.6. Southern Idaho soils are mostly neutral to alkaline, with a pH of around 7.0 to 8.5, however, most agricultural soils pH is declining to pH < 4.5. Soil acidification is becoming a rising issue in soil sustainability, in which approximately 30% of the world surface is covered by acidic soils. Low soil solution pH can be induced by continued irrigation that increases... K.L. Mookodi, J. Spackman, J. Sagers, K. Schroeder |
37. Barley Yield and Protein Response to Nitrogen and Sulfur Rates and Application TimingThe introduction of new barley varieties, as well as changes in management practices, necessitate a re-evaluation of nitrogen (N) and sulfur (S) nutrient management guidelines. Nitrogen has a significant impact on barley grain quality and yield. Overapplication of N can result in lodging, groundwater pollution, and high protein content, resulting in lower end-use quality of barley, while underapplication of N results in reduced grain quality and yield. Sulfur promotes N utilization in barley plant... O. Adeyemi, J. Spackman, J. Sagers, J. Marshall, Z. Hong, R. Findlay, J. Bevan |
38. Monitoring Soil Nitrate to Estimate Cover Crop N Contribution in Organic Vegetable Production FieldsOrganic vegetable growers rely on legume cover crops as an economical source of plant-available N. This research evaluated N contributions to summer vegetable crops by cover crops (CC) residues by monitoring soil nitrate (NO3-N) concentrations during the summer crop growing season. Replicated field plots were established with three CC mixes: solo common vetch (V), phacelia + V (PV), and cereal rye + V (RV), plus a winter fallow (F) control in grower fields in the north Willamette Valley... D. Sullivan, N. Andrews |
39. Using Calcium Hydroxide for Lime Incubation Studies and Moisture Effects on LimingPlant health and productivity are negatively affected by soil acidity. Soil physical properties such as soil texture, soil organic matter, and nutrient content help soils resist changes in their acidity (buffering capacity). Soils have different buffering capacities; agricultural producers need to know how responsive a soil is to lime and how much lime is required to modify a soil to a certain pH (lime requirement). One method to evaluate soil liming requirements and buffering capacity is to add... C. Collins, E. Loera, R. Reid, J. Spackman |
40. 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 |
41. Optimizing Nitrogen Fertilizer Rates for Annual Cereal Forage ProductionNitrogen fertilizer provides one of the greatest returns on investment but also one of the highest operating expenses for annual cereal forage production. It is important to know the total nitrogen required by a crop to optimize yield and quality and to minimize nitrogen losses to the environment. It is also possible that annual cereal forage species and cultivars will have varying responses to nitrogen availability. The objective of this study was to determine the optimal nitrogen fertilizer... J. Spackman, R. Findlay, J. Sagers, J. Pandey |
42. Polymer Coated Urea: Microplastics in the Urban LandscapePolymer Coated Urea (PCU) in urban landscapes has recently become a controversial practice as some fear the repercussions of the polymer coatings left behind in soils and the environment to potentially be detrimental to land and water ecosystem health. The use of PCU has been beneficial in effectively supplying nitrogen (N) to plants with less leaching, denitrification, and volatilization losses to the environment. However, the pollution of microplastics may outweigh these benefits. The purpose... C. Seely , B. Hopkins |
43. Irrigation Management and Drought-tolerant Genetics on Nutrient UptakeAlfalfa is exceptional at obtaining nutrients from the soil with its deep tap root. However, with its ability to consume vast amounts of phosphorous and potassium more is used than what is made available each year. This results in the need of nutrient management plans. With the continuing of the drought, nutrient management becomes more difficult. Irrigation management, drought tolerant genetics, and sprinkler technology can play an important role in nutrient management and affect financial outcomes... D. Boren, M. Yost, T. Sullivan |
44. Nutrient Management for Semi-arid Cannabis ProductionThe industrial hemp (Cannabis sativa L.) industry rapidly emerged in Utah in 2019 with nearly 480 new hectares of hemp production. Production declined and stabilized during 2019-2022 due to low returns in a flooded pharmaceutical market. Though small and specialized, the hemp production industry is still viable in Utah and surrounding states. Many questions remain on optimal production practices for this new and potentially high-value crop. Research throughout the United States... T. Sullivan, M. Yost, D. Boren, E. Creech, B. Bugbee |
45. Nitrogen Fertilizer Rate and Timing Implications for Malt, Food, and Feed Barley Production in Southern IdahoNitrogen is an essential nutrient required to produce high-yielding barley. Nitrogen strongly impacts barley yield, grain protein, tillering, and lodging potential. Unlike other crops such as corn, available nitrogen must be carefully managed for producers to achieve both optimal yield and grain quality for malt, food, and feed barley. Exessive nitrogen availability increases grain protein concentration that may be unsuitable for malting but may be ideal for feed or food barley. The objective... J. Spackman, O. Walsh, A. Adjesiwor, O. Adeyemi, J. Sagers, R. Findlay, J. Bevan |
46. Response of Soil N Cycling, Nitrifying Organisms, and Winter Wheat Yield and Quality to Nitrification Inhibitors in High Rainfall Zones of Northern IdahoLeaching of fertilizer nitrogen contributes to environmental pollution and is an economic loss for agricultural producers. Leaching of inorganic nitrogen fertilizers is intensified when applied to areas of high rainfall zones in excess of crop requirements. Reduction of this nitrogen loss may be achieved through the application of nitrification inhibitors at the time of planting to prevent the transformation of ammonia to more leachable nitrate by nitrifying organisms. Much research on nitrification... S. Philpott, H. Tao, K. Schroeder |
47. Variable Rate N and P Management for High-value Vegetable Cropping SystemsThe Lower Colorado River Region (LCRR) of Arizona and California and their environs produce more than 90% of the nation’s cool season vegetables during the fall-winter-spring period. Large amounts of N and P fertilizers are currently utilized for maximum yield and quality. Phosphorus fertilizers are applied pre-plant based on a soil test of a composite field sample. Nitrogen is applied by side-dress based on a plant midrib or petiole N analysis, or soil nitrate-N test, from a... C.A. Sanchez, P. Andrade |
48. Floral Hemp Responses to Nitrogen Fertilization in the High DesertThe performance of floral hemp under N fertilization is influenced by environmental conditions, management and cultivar selection. This field study evaluated the effect of no supplemental N and N fertilization at 90 kg ha-1 on three hemp cultivars (Berry Blossom, Red Bordeaux, and Tahoe Cinco) in Northern Nevada. Nitrogen increased plant height, canopy cover, stem diameter and shoot biomass, but other physiological parameters were dependent on cultivar. We evaluated the use... F. Barrios masias, M. Farnisa, J. Solomon, G. Miller |
49. Optimizing Fertigation for High Value CropsIn irrigated farming systems, soluble and mobile fertilizers, such as sources of nitrogen, are often applied to crops through fertigation. Fertigation presents both opportunities and challenges. Potential opportunities include better synchronization of nutrient availability with crop demand through the growing season and potential energy savings. Challenges include the need for additional investment on infrastructure for nutrient injection into the irrigation conveyance and distribution system,... C.A. Sanchez, D. Zerihun |