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1. The Fertilizer Recommendation Support Tool (FRST) Initiative: National Survey on Soil Fertility Recommendations and Correlation/Calibration DatabaseSoil fertility testing is an integral tool used in nutrient management planning, providing information needed to determine where nutrients are required and how much to apply. While a great deal of effort has been successfully invested in standardizing soil test methods in the U.S. over the last few decades, up-to-date correlation/calibration studies are lacking in many states. In most cases, soil test correlation/calibration efforts lead by land-grant universities are on a state-by-state or lab-by-lab... S.E. Lyons, J.T. Spargo, D.L. Osmond, A.W. Pearce, N.A. Slaton, D.K. Arthur, P.J. Kleinman, J.M. Mcgrath |
2. Stacking and Intersecting Nutrient 4Rs and Using In-Season Canopy Health and Petiole Nitrate Analysis on Russet Burbank PotatoesThe 4Rs of nutrient management is a global outreach with an aim to improve the sustainability of major cropping systems and the environment. The objective for this project is to evaluate individual and stacked 4R management practices and how they intersect in Russet Burbank potato at a field near Grace, Idaho in 2020. Nitrogen (N) fertilizer treatments included all combinations of two sources [urea vs polymer coated urea (PCU)], two rates (207 vs. 247 kg ha-1), and two timing/placements... S. Stapley, B. Hopkins |
3. Overview of the Efficacy of BiostimulantsSo-called “biostimulants” have been around a long time, but interest in these crop production products is growing exponentially. A survey of major fertilizer companies indicates it is one of the top three current trends in their businesses— with significant research, development, and investment. However, this major trend in agriculture is fraught with misperception, confusion, and generally lacking credentialed recommendations. Biostimulant is not listed as a word... B. Hopkins |
4. Polymer Coated Urea and Urea Blends on PotatoPotato (Solanum tuberosum L.) is a globally important crop with significant economic and environmental impacts. Nitrogen (N) has a large impact in both instances. Polymer coated urea (PCU) is a N source with the ability of improving production and the environment. Environmentally Smart Nitrogen (ESN) is a PCU that may reduce the need for continual N application throughout the season. The objective of this research was to evaluate the impacts on potato tuber yield and quality with uncoated... E. Carlock, A. Weigel, T. Searle, T. Hopkins, J. Williams, B. Hopkins |
5. Polymer Coated Urea Impact on Barley Yield and ProteinPolymer coated urea (PCU) is an enhanced efficiency nitrogen (N) fertilizer shown to regulate N release over a season benefiting production and reducing nutrient pollution. The purpose of this study was testing the effect of uncoated and coated urea blends on irrigated barley yield and protein. The study consisted of three N rates applied as all urea or a 50-50 blend of PCU and urea. As expected, N rates increased yields and protein. In general, urea resulted in increased yields with... S. Fahning, T. Searle, A. Weigel, R. Buck, T. Hopkins, B. Hopkins |
6. Struvite Phosphorous Fertilizer on Sugar BeetSugar beet is very sensitive to P deficiency early in the growing season. Crystal Green is a struvite phosphorus (P) fertilizer source that may uniquely enhance uptake in sugar beet. In this study, we examine the effect of struvite applied to sugar beet and compare the results against the use of traditional monoammonium (MAP) fertilizer and a control. There was a significant increase in response to MAP over the control for both total and sugar yield. The struvite based fertilizer had an additional... J. Fisher, E. Woolley, J. Svedin, B. Hopkins |
7. Water and Nitrogen Interactions in Kentucky BluegrassPressure is increasing in arid regions to conserve water, especially during drought. Turfgrass is the irrigated crop of greatest acreage in the United States and is coming under scrutiny in urban ecosystems. The purpose of this study was evaluating water use by Kentucky bluegrass (Poa pratensis L.) under various irrigation and nitrogen (N) regimes. A study was conducted in an established stand of Kentucky bluegrass in Provo, UT, USA. The turfgrass was split equally into 27 plots (11... A. Hopkins, C. Campbell, B. Hopkins, N. Hansen |
8. 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 |
9. Polymer Coated Urea in Kentucky BluegrassNitrogen (N) is a commonly over-applied nutrient in urban environments. This over-application has led to nutrient pollution of the atmosphere and hydrosphere. The losses of N to the environment can be mitigated with the use of enhanced efficiency fertilizers, such as polymer coated urea (PCU). Some PCU labels state that a single annual application is a best management practice. The objective of this study was to evaluate a PCU compared to monthly applications of ammonium sulfate/urea.... S. Stapley, J. Buss, B. Hopkins |
10. Phosphorus Fertilizer and Hydrogel for Rangeland SeedingThe US Air Force uses live munitions at Hill Air Force Base, a desert testing range west of Salt Lake City, Utah, USA. Resultant fire has disturbed rangeland vegetation. Revegetation of the area is impeded by low average precipitation rates of approximately 0.025 m per year, and opportunistic invasive species. Previous studies indicated hydrogel increases soil water content and the longevity of bottlebrush squirrel tail seedlings. In this glasshouse study, the effects... M. Valencia, S. Nelson, B. Hopkins |
11. Struvite Phosphorus Fertilizer on PotatoPotato (Solanum tuberosum L.) is a staple in the global economy and on the dinner table. It has an unusually high demand for phosphorus (P) due to its shallow, inefficient root system. Most P fertilizers are water soluble, but then precipitate quickly—potentially resulting in poor plant uptake. Crystal Green (a struvite based fertilizer) is acid soluble, but not water soluble. In theory, it remains undissolved until plant roots exude acids— potentially avoiding the precipitation... R. Woolley, J. Svedin, E. Woolley, B. Hopkins |
12. Boron Fertilization with Aspire® in Alfalfa and PotatoPotassium (K) and boron (B) are essential nutrients. The spatially even distribution of applying K fertilizer is typically not a problem, but for B fertilizer application, it is a problem. This is especially difficult for crops such as alfalfa (Medicago sativa L.) and potato (Solanum tuberosum L.) due to low B rate and limited soil exploration by roots. Fertilizer with K and B fused into a single granule could result in even distribution. Trials were performed to evaluate the performance... E. Woolley, T. Searle, T. Hopkins, J. Williams, B. Hopkins |
13. New Hydroponic System for Testing Mineral Nutrient Deficiencies and its Application to QuinoaCorrelating plant tissue nutrient concentrations with visual symptoms is valuable in combating mineral nutrient deficiencies and toxicities. Major crops tend to have large amounts of information regarding nutrient concentrations and visual symptoms of deficiencies, but this information is often lacking for minor crops, including quinoa (Chenopodium quinoa L.) Because nutrient concentrations can be easily controlled, hydroponics effectively demonstrate isolated specific nutrient related symptoms.... D. Cole, R. Woolley, R. Buck, B. Hopkins |
14. Evaluation of Nitrogen Fertilization and Drip Irrigation Levels on Yields of San Joaquin Valley, California, Forage Corn and Sorghum CultivarsIn California (CA), approximately 500,000 acres of corn are grown annually, with most grown for dairy forage. Under reduced irrigation water (IW) supply conditions, forage sorghum acreage can increase to 90,000 acres annually. Corn nitrogen (N) demand is well documented in studies conducted outside of CA, but little research on forage corn and sorghum N use efficiency (NUE) under varying levels of IW has been conducted. With such a large statewide acreage, it is important to improve... R. Hutmacher, N. Clark, J. Dahlberg, J. Angeles |
15. Soil Water and Plant Canopy Sensor Technologies to Optimize Water and Nutrient UseIn many respects, agricultural technology is doing things now that were only imagined 20 to 30 years ago. Yet, grower tools that provide information and actionable knowledge on water and nutrient availability still remain a challenge. Clearly, rapid development of data transfer and processing platforms to date has provided rich maps of grower fields with overlays of location-specific information but their utility is still limited by our ability to accurately measure the parameters that are the... C. Campbell, N. Hansen, B. Hopkins, S. Evans, E. Campbell, A. Campbell, L. Rivera, D. Cobos |
16. Nitrogen and Water Interactions: Crop Production Systems Case StudiesFarmers and urban land managers have to strike a tenuous balance between achieving plant growth goals while responsibly managing natural resources. Water quality and scarcity issues are prominent concerns, along with soil quality preservation and conservation of fuel and fertilizer resources. The purpose of this presentation will be to highlight case studies where water and crop management practices were considered together to improve the efficiency of resource use. Evidences of water scarcity... B. Hopkins, N. Hansen |
17. Soil Management Assessment Framework Use for Identifying Soil Quality Changes in Irrigated AgricultureThe 820 km2 Twin Falls (Idaho) irrigation tract is part of the Natural Resources Conservation Service (NRCS) - Conservation Effects Assessment Project (CEAP). Furrow irrigation was initiated in the early 1900s but, since the 1990s, the NRCS Environmental Quality Incentives Program (EQIP) and other specialty projects have resulted in conversion of approximately 40% of the irrigation tract area to sprinkler irrigation. Most past CEAP research has focused on water quantity and quality, effects... J. Ippolito, D. Bjorneberg, D. Stott, D. Karlen |
18. 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 |
19. Creating Prescription Variable Rate Irrigation and Fertilization Zones: Water and Nutrient Management InteractionsVariable rate irrigation (VRI) and variable rate fertilization (VRF) technologies allow irrigation and fertilization rates to be spatially customized. VRF is widely adopted, but VRI is an emerging technology with minimal adoption. As water is often the driving force in nutrient cycling, our overall objectives are to evaluate VRI influences on VRF and vice versa; and to combine these technologies to significantly increase crop yield and quality, conserve water, and minimize environmental impacts... J. Svedin, N. Hansen, R. Kerry, R. Christensen, B. Hopkins |
20. Improving Phosphorus Use Efficiency: Right Rate, Timing, and Placement and Enhanced Efficiency Fertilizer Sources: Research SummaryPhosphorus (P) fertilization is essential for societal sustainability. However, plant P uptake is inefficient due to poor soil P solubility, especially for crops such as potato (Solanum tuberosum L.) plant due to relatively poor rooting efficiency and high demand. Phosphorus use efficiency (PUE) improves with the right rate, timing, placement, and with using enhanced efficiency fertilizer products (EEF). We have conducted several dozen studies over nearly two decades showing PUE is improved... E. Shipp, T. Hopkins, B. Hopkins |
21. Nitrogen and Irrigation Water Interactions in Drought Stressed Kentucky BluegrassThere is increasing pressure in arid regions to conserve water, especially during drought. Turfgrass is the irrigated crop of greatest acreage in the United States and water use for irrigating turf is coming under scrutiny in urban ecosystems. The purpose of this study was to evaluate water use and growth of Kentucky bluegrass (Poa pratensis L.) under various irrigation and nitrogen (N) regimes. A study was conducted in an environmentally controlled growth chamber with established Kentucky... K. Russell, A. Hopkins, N. Hansen, B. Hopkins |
22. Polymer Coated Urea: Meeting Plant Needs While Mitigating Environmental Impacts — Research SummaryFertile soil is the foundation of food production and is maintained by replacing nutrients lost in harvest or to the atmosphere and hydrosphere. Nitrogen (N) accounts for approximately half of global fertilizer inputs. However, N recovery by plants is inherently inefficient due to “leaks” in the system, causing air and water pollution. Additionally, poor fertilizer efficiency is a waste of natural resources and potentially reduces yields, crop quality, and grower profits. Nitrogen-use... S. Bartholomew, T. Hopkins, B. Hopkins |
23. Drought and Nitrogen Stress Effects on Maize Canopy TemperatureWater scarcity is a major threat to the sustainability of irrigated agriculture. Management practices, such as limited irrigation, that seek to maximize the productivity of a limited water supply are critical. Remote sensing of crop canopy temperature is a useful tool for assessing crop water status and for more precise irrigation management. However, there is potential that nutrient deficiencies could compound the interpretation of water status from leaf temperature by altering leaf color and... A. Carroll, C. Lindsey, J. Baker, B. Hopkins, N. Hansen |
24. Phosphorus and Organic Acid Bonding Impacts at Varying Soil pHPhosphorus (P) fertilizer is essential for crop production, but reductions are warranted to conserve resources and minimize environmental impacts. Several lab, glasshouse, growth chamber, and field studies have been performed over the past six years with a new P fertilizer (Carbond P; CBP; Land View Fertilizer, Rupert, ID, USA) mostly in calcareous, low OM soil. Studies comparing CBP to ammonium polyphosphate (APP) and monoammonium phosphate (MAP) applied to soil show season-long increases in... T. Blair, C. Ransom, P. Hosford, J. Svedin, L. Sutton, A. Winchester, K. Manning, T. Hopkins, B. Hopkins |
25. Minimizing Nitrogen Inputs While Optimizing Verdure and Growth of Kentucky Bluegrass with Polymer Coated UreaNitrogen (N) fertilizer increases turfgrass verdure but also increases maintenance costs due primary to mowing. A two-year fertilization study was initiated April 2014 at two established Kentucky bluegrass sites with sand and loamy sand constructed field soils in Provo, UT. A grower’s standard practice (GSP) of urea split applied monthly was compared to blend of uncoated and polymer coated urea (PCU). The PCU was applied in 1, 2, or 3 split applications. The dual application applied at 50,... J. Buss, J. Gish, B. Hopkins |
26. Cropmanage: an Online Decision Support Tool for Irrigation and Nutrient ManagementVegetable and berry growers on the central coast of California are under growing regulatory pressure to reduce nitrate loading to ground and surface water supplies. Two tools available to farmers to improve nitrogen use efficiency of these crops are the soil nitrate quick test (SNQT) for monitoring soil residual N concentrations and evapotranspiration (ET)-based irrigation scheduling for estimating crop water requirements. We developed a web-based software application, called CropManage (https://ucanr.edu/cropmanage),... M. Cahn, T. Hartz, R. Smith, B. Noel, L. Johnson, F. Melton |
27. 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 |
28. Cover Cropping in the Semi-arid West: Effects of Termination Timing, Species, and Mixtures on Nitrogen Uptake, Yield, Soil Quality, and Economic ReturnSummer fallow still dominates some areas of the northern Great Plains (NGP), providing an opportunity to grow a partial season cover crop for increased soil health or nutrient availability. Over 12 years of research on single species cover crops in semi-arid Montana have revealed the benefits of early termination and multiple cover crop cycles on N availability, subsequent crop yield, soil health, and economic return. Due to high N fixation, pea cover crops have fairly consistently increased subsequent... C. Jones, P. Miller, S. Tallman, M. Housman, C. Zabinski, M. Burgess, J. O'dea, A. Bekkerman |
29. Nitrogen Nutrition Impact on Incidence of Rhizoctonia Infection of Agrostis StoloniferaCreeping bentgrass (Agrostis stolonifera L.) is tolerant of short mowing and high traffic, but these conditions increase pathogen susceptibility. A prevalent disease on bentgrass golf course greens and tee boxes is Brown Patch (Rhizoctoniasolani). One potential component of integrated pathogen management is correct nitrogen (N) fertilization. Bentgrass was grown in a chamber hydroponically at deficient, optimum, and excessive levels of N (2.5, 10, and 80 mM; equivalent to 6.9, 27.5, and 220... B. Hopkins, B. Black, B. Neville, C. Ewell, B. Geary |
30. Summarization of 471 Field Comparisons of Avail®Phosphorus (P) is a commonly deficient essential nutrient required for crop production. Economic, environmental, and conservation issues have motivated significant efforts to enhance fertilizer efficiency. AVAIL® is a specialty fertilizer product with claims of enhancing P use efficiency to potentially increase crop yield and quality. There have been at least 471 field comparisons to evaluate the effectiveness of AVAIL with a wide variety of crops. The objective of this summarization... B. Hopkins, K. Fernelius, M. Pryor |
31. Effects of Post-fire Soil Hydrophobicity on Inorganic Soil Nitrogen and Sulfur CyclingFire plays an important role in many native ecosystems, and its suppression has increased woody encroachment across the globe. Restoring native herbaceous communities following fire in encroached systems is often challenging. Post-fire soil hydrophobicity is one factor that may further limit site restoration by limiting soil moisture, which may in turn affect soil nutrient dynamics. We conducted a field study in a burned pinion-juniper woodland to understand the effects of post- fire soil hydrophobicity... B. Hopkins, K. Fernelius, M. Madsen, K. Russell, B. Roundy |
32. Turf Response to Reduced Rates of Polymer-coated UreaPolymer-coated urea (PCU) is a controlled-release fertilizer which can enhance nitrogen (N) use efficiency (NUE), reduce N pollution, reduce the need for repeated fertilizer applications, and reduce turfgrass shoot growth and associated costs. A PCU fertilizer rated for 120 d was applied at 50, 75, and 100% of the recommended full rate and compared to an unfertilized control and urea, applied either all at once or split monthly at the full recommended rate. Spring applied PCU showed no initial... B. Hopkins, C. Ransom, M. Ruth, T. Blair, L. Sutton, D. Bradshaw, K. Campbell |
33. Phosphorus and Organic Acid Bonding Enhances Uptake Efficiency and Yield Response in Crop PlantsPhosphorus (P) fertilizer is essential for crop production, but reductions are warranted to conserve resources and minimize environmental impacts. Several lab, glasshouse, growth chamber, and field studies have been performed over the past seven years with a new P fertilizer (Carbond P; CBP; Land View Fertilizer, Rupert, ID, USA) in calcareous, low OM soil. This paper will be a review of a portion of that data. Studies comparing CBP to ammonium polyphosphate (APP) and monoammonium phosphate (MAP)... B. Hopkins, T. Blair, J. Selman, C. Ransom, T. Hopkins |
34. Evaluation of Nitrogen Gas Loss from Polymer Coated and Polymer Sulfur Coated UreaPrevious research showed reduced nitrogen (N) gas emissions from polymer coated (PCU) and polymer sulfur coated urea (PSCU) when surface applied to soil. To further verify and quantify (N) loss, experiments were conducted to measure N gas emissions. Fertilizer prills were surface applied in a semi enclosed system to allow atmospheric gases in but to prevent loss of N gases from the headspace. Nitrous oxide (N2O) and ammonia (NH3) emissions were continuously measured every 20 minutes using photoacoustic... B. Hopkins, J. Svedin, C. Ransom, J. Buss, T. Blair |
35. Sensor-based Technologies for Nitrogen Management in Spring WheatCrop sensor-based systems with developed algorithms for making mid-season fertilizer nitrogen (N) recommendations are commercially available to producers in some parts of the world. Although there is growing interest in these technologies by grain producers in Montana, use is limited by the lack of local research under Montana’s semiarid conditions. A field study was carried out at two locations in 2011, three locations in 2012, and two locations in 2013 in North West Montana. The objectives... O. Walsh, A. Pandey, R. Christiaens |
36. Evaluation of Micro-carbon Technology-based P Fertilizer, Super Phos®, in Spring WheatSuper Phos® (SP; 0-50-0) by Bio Huma Netics Inc. (Gilbert, AZ) is a Micro Carbon TechnologyTM – based phosphorus (P) fertilizer specifically formulated to resist “tie-up” with calcium (Ca) and magnesium (Mg) to remain water soluble and available to plant roots. The objective was to compare the efficiency and effectiveness of topdress and foliar application of SP, with traditional P fertilizers – ammonium polyphosphate (APP; 10-34-0), diammonium phosphate (DAP;... O. Walsh, A. Pandey, R. Christiaens |
37. Environmentally Smart Nitrogen Performance in Northern Great Plains’ Spring Wheat Production SystemsField trials were conducted at three locations in Montana to evaluate the efficacy of Environmentally Smart Nitrogen (ESN) (44-0-0) as a nitrogen (N) source for spring wheat. The ESN, urea (46-0-0), and a 50%-50% urea-ESN blend was applied at seeding at three rate levels - low, medium, and high - with actual rated dependent on the yield goal at each location, followed by urea application of 0 or 40 lb N/a at Feekes 5. Grain yield (GY) varied from 265 to 815 lb/a and grain protein (GP) content... O. Walsh, A. Pandey, R. Christiaens |
38. Liquid N Fertilizer Evaluation in Spring WheatSeveral liquid N products are currently marketed for fertilization in various crops, including spring wheat. Urea ammonium nitrate (UAN) - the most commonly used liquid N fertilizer - is associated with crop damage due to corrosiveness. This study aimed to answer the following questions: (1) Are liquid urea (LU) and High NRG-N (HNRGN) superior to UAN in improving spring wheat grain yield and protein content? And (2) what is the optimum dilution ratio of foliar fertilizers and the threshold at... O. Walsh, A. Pandey, R. Christiaens |
39. Phosphorus and Organic Acid Bonding Enhances Uptake Efficiency in Crop PlantsPhosphorus (P) fertilizer is essential for crop production, but reductions are warranted to conserve resources and minimize environmental impacts. Several lab, glasshouse, growth chamber, and field studies have been performed over the past five years with a new P fertilizer (Carbond P; CBP; Land View Fertilizer, Rupert, ID, USA) in calcareous, low OM soil. This presentation will be a review of that data. Studies comparing CBP to ammonium polyphosphate (APP) applied to soil show season-long increases... B. Hopkins, T. Blair, M. Hill, C. Ransom |
40. Irrigation and Nitrogen Management Web-based Software for Lettuce ProductionLettuce growers on the central coast of California are under increased regulatory pressure to reduce nitrate loading to ground and surface water supplies. Two tools available to farmers to improve nitrogen use efficiency of lettuce are the quick nitrate soil test (QNST) for monitoring soil mineral nitrogen levels and weather-based irrigation scheduling for estimating water needs of the crop. We developed a web-based software application, called CropManage (https://ucanr.edu/cropmanage), to facilitate... M. Cahn, R. Smith, T. Hartz, B. Noel |
41. Inhibitors, Method and Time of Nitrogen Application for Improved Winter Wheat Production in Central MontanaThe contribution of nitrogen (N) fertilizer to boost yield and improve quality is unquestionable. Inefficient use of applied N is economically significant and environmentally unsafe. Ammonia loss can exceed 40% of applied N. Nitrogen leaching is polluting wells. Use of urease and nitrification inhibitors along with appropriate timing and method of nitrogen application can reduce nitrogen loss, improve yield and quality of wheat. This experiment investigated the effect of timing and method of N... Y. Mohammed, T. Jensen, J. Heser, C. Chen |
42. Exploring Controlled Release Nitrogen Fertilizers for Vegetable and Melon Crop Production in California and ArizonaVarious forms of polymer coated urea (PCU) were examined as sources of controlled release nitrogen for production of cauliflower, watermelon, carrot, and spinach in Arizona or California. Studies were designed to demonstrate the effectiveness of PCU for supplying 100 percent of the fertilizer nitrogen needed for an entire growing season in a single pre-plant application. In each study, two or more N rates were tested. PCU having an appropriate release time for a given set of growing conditions... R. Smith, A. Blaylock, E. Ellison, C. Sanchez |
43. Efficient N Fertility and Irrigation Management in Vegetable and Berry ProductionNitrogen (N) fertility and irrigation management for vegetable and berry production has historically been done on an ‘agronomic’ basis, with the sole focus on producing the optimal crop. For these crops N fertilizer and water costs are a small portion of overall production costs, and an even smaller portion of crop value; consequently, these inputs have not been scrutinized as closely as they have been for lower value crops. However, throughout the West concern over environmental water... T. Hartz, R. Smith, M. Cahn |
44. Polymer Coated Urea (ESN): Impacts on Potato Crop and N LossesPotato (Solanum tuberosum L.) production is sensitive to a steady, adequate supply of nitrogen (N). Synergistically optimizing grower profits while maximizing N use efficiency (NUE) is critical to conserve nonrenewable natural resources used to manufacture N fertilizer and minimize N pollution to water and the atmosphere. Polymer coated urea (PCU, Environmentally Smart N or ESN®) is one type of N fertilizer which uses temperature-controlled diffusion to control N release to better match plant... B. Hopkins, C. Ransom, T. Taysom, J. Lemonte |
45. Polymer Coated Urea (Duration) in Turfgrass: Impacts on Mowing, Visual, and Loss to EnvironmentFall and spring applied N fertilizer trials were conducted over two years in an effort to determine if various slow and controlled release N fertilizers were equivalent to traditional urea and to determine if a reduced rate of controlled release N could be used for improved N use efficiency. An unfertilized control was compared to sulfur coated urea (SCU), polymer and sulfur coated urea (XCU), polymer coated urea (Duration 75 or 125; DR) at 50, 75, and 100% (full) rate, and urea either applied... B. Hopkins, L. Sutton, C. Ransom, T. Blair, J. Moody, K. Manning, S. Bergsten |
46. Improving Phosphorus Use Efficiency with Carbond PPhosphorus (P) fertilizer is integral for maximizing crop production and is used abundantly to achieve desired yields. However, reduction of P fertilizer is warranted, as it is the primary source of nutrient pollution in surface waters (eutrophication leading to hypoxia) and is derived from non-renewable mineral resources. Two research studies were conducted in 2009 to evaluate a new fertilizer product, Carbond® P against traditional fertilizers ammonium polyphosphate (APP) and monoammonium... B. Hopkins, B. Webb, M. Hill, C. Ransom |
47. Advances in Nutrient Use EfficiencyThe improvement of fertilizer efficiency is driven by narrow profit margins, environmental concerns, and resource conservation. Fertile soil is the foundation for food production and successful civilizations; it is developed and maintained through the addition of nutrients lost through harvest. However, nutrient uptake by plants is inherently inefficient and the nutrients remaining in the soil after uptake can cause negative air and water resource impacts. In addition, poor fertilizer efficiency... B. Hopkins |
48. Measured and Predicted Temporal Changes in Soil Nitrate-n Levels from Late Summer to Early Spring in MontanaMost soil sampling is conducted from August to November in Montana because of better soil sampling conditions and because it provides more time for growers to make fertilizer decisions prior to application. Fertilizer guidelines in Montana are based on spring nitrate-N levels in the upper 2 ft because they are more indicative of growing season available N than fall nitrate-N levels. It is not known how much nitrate-N levels change between late summer and spring, nor is it known what factors affect... C. Jones, A. Lenssen, C. Chen, K. Mcvay, B. Stougaard, M. Westcott, J. Eckhoff, J. Weeding, M. Greenwood |
49. Dicarboxylic Acid Polymer (Avail®) Phosphorus Fertilizer Additive: ReviewImproving P use efficiency (PUE) is desirable but difficult due to poor P solubility in soils. A dicarboxylic acid copolymer (AVAIL®) fertilizer additive may enhance PUE due to increased P solubility as a result of sequestering of interfering cations. Field trials have been conducted on a wide variety of crops, with results to AVAIL addition to P fertilizer mixed—seemingly related primarily to soil test P concentrations and fertilizer P rate. Positive results were seen in many of these... B. Hopkins, C. Ransom |
50. 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 |
51. 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 |
52. 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 |
53. 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 |
54. 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 |
55. 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 |
56. 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 |
57. 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 |
58. Tillage Effects on Phosphorus AvailabilityVertical stratification of phosphorus (P) has been documented in both no-till and reduced tillage systems, yet very few studies have determined if this stratification has affected P uptake, and none of these studies have been conducted in Montana. Stratification of P was compared in 1.2 in layers in a small plot study composed of four tillage systems: long-term conventional (sweep) till (CT), 10-yr no-till (NT), 1-yr NT and 1-yr CT. Olsen P was measured in the upper 12 in., and a sequential extraction... C. Jones, K. Neill, C. Chen, E. Allison |
59. Grain Protein Content and Composition of Winter Wheat Cultivars Under Different Levels of N and Water StressThis study investigated the combined influences and interactions of N fertilization and moisture deficit during grain-fill on wheat grain protein content and grain protein composition of nine white winter wheat cultivars. Grain was obtained from seven HWW wheat cultivars and two soft white winter (SWW) wheat cultivars grown under line-source irrigation systems at two Oregon locations during two years. The low N level treatment consisted in a single fertilization of 150 lb N/a in March,... A. Ross, C. Saint pierre, C. Peterson, J. Ohm, M. Verhoeven, M. Larson, B. Hoefer |
60. 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 |
61. 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 |
62. 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 |
63. A Single Nutrient Source Hydroponic Solution: pH BufferingMES (2-[N-morpholino]ethanesulfonic acid) is a biological buffer that can be used to stabilize pH in a hydroponic system. It can, however, be toxic to plants, including soybeans. Hydroponic systems are efficient for studying plant nutrition. It is often desirable to adjust individual nutrients for unique species’ needs and/or to create multiple nutrient deficiencies within the same study. However, this is challenging to do with traditional solutions as nutrients are generally... J.D. Ioannou, B. Hopkins |
64. Impact of Variable-Rate Nitrogen on Potato Yield, Quality, and ProfitNitrogen application in agriculture is a vital process for optimal plant growth and yield outcomes. Factors such as: topography, soil properties, historical yield, and crop stress variably affect nitrogen (N) needs within a field. Applying variable N within a field could improve yields and nitrogen use efficiency (NUE). Optimal N management is a system that involves applying a conservative variable base rate at or shortly after planting followed by in-season assessment and, if needed, variable... E.A. Flint, M. Yost, B. Hopkins |
65. CropManage Decision Support Tool for Improving Irrigation and Nutrient Efficiency of Cool Season Vegetables in California: a Decade of Field Demonstrations and OutreachVegetable growers on the central coast of California are under regulatory pressure to reduce nitrate loading to ground and surface water supplies. California is also implementing the Sustainable Groundwater Management Act (SGMA) which may limit agricultural pumping in regions such as the central coast where the aquifer has been over-extracted for irrigation of crops. Growers could potentially use less N fertilizer, address water quality concerns, and conserve water by improving water... M. Cahn, R. Smith, L. Johnson, F. Melton |