Bryan Hopkins | Brigham Young University (original) (raw)

Papers by Bryan Hopkins

Verticillium dahliae is a soil-borne pathogen that causes a vascular disease of plants and is the... more Verticillium dahliae is a soil-borne pathogen that causes a vascular disease of plants and is the primary causal agent of potato early dying disease (PED), PED causes plant death before tubers have finished bulking and can reduce yields by 30-50%. Optimal pH, sulfur (S), chloride (Cl), and potassium (K) concentrations were used to grow potato to determine impacts on Verticillium infection. This was accomplished by inoculating plants grown in hydroponic solutions with varying pH and concentrations of S, Cl, and K. Solution pH levels were maintained at 5.0, 6.0, 7.0, and 8.0 using MES buffer and daily adjustment with HCl or KOH. Low, moderate, optimum, and toxic concentrations of S, Cl, and K were were used to determine influence on Verticillium, all other essential nutrients were kept constant. Impacts of these treatments on Verticillium development were tested by inoculation of each treatment solution with 40 ml of a 100,000 spore per ml solution and by growing plant roots in this i...

Idaho soils tend to be high in pH and calcium carbonate (free lime), both of which reduce phospho... more Idaho soils tend to be high in pH and calcium carbonate (free lime), both of which reduce phosphorus solubility and availability to plants. Considerable research has occurred in Idaho during the recent past to elucidate optimum phosphorus rates for potatoes (Solanum tuberosum). The question remains, does method and/or timing of phosphorus applications impact yield and quality of potatoes. Research shows that excess phosphorus rates decrease yield and quality. Research in other crops shows that excessive phosphorus does not create phosphorus toxicity; rather excessive phosphorus induces zinc or other micronutrient deficiencies. No research has been conducted to determine the reason why excess phosphorus rates reduce yield and quality in Idaho potato production. Due to soil variability and relatively high phosphorus application rates to potatoes, many fields in Idaho have at least some portion that is substantially over-fertilized. The severity and nature of this problem needs to be e...

Journal of Plant Nutrition, 2010

Potato (Solanum tuberosum L.) has surface roots with enhanced activity upon canopy closure that s... more Potato (Solanum tuberosum L.) has surface roots with enhanced activity upon canopy closure that should allow application of phosphorus (P) via fertigation. Fertilizer trials were conducted in 2005-2006 with four pre-plant broadcast (0, 112, 224, or 336 kg P2O5 ha-1) and two ...

Potatoes are grown in almost every state and province in North America. Some potatoes are grown f... more Potatoes are grown in almost every state and province in North America. Some potatoes are grown for fresh consumption, while others are used for processing into fries, chips, or frozen products. Whatever the end use, the objective of every potato grower is to provide high quality potatoes that meet the market objectives at a price that is economically profitable and environ-mentally sustainable. Potatoes are an important part of our diet. In North America, a typical consumer uses over 130 lb of potatoes each year (fresh and processed). Global con-sumption of potatoes continues to increase…with the largest consumers in Eastern Europe and with China now the world’s largest potato producer. Of the 40 billion pounds (400 million hundred weight) of potatoes grown in the USA in 2007, over 60 % of the fall production occurs in the Pacific Northwest. A unique combination of soil, environment, and man-agement practices has led to the success of the potato

Journal of European Industrial Training, 2011

IEEE INFOCOM 2004

We present an approach to support massively multi-player games on peer-to-peer overlays. Our appr... more We present an approach to support massively multi-player games on peer-to-peer overlays. Our approach exploits the fact that players in MMGs display locality of interest, and therefore can form self-organizing groups based on their locations in the virtual world. To this end, we have designed scalable mechanisms to distribute the game state to the participating players and to maintain consistency in the face of node failures. The resulting system dynamically scales with the number of online players. It is more flexible and has a lower deployment cost than centralized games servers. We have implemented a simple game we call SimMud, and experimented with up to 4000 players to demonstrate the applicability of this approach.

HortTechnology

Recent advances in irrigation technologies have led many states to incentivize homeowners to purc... more Recent advances in irrigation technologies have led many states to incentivize homeowners to purchase United States Environmental Protection Agency WaterSense-labeled, smart irrigation controllers. However, previous research of smart controllers has shown that their use may still result in excess water application when compared with controllers manually programmed to replace actual water loss. This study compared kentucky bluegrass (Poa pratensis) irrigation applications using three smart irrigation controllers, a conventional irrigation controller programmed according to Cooperative Extension recommendations, and the average irrigation rate of area homeowners in Utah during 2018 and 2019. Of all the controllers tested, the manually programmed controller applied water at amounts closest to the actual evapotranspiration rates; however, smart controllers applied from 30% to 63% less water than area homeowners, depending on the controller and year of the study. Kentucky bluegrass healt...

Better crops with plant food, 2013

Maintaining an adequate P supply is critical for potato plant development, tuber growth, and enha... more Maintaining an adequate P supply is critical for potato plant development, tuber growth, and enhancing tuber maturity. Phosphorus defi ciencies can signifi cantly reduce tuber yield and size. Therefore, fertilization practices must be customized for the characteristics of the cropping system and local conditions to maintain adequate P availability throughout the growing season. Concentrations of soluble P in soils of the potato-producing regions in the Pacifi c Northwest, USA are usually very low and must be constantly replenished from soil P sources during the growing season. In these alkaline soils, the primary factors used in determining P fertilizer recommendations are soil test P concentration, amount of excess lime (CaCO 3 ), and the yield goal. Excess lime in the soil increases P sorption on CaCO 3 surfaces and increases P precipitation as Ca-P minerals. The combined effect of these processes is an overall reduction in P availability to plants. This is refl ected in regional ...

Social Work, 2018

Although bear-inflicted (Ursus spp.) human fatalities are rare in North America, human injuries, ... more Although bear-inflicted (Ursus spp.) human fatalities are rare in North America, human injuries, property damage, and bear mortalities occur wherever bears and humans commingle. We investigated the efficacy of portable electric fencing systems for bear deterrence under a variety of environmental conditions in the lab and field. Our results showed that the bear deterrent systems we evaluated were effective in protecting humans, their food, and property from bears >99% of the time. Herein, we discuss the benefits of using electric fencing, reasons why fences sometimes fail, and provide guidance regarding the most effective implementation of the systems we evaluated. Lastly, we also explore why this deterrent is not yet in widespread use. We encourage the use of electric fencing in bear country for protecting humans, their camping gear and food, and ultimately to promote bear conservation.

Better Crops with Plant Food, 2019

You don’t run a marathon on a diet. Just as high-performance athletes require carefully managed n... more You don’t run a marathon on a diet. Just as high-performance athletes require carefully managed nutrition, producing high-yielding crops necessitates knowledge and care when it comes to nutrient management. This is especially true for P, which is often inadequately supplied to sustain high crop yields.

Journal of environmental management, Jan 22, 2016

After nearly a century of use in numerous munition platforms, TNT and RDX contamination has turne... more After nearly a century of use in numerous munition platforms, TNT and RDX contamination has turned up largely in the environment due to ammunition manufacturing or as part of releases from low-order detonations during training activities. Although the basic knowledge governing the environmental fate of TNT and RDX are known, accurate predictions of TNT and RDX persistence in soil remain elusive, particularly given the universal heterogeneity of pedomorphic soil types. In this work, we proposed a new solution for modeling the sorption and persistence of these munition constituents as multivariate mathematical functions correlating soil attribute data over a variety of taxonomically distinct soil types to contaminant behavior, instead of a single constant or parameter of a specific absolute value. To test this idea, we conducted experiments measuring the sorption of TNT and RDX on taxonomically different soil types that were extensively physical and chemically characterized. Statistic...

Fire plays an important role in many native ecosystems, and its suppression has increased woody e... more Fire 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 postfire soil hydrophobicity on soil moisture and soil nutrients. Plots centered on Juniperus osteosperma or Pinus monophylla trees were either left untreated or treated with a surfactant to ameliorate soil hydrophobicity, and then left bare or seeded with Pseudoroegneria spicata. Measurements were taken two years after fire in May, by which time the surfactant treatment had 124.4% higher soil water content than the repellent control. This effect was a function of a thick, hydrophobic layer in the control as compa...

Journal of Plant Nutrition, 2020

Major crop nutrient symptoms are well documented. In contrast, there is often minimal or no simil... more Major crop nutrient symptoms are well documented. In contrast, there is often minimal or no similar information for minor crops, including quinoa (Chenopodium quinoa Willd.). This knowledge gap can be efficiently filled by using hydroponic systems. However, creating multiple nutrient deficiencies with plants in the same study is challenging because nutrients are often added as dual nutrient salts. For example, if potassium sulfate is the potassium (K) source, varying K concentration also impacts sulfur (S) concentration, possibly creating dual deficiencies or other interactions. A new hydroponic system was created to impose nutrient deficiencies using single nutrient sources: ammonium nitrate; phosphoric, sulfuric, hydrochloric, and boric acids; potassium, calcium, magnesium, zinc, and copper carbonates; manganese acetate; sodium molybdate; iron EDDHA, with HEDTA as an additional chelate. Fourteen treatments were established including a positive control with nutrient concentrations anticipated to be optimal compared with individual deficiencies of nitrogen (N), phosphorous (P), K, S, calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), boron (B), molybdenum (Mo), and chloride (Cl). The "deficient" treatments were created by reducing concentrations by 80% for N and 90% for the others. The solution proved to be mostly effective as quinoa plants were grown to maturity. Stem size, plant height, and shoot and root biomass were impacted, especially for treatments with reduced N, P, and K. Unfortunately, the predicted adequate levels of some nutrients were likely excessive, especially B and Mn. Additional fine tuning is required to create a solution optimal in all nutrients.

PLOS ONE, 2018

Although N is beneficial and essential for life, it is also a common atmospheric pollutant as nit... more Although N is beneficial and essential for life, it is also a common atmospheric pollutant as nitrous oxide (N 2 O) and ammonia (NH 3)-contributed largely from N fertilization. Polymercoated urea (PCU) fertilizer is a promising controlled release fertilizer that provides improved N-release timing. Glasshouse studies were conducted to compare N 2 O and NH 3 emissions from PCU and uncoated urea to an untreated control utilizing a non-static, nonflow-through chamber in conjunction with photoacoustic infrared spectroscopy (PAIRS) for gas collection and analysis. Three short-term 20-Day Studies with sand, sandy loam, and loam soils and a full-term 45-Day Study with loam soil were completed. Volatilization of NH 3 was reduced by 72% and 22% in the sandy loam and loam soils, respectively, in two of the short-term studies and by 14% in the loam in the full-term study. Evolution of N 2 O was reduced by 42% and 63% in the sandy loam and loam soils of the short-term studies and by 99% in the loam soil of the full-term study. No differences were observed in the sand soil. Overall, PCU decreased gaseous losses of N following fertilization while providing a steady supply of N to the plant. Higher temporal resolution was observed with the PAIRS instrumentation as compared to what is typically reported and, as such, we recommend PAIRS analysis as a viable method for studying N gas emissions.

Journal of Plant Nutrition, 2017

Phosphorus (P) is poorly soluble in soil and has poor plant uptake efficiency. AVAIL Ò and Carbon... more Phosphorus (P) is poorly soluble in soil and has poor plant uptake efficiency. AVAIL Ò and Carbond P (CBP) are fertilizers that increase P-use efficiency (PUE) and yields on P limiting soils. The objectives of this study were to determine if mode of action for these products is related to physiological response, and to evaluate possible toxicity. AVAIL and CBP were compared to ammonium polyphosphate (APP) at pH 6 or 8 for hydroponically grown maize (Zea mays L.). Not surprisingly, biomass and P concentration increased with increasing P concentration of the solution. However, neither AVAIL nor CBP had any positive or adverse effects. These results, coupled with previous soil-based studies, show that the observed increase in PUE is not a physiological growth stimulant response, but rather the result of impacts on soil P solubility. Furthermore, these materials are not toxic when in direct contact with plant roots-even at relatively high concentrations.

Native Plants Journal, 2018

Journal of Arid Environments, 2017

Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, t... more Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, this zone is often found to be water repellent. This study aimed to understand the effects of post-fire water repellency on soil water and inorganic nitrogen and their effects on plant growth of the introduced annual Bromus tectorum and native bunchgrass Pseudoroegneria spicata. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with surfactant to ameliorate water repellency. After two years, we excavated soil from the untreated and treated plots and placed it in zerotension lysimeter pots. In the greenhouse, half of the pots received an additional surfactant treatment. Pots were seeded separately with B. tectorum or P. spicata. Untreated soils had high runoff, decreased soilwater content, and elevated NO 3 eN in comparison to surfactant treated soils. The two plant species typically responded similar to the treatments. Above-ground biomass and microbial activity (estimated through soil CO 2 gas emissions) was 16.8-fold and 9.5-fold higher in the surfactant-treated soils than repellent soils, respectably. This study demonstrates that water repellency can influence site recovery by decreasing soil water content, promoting inorganic N retention, and impairing plant growth and microbial activity.