bluuebunny/crossref_metadata_2025 huggingface dataset:
New Mixer System Enhances Saudi Aramco GOSP Crude-Water Separation Performance
Authors: Boudi Adnan A. , Linga Harald , Al-Johar Zaki A. , Al-Yousef Khaled K.
Published: October 2011

The paper concerns the achievement in separation performance by using a new mixer device for the injection and mixing of the demulsifier into the crude-water flow.

The target for the injection of the demulsifier into the crude-water flow is to modify the surface properties of the crude-water interfaces such that the conditions for droplet-droplet coalescence for the dispersed phase within the two liquid bulk phases are improved. The costs for such production chemicals may become significant at the same time as the impact on the crude-water separability may be non-satisfactory. Facing this, Saudi Aramco has installed and field-tested a new mixer system, denoted ProMix, for more efficiently distributing the demulsifier into the crude-water flow, targeting lower consumption and improved separability.

The operational performance and results for the full scale 20" mixer installation at UGOSP-4 (Uthmaniyah Gas-Oil Separation Plant), normal operating flow rate 275,000 BPD, has been recorded both for winter and summer conditions.

Compared to the existing mixing valve, the ProMix mixer device has served to;

Reduce the demulsifier consumption Improve the crude oil produced water separation Reduce the pressure drop across the mixer installation to typical 1-2 psi Improve operational robustness

The annually averaged reduction in demulsifier consumption has been estimated to 20 %. In addition the oil-inwater content for the water separated from the dehydrator has dropped significantly by the use of the new mixer system, allowing for improved operation of the crude-water interfacial level for the dehydrator. For the operational robustness the introduction of the new mixer system has also served to minimize the dehydrator electrostatic grids failures during the winter conditions.

The reduced pressure drop and improved separability also allows for higher crude flow production in addition to reduced demulsifier consumption. As the ProMix is a compact flange mounted spool piece unit it can easily replace an existing choke or globe valve mixer in order to debottleneck existing separation trains, in addition to serve as mixer units for grass-root installations.
The United Nations Framework Classification for Fossil Energy and Mineral Reserves and Resources 2009
Authors: MacDonald D. , Lynch-Bell M. , Ross J. , Heiberg S. , Griffiths C. , Klett T.
Published: October 2011

Effective resource management in a globalizing economy requires accurate assessments of fossil energy and minerals resources. The recoverable quantities must be described and categorized in a manner that is consistent with scientific and social/economic information describing the economy as well as with the information describing the projects to recover them. A number of different standards have evolved over time in response to various professional needs

Under a mandate given by the United Nations Economic and Social Council, the United Nations Economic Commission for Europe (UNECE) has cooperated with Governments, regulatory agencies, industry, international organizations, and professional organizations (including Committee for Mineral Reserves International Reporting Standards (CRIRSCO), the Society of Petroleum Engineers (SPE), the American Association of Petroleum Geologists (AAPG), and the Society of Petroleum Evaluation Engineers (SPEE)), as well as with outstanding experts, to define a global classification for extractive activities (including oil, gas, heavy oil and bitumen extraction) that reflects the principal concerns of existing petroleum and mineral classifications.

The United Nations Framework Classification for Fossil Energy and Mineral Reserves and Resources-2009 (UNFC-2009) aims to serve the following four principal needs:

The needs in international energy and mineral studies to formulate robust and long-sighted policies. The needs of governments in managing their resources accordingly, allowing market prices to be transferred to the wellhead with as little loss as possible. The industries’ needs for information while deploying technology, management and finance to secure energy supplies and capture value efficiently within the established frameworks to serve its host countries, shareholders and stakeholders. The financial community's need for information to allocate capital appropriately, providing reduced costs and improved long-sightedness through the application of lower risk-compensated discount factors.

The projects are categorised with respect to economic and social viability, project feasibility and maturity and uncertainty with respect to the quantities addressed. The categorisation of projects rather than of accumulations provides coherence with other critical management information such as production, cash flows, value and demand for various input factors.

This key aspect of UNFC-2009 reflects the critical relationship between the quantities that can be recovered economically and the recovery processes (projects) that must be implemented to achieve those recoveries. It facilitates the recognition of potential wastage of resources through flaring or inefficient recovery processes and therefore also the potential for improvement.
Nonlinear Gas Well Test Problems: A Generalized Perturbative Solution Applied to a Vertical Well near a Sealing Fault
Authors: Barreto Abelardo Borges
Published: October 2011

In transient real gas flow in porous media the fluid properties are pressure-dependent which makes the diffusivity equation nonlinear. The gas well testing literature shows few attempts to derive exact solutions that handle the nonlinearities analytically. Most of the published articles approach the gas well testing problem by finite difference schemes. More than 40 years has passed since the introduction of the pseudo pressure function that became the standard procedure to analyze field data from gas wells. The pseudo pressure function, however, do not completely linearize the flow equation, as it fails to account for the variation on the gas viscosity-compressibility product. Such variation is very often ignored without justification by assuming it constant during the time range of interest. Recently, a new generalized solution based on a perturbation technique, that properly takes into account all the nonlinearities, was derived. In this work, this general solution is applied to obtain an analytical expression for a vertical gas well near a sealing fault. It is shown that the characteristic doubling of the slope of the pressure versus time semilog plot observed for constant fluid properties also appears on drawdown test for gas reservoirs. The results obtained by this new solution procedure are compared to a finite difference model showing close agreement.
Statistical Evaluation of Reservoir Rock Type in a Carbonate Reservoir
Authors: Abedini Ali
Published: October 2011

Reservoir rock type determination is one of the main parameters for simulation and prediction of the hydrocarbon reservoir behavior. Hence, it is of great importance to use a method which is capable of determining the rock type accurately. In this study, some of the most useful methods such as capillary pressure, Leverett dimensionless J-function, Winland R35 method, Flow Zone Indicator (FZI) and Discrete Rock Type (DRT) were applied to samples from a carbonate reservoir to determine the various reservoir rock types. The sample set consisted of 265 routine core data and 18 data sets of capillary pressure versus initial water saturation; all were analyzed using the aforementioned determination methods. Results of this study showed that both capillary pressure and Winland R35 were not accurate enough to determine rock types for this carbonate reservoir, mainly because of the high heterogeneity in the reservoir rock properties. For the same reason, the Leverett J-function method was found to be problematic in normalizing all the capillary data into one unique curve. However, FZI and DRT methods successfully classified all data into four discrete rock types while satisfying the relationships between permeability and porosity for each of them. The calculated permeability data for each rock type classified by FZI and DRT methods were in good agreement with core permeability data.
HPHT Gas Viscosity Measurements Quantify Error in Existing Models
Authors: Davani Ehsan
Published: October 2011

Measured gas viscosity data at high pressures and high temperatures indicates that the most common gas viscosity correlations return up to 9% relative error in cumulative gas recovery factor at extreme conditions, which translates to significant economic error in current giant natural gas reservoirs.

This error may increase in high-pressure/high-temperature (HPHT) gas reservoirs where no measured data is available above 10,000 psi. Modeling the performance of these unconventional reservoirs requires the understanding of gas behavior at elevated pressure and temperature. Gas viscosity is an important fluid property that dictates the fluid flow through the porous media and production pipeline. Accurate measurements of gas viscosity at HPHT conditions are both extremely difficult and expensive, and the accuracy of the resulting correlations may be doubtful for predicting gas viscosity at HPHT conditions.

An oscillating piston viscometer was used to measure the viscosity of mixture of nitrogen and methane and mixture of CO2 and methane at HPHT conditions. The subsequent measured data, recorded over a wide range of pressure and temperature, was then used to evaluate the reliability of the most commonly used correlations in the petroleum industry.
Estimation of Fluid Transmissibility and Oil Production Allocation in Faulted Multi Layered Reservoirs using Material Balance Analysis
Authors: Ogbodu Ejiro Desmond
Published: October 2011

In the oil rich Niger Delta region of Nigeria, there be existent huge faulted multilayered reservoirs having fluid transmissibilities and pressure communication across the different layers of the stacked reservoir sands. This phenomenon has over time given rise to the problem of incorrect reservoir allocations especially after production has commenced from two or more of these reservoir sands. This thus consequently creates considerable challenges in quoting accurate reserves per reservoir in such fields. This occurrence also has led to great perplexity in understanding/estimating the individual reservoir properties such as the pressures trends of these sands which are, in this case, complex. This complexity is as a result of the separate reservoir sands being in Fluid/pressure communication with each other due to sand juxtaposition. As such similar property behaviour may not be as expected across all the areas within even the same reservoir depending on several geological and petrophysical factors.

The major aim of this work would be to try quantifying the inter-reservoir fluid transmissibility i.e. the Interlayer cross flows neglecting the wellbore conditions and all other production constraints outside the reservoir, and only taking into consideration all the possible geological and petrophysical factors that could influence flow in the reservoir, using models which were built using the MBAL simulation program. Actual production and pressure data of a faulted Multilayered field producing from the Niger Delta region of Nigeria (taking two major reservoir sands D5.0 &D6.0) are used in the modelling, for which a thorough quality check was done on the data. Pressure trend analysis, Production performance analysis, PVT characterization, and Fault seal analysis was done to determine a lot of the conclusions presented. Attempted also was the determination of the reservoir allocation using the horizontal permeability and the transmissibility values.
Laboratory Studies: Analysis of Resin Composition to Handle Sand Problems on Unconsolidated Gas Formation
Authors: Purnama G. W.
Published: October 2011

At the beginning to handle sand production is using mechanical methods (gravel pack, slotted liner, sand screen, and others). This method is successful to hold the sand on consolidated formation in the reservoir, but not success for formation with a poorly consolidated and unconsolidated formation.

The purpose of this research is to produce hydrocarbons (gas) without producing sand. The method is making a strength bonds between sand particles (sand consolidation) using chemicals (resin) without reduce to much the value of porosity and permeability.

This research is using artificial core which made based on unconsolidated formation of reservoir characteristics, such as: (i) matrix grain size in the range of mesh size between 80-120, (ii) Cemented between the matrix is weak, (iii) 25-30% Porosity, (iv) 50-300 mD permeability. Experiment condition conducted at reservoir temperature and pressure, which is 102 ° C and 3145 psi.

Testing of resin effect to the strength of rock stress is done by triaxial stress, which developed and manufactured with the application of high pressure, high temperature, the axial pressure, and radial pressure that using gas and liquid fluid.

The results of this study show that mixing a resin with core can increase rock strength up to 700-800 psi, which can handle sand problems.
In-Situ Combustion Kinetics of a Central European Crude for Thermal EOR
Authors: Glatz G.
Published: October 2011

In-Situ combustion is one method of enhanced thermal recovery to access heavy-oil resources. By oxidizing a small fraction of the hydrocarbons in place, thermal energy is released thereby aiding the displacement of the remaining oil. A combination of gas, steam, water drive, and viscosity reduction helps to push the oil towards the producer. Not every oil, however, is a proper candidate for in-situ combustion. Whether or not a crude oil would be a viable candidate is not only governed by the composition of the oil but also by the reservoir matrix. The experimental testing required to determine if in-situ combustion would work in the field is expensive. Therefore, the sooner an oil can be ruled out as as a candidate, the better.

Isoconversional methods have been successfully applied in the past in order to determine effective activation energies of crude-oil oxidation. In addition, the technique can be used as an inexpensive screening tool to determine a priori if a combustion tube experiment, and, therefore, field implementation, would be successful or not. This paper discusses practicability of isoconversional analysis for a heavy oil for which in-situ combustion is economically successful.
Numerical Reservoir Simulation Coupled with Geomechanics State of the Art and Application in Reservoir Characterization
Authors: Rodríguez Hernández Inti Illimani
Published: October 2011

Currently, conventional reservoir simulators are not able to reproduce the changes inferred upon fundamental properties such as porosity and permeability by the action of the stress field and the deformation associated to geomechanics as the reservoir is being depleted. The prediction of the impact of these variables in surface facilities and the integrity of wells is also important. Hence, in many cases it is required to couple the effect of geomechanics in numerical reservoir simulation in order to have a more realistic response on the behavior of the reservoir and more accurate predictions. The coupling between the numerical simulation and reservoir geomechanics can be reached by considering the interaction between the main equations governing fluid flow in porous media, the fundamental equations of rock mechanics and the constitutive laws that describe the deformation of rocks in response to an applied stress in a given time. In this paper the evolution and development of the coupled simulation technology are analyzed through the study of 132 available publications, which include dissertations, reports and articles. This paper also describes the main fields of application of this technology, comprising compaction, subsidence, naturally fractured reservoirs, steam assisted gravity drainage, water injection, steam injection, sanding, hydraulic fracturing, fault recovery and pressure testing, among others. Furthermore, a conceptual numerical simulation example with reservoir features of the Orinoco Oil Belt is presented.

Based on the documented experiences, a generic methodology for the implementation of coupled simulations is presented. A description of the historical evolution of the major mathematical developments in this area is shown and, a ranking of the different coupling techniques in studies of behavior and development of reservoirs focused on solving real problems is performed. The ultimate purpose of this study is to establish a technical base criterion that may be used as a guide to apply this technology in reservoir studies.
Determining the Flow and Erosion Models So Frac Sand Can Be Evenly Distributed into the Formation
Authors: Adams Jeffrey
Published: October 2011

A program was created that successfully models the way frac sand flows through each perf cluster and erodes it away. The models represented in the program successfully match camera photos that were taken of the initial and final perf hole sizes. Our frac jobs were having difficulty evenly distributing the frac sand into the formation. We needed to better understand how the sand was eroding and flowing through the perfs. When these flow and erosion models were determined, the program successfully represented a frac job. Therefore the program can be used to adjust the hole distribution to evenly distribute the sand in to the formation.
Molecular Thermodynamic Modeling of Micellar and Microemulsion Solutions
Authors: Moreira Livia A.
Published: October 2011

Surfactant-based processes are explored in the pledge of using low volumes of amphiphile molecules. In oil and gas production, they can be used to solve problems efficiently in a broad variety of processes, such as water and oil separation, flow assurance, improved oil recovery, oil spills remediation, and drilling and fracturing fluids. In our work, we develop thermodynamic models of micellar and microemulsion systems that can predict phase behavior of these complex systems. We investigate the effect of alcohols and salts in micellar systems and present a thermodynamic model in which the alcohol molecules play two roles: cosurfactant and cosolvent. Our model improves the understanding of the effect of short- and medium-chain alcohols in self-assembly of molecules. For the effect of salts, we present a molecular thermodynamic theory for ionic-surfactant solutions that accounts for the headgroup-counterion specificity and address ion-specific effects. We assume that the charged headgroup and the counterion at the Stern layer form solvent-shared ion pair with different degrees of cosphere overlap. As environmental considerations increasingly shape the development of many industrial products and processes, studies on the physical chemistry of surface-active systems are essential in designing surfactants with minimal environmental impact.
Electrothermal Method of Processing the Near-well Area
Authors: Maria Khusid
Published: October 2011

The report focuses on the results of simulation of the near-well area heating by an electric current and the substantiation of using an electric field as a thermal method of oil production intensification. We give the description of such programs as NKAR (the program of the numerical solution of the direct problem of electrical logging), THERM3C (the program of solving the direct three-dimensional problem of thermometry) which were used in the simulation.
Express-estimation of Effectiveness of System Development Options for Oil Fields with Gas Cap at Conceptual Design Stage
Authors: Prokopyev Mikhail
Published: October 2011

In this paper it is suggested to consider known but narrowly distributed approach to simulation flowsheet development of field. The main principles of computational models hierarchy is the theoretical base of approach considered. Mathematical tools, which are the base of high-level model developed, are considered in the paper along with correlation analysis in various media of simulation. Besides in this paper it is developed the optimization algorithm, which allows to limit significantly the number of economically justified field development options at the stage of conceptual design.
Water Coning Management in Gas Reservoir via Downhole Water Dump Flood
Authors: Buranatavonsom Napat
Published: October 2011

Water coning, the upward encroachment of water into a perforation zone of a well, is one of the main problems in many petroleum fields especially in strong bottom water-drive reservoirs. It results in high water cut and low oil rate that lead to early shut-in of a well without adequate recovery of hydrocarbons in place.

Over many years, many authors or reservoir engineers have attempted to find the efficient ways to handle with water coning. For a long time ago, conventional method to control or delay water influx is to produce hydrocarbon less than critical flow rate; but, the critical flow rate is proven not commercially economical. In recent years ago, Downhole Water Sink (DWS) is the new method to control water coning effectively which is proven by both theoretical calculation and field examples; however, this method needs to produce a large amount of water at another well and then requires to be handled in water treatment system on the surface.

From the reason mentioned above, the new method called "Downhole Water Dump Flood (DWDF)" is proposed. This method can reduce water coning by the same principle of DWS method but it is not required to produce water into surface and also to drill a well for water production. Therefore, it can minimize cost of drilling and water treatment system.
Analytical and Numerical Solution for Large Plastic Deformation of Solid Expandable Tubular
Authors: Al-Abri Omar S.
Published: October 2011

This paper presents analytical and numerical solutions developed to investigate the structural response of thick circular cylindrical shells subjected to large plastic deformation due to expanding them using rigid mandrel of conical shape. The work is especially focused on the petroleum drilling application known as Solid Expandable Tubular (SET) technology. Equilibrium equations, incompressibility conditions and Levy-Mises flow rule were used to develop analytical model which relates the expansion ratio and the mandrel-tubular system configuration to the force required for expansion and the tubular length and thickness variations. In addition, Tresca's yield criterion was used to represent the plastic behavior of the tubular material. The developed analytical model is capable of predicting the force required for expansion and the length and thickness variations induced in the tubular due to the expansion process. A numerical solution of the tubular expansion process was also developed using the commercial finite element software ABAQUS. Experiments have been conducted for tubular expansion on a full-scale test-rig in the Engineering Research Laboratory at Sultan Qaboos University to validate the analytical and numerical solutions. A standard tubular of 7⅝ inch (193.68 mm) outer diameter and ⅜ inch (9.525 mm) wall thickness was expanded using expansion ratios of 16%, 20%, and 24%, the mandrel semi-cone angle being 10°. The parameters like thickness variation, length shortening and expansion force were measured experimentally and calculated through analytical and numerical models. Analytical and numerical results were in good agreement with the experimental values. Expansion ratios of 16%, 20%, and 24% resulted in tubular thickness reduction of approximately 6.67%, 10.3%, and 13.16%, respectively. Also, the required expansion force for the same expansion ratios was around 940 kN, 1092 kN, and 1213 kN.
Improved Estimation of Bubble Point Pressure of Crude Oils: Modelling by Regression Analysis
Authors: Bandyopadhyay Parag
Published: October 2011

The Bubble Point Pressure of crude oil is a critically important property for the description of reservoir fluid behaviour. Accurate estimation of such properties is required for important reservoir and production engineering calculations such as reserve estimation, production forecasting and design of Enhanced Oil Recovery (EOR) projects. A comprehensive literature review was carried out to understand and analyze the limitations of currently available methods for estimation of bubble point pressure. A large database consisting of the compositional analysis, temperature and measured bubble point pressure of more than 140 crude oil samples of varying geographical origins was compiled. The parametric form of the model was constructed based on the analysis of trends from collected experimental data and theoretical inputs. The model was then calibrated, using non-linear regression techniques, to a major portion of the data set. The remaining data was used to validate the calibrated model and verify its conformity to physical processes. The performance of the model was then compared and found to be more accurate than existing methods such as Equations of State (EOS). The various applications of this new model to the simulation of Liquid-Vapour phase boundary were explored. Laboratory experiments such as the swelling test were simulated using this model and the predictive performance was found to be better than that of an EOS. These laboratory tests, especially swelling tests, are integral for the design of miscible flooding EOR projects. Other applications and modifications of this model were also such explored in the latter portion of this work. It is concluded that the performance of this new model is better than other current methods when operating in a purely predictive mode and that the model could be manipulated as a powerful tool for applications which require identification and simulation of the Liquid-Vapour phase boundary.
Study of the Horizontal Wellbore and Reservoir Coupling
Authors: Oliveira Rodolfo
Published: October 2011

Over the last two decades, directional and horizontal wells have become the most usual design in Brazilian offshore scenarios. The increasing use of these types of wells relies upon new drilling and completion techniques being developed at the same time so as to achieve the full benefits of this practice. The main usages of horizontal wells are: to increase the drainage area; to improve the ability to exploit thin reservoirs; for exploration of natural fractured formations; for water/gas conning reduction; and to increase the efficiency of Enhanced Oil Recovery (EOR) methods. The aim of this work is to present case studies involving horizontal wells simulations using computational fluid dynamics techniques. In order to predict the total flow rate and flow distribution along the extended reach horizontal wells, the three-dimensional CFD model was built comprising of the well geometry and its drainage radius over the reservoir. This methodology makes it possible for well engineers to determine, for specific scenario, the optimum configuration for a horizontal well design. The predicted flow fields obtained from the CFD simulations were in agreement not only with results found in literature (Troll Field - Ozkan et al. 1999), that were used to validate the model, but also with production data from some Petrobras oilfields (Sansoni et al. 2007). Using this CFD tool, it was possible to identify situations where the infinite conductivity approach is valid, and the cases where this assumption results in great errors in the production forecast.
The Effect of Oil on Foam Flow in Pipes for Underbalanced Drilling Processes
Authors: Panchadhara Sneha
Published: October 2011

Recent experimental studies on foams in pipes show that there exist two foam flow regimes: a "high-quality regime" in which unstable pressure response prevails due to slug flow pattern; and a "low quality regime" in which the pressure response is stable and dominated by segregated or plug flow. These two flow regimes are shown to be separated by fg* which is a function of many experimental conditions. Lousiana

In line with these previous accomplishments, this study for the first time focuses on the effect of N-decane, as the oil phase in this study, on two foam-flow regimes by conducting a series of flow experiments in a wide range of conditions. More specifically, the experiments were conducted within the foam-quality range of 80 – 95%, by using two different surfactants at varying concentrations and two different oil rates. The pipe dimensions were 0.36 inch inner and 0.5 inch outer diameters and 12 ft in length, with 8 pressure taps installed along its side.

The results showed that the presence of oil impacted foam stability significantly reducing the steady-state pressure drops and fg* values. This implies that foam modeling and simulation during foam drilling processes should take the presence of oil into account for reliable hydraulics calculations.
Upscaling for Field-scale In-situ Combustion Simulation
Authors: Zhu Zhouyuan
Published: October 2011

In traditional thermal reactive reservoir simulation, mass and energy balance equations are solved numerically on discretized reservoir grid blocks. The reaction terms are calculated through Arrhenius kinetics using cell-averaged properties, such as averaged temperature and reactant concentrations. The chemical reaction front is physically very narrow, typically a few inches thick. To capture accurately this front, centimeter-sized grids are required that are orders of magnitude smaller than the affordable grid block sizes for full field reservoir models. We propose a new method based on a non-Arrhenius kinetic upscaling approach. We do not resolve the combustion front on the grid, but instead use a subgrid-scale model that captures the overall effects of the combustion reactions on flow and transport, i.e. the amount of heat released, the amount of oil burned and the reaction products generated. The subgrid-scale model is calibrated using fine-scale highly accurate numerical simulation and laboratory experiments. This approach significantly improves the computational speed of in-situ combustion simulation as compared to traditional methods. We are currently developing a field-scale simulator using the above ideas. Test cases illustrate the solution consistency when scaling up the grid sizes in multidimensional heterogeneous problems. The methodology is also applicable to other subsurface reactive flow modeling problems with fast chemical reactions and sharp fronts.
Nitrogen Delivery from Legume Cover Crops in No‐Till Organic Corn Production
Authors: Parr M. , Grossman J. M. , Reberg‐Horton S. C. , Brinton C. , Crozier C.
Published: November 2011

Sixteen winter annual cover crop cultivars were grown in North Carolina to determine total N accumulation, biological N fixation (BNF) potential, and compatibility with a roller‐crimper‐terminated organic corn (Zea maysL.) production system. Cover crops and termination dates were tested in a stripped block design. Treatments included hairy vetch (Vicia villosaRoth), common vetch (Vicia sativaL.), crimson clover (Trifolium incarnatumL.), Austrian winter pea (Pisum sativumL.), berseem clover (Trifolium alexandrinumL.), subterranean clover (Trifolium subterraneumL.), narrow leaf lupin (Lupinus angustifoliusL.), and Balansa clover (Trifolium michelianumSavi.), as well as bicultures of rye (Secale cerealeL.), hairy vetch, and Austrian winter pea. Roller‐crimper termination occurred in mid‐April, early May, and mid‐May. Total biomass, N concentration, and C/N ratios were determined for cover crops at all roll times and natural15N abundance at the optimal kill date. Hairy vetch and crimson clover monocultures had the greatest overall biomass in 2009, and bicultures the greatest biomass in 2010. Crimson clover successfully terminated in late April, hairy vetch and Austrian winter pea in mid‐May, and berseem clover and common vetch in late May. All cover crops except lupin and subterranean clover derived between 70 and 100% of their N from the atmosphere. Corn response to cover crop mulches was significantly affected by the time of rolling, with poor stands resulting from competition with insufficiently terminated mulches. Crimson, Balansa, and subterranean clover mulches resulted in poor corn yields despite relatively high levels of total N. The highest corn yields were achieved in hairy vetch and rye plus hairy vetch bicultures.
Genotype × Environment Interactions for Mineral Concentration in Grain of Organically Grown Spring Wheat
Authors: Murphy Kevin M. , Hoagland Lori A. , Yan Lin , Colley Micaela , Jones Stephen S.
Published: November 2011

Genotype × environment (G×E) interactions for Ca, Cu, Fe, Mg, Mn, P, and Zn concentrations are not well understood, particularly in the context of organic farming systems. The objectives of this study were to: (i) investigate G×E interactions for mineral nutrient concentration in organically grown wheat; and, (ii) assess whether grain mineral concentration is a broadly or narrowly adapted trait when grown in contrasting environments over time. We evaluated 18 spring wheat (Triticum aestivum L.) cultivars on three organic farms in Washington State for mineral concentration and for grain yield in 2008 and 2009. The G×Year (Y) interactions were found for grain yield and all minerals except Fe, Mn, and P and G×Location (L) interactions were found for grain yield and all minerals except Fe. The G×E (G×L×Y) interactions were found for grain yield and all minerals except for Mn. Grain yield was not consistently correlated with mineral nutrients across years and locations. Among minerals, Mg:P, P:Zn, and Mg:Zn were positively correlated in at least five of six site‐years, suggesting the potential for simultaneous selection of these minerals. Grain mineral concentrations of Cu, Fe, and P showed relatively broad adaptation across years when compared with Ca and Mg concentrations. Fewer cultivars were broadly adapted spatially than temporally for stable levels of mineral concentration. Several cultivars had relatively high concentrations of two or more minerals across locations, indicating the potential for farmer utilization of broadly adapted cultivars and varietal blends that will significantly increase grain mineral concentration.
Remote Estimation of Crop Chlorophyll Content by Means of High‐Spectral‐Resolution Reflectance Techniques
Authors: Delegido Jesús , Vergara Cristian , Verrelst Jochem , Gandía Soledad , Moreno José
Published: November 2011

The chlorophyll content (Chl) of plants is an important variable in assessing their physiological status and photosynthetic performance. High‐spectral‐resolution reflectance measurements have shown a powerful capacity to detect the subtle variations in spectral absorption features related to changes in Chl. This study proposed a simple technique based on an empirical linear relationship between Chl and the normalized area over reflectance curve (NAOC) index to remotely estimate the spatial distribution of Chl. The NAOC is based on the calculation of the Chl‐sensitive spectral interval obtained by hyperspectral measurements. The data sets used came from four recent European Space Agency campaigns that aimed to study crop properties from space: SPARC (Spain, 2003–2004), AgriSAR (Germany, 2006), CEFLES2 (France, 2007), and Sen3Exp (Spain, 2009). The following steps were undertaken to investigate the proposed relationship: (i) calibrating the SPAD‐502 chlorophyll meter, (ii) collecting spatially distributed Chl data across various crops during the Sen3Exp campaign by using the calibrated SPAD‐502 m, and (iii) fitting a NAOC with Chl field data and tuning it using data from the other campaigns so that a broad variety of crops, climatic conditions, and soil types was covered. The proposed technique was applied to multitemporal hyperspectral images during June 2009. The Chl maps were generated with a RMSE accuracy of 10 μg/cm2. Mapping their differences revealed the spatial distribution of greening up and senescing across crop fields. This new technique shows great potential for remotely monitoring the physiological status of crops.
Use of the Canopy Chlorophyl Content Index (CCCI) for Remote Estimation of Wheat Nitrogen Content in Rainfed Environments
Authors: Cammarano Davide , Fitzgerald Glenn , Basso Bruno , O'Leary Garry , Chen Deli , Grace Peter , Fiorentino Costanza
Published: November 2011

Estimation of canopy N content in rainfed environments early in the growing season and across different locations is challenging due to differences in canopy structure, canopy cover, and soil reflectance. The hypothesis of this study was that the combination of the remotely sensed Canopy Content Chlorophyll Index (CCCI) and the Canopy Nitrogen Index (CNI) allows for the estimation of canopy N status directly from remote measurements, independently of cultivar and site. The aims of this study were to (i) estimate canopy N content from CCCI and CNI in two rainfed environments and on two different wheat cultivars; (ii) study the effects of different ways of deriving the CCCI on the estimation of canopy N content. Data were collected from two rainfed sites cropped to wheat, one in Italy (Foggia) and the other in Australia (Horsham, Victoria). Studies were conducted during the growing seasons 2006–2007 (December–June) and 2007 (June–December) for the Italian and Australian sites, respectively. The use of the CCCI in combination with the CNI show that it is possible to estimate canopy N content early in the season (DC 30), (y = 0.94x + 0.15; r2 = 0.97; RMSE = 0.20 g N m−2) when farmers make their N fertilization decisions. Future research is needed to further validate such approach on independent locations with different growing season rainfall; and to study the robustness of the CCCI boundaries on different environments and different crop types and develop a method to estimate biomass under chronic and acute water stress.
Nitrogen and Cutting Height Influence Root Development during Warm‐Season Turfgrass Sod Establishment
Authors: Wherley B. G. , Sinclair T. R. , Dukes M. D. , Schreffler A. K.
Published: November 2011

Effective water conservation in the landscape requires identification of cultural management practices that maximize the genetic rooting potential of establishing turfgrass sod. Nitrogen is critical for successful turfgrass establishment; however, there has recently been debate over whether to restrict N fertilization during summer periods in parts of Florida and the United States. This study was undertaken to examine within four warm‐season turfgrass species, the relative influences of cutting height and N fertility on the (i) rate of root extension and (ii) root biomass produced over a 10‐wk period. ‘Tifway 419’ bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy), ‘Empire’ zoysiagrass (Zoysia japonica Steud.), ‘Argentine’ bahiagrass (Paspalum notatum Flugge), and ‘Floratam’ St. Augustinegrass (Stenotaphrum secundatum Walt. Kuntze) were established from 10‐cm diam. by 5‐cm deep plugs of turfgrass sod into 90‐cm tall, clear acrylic tubes. Experimental treatments were arranged in a complete factorial that was repeated over two growing seasons. Rates of root extension were calculated from weekly measures of the deepest visible root in each column. Root extension rates ranged from ∼1.0 to 1.8 cm d−1 during the studies, with bahiagrass exhibiting the most rapid root extension of the four species. The results demonstrated that increasing N fertility during establishment increased rates of root extension into deep soil, particularly in bermudagrass. Height of cut had no effect on rate of root extension for most species, but higher cutting height did promote more rapid root extension in bermudagrass. Although not significantly accelerating vertical root extension in most species, maintaining sod at the higher cutting heights resulted in significantly greater root proliferation within both upper and lower soil depths for all species. The results emphasize the importance of proper N fertility and cutting heights for optimizing root development of different turfgrass species during sod establishment.
Manure and Mineral Fertilizer Effects on Seasonal Dynamics of Bioactive Soil Phosphorus Fractions
Authors: Schwartz R. C. , Dao T. H. , Bell J. M.
Published: November 2011

Seasonal fluctuations in bioavailable soil P can influence soil test results and associated assessment of off‐site transport risk. Our objective was to evaluate changes in soil P speciation and availability with time following applications of grain fed cattle (Bos taurus) manure or monoammonium phosphate (MAP). Beef cattle manure or MAP was applied at a targeted rate of 200 kg P ha−1 on a Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustolls) in 2005 and 2006 and planted to grain sorghum [Sorghum bicolor (L.) Moench]. Soil samples (0–0.15 m) were collected before and throughout the growing season and analyzed for Mehlich‐3 phosphorus (Me3P), 1:10 water‐extractable phosphorus (WEP10), water extractable cations, pH, and fractions of bioactive soil phosphorus (TBIOP), which comprised 1:100 water extractable P, ethylenediamine‐N,N,N′,N′‐tetraacetate (EDTA)‐exchangeable inorganic phosphorus (EEPi) and the EDTA‐exchangeable phosphohydrolase‐labile phosphorus (EPHP). Levels of soil Me3P, WEP10, and all fractions of TBIOP in MAP‐amended plots fluctuated significantly (p < 0.05) during both seasons. Except for Me3P, manure amended plots also exhibited significant (p < 0.05) seasonal variations in soil extractable P and a delayed release of P that extended well into the growing season. In contrast, fluctuations in extractable soil P in unamended plots were not significant except EPHP. In water extracts, a significant (p < 0.05) dependence of solution P on pH and Ca suggested that precipitation‐dissolution reactions contributed to observed seasonal fluctuations in P. Fluctuations in total bioactive soil P were two to four times greater than aboveground biomass P highlighting the importance of accounting for seasonal dynamics in assessing offsite P transport risks.
Growth and Nutritive Value of Grass Pea in Oklahoma
Authors: Rao Srinivas C. , Northup Brian K.
Published: November 2011

The cool‐season pulse grass pea (GP, Lathyrus sativus L.) has the potential to provide late‐spring forage in the southern Great Plains (SGP), but genetic materials for development of new cultivars is limited. Our objective was to evaluate seasonal forage production and grain yield of 10 new Mediterranean‐origin GP lines, in central Oklahoma. Replicate (n = 3) plots (3 by 10 m) were disked, fertilized (60 kg ha−1 P2O5), and sown (60 kg seed ha−1) in 60 cm rows with GP lines 190, 288, 289, 290, 299, 387, 390, 736, B22, B111, and AC‐Greenfix (control) that were treated with inoculum (Rhizobium leguminosarum) during early March in 2007, 2008, and 2009. Whole plant samples were collected 59, 73, 94, and 115 d after planting. Biomass collected on Day 115 was separated into seed and nonseed biomass. Biomass accumulation, N concentration and nongrain digestibility showed significant (P ≤ 0.05) line, year, and sampling date effects. Grain biomass, N concentration and digestibility also showed significant line and year effects. AC‐Greenfix produced the most nongrain biomass each year [2499 kg ha−1 for AC‐Greenfix vs. an average of 1899 (±145) kg ha−1 for the other 10 lines] and sampling date. Line × year interactions for grain biomass was statistically significant, with 2008 being the most productive year for all lines. Additional development is needed for these new Mediterranean GP lines to perform with the same consistency as AC‐Greenfix in the SGP.
Potassium Management during the Rotation from Alfalfa to Corn
Authors: Yost Matt A. , Russelle Michael P. , Coulter Jeffrey A. , Sheaffer Craig C. , Kaiser Daniel E.
Published: November 2011

High K fertilizer prices in recent years have made it imperative for growers to apply optimum K rates to alfalfa (Medicago sativa L.). Current university fertilizer guidelines in the Corn Belt do not change for the last production year, when alfalfa stand persistence is not a major concern. Furthermore, little is known about carryover of K applied to alfalfa on first‐year corn (Zea mays L.) grain and silage yields. In 2008 to 2010, on‐farm research was conducted on 10 fields with medium soil test potassium (STK) to determine response to K for alfalfa yield and quality in the last production year, and to estimate K carryover to first‐year corn. Alfalfa yield and relative feed value (RFV) and quality (RFQ) did not improve with K fertilization. Herbage K concentration and K uptake increased with K fertilization across sites, indicating that applied K was available during the season of application. When corn relied on carryover K alone, each 100 kg ha−1 increase in the index of available K increased corn grain yield by 0.5 Mg ha−1, decreased stover yield by 0.4 Mg ha−1, and did not affect silage yields. Regardless of K rate applied to alfalfa, additional K applied to corn increased corn stover and silage yields by 10 and 8%, respectively. This suggests that carryover K was less available than K applied to corn. On medium STK soils going into the last year of alfalfa, applying fertilizer K to first‐year corn rather than alfalfa may enhance economic return.
Reliability and Validity of the Multidimensional Scale of Perceived Social Support (MSPSS): Thai Version
Authors: Wongpakaran Tinakon , Wongpakaran Nahathai , Ruktrakul Ruk
Published: November 2011

This study examines the Thai version of the Multidimensional Scale of Perceived Social Support (MSPSS) for its psychometric properties.

Methods:

In total 462 participants were recruited - 310 medical students from Chiang Mai University and 152 psychiatric patients, and they completed the Thai version of the MSPSS, the State Trait Anxiety Inventory (STAI), the Rosenberg Self-Esteem Scale (RSES) and the Thai Depression Inventory (TDI). Test-retest reliability was conducted over a four week period.

Results:

Factor analysis produced three-factor solutions for both patient (PG) and student groups (SG), and overall the model demonstrated adequate fit indices. The mean total score and the sub-scale score for the SG were statistically higher than those in the PG, except for ‘Significant Others’. The internal consistency of the scale was good, with a Cronbach’s alpha of 0.91 for the SG and 0.87 for the PG. After a four week retest for reliability exercise, the intra-class correlation coefficient (ICC) was found to be 0.84. The Thai-MSPSS was found to have a negative correlation with the STAI and the TDI, but was positively correlated with the RSES.

Conclusion:

The Thai MSPSS is a reliable and valid instrument to use.