bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of nutrient concentrations in a temperate forest stream: Roles of upland, riparian, and instream processes
Authors: Mulholland Patrick J.
Published: April 2010

The roles of terrestrial and instream processes in controlling stream‐water N and P concentrations were studied over a 2‐yr period in a deciduous forest stream in eastern Tennessee. Upper soil horizons were highly effective sinks for inorganic N and P in throughfall, and weathering of the parent dolomite was the dominant source of inorganic P to the stream. The riparian zone was a potential source of NH4+ and P to the stream when dissolved oxygen concentrations in riparian groundwater were low, but a sink for P when dissolved oxygen concentrations were high. High rates of instream immobilization of inorganic N and P were observed from late autumn to spring, primarily as a result of uptake by microbes on decomposing leaves and secondarily by algae. Immobilization of inorganic N and P resulted in longitudinal declines in concentrations with distance downstream from groundwater inputs (springs), thereby increasing the importance of organic forms of these nutrients in stream water in downstream reaches. The seasonal pattern of winter minima and summer maxima in stream‐water N and P concentrations observed here is opposite to the pattern observed in many northern streams, suggesting the importance of winter nutrient cycling processes in soils and streams in warmer climates.
Contrasting effects of Daphnia on ratios of nitrogen to phosphorus in a eutrophic, hard‐water lake
Authors: Sarnelle Orlando
Published: April 2010

Daphnia manipulation in large enclosures, and whole‐lake observations before and after a fishkill, showed that intense Daphnia grazing produces large elevations in particulate N : P ratios (PN : PP) during clear‐water periods in a eutrophic lake. The direction of this effect was consistent with expected taxonomic variation among zooplankton in the N : P of excretion.

N and P sedimentation (mg m−2 d−1) was reduced during Daphnia‐induced, clear‐water periods, despite increases in particle sinking velocities. In addition, there was an unexpected difference between seston N : P and the N : P of settled particles during clear water, resulting in a differential increase in average sinking velocity calculated for PP relative to PN.

Daphnia effects on N : P later in the season appeared to be opposite to those during clear water. My data suggest that Daphnia grazing can reduce carbonate precipitation (whitings) by controlling algal biomass. Whitings were accompanied by large increases in sedimentary loss rates for total P (TP) and elevated TN : TP in the euphotic zone. Thus, Daphnia grazing may maintain relatively low TN : TP during summer in eutrophic, hard‐water lakes.
Shifts in seston characteristics after inundation of a European coastal salt marsh
Authors: Hemminga M. A. , Klap V. A. , van Soelen J. , de Leeuw J. , Boon J. J.
Published: April 2010

A microbial assay and in‐source pyrolysis mass spectrometry were used to demonstrate a shift in the characteristics of sestonic particulate organic matter after tidal inundation of a coastal salt marsh in the southwest Netherlands. Analysis of seston samples collected from the main tidal creek of the marsh during a series of tidal cycles showed that an increase in microbial degradability accompanied a more pronounced lipid character of the seston after inundation. No evidence was found that the halophyte vegetation contributed to the efflux of particulate organic matter from the marsh, indicating that the vegetation of the poorly flooded European Atlantic salt marshes may be a minor contributor of particulate organic matter to adjacent bodies of water.
Pelagic‐benthic coupling‐The importance of diatom interannual variability for population oscillations of Monoporeia affinis
Authors: Johnson Richard K. , Wiederholm Torgny
Published: April 2010

The amphipod Monoporeia affinis (Lindström) exhibits long‐term population oscillations in oligotrophic Lake Vänern. Correlation showed profundal oxygen and temperature, and intraspecific and predatory interactions to be poor explanatory variables. Conversely, the interannual variability in food availability—diatom biovolume—was highly correlated with amphipod total density at t + 1 yr and the density of 0+ amphipods and growth (amphipod body length in August) of 0+, 1+, and 2+ generations. Amphipod recruitment success of 0 animals may be an important factor governing long‐term population dynamics, and strong 0+ year classes result in greater 1+ and 2+ population densities. Fish predation, although tentatively not an important population‐regulating factor, was negatively correlated with amphipod total body lengths of the 1+ and 2 age classes in May. Size‐selective fish predation pressure on juveniles and adults may facilitate coexistence of the 3‐yr age classes.
Can phytoplankton maintaina positive carbon balance in a turbid, freshwater, tidal estuary?
Authors: Cole Jonathan J. , Caraco Nina F. , Peierls Benjamin L.
Published: April 2010

An analysis of phytoplankton primary production in the tidal freshwater portion of the Hudson River estuary suggests that net primary production is strongly limited by light and mixing regime. In this turbid, well‐mixed system, cells spend from 18 to 22 h d−1 below the 1% light level. Autotrophic dark respiration, conservatively estimated at 5% of Pbmax, is of sufficient magnitude to make positive algal growth impossible over much of the river and much of the year. It is particularly difficult to explain the observed increase in algal biomass during blooms in spring and summer. We hypothesize that such blooms can occur only in a small fraction of the river where depth is ≲4 m.
Effects of constant and intermittent food supply on life‐history parameters in a marine copepod
Authors: Davis Cubell S. , Alatalo Philip
Published: April 2010

Laboratory experiments were used to determine effects of long‐ and short‐term food limitation on birth, growth, and death rates in Centropages typicus (Copepoda, Calanoida), a species previously reported to be sensitive to patchy food resources. Life‐history parameters were measured in cohorts from hatching to senescence in a range of constant food treatments (0.2–7 µg Chl a liter−1) and in two pulsed treatments that cycled between 0.5 and 2.0 µg Chl a liter−1 at periods of ~0.5 and 1.0 d. A flow‐through culture system minimized biochemical and grazing‐induced changes in food supply and allowed automated measurement of food levels (fluorescence). Particulate carbon, nitrogen, lipid, carbohydrate, and protein were measured also. Results show that even the “food‐sensitive” copepod, C. typicus, can integrate daily fluctuations in food supply at amplitudes comparable to patchiness levels observed in the field. This finding has important implications for field and laboratory studies that relate zooplankton growth and fertility to ambient food supply. Additional new findings include exponential growth in body length, sustained high fertility with age, ingestion of large algal and animal prey, and low contribution of carnivory to the diet. Comparisons with field data suggest that C. typicus is restricted to shelf regions due to food limitation, but that on the shelf it is a major contributor to total copepod production in the fall.
Behavior of Acartia tonsa in patchy food environments
Authors: Tiselius Peter
Published: April 2010

Motility of individual female Acartia tonsa in response to patchiness of the diatom Thalassiosira weissflogii was investigated with a digitizing technique and standard video recordings. Motility, measured as 10‐s displacement, was reduced after 24 h of starvation but was unaffected by 4 h of starvation; it increased temporarily after transfer from food to filtered seawater. When food was present only in the upper half of the aquarium, copepods spent most of their time there and produced as many fecal pellets as in homogeneous food distributions. Detailed video analysis showed that feeding bout frequency was higher and jump frequency lower in the presence of food than in filtered seawater. Copepods performed fast vertical ascents by repetitive jumps to reach the food layer from greater distances; by such behavior they were able to remain in food layers only 30 mm thick placed in the middle of a 200‐mm column of filtered seawater. Even with such thin layers of food, copepods produced as many fecal pellets as in homogeneous food distributions over 2‐h periods. Fast response to food and strong ability to remain inside patches probably is crucial for copepods confronted with ephemeral or thin patches of food.
Bio‐optical characteristics of coastal waters: Absorption spectra of phytoplankton and pigment distribution in the western North Atlantic
Authors: Hoepffner Nicolas , Sathyendranath Shubha
Published: April 2010

The vertical structure in fluorescence and beam attenuation (at 660 nm) is related to local hydrographic features and the composition of photosynthetic pigments for the Gulf of Maine region at the end of summer. Phytoplankton and covarying material appear to be the major factors affecting the beam attenuation coefficient through changes in species composition and pigment concentration and through photoadaptation. The specific absorption coefficient of phytoplankton at 440 nm decreased significantly from stratified waters in the open ocean to the well‐mixed area in the central part of the Georges Bank. We combined detailed pigment analysis with measurement of in vivo phytoplankton absorption spectra and consequently have interpreted the variability in the specific absorption spectra of phytoplankton in terms of changes in the pigment composition. We found major regional differences in the phytoplankton absorption spectra linked to regional differences in the phytoplankton community.
A three‐layered sphere model of the optical properties of phytoplankton
Authors: Kitchen James C. , Zaneveld J. Ronald V.
Published: April 2010

Theoretical scattering computations are performed on a phytoplankton model consisting of three concentric spheres. The outer sphere represents the wall, membrane, or frustule and is assigned a relatively high index of refraction with no absorption. The middle layer represents the chloroplasts and is assigned a relatively low index of refraction with absorption. The core represents the balance of the cytoplasm and is given a low index of refraction with no absorption. The model is applied to an observed size distribution from the Pacific central gyre. This model produced significantly more backscattering and attenuation than a low‐index, homogeneous‐sphere model. Changing the distribution of cell‐wall thickness as a function of particle size produces much variation in the shape of the volume scattering function.
Chaotic solutions for irradiance‐regulated buoyant motion of cyanobacteria
Authors: Sanderson Brian G. , Webster Ian T. , Humphries Stella E.
Published: April 2010

A very simple model for the irradiance‐regulated buoyant motion of the cyanobacterium Oscillatoria agardhii is described. Removing the dimensions from this model enables us to find three independent parameters (a, b, c) that control the character of the motion. Small changes in the three parameters can cause large changes in the average irradiance incident upon a colony. The motion can be either periodic or chaotic depending on the values of these parameters. Motion with periods of 2 d is possible, in which case there can be subpopulations that move synchronously but 1 d out‐of‐phase with one another. The model is intrinsically nonlinear in any conceivable natural setting, but an analytic family of solutions exists for nighttime and an analytic family of approximate solutions for daytime can be found for velocity as a function of depth. The numerical solutions can be interpreted by switching between these analytic families of solutions. Vertical turbulent diffusivity causes a mean buoyant velocity that acts to oppose the downward diffusive flux. This turbulence results in the organism seeing less light, although its average depth is hardly changed because it is mixed deeper during the day and rises more at night.
Early diagenesis in a marine sapropel, Mangrove Lake, Bermuda
Authors: Boudreau Bernard P. , Canfeld Donald E. , Mucci Alfonso
Published: April 2010

The pore waters of a marine sapropel in Mangrove Lake (Bermuda) have been analyzed for a suite of diagenetically sensitive species, i.e. pH, SO42−, ∑H2S, Ca2+, ∑CO2, ∑NH4, ∑P04i Fe2+, and Mn2+. We have also measured a 210Pb depth profile (suggesting a burial velocity of 0.94 cm yr−1) and experimentally determined the rate constant for sulfate reduction (0.062 yr−1).

Waves and turbulence have mixed sediment and pore waters to a depth of 15 cm. However, both stoichiometric and transport‐reaction models argue that molecular diffusion dominates solute transport beneath this mixed zone and that the pore waters are open to diffusion despite rapid burial. Diagenetic modeling shows further that diffusion accounts for 95% of the SO42−, ∑H2S, and ∑CO2 fluxes below the mixed layer. Comparison of model results with sulfur burial fluxes indicates that at least 94% of the generated ∑H2S diffuses out of the sediments. The pore‐water ∑CO2 is also within 5% of that predicted by our models. The : N ratio of the decaying organic matter is calculated to be between 3.86 and 6.87, which is less than half that obtained by analysis of the solids.

The carbonate chemistry of the pore waters suggests that they are nearly saturated with respect to aragonite in the mixed zone, even though this mineral has not been identified in the solids. Precipitation in the mixed zone is confirmed by comparing the observed dissolved Ca profile with that expected for conservative behavior.
Toxic compounds isolated from Microcystis PCC786 that are more active against Daphnia than two microcystins
Authors: Jungmann Dirk
Published: April 2010

Microcystis strain PCC7806 was toxic to Daphnia pulicaria. The toxicity of a crude water extract from lyophilized cells of Microcystis was determined in order to characterize the toxic compound. The LC50 of the crude extract was 47.4 µl ml−1. The crude extract was fractionated by solid‐phase extraction and tested for toxicity. The microcystins in the different fractions were analyzed by HPLC. The crude extract contained 22 µg ml−1 microcystin‐LR and 12.3 µg ml−1 3‐desmethylmicrocystin‐LR, the C‐18 eluate contained 16.3 and 9.1 µg ml−1 of these compounds, respectively. Neither compound was detected in the C‐18 cartridge‐passed crude extract. Nevertheless the C‐18 cartridge‐passed fraction was toxic to Daphnia. Hence I conclude that the two microcystins in the crude water extract are not the compounds in Microcystis PCC7806 which are toxic to Daphnia.
Simple calculation of daily photosynthesis by means of five photosynthesis‐light equations
Authors: McBride Graham B.
Published: April 2010

The performance of five well‐known photosynthesis‐light equations is compared by presenting a wide range of solutions in the form of dimensionless nomographs for the case where photosynthetically available radiation (PAR) reduces exponentially down the water column and is distributed sinusoidally through the photoperiod. These provide a simple means of calculating daily photosynthesis at any depth (e.g. at a benthic layer), or through a water column, avoiding the need to perform complex integrations. An examination is made of the accuracy of common approximate methods for calculating daily photosynthesis, assuming constant PAR. For optically deep water a modification is proposed to Talling’s planimetric solution, to enable daily photosynthesis to be calculated more accurately, yet simply, over the whole range of possible PAR values. The errors induced by approximating the daily PAR distribution as a half‐sinusoid are also reported.
Spectral light measurements in microbenthic phototrophic communities with a fiber‐optic microprobe coupled to a sensitive diode array detector
Authors: KÜhl Michael , JØrgensen Bo Barker
Published: April 2010

A diode array detector system for microscale light measurements with fi–ber‐optic microprobes was developed; it measures intensities of 400–900‐nm light over >6 orders of magnitude with a spectral resolution of 2−5 nm. Fiber‐optic microprobes to measure field radiance or scalar irradiance were coupled to the detector system and used for spectral light measurements in hypersaline microbial mats and in laminated phototrophic communities of coastal sediments. The vertical distribution of major photopigments of microalgae, cyanobacteria, and anoxygenic phototrophic bacteria could be identified from extinction maxima in measured radiance spectra at 430–550 nm (Chl a and carotenoids), 620–625 nm (phycocyanin), 675 nm (Chl a), 745–750 nm (BChl c), 800–810 nm, and 860–880 nm (BChl a). Scalar irradiance spectra exhibited a different spectral composition and a higher light intensity at the sediment surface as compared to incident light. IR light thus reached 200% of incident light at the sediment surface. Maximal light penetration was found for IR light, whereas visible light was strongly attenuated in the upper 0–2 mm of the sediment. Measurements of photon scalar irradiance (400–700 nm) were combined with microelectrode measurements of oxygenic photosynthesis in the coastal sediment. With an incident light intensity of 200 µEinst m−2 s−1, photon scalar irradiance reached a maximum of 283 µEinst m−2 s−1 at the sediment surface. The lower boundary of the euphotic zone was 2.2 mm below the surface at a light intensity of 12 µEinst m−2 s− 1.
CAREER EXPLORATORY BEHAVIORS OF POSTSECTONDARY AGRICULTURE STUDENTS
Authors: Esters Levon T. , McCulloh Rachel E.
Published: April 2010

The purpose of this study was to explore the extent of career exploratory behaviors of students enrolled in Iowa State University’s College of Agriculture and Life Sciences. Career exploration was measured using the self and environmental exploration scales of the Career Exploration Survey (CES; Stumpf, Colarelli, Hartmann, 1983). A MANOVA indicated significant main effects for year in school for the environmental and self exploration scales. For both the environmental and self exploration scales, seniors scored significantly higher than freshmen, indicating greater use of these career exploration strategies in the career exploration process. Findings of this study were consistent with theory and research suggesting that college students are primarily in the exploration phase of career development. Recommendations and implications for students enrolled in postsecondary programs of agriculture are presented.
TEACHING ADVANCED LIFE SCIENCES IN AN ANIMAL CONTEXT: AGRICULTURAL SCIENCE TEACHER VOICES
Authors: Balschweid Mark , Huerta Alexandria
Published: April 2010

The purpose of this qualitative study was to determine agricultural science teacher comfort with a new high school Advanced Life Science: Animal course and determine their perceptions of student impact. The advanced science course is eligible for college credit. The teachers revealed they felt confident of their science background in preparation for teaching the course and they emphasized their intensive science background in preparing to become agricultural science teachers. Teachers indicated they had significant background in advanced science concepts, but they hadn’t used the previous knowledge and it required effort to review the concepts related to the new course. Teachers indicated they weren’t completely comfortable with the supplies and equipment necessary for teaching the various laboratories associated with the course but they were able to utilize local resources to assist them. Students interested in health occupations careers found the course fulfilling their needs. Teachers indicated that the transferable skills students gained from the course included the ability to conduct lab write-ups, function in experimental settings, work in teams, and solve problems.
FIFTEEN-YEAR ENROLLMENT TRENDS RELATED TO THE THREE COMPONENTS OF COMPREHENSIVE AGRICULTURAL EDUCATION PROGRAMS
Authors: Retallick Michael S. , Martin Robert
Published: April 2010

The purpose of this study was to identify the agricultural education enrollment trends in Iowa using 15 years of data collected from 1991 to 2005. It was found that agricultural education enrollment, Supervised Agricultural Experience (SAE) participation, and FFA membership have grown. Using annualized growth rates, agricultural education enrollment (4.06%) grew more rapidly than SAE participation (1.65%) and FFA membership (2.39%). Although growth was realized in all three components, the widening gap between students who only enroll in agricultural education and those who also choose to participate in SAE and FFA is a concern. Increased female participation, 31.96% in 2005, accounted for much of the overall growth in total enrollment. SAE growth was attributed to increased participation in agriscience and agribusiness. The findings have implications for the profession’s ability to put into practice experiential learning theory, the philosophical approach of agricultural education, local program development and management, and the future of agricultural education.
PREPARATION OF AGRICULTURAL EDUCATION STUDENTS TO WORK WITH DIVERSE POPULATIONS
Authors: Talbert B. Allen , Edwin James
Published: April 2010

This study investigated how agricultural education programs prepare teacher education students for work in diverse situations. It assessed the extent to which agricultural education programs are infusing diversity, multiculturalism, and pluralism into their curriculum as courses, field experiences, and in-service for current teachers. This census study included all universities with an agricultural education program as identified in the 2005 Directory of Agricultural Education on the American Association for Agricultural Education (AAAE) website. The instrument was web based and was accessed by 57 program leaders. The program leaders indicated their agricultural education programs provided students with instruction on diversity through required courses, optional courses, or infusion of these topics into agricultural education courses. Results showed that students are involved in early field experiences and student teaching in settings where agricultural education undergraduates interact with people different from themselves. Coursework on diversity and in-service offerings for current teachers showed more mixed results.
AGRICULTURAL LITERACY: CLARIFYING A VISION FOR PRACTICAL APPLICATION
Authors: Powell David , Agnew David , Trexler Cary
Published: April 2010

“Agricultural literacy” is a working concept with considerable range in meaning and impact. An overview of agricultural literacy curricula shows complementary deductive and inductive approaches to the systematic incorporation of agricultural education in K-12 classrooms. Based on positions discussed at the 2005 Agricultural Literacy Special Interest Group meeting of the American Association for Agricultural Education, the authors identified three curricular approaches to promote agricultural literacy: (1) a deductive approach based on programmed frameworks, (2) an inductive approach based on the application of knowledge and process skills, and (3) a utilitarian, values-based approach promoting evaluation of agri-food system issues. The authors provide an original conceptual model underscoring points of possible synergy between these approaches. The model points out interactions imposed on the system by cognitive-constructivist expectations for learning, which conflict with political and social pressures for a “traditional” curriculum assessed through “high-stakes” tests. The authors suggest capitalizing on the strengths of each approach to lever change within the current public education environment. The authors offer a systematic plan that may resolve the external conflict between the expectations of agricultural educators and political/social advocates of standardized curricula and high stakes testing, turning these pressures into forces to promote agricultural literacy.
INTEGRATING SCIENCE IN THE AGRICULTURE CURRICULUM: AGRICULTURE TEACHER PERCEPTIONS OF THE OPPORTUNITIES, BARRIERS, AND IMPACT ON STUDENT ENROLLMENT
Authors: Myers Brian E. , Washburn Shannon G.
Published: April 2010

The essential nature of public school student performance on standardized examinations is becoming increasingly apparent. As schools across the nation are examined more closely based on the science achievement of students, career and technical education programs will be expected to contribute to this effort. Through the lens of Ajzen and Madden’s (1986) Theory of Planned Behavior, this study examined 217 Florida agriculture teachers’ perceptions of science integration in the agriculture curriculum as it pertains to attitudes, perceived barriers, impact on enrollment, and support from key stakeholders. The study found teachers to have positive perceptions, relatively few perceived barriers, high perceived support, and high perceived behavioral control for the integration of science in the agriculture curriculum.
TRANSACTIONAL, TRANSFORMATIONAL, OR LAISSEZ-FAIRE LEADERSHIP: AN ASSESSMENT OF COLLEGE OF AGRICULTURE ACADEMIC PROGRAM LEADERS’ (DEANS) LEADERSHIP STYLES
Authors: Jones David , Rudd Rick
Published: April 2010

The purpose of this study was to determine if academic program leaders in colleges of agriculture at land-grant institutions use transactional, transformational, and/or laissez-faire leadership styles in performing their duties. Academic program leaders were defined as individuals listed by the National Association of State University and Land-Grant Colleges as the Dean of Academic Programs in School and Colleges of Agricultural and Life Sciences or Agriculture and Natural Resources. These academic program leaders were assessed using the Multifactor Leadership Questionnaire (MLQ) developed by Bass and Avolio (2000) to determine their utilization of transactional, transformational, and Laissez–Faire leadership as well as elements of transactional and transformational leadership in their duties. Findings of this study imply that academic program leaders in colleges of agriculture at land-grant institutions have a more transformational leadership style. Additionally, males in this research use transformational leadership behaviors as well as transactional leadership behaviors more often than their female counterparts. Findings of this research show males scoring slightly higher than females in all leadership scale scores. Leadership scale scores included Contingent Reward, Intellectual Stimulation, Management-by-Exception (passive), Management-byException (active), Idealized Influence (behavior), Idealized Influence (attributed), Individualized Consideration, and Inspirational Motivation. This research showed ethnicity had no significant effect on leadership behaviors.
PROFESSIONAL ROLES AND RESPONSIBILITIES: CHALLENGES FOR INDUCTION TEACHERS
Authors: Burris Scott , Keller Jamie
Published: April 2010

The purpose of this study was to identify challenges faced by induction-year teachers in Texas. The target population for the study was induction teachers in Texas during the 2005-2006 school year (N = 98). A census was conducted and 73 teachers responded resulting in a 77% response rate. Data were collected using an electronic questionnaire administered over the Internet. The questionnaire contained three parts. Part one sought to determine teachers’ perceived level of importance of 44 teaching competencies representing five effective teaching competency categories. Part two of the instrument sought to determine the teachers’ perceived level of preparation on the same competencies and categories. The final section of the instrument sought to describe demographic characteristics of participants. Mean weighted discrepancy scores were calculated to determine the teaching competencies that are most challenging. Correlations were conducted to determine the relationships between the summated weighted discrepancy score and selected personal characteristics.
CAREER DEVELOPMENT EVENT PARTICIPATION AND PROFESSIONAL DEVELOPMENT NEEDS OF KANSAS AGRICULTURAL EDUCATION TEACHERS
Authors: Harris Clark R.
Published: April 2010

Past studies have shown that agricultural education teachers perceive a need for professional development in Career Development Events (CDEs) preparation, but they did not identify the individual CDEs where training was needed. This study examined the CDEs that Kansas schools were participating in at the district and state levels and the CDEs where teachers perceived a need for professional development. A questionnaire was administered via the Internet, and 114 teachers responded. Of the respondents, 83.33% were interested in a weeklong professional development workshop or graduate course in CDE preparation. CDEs that were identified for professional development, such as agricultural sales, agribusiness management, food science and technology, and agricultural communications were not ranked high in regard to current participation. The livestock evaluation CDE had the highest participation at the district and state levels but ranked 17th in regard to teachers’ interest in professional development. It was concluded that teachers participate in CDEs they feel comfortable with and are less likely to participate in CDEs that they feel less familiar. The study also found that most teachers used Internet resources to help prepare students for some CDEs.
INFLUENCE OF CAREER EXPLORATION PROCESS BEHAVIORS ON AGRICULTURE STUDENTS’ LEVEL OF CAREER CERTAINTY
Authors: Esters Levon T.
Published: April 2010

The purpose of this study was to determine the extent to which career exploration process behaviors influence the level of career certainty of agriculture students. Data were gathered from 181 freshmen and 131 senior students enrolled in the College of Agriculture and Life Sciences at Iowa State University. Career certainty was assessed using items from the Career Decision Scale (Osipow, 1987) Career exploration was assessed using selected career exploration process behavior scales from the Career Exploration Survey (Stumpf, Colarelli, & Hartmann, 1983). Findings indicated that students were relatively certain in having made a decision about a career but only moderately engaged in various career exploratory process behaviors. Stepwise regression analysis revealed that two career exploration process behaviors explained 35% of the variance in the level of career certainty for freshmen, whereas one career exploration process behavior explained 40% of the variance in the level of career certainty for seniors. Thus, to increase students’ level of career certainty, a major focus should be on the extent of career exploration involving self-assessment and retrospection (i.e., Self-Exploration) as well as occupational preferences (i.e., Focus). Implications and recommendations for future research are discussed.
DESCRIPTION OF THE USE OF GREENHOUSE FACILITIES BY SECONDARY AGRICULTURAL EDUCATION INSTRUCTORS IN ARIZONA
Authors: Franklin Edward A.
Published: April 2010

The purpose of this study was to determine the status and use of greenhouse laboratory facilities by secondary agricultural education instructors in Arizona. Specific objectives were to determine the number of programs with operating greenhouses, types of operating systems, how the facilities are used in the local program, level of preparation of instructors to use greenhouses, use of greenhouse to meet science standards, and barriers to the use of greenhouses. Findings suggest that 75% of agricultural education programs in Arizona have a greenhouse. Teachers are more likely to use the greenhouse for classroom instruction, SAE, and fundraising and less likely to use it for CDE training and agriscience research. Teachers are likely to use a greenhouse to teach to state science standards. Most teachers have little or no postsecondary preparation or previous work experience in horticulture prior to entering teaching and are not satisfied with quantity or quality of use of their greenhouse. Teachers are supportive of a university-level course to prepare preservice teachers to use a greenhouse for education. Lack of funding and experience are perceived barriers to not having a greenhouse as part of the local agricultural education program.
RIGOR IN AGRICULTURAL EDUCATION RESEARCH REPORTING: IMPLICATIONS FOR THE DISCIPLINE
Authors: Fuhrman Nicholas E. , Ladewig Howard
Published: April 2010

Agricultural education has been criticized for publishing research lacking many of the rigorous qualities found in publications of other disciplines. A few agricultural education researchers have suggested strategies for improving the rigor with which agricultural education studies report on methods and findings. The purpose of this study was to determine whether studies in agricultural education have followed the methodological suggestions proposed by these select researchers. Every study published in the Journal of Agricultural Education between 2000 and 2006 (N = 244) was examined using content analysis techniques. Specifically, quantitative, inferential studies were assessed with regard to the conveyance of practical significance, the stating of research hypotheses, and explicitly acknowledging how statistical assumptions were addressed and confirmed. Of the 88 inferential studies published in the Journal since 2000, 52% did not convey the practical significance of their research findings and 74% did not explicitly state research hypotheses. Nearly 80% did not acknowledge how the assumptions associated with statistical tests used were addressed and confirmed. Studies that conveyed practical significance, stated hypotheses, and addressed statistical assumptions are cited as examples to follow. Perhaps an increase in pages allotted to each article would provide authors with adequate space to report such items.
THE RELATIONSHIP BETWEEN TEACHER IMMEDIACY AND STUDENT MOTIVATION
Authors: Velez Jonathan J. , Cano Jamie
Published: April 2010

This descriptive correlational study examined the relationships between teacher immediacy and student motivation. Specifically, verbal and nonverbal independent variables were compared with dependent traits of expectancy-value and approach-avoidance motivation. Students selfreported perceived levels of instructor immediacy and self-rated their resulting motivation. The measures of verbal and nonverbal immediacy showed a substantial positive correlation with each other; nonverbal immediacy and expectancy-value evidenced a moderate association. In addition, approach showed a moderate positive correlation with avoidance. Results indicated immediacy does have an association with motivation, specifically nonverbal with expectancyvalue. Students also indicated a difference in immediacy between professors and graduate students. These differences yield important insight into ways instructors can analyze and reflect on classroom communication methods. This study provides useful, descriptive data indicating the need and direction for future research.
CLASSROOM EVALUATION OF AN ELEMENTARY EDUCATIONAL SWINE CURRICULUM: THERE’S A PIG IN MY CLASSROOM
Authors: Wagler Sarah , Rusk Clinton P. , Blomeke Christine R. , Richert Brian T. , Latour Mickey A. , Talbert B. Allen
Published: April 2010

The purpose of this study was to test an educational swine curriculum geared toward fifth grade classrooms to measure the change in students’ knowledge about the pork industry, pork as a nutritious protein source, and the value of byproducts derived from pork production. Objectives of this study were to evaluate overall change in students’ knowledge of the pork industry and the effect of specific demographics on the change in students’ knowledge following participation in an educational swine curriculum. Effectiveness of the curriculum was measured by a pretest/post-test survey of fifth grade students (n = 435), with classrooms divided into treatment and control groups. Findings indicated that participating in the educational swine curriculum increased the students’ knowledge of the pork industry by 37.4%; demographics such as 4-H experience, farm experience, or prior experience with pigs had limited effect on knowledge gained.
DEVELOPING BEST PRACTICES OF TEACHER INDUCTION
Authors: Moore Lori L. , Swan Benjamin G.
Published: April 2010

Problems and challenges faced by beginning teachers have been well documented in the literature and have created the need for teacher induction programs in all disciplines, including agricultural education. This paper used literature from inside and outside the agricultural education discipline to identify and describe best practices in teacher induction yielding a framework called the Best Practices of Teacher Induction for Agricultural Education. This framework is based on the work of Camp and Heath (1988), who identified four contributor groups responsible for teacher induction, and the work of Stansbury and Zimmerman (2000), who identified high and low intensity teacher induction activities. Within the framework, the roles and responsibilities of four contributor groups (local school districts, professional associations, state department of education, and teacher educators) have been described within the context of both high and low intensity activities.
PRIORITIES FOR UNDERGRADUATE EDUCATION AND THE INCLUSION OF INTERNATIONALIZED CURRICULUM IN COLLEGES OF AGRICULTURE: INTERPRETING THE “COMPARISON DILEMMA”
Authors: Navarro Maria , Edwards M. Craig
Published: April 2010

To adapt to major social, cultural, technological, and globalization forces, scholars frequently discuss the purpose, structure, and content of higher education in agriculture. Most agree that change in the curriculum is imperative. The questions are who will champion the change, who will implement it, and whether faculty are willing to be an essential part of the process. So, the purpose of this study was to analyze what the faculty of the colleges of agriculture (COA) of the University of Georgia and Texas A&M University perceived to be priorities for the curriculum and the degree of relevance associated with internationalizing it. Accordingly, the respondents’ perceptions were considered to be proxies for their future behaviors. A census of undergraduate teaching faculty in the two COA responded to an online questionnaire. Interviews of selected faculty were also conducted. Faculty gave preference to improving student development of analytical and communication skills over enhancing technical content. Increasing international awareness ranked last in priority; however, internationalization of the curriculum was viewed as very relevant. The tendency to compare issues often dilutes the emphasis given to internationalization, especially if viewed as a mutually exclusive alternative. That tendency to compare is herein referred to as the “comparison dilemma.” Selected findings and conclusions are discussed accordingly.
FACTORS THAT INFLUENCE THE DECISION TO PARTICIPATE IN YOUTH ORGANIZATIONS IN RURAL HIGH SCHOOLS IN THREE STATES
Authors: Rayfield John , Compton Kirsten , Doerfert David , Fraze Steven , Akers Cindy
Published: April 2010

This study sought to determine the factors that influenced student decisions to participate in FFA in a rural school and their level of involvement as an FFA member. Data was collected from 2,111 high school students in 41 rural high schools in Arizona, Florida, and Texas. Discriminant analysis identified four factors that influence participation in FFA in the respondents: high school GPA, participation in on-campus (non-Career/Technical organizations) activities, agreement with the statement “Leadership activities have made me a more confident person,” and the student’s year in school. Factors identified that influenced the level of involvement in FFA by the respondents were: involvement in on-campus athletics, involvement in on-campus (non-Career/Technical organizations) activities, high school GPA, and agreement with the statement “My friends would think less of me.” Future research is recommended, including a replication of this study with urban students.
AN ASSESSMENT OF THE EMPLOYABILITY SKILLS NEEDED BY GRADUATES IN THE COLLEGE OF AGRICULTURE, FOOD AND NATURAL RESOURCES AT THE UNIVERSITY OF MISSOURI
Authors: Robinson J. Shane , Garton Bryan L.
Published: April 2010

The purposes of this descriptive study were to assess graduates’ perception of the importance and competence levels of performing identified transferable skills in the workplace and use the Borich (1980) needs assessment model to identify the skills most in need to enhance the curriculum. The findings revealed that solving problems, working independently, and functioning well in stressful situations were perceived by graduates as being most important to their job, and identifying political implications of the decisions to be made was the least important. In terms of competence, graduates perceived themselves to be most competent at working independently, relating well with supervisors, and working well with fellow employees and least competent at identifying political implications of the decisions to be made. When using the Borich model, solving problems, allocating time efficiently, communicating ideas verbally to groups, and accepting constructive criticism were the skills with the highest mean weighted discrepancy score, indicating a high need for curriculum enhancement.
COLLABORATION BETWEEN SCIENCE AND AGRICULTURE TEACHERS
Authors: Stephenson Lee G. , Warnick Brian K. , Tarpley Rudy S.
Published: April 2010

The focus of this descriptive study was to determine the type and frequency of collaborative activities occurring between agriculture teachers and science teachers who taught in schools with agricultural education programs. Additional foci of this study included determining the extent to which science and agriculture teachers value collaborative practices, identifying factors that facilitate collaboration, and identifying barriers inhibiting collaboration. Although results indicate that most science and agriculture teachers hold positive attitudes concerning the potential for collaboration, reported collaborative activities between the groups was limited, with science teachers indicating less collaboration occurring than agriculture teachers. The large majority of science teachers indicated that they have not attended workshops demonstrating agriscience integration, and both groups identified lack of preparation time as the most significant barrier inhibiting collaboration. Moreover, both groups indicated that close proximity of facilities, teacher commitment, teacher attitude toward science and agriculture, frequent professional interaction, and administrator support facilitate collaboration.
PRESERVICE AGRICULTURAL EDUCATION TEACHERS’ SENSE OF TEACHING SELF-EFFICACY
Authors: Stripling Christopher , Ricketts John C. , Roberts T. Grady , Harlin Julie F
Published: April 2010

The purpose of this study was to perform a longitudinal examination of the teaching self-efficacy of preservice agricultural education teachers. Data were collected for two years at The University of Georgia and Texas A&M University during the Fall 2004 and Spring 2005 and the Fall 2005 and Spring 2006 semesters (N = 102). Data were collected at the following three collection points: (1) before methods class, (2) after methods course/before student teaching, and (3) after student teaching. Teacher efficacy scores in student engagement, instructional strategies, and classroom management improved at each point of data collection. Preservice teachers were the most efficacious in instructional strategies and classroom management and the least efficacious in student engagement.
Structured Communication: Effects on Teaching Efficacy of Student Teachers
Authors: Edgar Don W. , Roberts T. Grady , Murphy Tim H.
Published: April 2010

Teaching efficacy beliefs of agricultural science student teachers during field experiences may affect the number of student teachers entering the profession. The purpose of this study was to examine the effects implementing structured communication between cooperating teachers and student teachers would have on student teachers' self-perceived teaching efficacy during field experiences. The learning environment of field experiences must be more fully understood to explain why some student teachers enter the profession of agricultural science teaching and others do not. This study employed a quasi-experimental design with a nonrandom sample in a multiple time-series design. The average respondent in this study was a 23-year-old white undergraduate female located at a multiple-placement cooperating center. Respondents in an environment where the amount and type of communication between student teachers and cooperating teachers was structured were less efficacious when compared with respondents who were not in a structured communication setting. In addition, student teachers in a structured communication environment declined in their teaching efficacy measurements overall, whereas student teachers who were not involved in structured communication increased in self-perceived teaching efficacy levels.
Selected Effects of a Curriculum Integration Intervention on the Mathematics Performance of Secondary Students Enrolled in an Agricultural Power and Technology Course: An Experimental Study
Authors: Parr Brian , Edwards M. Craig , Leising James G.
Published: April 2010

The purpose of this study was to empirically test the posit that students who participated in a contextualized, mathematics-enhanced high school agricultural power and technology (APT) curriculum and aligned instructional approach would develop a deeper and more sustained understanding of selected mathematics concepts than those students who participated in the traditional curriculum and instruction.This study included teachers and students from 38 high schools in Oklahoma (18 experimental classrooms; 20 control classrooms).Students were enrolled in an APT course in the spring of 2004.The experimental design used was a posttest only control group; unit of analysis was the classroom.One-way analysis of variance (ANOVA) was used to test the study's null hypotheses.The math-enhanced curriculum and aligned instructional approach did not significantly affect (p > .05) a student's mathematics ability as measured by a traditional test of student math knowledge or by an "authentic" assessment of student ability to use math to solve workplace problems.Thus, the study's null hypotheses were not rejected.However, because of incomplete implementation of the treatment as reported by some experimental teachers coupled with an intervention time frame of only one semester, a one-year replication of the study is recommended.
Exploring Principals' Perceptions of Supervised Agricultural Experience
Authors: Rayfield John , Wilson Elizabeth
Published: April 2010

This study explored the perceptions of principals at high schools with agricultural education programs in regard to Supervised Agricultural Experience (SAE). There is evidence that suggests that high school principals' attitudes may both directly and indirectly affect factors that influence school climate and student achievement. In this study, principals were found to value SAE. No differences were found in the perceptions of those with prior experience in Agricultural Education/Supervised Agricultural Experiences or those who lead urban/rural schools. This is a promising finding since many of today's principals possess less experience with agricultural education and rural communities. The majority of principals in this study did not recognize their teachers for conducting SAEs. Teacher recognition for SAE participation was most likely given in the form of face-to-face conversation and not in the direct formal evaluation processes. A strong relationship was found to exist between the value principals possess of Career and Technical Education (CTE) and their value of SAEs. National and state staff should consider developing more award programs where principals and teachers can be recognized for SAE participation. In-service should be targeted at principals who do not value Career and Technical Education in general.