Soil carbon, nitrogen, and physical properties in cropping systems of Oklahoma

Abreu, Silvano Luiz de Oklahoma State University 2011 해외박사(DDOD)

Soils across the State of Oklahoma where areas of conventional and long term no-till are under similar climate conditions and soil properties (same soil series) were sampled in 4 points of a transect across the field at 110 cm depth and divided in 5 different depths (0--10; 10--20; 20--40; 40--70; and 70--110 cm). Samples were air dried and sieved at 2mm mesh. Sixteen farm fields (eight no-till and eight conventional till) were sampled in the principal agricultural areas of Oklahoma. Also, two tillage experiments that have no-till and conventional till treatments combined with different crop rotations where sampled and compared as well. Organic C and total N were analyzed. Besides, bulk density was determined at each depth and sampling point in order to account for the amount of organic carbon and nitrogen storage in the soil profile. Results were analyzed by LSD comparing tillage system. Organic carbon and total nitrogen was analyzed by LECO analyzer and carbonates were analyzed so the amount of organic carbon can be calculated. Another chapter of the study analyzed the use of cover different cover crops; including forage radish, sunn hemp, pigeon pea, cowpea, and Austrian winter pea in cash crop rotations that included soybean, corn, and wheat. Grain yield, biomass, and soil physical properties were analyzed in two locations in Central Oklahoma. For most Oklahoma studied areas, no-till soils had higher organic carbon and total nitrogen stock in the soil profile than conventional till. Top soils no-till have also more carbon stock in no-till compared to conventional till soils. The increasing of crop intensity and diversity did not affect grain yield in the cash crops, but increased biomass production. After two years of rotations no effect of crop rotation or crop intensity was observed in soil physical properties.

Thermal State of the Arkoma Basin and the Anadarko Basin, Oklahoma

이영민 University of Oklahoma 1999 해외박사

Subsurface temperature and thermal gradients, along a north-south cross section through the Arkoma Basin and the Oklahoma Platform in southeastern Oklahoma were estimated from 345 bottom hole temperatures from 199 oil and gas wells. The average geothermal gradient in the southern part of the basin near the Ouachita Front is 20 ℃/km, exceeds 30℃/km in the middle part of the basin, and is 24 ℃/km on the Oklahoma Platform to the north. Drill cuttings obtained from 11 oil and gas wells were used for 843 thermal conductivity measurements. Thermal conductivity data, corrected to in situ conditions, were used to estimate heat flow. Estimated heat flow (±20%) in the deep part of the Arkoma Basin near the Ouachita Front is 35-40 mW/m2 and increases systematically northward to 60-65 mW/㎡ on the Oklahoma Platform. Average heat production, estimated from gamma ray logs, is 2.3±0.2㎼/㎥ for basement rocks underlying the Arkoma Basin and 2.8±0.1 ㎼/㎥ for basement rocks in the Oklahoma Platform area. Numerical models show that heat refraction from the less conductive sedimentary rocks (∼1.6 W/m-K) of the Arkoma Basin to the more conductive crystalline rocks (∼3.0 W/m-K at 25℃) of the Oklahoma Platform and the Ouachita Mountains accounts for about 5-10 mW/㎡ of the observed 20-30 mW/㎡ decrease in heat flow from north to south. Changes in crystal heat production related to compositional changes and crystal thinning account for another 5-15 mW/㎡ of the observed heat flow change. If the remaining 0-20 mW/㎡ difference in heat flow is attributed to heat transport by topographically driven groundwater flow, the average basin-scale permeability of the Arkoma Basin and the Oklahoma Platform can be no greater than 10^(-15) ㎡. Results of this study are not generally supportive of theories which invoke topographically driven regional groundwater flow from the Arkoma Basin in Late Pennsylvanian-Early Permian time (~290 Ma) to explain the genesis of Mississippi Valley-type lead-zinc deposits, paleothermal anomalies, and regional diagnoses in the North American mid-continent.

Genesis, distribution, and classification of sodic soils in Oklahoma

Jigoulina, Elena Igorevna Oklahoma State University 2001 해외박사(DDOD)

<italic>Scope and method of study</italic>. Aspects of sodic soil spatial distribution, classification, and genesis are studied. The objectives of this study were: (1) to determine the effect of the climate and other factors on the distribution and properties of sodic soils in Oklahoma, (2) to expand sodic soil classification by using soil properties that reflect soil moisture conditions, (3) to analyze selected major types of sodic and leached sodic (Solods) soils to reveal the formation pathways. Fourteen sodic soil series from 19 Oklahoma counties were sampled in 1997. Horizon delineation and in-situ soil descriptions were made using standard techniques. Characterization of each profile was performed by conventional methods. Data on dispersion characteristics for each horizon were obtained from Oklahoma Department of Transportation Testing Laboratory. Classification of soils under study was conducted using Soil Taxonomy. Maps visualizing soil spatial distribution were generated in ArcView/GIS computer software. <italic>Findings and conclusions</italic>. There is a gradual change in sodic soils properties along the Precipitation-Evaporation (P-E) Index and soil moisture regime gradients. Depth and value of salinity (EC), depth to carbonates, depth and values of maximum relative sodium content and SAR, and pH increased with decreasing P-E index. Variability of sodic soils on a local scale was affected by position on the landscape, which influences presence of water table close to the surface. Parent material affected soil occurrence, as well as soil color, texture, chemical composition of soil water solution, and clay mineralogy. The presence of a ground water with relatively large sodium content determines the occurrence of sodic soils in the area. Suggested classification for sodic soils in Oklahoma takes into account soil salinity, which differs significantly between soils with different moisture regimes and landscape positions and is recognized on a subgroup level. Three types of sodic soils, which differ in the amount of salts, SAR values, acidity and pH, are formed under the humid conditions of southeast Oklahoma. The first type, Natrudalfs, has SAR up to 30 and moderate to high salinity (EC > 2) and occur in the lowest position on a landscape. The second type, sodic Hapludalfs, is located on an intermediate landscape position, and has lower salinity and sodium content compared to Natrudalfs. The third type, solodic Hapludalfs, is the leached sodic soils of terraces and uplands.

Studies on the genesis of selected soils of Oklahoma

Ward, Phillip Amos, III Oklahoma State University 2003 해외박사(DDOD)

<italic>Scope and method of study</italic>. Chapter 1 is a discussion of amounts of dispersion and soil properties associated with dispersion in some soil horizons affected by dispersion from soils of Oklahoma. Chapter 2 is a summary of the effects of addition of amending materials on soil properties associated with dispersion in some of the soil horizons discussed in Chapter 1. Materials tested for amending potential included gypsum, hydrated lime, cement kiln dust, fly ash, humate, calcium chloride, and sulfuric acid. Chapter 3 is an evaluation of the temporal effects of rainfall on the temperature and chemistry of water in a shallow, unconfined aquifer in sediments along Boomer Creek in the Stillwater, Oklahoma vicinity. <italic>Findings and conclusions</italic>. Amount of dispersion measured in soil horizons ranged from 0 to 96 percent. Soil horizons with greater than 65 percent dispersion have greater bulk density, pH, sodium adsorption ratio, and ratio of sodium ions to sum of sodium and calcium ions in soil water, and less clay and organic matter than less-dispersed horizons. Critical sodium adsorption ratios are 8.0 and 4.5 for moderately saline (electrical conductivity between 1.0 and 9.0 decisiemens per meter) and slightly saline (electrical conductivity less than 1.0 decisiemen per meter), respectively. Gypsum proved most effective for improving properties of soil horizons associated with dispersion. Few treatments lowered sodium adsorption ratios of tested horizons below critical values. Treatments were less effective on soil horizons with more clay and greater sodium adsorption ratios and electrical conductivities. Rainfall affected chemistry of water in the Boomer Creek aquifer for a longer time than temperatures in the aquifer. Antecedent moisture in the sediments and amount of rainfall influenced the impact of the rainfalls on the aquifer.

Optical and human assessment of winter wheat cultivars for competitiveness against jointed goatgrass, and characterizing Oklahoma jointed goatgrass-winter wheat hybrids

Stone, Amanda Elizabeth Oklahoma State University 2003 해외박사(DDOD)

<italic>Scope and method of study</italic>. Characteristics other than mature height contribute to competitive ability of wheat, but the literature has not identified any other useful traits. Twenty-four winter wheat cultivars were seeded with and without jointed goatgrass (<italic>Aegilops cylindrica </italic> Host.) in five environments, 1999–2001. Wheat stand density, forage yield, height at Zadocks 32, 37, and 91, spike density, and yield were measured. Additionally, mature height, spike density, spikelet production, and spikelet density of jointed goatgrass were measured. An Oklahoma State University sensor was used to record incident and reflected wavelengths from the canopy of the 24 winter wheat cultivars grown with and without jointed goatgrass, 1999–2001. Normalized difference vegetative index (NDVI) was calculated. The introduction of imazamox tolerant winter wheat has increased interest in jointed goatgrass-winter wheat hybrids [<italic>Aegilotriticum sanctiandreae</italic> (Degen) Soó]. However, little is known about such hybrids in Oklahoma. Hybrid plants were collected from central Oklahoma, 2000 to 2002, for characterization and germination. <italic>Findings and conclusions</italic>. Yields of the 24 wheat cultivars, at four environments were not affected by jointed goatgrass competition. Cultivars varied substantially in their ability to suppress jointed goatgrass spikelet production. Wheat stand density varied greatly and appeared to be related to competitive ability. Wheat forage production, height at Zadocks 32 and 91, and spike density were minor factors in suppressing jointed goatgrass spikelet production. Wheat height at Zadocks 37 was inversely related and wheat yield was variably related to jointed goatgrass spikelet production. NDVI was useful in estimating spike density, spikelet production, and spikelet density of jointed goatgrass, as well as estimating stand density and forage yield of the wheat cultivars grown without jointed goatgrass. NDVI was variable in estimating wheat height at Zadocks 32, 37, and 91, wheat spike density, and wheat yield. When the published morphological characteristics of the 24 wheat cultivars were considered, estimations improved. When certain stress factors such as plant diseases and late season drought were absent, correlations approached 0.9. Hybrid plants varied in mature height and spike length. Hybrid spike color was darker than mature wheat spike color and mature hybrid spikes disarticulated intact, unlike jointed goatgrass. Wheat cultivars varied in hybrid production ability.

Optimal nitrogen and choice of reduced tillage systems for wheat production in north western Oklahoma

Bocoum, Kolado Oklahoma State University 2000 해외박사(DDOD)

<italic>Scope and method of study</italic>. Simulation data from the Erosion Productivity Impact Calculator Model (EPIC) and enterprise budget elaborated from the Oklahoma State University Budget Generator were used to study the long-term onsite and offsite effects of soil erosion on wheat production in Garfield County, Oklahoma. It was assumed that the farm has six soil types, and in each, the producer would choose for each of the 100 years of the planning period, a level of nitrogen application and one of four possible tillage systems. The study estimated the functions of erosion, yield, nitrogen carryover, and nitrogen loss functions per soil type. A discrete dynamic economic model was used to determine the private and social optimum rate of nitrogen application and choice of reduced tillage systems under different assumptions of market prices of wheat and nitrogen, cost of erosion and nitrogen loss, and discount rates. Because of the complexity inherent in using dynamic programming for this problem, the study developed a branching method, which is a simpler approach to solving for the optimal solution. <italic>Findings and conclusions</italic>. It was found that the optimal tillage system was different from private versus social choice. The optimum rates of applied nitrogen were almost identical for the sweep systems, varying from 117 kg/ha to 132 kg/ha across all soil types. The corresponding rates were slightly higher for disk chisel. They varied between 124 kg/ha and 135 kg/ha. The plow system required much higher rates of nitrogen application that vary from 136 kg/ha to 145 kg/ha. The net present value of the disk chisel was higher than the other tillage systems for private optimization, and the net present value of sweep system twice was the highest for social optimization where the farmer is responsible for offsite damage costs of soil erosion. The optimal choice of tillage systems and resulting nitrogen application was not sensitive to changes in wheat and nitrogen prices, and discount rates for either private or social optimization. However, the optimum tillage sequence was sensitive to changes in the cost of erosion and nitrogen loss. A 50% reduction in these costs would make farm shift from using sweep systems to using disk chisel. The results imply that policies aimed at reducing soil erosion are bound to be less effective without internalizing the cost of offsite damages.

Evaluating the response of teff [Eragrostis tef (Zucc.) Trotter] and hard red winter wheat (Triticum aestivum L.) to yield limiting factors in Oklahoma

Ali, Muaid Shaker Oklahoma State University 2013 해외박사(DDOD)

Scope and Method: Weather conditions such as temperature and precipitation are the most important crop growth limiting factors in Oklahoma. Less precipitation is available for crop growth during the summer months due to high evapotranspiration attributed to high temperature. In some years, the winter is dry affecting performance of winter crops. Soil applied phosphate fertilizers use efficiency in winter wheat is low because of soil and weather related factors. Therefore, control and field experiments were established to determine teff growth and yield. The growth chamber teff study comprised three temperature regimes, four levels of soil moisture, three times of watering intervals, and two photoperiods. Treatments for the field study included four levels of irrigation and two watering intervals. Foliar phosphorus improves P use efficiency of crops. However, no effective foliar products are available on the market. The objective of the phosphite study was to evaluate Nutri-phite, a foliar phosphorous product on winter wheat yield, quality and nutrient use efficiency in five fields over two years. Treatments for the foliar P study included application of a Nutri-phite at two growth stages of winter wheat. Nutri-phite was applied with and without N at 100 and 75% of crop need and P at 100 and 80% of P sufficiency a long a check (no fertilizer) and standard (farmer practice) treatments. Findings and Conclusions: In the control study, teff biomass and grain yields increased with increasing soil moisture and decreased with increasing temperature and photoperiod. Grain yield was more affected by high temperature and drought than biomass yield in the growth chamber study. In the field experiment, biomass and grain yield were highly related to water amount. Teff produced acceptable biomass and grain yields under rainfall treatment. The Nutri-phite product improved grain yield of wheat in some fields, especially when rainfall is not limiting during the growing season. In addition, Nutri-phite was more efficient in increasing grain phosphorus concentration compared with the check treatment. Thus, application of Nutri-phite might improve the wheat growth and yield if weather conditions are normal, and the right amount of Nutri-phite is used.

Oklahoma public high school students' perceptions of religious neutrality

Logan-Fain, Laural Brooks The University of Oklahoma 2008 해외공개박사

The purpose of this dissertation was to determine Oklahoma public high school students' perceptions of student-initiated prayer clubs within their schools. The study sought to find out whether there are differences in perceptions based on a variety of potential variables, such as student grade level, gender, and peer influences. This quantitative study evaluated if these variables had an impact on whether or not students felt pressured by their peers to join student-initiated prayer clubs; students felt a teacher would give them a higher or lower grade based on their participation in a prayer club, or lack thereof; and students felt they would be treated differently by other students, teachers, and school administrators. The study included an analysis of more than 600 survey responses from public high school students around the state of Oklahoma. Analyses included a t-test, ANOVA, and correlation. Results showed that (1) There is no significant relationship between gender and students' ability to perceive neutrality in school support for student-initiated school prayer clubs; (2) there is no significant relationship between current grade level and students' ability to perceive neutrality in school support for student-initiated school prayer clubs; and (3) there is a significant relationship between peer pressure and students' ability to perceive neutrality in school support for student-initiated school prayer clubs. Based on the results of this study, proponents on both sides of this issue may be better able to examine the various arguments and make more informed decisions as related to student-initiated prayer clubs in public high schools.

The shared experiences of prospective agricultural education teachers: A phenomenology of supervised agricultural experiences

Whiddon, Ashley Seamon Oklahoma State University 2015 해외박사(DDOD)

The purpose of the qualitative, phenomenological study was to better understand SAE programs through the lived experiences from self-identified future agricultural education teachers in Oklahoma. Phenomenological methods were used to explore eight Oklahoma State University Future Agricultural Education Teachers Academy from each of the five agricultural education districts in the state. The research questions investigated the learning outcomes and experiences regarding SAE programs. Subjects in this study reported learning skills and external factors that attributed their SAE experiences. Four themes were revealed from the reported data to include: (a) subjects attain skills through SAE programs; (b) teachers have a great influence on subjects' SAE programs; (c) subjects have limited and narrow perceptions of SAE; and (d) subjects believe SAE programs diversify their experiences in agriculture. The essence was revealed that teachers determine learning through SAE programs, which provided the greatest opportunity for the acquirement of employability skills in the SBAE program. Recommendations were developed to address the findings and conclusions for each theme.

Remote sensing application in biomass crop production systems in Oklahoma

Foster, Anserd Julius Oklahoma State University 2013 해외박사(DDOD)

This study was conducted to evaluate the combined effects of nitrogen and cropping systems on biomass yield and quality and to describe the spatial variation of biomass yield, soil carbon and nitrogen within a switchgrass field. Field plots at Stillwater and Woodward in Oklahoma consisting of five nitrogen treatments and three cropping systems were used for the nitrogen x cropping system study and an 8 ha switchgrass field at Chickasha, Oklahoma was used to describe the spatial variability at fine (2.5 m sampling distance) and coarse scale (10 m sampling distance). Remote sensing technique was used to monitor biomass yield and quality to better understand N requirement and usage for production. Semivariogram were used to evaluate spatial variability of the soil parameters and biomass yield. The results of this study showed that maximum yield was produced at both locations with less than 84 kg N ha 1 and high biomass sorghum has potential to produce biomass yield > 20 Mg ha 1 under normal conditions in Oklahoma. The study results also showed that perennial grass systems are more reliable sources of biomass yield, especially under adverse climatic conditions of Oklahoma. Final biomass yield of high biomass sorghum could be predicted using both broadband (aerial photograph) and narrowband (GreenSeeker) normalized difference vegetation index (NDVI) from July to close to harvest, while biomass yield in the perennial grass was best predicted during June to July. Comparing simple ratios and best narrowband indices with partial least square regression (PLSR) models suggested that while PLSR calibration models produced significantly lower error and higher r2 for predicting biomass yield and N concentration within a growing season, the simple ratios and best narrowband indices were more stable and reliable when used for prediction across growing seasons. Spatial pattern in switchgrass field was described using both ground and aerial imagery. The NDVI computed from aerial imagery provided good precision at the fine scale in describing the spatial distribution of switchgrass yield. Remote sensing application in biomass production systems can greatly improve prediction models for predicting biomass yield and quality in feedstock materials with use of optimal hyperspectral narrowband.