Cotton (Gossypium hirsutum L.) is an important commercial crop in the northeastern part of Louisiana. Research-based information for irrigation scheduling in cotton is lacking in this region. A two-step reference evapotranspiration (ETo) - cotton crop coefficient (Kc) approach is considered a standard method of crop water use (ETc) estimation. Therefore, a study was conducted to determine stage-specific cotton water use crop coefficients (Kc), a ratio of ETc to ETo at the LSU AgCenter Northeast Research Station in 2010. For ETc estimation, paired weighing lysimeters were used. Cotton variety Stoneville 5458 B2RF was planted on weighing lysimeters by hands and surrounding field using a vacuum planter under similar growing conditions typical of the region on May 12. Cotton plants on lysimeters and surrounding field were irrigated throughout the season. Other crop management practices were carried out following the LSU AgCenter recommendations. To estimate ETo, an area of 102 m by 102 m seeded with Bermuda grass (Cynodon dactylon L.) was demarcated and a tower 10 m in height instrumented with weather sensors was installed in the center of demarcated area in July 2009. Daily measurements of maximum and minimum air temperature, minimum and maximum RH, wind speed, and total solar radiation were obtained and ETo was estimated using the Standardized Reference Evapotranspiration Equation (SREE) of the American Society of Civil Engineers (ASCE).An average Kc value of 0.42 for initial growth stage (0 to 25 days after planting), 0.89 for developmental (26 to 60 days after planting) and 1.41 for mid-season (61 to 132 days after planting) were observed. With the development of these Kc values, a simple internet based tool can be designed to help producers conduct a more efficient irrigation scheduling which will subsequently improve water use efficiency in this region.

Initially, 46 petroleum contaminated and non-contaminated soil samples were collected and scanned using visible near-infrared diffuse reflectance spectroscopy (VisNIR DRS) at three combinations of moisture content and pretreatment. The VisNIR spectra of soil samples were used to predict total petroleum hydrocarbon (TPH) content using partial least squares (PLS) regression and boosted regression tree (BRT) models. The field-moist intact scan proved best for predicting TPH content with a validation r2 of 0.64 and relative percent difference (RPD) of 1.70. Those 46 samples were used to calibrate a penalized spline (PS) model. Subsequently, the PS model was used to predict soil TPH content for 128 soil samples collected over an 80 ha study site. An exponential semivariogram using PS predictions revealed strong spatial dependence among soil TPH [r2 = 0.76, range = 52 m, nugget = 0.001 (log10 mg kg-1)2, and sill 1.044 (log10 mg kg-1)2]. An ordinary block kriging map produced from the data showed that TPH distribution matched the expected TPH variability of the study site. Another study used DRS to measure reflectance patterns of 68 artificially constructed samples with different clay content, organic carbon levels, petroleum types, and different levels of contamination per type. Both first derivative of reflectance and discrete wavelet transformations were used to preprocess the spectra. Principal component analysis (PCA) was applied for qualitative VisNIR discrimination of variable soil types, organic carbon levels, petroleum types, and concentration levels. Soil types were separated with 100% accuracy, and organic carbon levels were separated with 96% accuracy by linear discriminant analysis. The support vector machine produced 82% classification accuracy for organic carbon levels by repeated random splitting of the whole dataset. However, spectral absorptions for each petroleum hydrocarbon overlapped with each other and could not be separated with any classification scheme when contaminations were mixed. Wavelet-based multiple linear regression performed best for predicting petroleum amount with the highest residual prediction deviation (RPD) of 3.97. While using the first derivative of reflectance spectra, PS regression performed better (RPD = 3.3) than the PLS (RPD= 2.5) model. Specific calibrations considering additional soil physicochemical variability are recommended to produce improved predictions.

The internet is a ubiquitous part of todays society and is used by many as a primary source of information. The National Institutes of Environmental Health Sciences (NIEHS) realized the internets potential for connecting with stakeholders to transmit the findings of funded groups to make research accessible and applicable to communities and real world situations. This type of information exchange is part of what is known as research translation and is a main component of Superfund Research Programs (SRP) nationwide. Scientific communication is a burgeoning area of study, and little is known about the particular needs of the professional audience in terms of sharing information. This study explores the needs and preferences of the SRP professional audience in order to make recommendations for web design that will facilitate effective web-based research translation. The SRP Website Survey compares websites with opposing traits for each of the following dimensions of usability: comprehensibility, hyperlinks/homepage, layout, relevance, search option, structure, and user friendliness. Thirty-six respondents indicated his/her preferences for each dimension, and statistical significance was found in five areas layout, comprehensibility, user friendliness, search option and relevance. Based on these findings, SRPs should include a streamlined layout with short navigation menus and present information in short paragraphs or bulleted lists written in non-technical language. The professional audience also indicated a need for a prominently displayed search option as well as a definitions list of jargon they may encounter while exploring a site. The findings and recommendations presented in this study should serve as a template for SRPs to conduct web-based scientific communication and increase audience knowledge and readership.

In Louisiana, current N rate recommendations for sugarcane production are based on multiple year N response trials and refined based on soil and crop variables. Without accounting for current growing conditions, recommendations can potentially lead to over- or under-application of N. The objectives of this research were to 1) determine the ability of an in-season response index value (RINDVI) to estimate sugarcane yield response index (RIHarvest), 2) determine if sugarcane yield potential could be determined using normalized difference vegetative index (NDVI), and 3) estimate the optimum N rate and application timing for sugarcane production in Louisiana. Experiments were established in St. Gabriel and Jeanerette, LA from 2008 through 2011. A GreenSeeker® hand-held optical active sensor was used to obtain NDVI readings for all studies. Fertilizer N was applied as urea ammonium-nitrate (UAN, 32-0-0) at the rate of 0, 45, 90, and 135 kg N ha-1 for most experiments with application timings ranging from early-April through late-May. This study showed that NDVI could be used to accurately estimate both sugarcane RI and yield potential (YP). A RI value was determined using a traditional method, comparing non-limiting N to an unfertilized treatment, and modified method, comparing all N fertilized treatments to an unfertilized treatment. There was a strong relationship between RINDVI and RIHarvest for cane tonnage and sugar yield using both methods. Additionally, NDVI values demonstrated the ability to estimate sugarcane yield potential in-season. This relationship was improved when NDVI was adjusted using climatic variables. An additional study was established to investigate the N rate and application timing on sugarcane production. Fertilizer rate showed a significant positive effect on sugarcane yield for two of three experiments. For these experiments, critical N rates were substantially lower than the current N rate recommendations. The effect of application time was not as pronounced, with only the second stubble sugarcane crop in 2011 showing a significant decrease in sugarcane yield when N fertilization was delayed. Overall, the use of remote sensing principles shows promise in Louisiana sugarcane production. However, limitations such as timing of sensing will need to be overcome prior to implementation.

The Transylvanian Plain (TP) is a 395,000 ha region located in north-central Romania and is an area of agronomic importance in the region. The TP is characterized by hilly terrain, dissected by the Someş and Mureş Rivers. The terrain creates a unique situation when assessing pedology and soil temperature. Soils can change quickly across the landscape in the TP due to the terrain. To account for these differences, soil temperature was measured to predict soil temperatures as well as to evaluate growing conditions. Twenty stations were installed for a long-term temperature and pedology study. Pedons were described for morphological characterization at each location. Pedon descriptions were then classified using both US Soil Taxonomy (USST) and Sistemul Roman De Taxonomie A Solurilor (Romanian System of Soil Taxonomy- RSST). The two soil classification systems aligned for all 20 stations. Morphological descriptions showed that there were 10 Mollisols (Cernisoluri), 4 Alfisols (Luvisoluri), and 6 Inceptisols (Cambisoluri) according to USST (RSST). All locations had sufficient organic carbon to classify as mollic epipedons. However, other requirements such as: color and depth of epipedon were not met. Soil temperature is identified at the family level in USST and is not present in RSST. In addition to morphological characterization at the 20 locations, soil and air temperatures were measured via a data logging system. Soil temperature is a vital property when evaluating crop growth due to its influence on germination and root growth. Growing degree days (GDD) were evaluated for the summer of 2009 using air temperature for the TP. Craiesti and Filpisu Mare were significantly warmer than Matei and Zoreni and gained sufficient GDD for tasseling 21 days earlier. Mean annual soil temperature (MAST) was predicted using a multiple regression model and Landsat 7 ETM+. Landsat provided a better linear relationship to in situ MAST values with a coefficient of determination value (R2) of 0.63 compared to the multiple regression with an R2 of 0.42. Significant differences were found in MAST values between agricultural and urban land covers. The use of Landsat ETM+ could reduce the time and expense of large in situ field studies.

Thesis (Ph. D.)--Oregon State University, 2001. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

The Department of Energy (DOE) is responsible for the cleanup of nuclear waste at former nuclear weapons sites across the United States. Cleanup activities of particular interest include the containment of waste in near surface disposal facilities. There is a need to build confidence in the predictive nature of long-term cover performance models, particularly when considering long-term impacts from climate change. This research aimed to develop an approach to assessing long-term performance of near surface disposal facilities under climate change impacts. This was accomplished by: (1) defining a methodology using historical precipitation and temperature data; (2) using a Monte Carlo approach to assess performance based on past events; (3) performing a proof of concept application; and (4) developing and assessing future climate change scenarios relative to percolation thresholds. From this research, it was determined that the HELP model is a useful tool to assess the hydrological performance of near surface disposal facilities in humid climates when degradation of designs is considered by modifying various hydraulic inputs. In addition, changes in both precipitation and temperature have been found to influence landfill cover performance; in many cases, the potential negative effects of additional precipitation on landfill cover performance can be offset by warmer temperatures. These developments and findings can have meaningful implications on future regulatory policies and guidelines when considering naturally occurring climatic change and anthropogenic forcing.

Bermudagrass (Cynodon dactylon L. Pers.) collected from 17 Louisiana sugarcane (Saccharum spp. hybrids) fields and two sites outside sugarcane-growing area was evaluated for genetic diversity, growth characteristics and response to glyphosate. Random Amplified Polymorphic DNA (RAPD) genetic analysis and Jacards similarity coefficient, a dedrogram, based on unweighted pair group mean average (UPGMA) identified two cluster groups based on presence of common alleles. Bermudagrass considered most aggressive in establishment rate based on ground cover, plant height, and biomass production included the biotypes A (St. Martinville) and Q (Port Allen) in cluster A and R (St. Gabriel) in cluster B. Biotypes J (Samuels), N (New Iberia), and T (St. Joseph) considered least aggressive were included in cluster A. Rate of establishment for biotypes J, N, and T averaged 5.3 times slower and plant height was 61% less compared with A, Q, and R. Biomass production the first year averaged 7.8 times greater for biotypes A, Q, and R compared with J, N, and T. In greenhouse and field studies, bermudagrass biotypes A, C (Baldwin), and Q in cluster A were least sensitive to glyphosate and biotypes D (Centerville) and P (Patterson) in cluster B were most sensitive to glyphosate. In a competition study, pre-sprouted single node stem cuttings of HoCP 96-540 sugarcane were planted in 26.5 L pots with one, two, or four bermudagrass plants, sugarcane shoot weight 56 days after planting (DAP) was reduced on average 58%; two and four bermudagrass plants reduced sugarcane root weight on average 39%. In another study, two bermudagrass plants did not negatively affect shoot population 56 DAP for the cultivars HoCP 96-540, L 97-128, L 99-226, HoCP 00-950, L 01-283, and L 03-371. For L 97-128 and L 99-226, shoot weight averaged 1.7 to 3.0 times greater than the average of the other cultivars and root weight averaged 1.8 to 2.1 times greater than the average of the other cultivars. When the sugarcane cultivars were watered over a 42-day period with leachate collected from actively growing bermudagrass, sugarcane tiller height, tiller number, shoot weight, and root weight were not negatively affected.

Transport of heavy metals such as Ag is affected by several rate-limiting processes including adsorption and release reactions in soils. In this study, the objective was to qualify adsorption-desorption behavior and transport of silver in the different soils. This study also investigated the influence of the presence of Zn on Ag retention and transport in soils. Kinetic batch adsorption-desorption and column experiments were carried out to investigate the adsorption-desorption and transport of silver in soils having different properties in the presence of Zn. Transport of Ag was carried out using miscible-displacement experiments in water saturated soil columns. For all soils, results indicated that adsorption isotherms for Ag were highly nonlinear with greater affinity for Webster soil. Moreover, the presence of Zn resulted in reduced Ag sorption indicative of competitive behavior. Measured Ag breakthrough results (BTCs) from the column experiments indicated highest Ag mobility in Olivier soil whereas Webster soil exhibited least mobility. This finding is based on the Ag recovered and the retardation of the arrival of Ag in the effluent solution. Furthermore, the presence of Zn resulted in enhanced mobility of Ag. A multireaction and transport model (MRTM) that accounted for nonlinear reversible kinetics and irreversible reactions was capable of describing both Ag and Zn transport in all soil columns.

Research was conducted to evaluate corn (Zea mays L.) and soybean (Glycine max L. Merr.) injury and weed control with pyroxasulfone applied preemergence (PRE) and postemergence (POST). In corn, pyroxasulfone applied both PRE at 150 g/ha and POST at 60 g/ha with glyphosate controlled barnyardgrass, Palmer amaranth, sicklepod, prickly sida, browntop millet, ivyleaf morningglory, and entireleaf morningglory 90 to 99% 30 days after the POST application. Weed control was no greater than when pyroxasulfone at 150 g/ha was applied only PRE. Control of barnyardgrass, Palmer amaranth, smooth pigweed, and browntop millet was greater for pyroxasulfone PRE compared with atrazine PRE and lower corn yield was observed for the atrazine treatment. In a second corn study, pyroxasulfone applied alone PRE controlled barnyardgrass, smooth pigweed, Palmer amaranth, hophornbeam copperleaf, sicklepod, ivyleaf morningglory, pitted morningglory, and prickly sida 83 to 100% 66 days after application. Equivalent weed control was obtained for pyroxasulfone plus atrazine and atrazine plus S-metolachlor applied PRE. Corn yield was lower when pyroxasulfone was applied only PRE compared with pyroxasulfone plus atrazine PRE and atrazine plus S-metolachlor PRE. Soybean injury was observed when pyroxasulfone was applied at 60 to 300 g/ha, and at 10 days after application, injury was 2 to 5% when applied PRE and 15 to 21% when applied POST. Injury consisted of crinkling of leaflet surface, irregular leaflet margins, indentation of leaflet tips, and a drooping of leaf petioles (POST application only). Soybean yield was not negatively affected by pyroxasulfone regardless of application timing. In a second soybean study, pyroxasulfone applied alone PRE at 150 g/ha controlled, browntop millet an average of 99%, barnyardgrass 75%, hophornbeam copperleaf 99%, ivyleaf morningglory 86%, hemp sesbania 98%, sicklepod 95% and pitted morningglory 73% around 30 days after treatment. Compared with pyroxasulfone applied alone PRE at 150 g/ha, weed control was not improved when pyroxasulfone was applied PRE with saflufenacil, flumioxazin, fluthicet-methyl, or chlorimuron ethyl plus flumioxazin plus thifensulfuron methyl. Crop safety, consistency in weed control, and flexibility in application timing with pyroxasulfone suggests that it should have a fit in corn and soybean weed management programs in the mid-south.