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- Kika de la Garza Congressional Papers - Agriculture Committee News Releases (182)
- Theses and Dissertations (55)
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Articles 91 - 120 of 299
Full-Text Articles in Agriculture
Abiotic And Biotic Limitations To Nodulation By Leguminous Cover Crops In South Texas, Stephanie Kasper, Bradley O. Christoffersen, Pushpa Soti, Alexis Racelis
Abiotic And Biotic Limitations To Nodulation By Leguminous Cover Crops In South Texas, Stephanie Kasper, Bradley O. Christoffersen, Pushpa Soti, Alexis Racelis
School of Earth, Environmental, & Marine Sciences Faculty Publications
Many farms use leguminous cover crops as a nutrient management strategy to reduce their need for nitrogen fertilizer. When they are effective, leguminous cover crops are a valuable tool for sustainable nutrient management. However, the symbiotic partnership between legumes and nitrogen fixing rhizobia is vulnerable to several abiotic and biotic stressors that reduce nitrogen fixation efficiency in real world contexts. Sometimes, despite inoculation with rhizobial strains, this symbiosis fails to form. Such failure was observed in a 14-acre winter cover crop trial in the Rio Grande Valley (RGV) of Texas when three legume species produced no signs of nodulation or …
Investigating The Potential Of Weeds As Host Reservoir For Plant Parasitic Nematodes In South Texas, Habraham F. Lopez
Investigating The Potential Of Weeds As Host Reservoir For Plant Parasitic Nematodes In South Texas, Habraham F. Lopez
Theses and Dissertations
Presence and geographical distributions of three damaging nematode pest (R. reniformis, M. incognita, T. semipentrans) have been recorded in the LRGV. With year-round growing seasons, weed pest are a real problem for many LRGV growers. With some growers leaving the field fallow until planting season, these places can serve as potential host reservoirs for plant parasitic nematodes (PPN). This study examined the potential of weeds as host reservoirs for plant parasitic nematodes in the LRGV. Results demonstrated the presence of 5 of the 12 economically important plant parasitic nematode genus and demonstrated a difference in distribution of nematodes …
Contributions Of Historical Ecology To Ecological Services Assessments In The Lower Rio Grande Valley Texas, Julianna Katherine Schaefer Kurpis
Contributions Of Historical Ecology To Ecological Services Assessments In The Lower Rio Grande Valley Texas, Julianna Katherine Schaefer Kurpis
Theses and Dissertations
Historic and current anthropogenic land-use activities affect ecological functions and ecosystem services quality. The clearing of native Tamaulipan thorn forest and riparian forests for agricultural use and expansion followed by rapid urbanization and population growth resulted in profound ecological impacts to the Lower Rio Grande Valley (LRGV), Texas. The goals of this study are 1) document trends in land use change and vegetation health in the LRGV 2) evaluate and demonstrate the application of the Ecosystem Services Identification & Inventory Tool (ESII Tool) for collecting ecological data and measuring percent ecological performance and 3) use historical ecology indicators to compare …
Investigating Limitations To Nitrogen Fixation By Leguminous Cover Crops In South Texas, Stephanie L. Kasper
Investigating Limitations To Nitrogen Fixation By Leguminous Cover Crops In South Texas, Stephanie L. Kasper
Theses and Dissertations
Many farms use leguminous cover crops as a nutrient management strategy to reduce their need for nitrogen fertilizer. Biological nitrogen fixation (BNF) depends on a symbiotic relationship between legumes and nitrogen-fixing rhizobia. Under certain conditions despite inoculation with appropriate rhizobial strains, this symbiosis fails to form. Such failure was observed in a 14-acre winter cover crop trial in the Rio Grande Valley of Texas when three legume species (forage pea, crimson clover, and hairy vetch) produced no signs of nodulation and nitrogen fixation. This study examined nitrogen, phosphorus, moisture, micronutrients and biotic interference as potential causes for the failure and …
Effect Of Land Use Change On South Texas Bats, Katharine Leigh Jones
Effect Of Land Use Change On South Texas Bats, Katharine Leigh Jones
Theses and Dissertations
Bats were acoustically recorded in South Texas over the summer of 2017. Nine species of bats were recorded and identified.
Upscaling Capillary Pressure–Saturation Functions Using Different Reference Pressure Elevations, Chu-Lin Cheng, S. Clark Cropper, Edmund Perfect, Larry Mckay, Misun Kang
Upscaling Capillary Pressure–Saturation Functions Using Different Reference Pressure Elevations, Chu-Lin Cheng, S. Clark Cropper, Edmund Perfect, Larry Mckay, Misun Kang
School of Earth, Environmental, & Marine Sciences Faculty Publications
Choice of reference pressure elevation (RPE) on average effective saturation–capillary pressure functions, 〈〉(ψ), was investigated for monotonic drainage of homogeneous porous media. Nine columns of Flint sand with heights ranging from 4.3 to 55.0 cm were prepared. Measured 〈〉(ψ) functions were determined gravimetrically using the hanging water column method. Predicted 〈〉(ψ) functions were obtained by upscaling point function parameters determined by neutron radiographic imaging of a single drainage experiment. Bottom and midpoint RPEs resulted in the inaccurate parameterization of 〈〉(ψ) functions for tall columns. A top RPE produced accurate upscaled functions for all column heights. To evaluate the overall performance …
Removal Of Lead And Arsenic From Aqueous Solution By Biochar Produced From Locally-Sourced Biomass, Sergio I. Mireles
Removal Of Lead And Arsenic From Aqueous Solution By Biochar Produced From Locally-Sourced Biomass, Sergio I. Mireles
Theses and Dissertations
This study evaluated the effectiveness of four adsorbent materials, pyrolyzed corn stover, orange peel, pistachio shell, and magnetic biochar for their ability to adsorb lead (Pb) and arsenic (As III, As V) from aqueous solution. An increase in adsorption was seen as the pH of the solution increased from pH 2 to pH 6. Magnetic orange peel biochar with Fe3O4 particles precipitated on the surface of biochar was synthetized by co-precipitation and used for arsenic adsorption. Initial pH value had an influence on the adsorption behavior of As (III) and As (V). In the pH range of 2–6, As (V) …
Genetic Variation In Two Economically Important Arthropod Vectors Of Citrus Diseases, Alejandra Fuentes
Genetic Variation In Two Economically Important Arthropod Vectors Of Citrus Diseases, Alejandra Fuentes
Theses and Dissertations
Arthropod vectors are agriculturally and ecologically important because they transmit numerous plant pathogens. Commonly, control strategies for vector-borne plant pathogens focus on suppression of vector populations. Genetic variation studies in pest populations provide useful information for biological control, understanding pesticide resistance, and inferring global movement patterns. In chapter I, genetic variation of worldwide populations of Diaphorina citri, the vector of Citrus greening disease, was examined to assess potential sites of origin of invasive populations. The results showed population structure at regional levels, suggesting limited gene flow and revealing patterns of invasion. In chapter II, I explored the community of …
Multifunctionality Of Cover Crops On Organic Vegetable Farms In South Texas, Savannah M. Rugg
Multifunctionality Of Cover Crops On Organic Vegetable Farms In South Texas, Savannah M. Rugg
Theses and Dissertations
Situated in deep South Texas, the Lower Rio Grande Valley (LRGV) is considered one the most productive agricultural regions in the southern US. With the highest concentration of organic farms in the state (Hidalgo county), finding management practices that comply with organic certification is increasingly pertinent. Cover cropping can serve multiple functions in an agroecosystem such as: suppressing weeds, increasing soil organic matter (SOM), increasing soil nitrates, and enhancing soil biodiversity. The four cover crops (lablab, sunn hemp, sudangrass, and pearl millet) were assessed to see their potential to increase soil nitrogen, to increase soil organic matter, and to suppress …
Evaluation Of Control Strategies For The Spread Of Citrus Greening, Vicente Valle Martinez
Evaluation Of Control Strategies For The Spread Of Citrus Greening, Vicente Valle Martinez
Theses and Dissertations - UTB/UTPA
Huanglongbing, also known as citrus greening, is a vector-based disease in citrus (with no cure known to date) that has drastically affected the citrus production in Florida in less than a decade and has been recently detected in Texas and California. In this paper, an epidemic model of the spatial spread of the disease is implemented among commercial and residential groves by taking into consideration the diffusion patterns of the psyllid vectors. A system of differential equations resembling one for malaria infection in humans is derived to evaluate different control methods such as quarantine, treatment, removal, foliar treatment, and pest …
Management Of Silverleaf Whitefly, Bemisia Argentifolii Bellows And Perring (Hemiptera: Aleyrodidae), Using Non-Crop Companion Plants In Organically-Managed Cantaloupe Systems In South Texas, Ruth Renee Colyer
Theses and Dissertations - UTB/UTPA
Field trials in three separate phases of research were carried out from March, 2010, to August, 2012, to determine the effects of inter-cropping cantaloupe (Cucumis melo var. inodorus) with select non-crop companion plants in an effort to develop organic production strategies for melons in South Texas without the use of pesticides. A research program was designed and initiated to assess the effects of the companion plants and their ability to: 1) attract insect pollinators, and 2) repel or suppress pest species without affecting beneficial natural enemy complexes. The hypotheses were: 1) that organically-managed cantaloupe systems grown with non-crop companion plants …
Monitoring Citrus Nutrition In The Rio Grande Valley For Fertilizer Recommendations, Iram Lopez
Monitoring Citrus Nutrition In The Rio Grande Valley For Fertilizer Recommendations, Iram Lopez
Theses and Dissertations - UTB/UTPA
Soil fertility and plant nutrition is crucial for a better yield and consistent harvest in the Rio Grande Valley for local farmers growing citrus trees. A field of oranges and a field of grapefruits were monitored and nutrition deficiencies were noticed that played an important role during fruit set. Soil samples that were taken throughout the year were analyzed via a carbon dioxide extraction method that mimics the way plants naturally take up nutrients or extract nutrients from every soil type. Macronutrients such as the N, P, K, Na, Ca, Mg and some of the micronutrients (Zn, Fe, Mn, and …
Overview Of The Large-Scale Biosphere-Atmosphere Experiment In Amazonia Data Model Intercomparison Project (Lba-Dmip), Luis Gustavo Gonçalves De Gonçalves, Jordan S. Borak, Marcos Heil Costa, Scott R. Saleska, Ian Baker, Natalia Restrepo-Coupe, Michel Nobre Muza, Benjamin Poulter, Hans Verbeeck, Bradley O. Christoffersen
Overview Of The Large-Scale Biosphere-Atmosphere Experiment In Amazonia Data Model Intercomparison Project (Lba-Dmip), Luis Gustavo Gonçalves De Gonçalves, Jordan S. Borak, Marcos Heil Costa, Scott R. Saleska, Ian Baker, Natalia Restrepo-Coupe, Michel Nobre Muza, Benjamin Poulter, Hans Verbeeck, Bradley O. Christoffersen
School of Integrative Biological & Chemical Sciences Faculty Publications
A fundamental question connecting terrestrial ecology and global climate change is the sensitivity of key terrestrial biomes to climatic variability and change. The Amazon region is such a key biome: it contains unparalleled biological diversity, a globally significant store of organic carbon, and it is a potent engine driving global cycles of water and energy. The importance of understanding how land surface dynamics of the Amazon region respond to climatic variability and change is widely appreciated, but despite significant recent advances, large gaps in our understanding remain. Understanding of energy and carbon exchange between terrestrial ecosystems and the atmosphere can …
Inter-Annual Variability Of Carbon And Water Fluxes In Amazonian Forest, Cerrado And Pasture Sites, As Simulated By Terrestrial Biosphere Models, Celso Von Randow, Marcelo Zeri, Natalia Restrepo-Coupe, Michel N. Muza, Luis Gustavo G. De Gonçalves, Marcos H. Costa, Alessandro C. Araujo, Antonio O. Manzi, Humberto R. Da Rocha, Bradley O. Christoffersen
Inter-Annual Variability Of Carbon And Water Fluxes In Amazonian Forest, Cerrado And Pasture Sites, As Simulated By Terrestrial Biosphere Models, Celso Von Randow, Marcelo Zeri, Natalia Restrepo-Coupe, Michel N. Muza, Luis Gustavo G. De Gonçalves, Marcos H. Costa, Alessandro C. Araujo, Antonio O. Manzi, Humberto R. Da Rocha, Bradley O. Christoffersen
School of Integrative Biological & Chemical Sciences Faculty Publications
This study analyzes the inter-annual variability (IAV) of simulations of 21 different land surface model formulations, driven by meteorological conditions measured at 8 flux towers, located in rain forest, forest-savanna ecotone and pasture sites in Amazonia, and one in savanna site in Southeastern Brazil. Annual totals of net ecosystem exchange (NEE) of carbon and evapotranspiration (ET), measured and simulated by each model for each site-year, were compared in terms of year-to-year variability and possible relation to climate drivers. Results have shown that most of models simulations for annual totals of NEE and ET, and IAV of these fluxes, are frequently …
A Survey Of Heavy Metals In Water, Soil And The Surrounding Plants In The Lower Rio Grande Valley, Erving W. Morelius
A Survey Of Heavy Metals In Water, Soil And The Surrounding Plants In The Lower Rio Grande Valley, Erving W. Morelius
Theses and Dissertations - UTB/UTPA
Heavy metal pollution of the environment in recent years has become a major issue of importance for both human and environmental health. Samples were investigated for the potential pollution of the area as it is a vital produce producing area. During the study plant, soil and water samples were collected from the Donna Reservoir and Canal System to test the concentration of various heavy metals. The heavy metals tested included both potentially toxic and micronutrients in the samples which included arsenic, cadmium, chromium, copper, iron, lead, nickel and sulfur. During the study, a sixty day sampling period was used to …
A Comprehensive Method For Fractionating Soil Organic Matter Not Protected And Protected From Decomposition By Physical And Chemical Mechanisms, César Plaza, José M. Fernández, Engil Isadora Pujol Pereira, Alfredo Polo
A Comprehensive Method For Fractionating Soil Organic Matter Not Protected And Protected From Decomposition By Physical And Chemical Mechanisms, César Plaza, José M. Fernández, Engil Isadora Pujol Pereira, Alfredo Polo
School of Earth, Environmental, & Marine Sciences Faculty Publications
The objective of this work was to describe a method for isolating meaningful and measurable soil organic matter (SOM) pools that differ in the mechanisms by which they are protected from decomposition. The proposed method is appropriate for soil C stabilization and sequestration studies. Unlike previous fractionation schemes, this procedure allows free SOM located between aggregates (unprotected C pool) and SOM occluded within both macroaggregates and microaggregates (C weakly and strongly protected by physical mechanisms, respectively) to be recovered separately, freed from the soil mineral matrix and the mineral-associated SOM pool (C pool protected by chemical mechanisms) and thus well …
Comparison Of Soil Chemistry And Microbial Communities That Inhabit The Rhizosphere Of Native And Non-Native Grasses Of The Lower Rio Grande Valley, Jacqueline Valencia
Comparison Of Soil Chemistry And Microbial Communities That Inhabit The Rhizosphere Of Native And Non-Native Grasses Of The Lower Rio Grande Valley, Jacqueline Valencia
Theses and Dissertations - UTB/UTPA
Non-native grasses can modify the soils they invade. This study investigated microbial variation among native and non-native grasses in the Lower Rio Grande Valley. We hypothesized that rhizospheres of non-native grasses would support a higher density of microorganisms; therefore microbial communities of invasive plants would exploit more carbon sources than those of native plants. A second hypothesis stated that Streptomyces bacteria from the rhizosphere of non-native grasses would be better competitors. Samples of grasses, and soil from their respective rhizospheres were obtained in Arroyo City, TX. Results indicated a higher bacterial colony density, total activity and number of substrates utilized …
Soil Nitrogen Transformations Under Elevated Atmospheric Co2 And O3 During The Soybean Growing Season, Engil Isadora Pujol Pereira, Haegeun Chung, Kate Scow, Michael J. Sadowsky, Chris Van Kessel
Soil Nitrogen Transformations Under Elevated Atmospheric Co2 And O3 During The Soybean Growing Season, Engil Isadora Pujol Pereira, Haegeun Chung, Kate Scow, Michael J. Sadowsky, Chris Van Kessel
School of Earth, Environmental, & Marine Sciences Faculty Publications
We investigated the influence of elevated CO2 and O3 on soil N cycling within the soybean growing season and across soil environments (i.e., rhizosphere and bulk soil) at the Soybean Free Air Concentration Enrichment (SoyFACE) experiment in Illinois, USA. Elevated O3 decreased soil mineral N likely through a reduction in plant material input and increased denitrification, which was evidenced by the greater abundance of the denitrifier gene nosZ. Elevated CO2 did not alter the parameters evaluated and both elevated CO2 and O3 showed no interactive effects on nitrifier and denitrifier abundance, nor on total and mineral N concentrations. These results …
Evaluation Of Streptomycetes For Biological Control Of Gummy Stem Blight Disease Of Cantaloupe, Shima Chaudhary
Evaluation Of Streptomycetes For Biological Control Of Gummy Stem Blight Disease Of Cantaloupe, Shima Chaudhary
Theses and Dissertations - UTB/UTPA
Studies were conducted to evaluate the efficacy of Streptomyces isolates for the biological control of gummy stem blight (GSB) in cantaloupes (Cucumis melo var. ‘Primo’) in south Texas. Plants were monitored for seedling emergence, lesions, mortality and plant growth under laboratory, greenhouse and field conditions. Comparison of treatment groups indicated a significant reduction in plant mortality and enhanced growth of infected plants exposed to three Streptomyces isolates (MA1F4#2, WI1B#5, and MA2A4 #2), which appear to be most effective when used in combination. In all three experiments, GSB infection was associated with a significant reduction in reflectance of near-infrared wavelengths (700-1,100 …
Access To Credit, Plot Size And Cost Inefficiency Among Smallholder Tobacco Cultivators In Malawi, Gautam Hazarika, Jeffrey Roger Alwang
Access To Credit, Plot Size And Cost Inefficiency Among Smallholder Tobacco Cultivators In Malawi, Gautam Hazarika, Jeffrey Roger Alwang
School of Economics and Finance Faculty Publications
Using data from the Malawi Financial Markets and Household Food Security Survey, this paper examines the effect of access to credit from formal sources, and tobacco plot size, on cost inefficiency among Malawian smallholder tobacco cultivators. Farm-specific cost inefficiency is estimated within the framework of stochastic frontier analysis. Access to credit is measured as the sum of household members' self-reported credit limits at credit organisations, arguably a truer measure of an exogenous credit constraint than credit program participation or actual loan uptake. It is found that tobacco cultivation is significantly less cost inefficient per acre on larger plots. While access …
Comparison Of Native Brushland, Replanted, And Unaided Secondary Succession Plant Communities In The Lower Rio Grande Valley Of Texas, Mitchell Allen Sternberg
Comparison Of Native Brushland, Replanted, And Unaided Secondary Succession Plant Communities In The Lower Rio Grande Valley Of Texas, Mitchell Allen Sternberg
School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)
Agriculture and urban development have destroyed 95% of native brushland habitat in the Lower Rio Grande Valley (LRGV) of south Texas. Therefore, habitat restoration is an important issue in the LRGV. Since 1982, the U.S. Fish and Wildlife Service has been replanting areas in the LRGV to native brushland species to establish a wildlife corridor along the lower reach of the Rio Grande. Vegetation composition of a mature brushland, a replanted habitat and an unaided secondary succession site (fallow field) were examined at one locale in the LRGV in 1999. The mature brushland edge plot had the highest species richness …
Agriculture News Release - 1996-03-29, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1996-03-29, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-12-15, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-12-15, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-12-08a, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-12-08a, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-12-08b, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-12-08b, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-12-06, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-12-06, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-12-02, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-12-02, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-11-30, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-11-30, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-10-05b, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-10-05b, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.
Agriculture News Release - 1994-10-05a, United States. Congress. House. Committee On Agriculture, E. De La Garza
Agriculture News Release - 1994-10-05a, United States. Congress. House. Committee On Agriculture, E. De La Garza
Kika de la Garza Congressional Papers - Agriculture Committee News Releases
No abstract provided.