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Full-Text Articles in Physical Sciences and Mathematics

Nitrogen Use Efficiency Of Pretassel Nitrogen Applications In Corn, Robyn Brittlee Mulloy Dec 2022

Nitrogen Use Efficiency Of Pretassel Nitrogen Applications In Corn, Robyn Brittlee Mulloy

Graduate Theses and Dissertations

Corn (Zea mays L.) production continues to be a critical component of row-crop production systems within Arkansas and is seeing a resurgence in recent years. Nitrogen (N) is critical for corn growth and is often one of the single largest input costs associated with corn production. Research objectives for this study were to determine the nitrogen use efficiency (NUE) of late season N applications as influenced by sidedress N rate and timing of pretassel application and to quantify the nutrient uptake and partitioning in modern era corn hybrids within a furrow-irrigated production system. Research was conducted at the Milo J. …


Diagnosing Excess Nitrogen In Rice Using Post-Season Tissue Samples, Kyle Hoegenauer Dec 2022

Diagnosing Excess Nitrogen In Rice Using Post-Season Tissue Samples, Kyle Hoegenauer

Graduate Theses and Dissertations

Proper nitrogen (N) management in rice production can be difficult to achieve without the aid of tools such as soil and tissue tests. There are no tests currently available to rice producers that determine whether N has been managed properly throughout the season or that detect instances of over fertilization. Rice stalk samples were collected from N response trials within 3 days of harvest from the primary Arkansas rice growing region in 2016-2018. Stalk samples were analyzed for N concentration through a KCl extraction and spectrofluorometric quantification. Samples analyzed with leaf material intact contained statistically different N concentrations than samples …


Nitrogen Management In Rice Under Suboptimal Soil Conditions, Payton Suzanne Rhea Dec 2022

Nitrogen Management In Rice Under Suboptimal Soil Conditions, Payton Suzanne Rhea

Graduate Theses and Dissertations

In Mid-South rice (Oryza sativa, L.) production, nitrogen (N) fertilizer management for pureline varieties is most often recommended as a single preflood (SPF) or two-way split (2WS) application in a direct-seeded, delayed-flood system. Most of the N fertilizer is typically applied at the four- to six-leaf stage onto dry soil, and the second application, if necessary, into the floodwater during early reproductive growth stages (referred to as midseason). Environmental factors frequently prohibit growers from applying early N fertilizer under optimal dry soil conditions. A study was conducted to determine the best N fertilization management practices to utilize in rice when …


Assessing Consumer Demand, Producer Profitability, And The Environmental Impacts Of Conservation Agriculture Adoption In Sub-Saharan Africa, Willy Byamungu Mulimbi Aug 2022

Assessing Consumer Demand, Producer Profitability, And The Environmental Impacts Of Conservation Agriculture Adoption In Sub-Saharan Africa, Willy Byamungu Mulimbi

Graduate Theses and Dissertations

This dissertation explores three aspects of conservation agriculture (CA) in the Sub-Saharan African region (SSA). The first article examines the demand side of CA and explores whether urban maize (Zea mays L.) consumers in the Democratic Republic of the Congo (DRC) would be willing to pay a premium for CA-produced maize flour. The second article estimates the effects CA provides to adopters and their farms in smallholder farming systems in the DRC, focusing on changes in soil properties and cowpea (Vigna unguiculata) yields. The final article uses a Life Cycle Assessment (LCA) approach to monetize the environmental impacts of adopting …


Optimization Techniques For Soil Organic Carbon Prediction Using Mid-Infrared Spectroscopy, Minerva J. Dorantes Aug 2022

Optimization Techniques For Soil Organic Carbon Prediction Using Mid-Infrared Spectroscopy, Minerva J. Dorantes

Graduate Theses and Dissertations

Resource-efficient techniques for accurate soil carbon estimation are necessary to satisfy the increasing demand for spatiotemporal data. In the last thirty years, mid-infrared (MIR) soil spectroscopy has developed as an accurate, rapid, cost-effective, and non-destructive technique for soil organic carbon (SOC) analysis. In soil spectroscopy, a calibration model relates spectral data to a corresponding measured soil property and is subsequently used to predict this value from new spectral data. Various optimization techniques have been used to improve the statistical performance of calibrations; however, there is little consensus on the conditions that make these techniques effective. The objectives of this research …


The Effect Of Water Management And Ratoon Rice Cropping On Methane Emissions And Harvest Yield In Arkansas, Marguerita Leavitt Aug 2022

The Effect Of Water Management And Ratoon Rice Cropping On Methane Emissions And Harvest Yield In Arkansas, Marguerita Leavitt

Graduate Theses and Dissertations

Sustainable intensification of rice farming is crucial to meeting human food needs while reducing environmental impacts. Rice produces 8% of all anthropogenic CH4, which is a potent greenhouse gas. CH4 emissions can potentially be reduced by cultivation practices that minimize the number of days the fields are saturated, such as dry-seeding instead of water-seeding and irrigation using the alternate wetting and drying (AWD) technique instead of delayed, continuous flooding (DF). Ratoon cropping, wherein a second crop of rice is grown from the harvested stubble of the first crop, can be used to produce additional yield with minimal labor, but may …


Evaluation Of Factors That Contribute To Injury To Quizalofop-Resistant Rice From Quizalofop Applied Postemergence, Navdeep Godara Aug 2022

Evaluation Of Factors That Contribute To Injury To Quizalofop-Resistant Rice From Quizalofop Applied Postemergence, Navdeep Godara

Graduate Theses and Dissertations

Quizalofop-resistant rice technology allows for over-the-top applications of quizalofop, an acetyl-coenzyme A carboxylase-inhibiting herbicide. However, quizalofop caused significant injury to quizalofop-resistant rice in some Arkansas fields during the first year of commercialization. Experiments evaluated the effect of early-season soil moisture and nitrogen availability; pre-exposure to low rates of glyphosate and imazethapyr; planting date; and environmental conditions including, soil moisture content, air temperature, and light intensity on quizalofop-resistant rice tolerance to quizalofop applications. All experiments assessed sequential quizalofop applications made to 2-leaf followed by 5-leaf stage of rice. Sequential quizalofop applications alone and with surface irrigation or nitrogen application at the …


Using Thermal Units To Predict Biomass Accumulation And Total Nitrogen Uptake For Cover Crops In Arkansas, Mila Victório Pessotto May 2022

Using Thermal Units To Predict Biomass Accumulation And Total Nitrogen Uptake For Cover Crops In Arkansas, Mila Victório Pessotto

Graduate Theses and Dissertations

Including cover crops in agricultural production systems is an important management practice. Cover cropping can improve soil health, increase plant-available nitrogen (N), provide surface residue to prevent erosional soil loss, increase water infiltration, and increase weed suppression. Cover crops growth can be predicted using thermal days or growing degree days [GDD] similar to commodity crops such as corn (Zea mays L.) or rice (Oryza sativa). Growing degree day calculations are a well-known tool to predict crop growth stage or development stage and can be adapted for use in any plant species, including cover crops. Identifying and developing the relationship between …