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Plant Stimuli-Responsive Biodegradable Polymers For The Use In Timed Release Fertilizer Coatings, Spencer Heuchan

Electronic Thesis and Dissertation Repository

The use of nitrogen-based fertilizers continues to accelerate with human population growth and increases in global food requirements. Enhanced efficiency fertilizers (EEFs) have been developed to improve the synchronization between nutrient supply and crop nutrient demand. However, many of the current controlled release fertilizers are coated with non-degradable polymers that contribute to accumulation of microplastics within ecosystems. This thesis describes research towards the development of a new class of fertilizer coatings using a self-immolative polymer known as poly (ethyl glyoxylate) (PEtG). PEtG itself does not have suitable properties to produce a viable coating but once blended with another degradable polyester …

The Effects Of Biochar And Nitrogen Stabilizers Application On Forage Crop Growth, Greenhouse Gas Emission And Soil Quality, Joseph Elias Rodrigues Mikhael

LSU Doctoral Dissertations

ABSTRACT

Forage systems are important for animal production. Nitrogen fertilization and herbicides use has led to a significant increase in forage production. Therefore, this study aimed to investigate the effects of biochar and N-(n-butyl) thiophosphoric triamide + dicyandiamide (NBPT+DCD) application on manure and urea fertilized soil by focusing on nitrogen fertilizer efficiency use, greenhouse gases emissions, microbial community, soil aggregate stability, and organic carbon functional groups. In addition, herbicides effect on greenhouse gases emission was assessed. Biochar and NBPT+DCD increased nitrogen use efficiency of both fertilizers managements and reduced the N₂O emissions following manure fertilization. However, NBPT+DCD was …

Effect Of Increasing Levels Of Monosilicic Acid On Arsenic And Phosphorus Sorption In Soil, Flávia Bastos Agostinho

LSU Doctoral Dissertations

Arsenic (As) accumulation in rice (Oryza sativa) grains has increased human’s daily intake. Studies have shown that arsenite is taken up through known silicon (Si) transporters in rice. Moreover, the availability of As in soil is affected by chemically similar ligands that have high affinity to oxides surfaces, such as Si and phosphorus (P). Studies were conducted to: (I) investigate the role of elevated levels of Si on the concentration of different As fractions in soil and on As uptake by rice; (II) evaluate the effect of increasing monosilicic acidconcentrations on As sorption and kinetics in soil; and …