Date of Award

12-2025

Document Type

Thesis

Degree Name

Master of Science

Department

Natural Resources and Environmental Sciences

Abstract

The intensive use of synthetic fertilizers in cotton production has improved yields but has also contributed to soil degradation, nutrient imbalance, and greenhouse gas emissions. To promote sustainable nutrient management, this study evaluated the field-scale potential of algal biomass as a biofertilizer for enhancing soil health, carbon sequestration, and cotton yield in the southern U.S. agroecosystem conditions. A two-year experiment (2023-2024), was conducted at Prairie View A&M University’s research farm in Texas, utilizing a randomized complete block design. The first year (2023) established baseline data with four synthetic nitrogen fertilizer rates: Control (no fertilizer), Double recommended, Recommended, and Half recommended, while the second year (2024) examined six treatments: Algae+NPK, Algae, NPK, Sterilized Algae+NPK, Sterilized Algae, and Control on 36 field plots. Soil physicochemical properties, greenhouse gas fluxes (CO₂, CH₄, N₂O), and yield parameters were monitored using in-situ soil moisture sensors, trace gas analyzers, and laboratory analyses (CHNS and ICP). Results showed clear distinctions between the two experimental years.

In 2023, soil carbon and nitrogen levels declined after the application of synthetic fertilizer treatments. In 2024, with Algae and Algae+NPK treatments, increased soil The intensive use of synthetic fertilizers in cotton production has improved yields but has also contributed to soil degradation, nutrient imbalance, and greenhouse gas emissions. To promote sustainable nutrient management, this study evaluated the field-scale potential of algal biomass as a biofertilizer for enhancing soil health, carbon sequestration, and cotton yield in the southern U.S. agroecosystem conditions. A two-year experiment (2023-2024), was conducted at Prairie View A&M University’s research farm in Texas, utilizing a randomized complete block design. The first year (2023) established baseline data with four synthetic nitrogen fertilizer rates: Control (no fertilizer), Double recommended, Recommended, and Half recommended, while the second year (2024) examined six treatments: Algae+NPK, Algae, NPK, Sterilized Algae+NPK, Sterilized Algae, and Control on 36 field plots. Soil physicochemical properties, greenhouse gas fluxes (CO₂, CH₄, N₂O), and yield parameters were monitored using in-situ soil moisture sensors, trace gas analyzers, and laboratory analyses (CHNS and ICP). Results showed clear distinctions between the two experimental years.

In 2023, soil carbon and nitrogen levels declined after the application of synthetic fertilizer treatments. In 2024, with Algae and Algae+NPK treatments, increased soil carbon and nitrogen content were observed, stimulating root growth and improving below-ground biomass accumulation. Algal biomass substantially improved soil moisture retention and moderated electrical conductivity (EC) compared to conventional NPK and control treatments. CO₂ fluxes in 2023 were low and stable, ranging from approximately 0.1 to 0.6 g/m²/d across treatments. In 2024, greenhouse gas fluxes did not differ significantly across treatments; however, CO₂ emissions were higher and more variable than in 2023, ranging from ~0.5-12 g/m⁻² day⁻¹, particularly in Sterilized Algae+NPK plots. Algae-treated plots exhibited slightly lower median N₂O fluxes and mild CH₄ uptake (−50 to −150 μg m⁻² day⁻¹), suggesting improved nitrogen cycling and potential co-benefits for climate mitigation. Cotton yield in algae-treated plots was ~1600 Kg/ha, comparable to 2023 and all other treatments, confirming that algal biomass can sustain yield while reducing dependence on synthetic fertilizers. Overall, this research provides field-based evidence that algae-based biofertilizers enhance soil health, support crop yield, and contribute to sustainability in cotton cropping systems.

Index Terms- Algal biofertilizer, carbon sequestration, cotton yield, greenhouse gas emissions (GHG), sustainable agriculture.

Committee Chair/Advisor

Ram L.Ray

Committee Member

Richard Griffin

Committee Member

Abdul L. Khan

Committee Member

Gebrekidan Tefera

Publisher

Prairie View A&M University

Rights

© 2021 Prairie View A & M University

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Date of Digitization

10/27/2026

Contributing Institution

J B Coleman Library

City of Publication

Prairie View

MIME Type

Application/PDF

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