Thesis - Open Access
Master of Science (MS)
Agricultural and Biosystems Engineering
The current efficiency of conventional nitrogenous fertilizers (e.g. urea, ammonium sulfate, etc.) in agricultural practices is low, fluctuating from 30 to 40%. Approximately 60% of nitrogenous fertilizers were wasted due to vaporization into the air, runoff or leaching into water systems. The lost nitrogen (N) resulted in not only high production cost but also serious environmental problems, such as greenhouse gas (N2O) emission in the atmosphere, algal blooms, oxygen depletion, fish kills, and loss of biodiversity in surface water due to eutrophication or pollution. To address these problems, this study aimed to utilize low-cost biochar-based materials to develop a controllable, affordable, and environmentally friendly nitrogen fertilizer. The studies of activated biochar, biochar-based controlled release nitrogenous fertilizer (BCRNF), and asphalt-based controlled release nitrogenous fertilizer (ACRNF) were carried out to achieve the goal. To improve the adsorption ability of biochar, biochar was activated by steam-method. After steam-activation, activated biochar (AB) has attained approximate methylene blue (MB) adsorption with activated carbon (AC). Besides, the film produced in this study by AB and cellulose nanofibrils has formed a stable form, promising to part of BCRNF in the future. To attain a controllable and endurable N-release pattern, polylactic acid (PLA), that, has a strong hydrophobic property, and biochar that possesses, a strong adsorption capability, were chosen as coating material and N carrier respectively to prepare BCRNF In BCRNFs’ N-release in water experiment, BCRNF-P10 continually released N in water in 12 days. In the soil column leaching experiment, for BCRNF-P10 sample, it continually released N for 25 days and only 33.57% of N was leached into water under a rainy simulated environment. These results indicate that the BCRNF has the potential for developing controlled release nitrogen fertilizer in the future. To attain a more durable N-release pattern, another biochar-based nitrogen fertilizer, asphalt-based controlled release nitrogenous fertilizer (ACRNF) was developed. The asphalt used as N carrier in the fabrication of ACRNF was produced from bio-based materials: corn stover and sawdust by pyrolysis and liquefication, respectively. Granular ammonium sulfate was either mixed or coated with asphalt to control N-release. Different ACRNF samples were tested to examine their N-release in water. The results showed that the N-release patterns of ACRNF were significantly different when ammonium sulfate particles were mixed or coated with asphalt under different processing conditions. The Nrelease time of 80% N for the sample ACRNF 230 was more than 20 days. The performance of other ACRNF samples also demonstrated the concept of controllable Nrelease if ammonium sulfate was properly mixing or coating with asphalt. Although further research is needed, the ACRNF has shown very promising potential to improve nitrogen use efficiency in corn production in the controlled release fertilizer market.
Number of Pages
South Dakota State University
Copyright © 2021 the Author
Cen, Zhisheng, "Develop Biochar-based Controlled Release in Nitrogen Fertilizers" (2021). Electronic Theses and Dissertations. 5218.