Author: Sushma Koirala
Koirala, Sushma, 2024 Investigating the efficacy of stearic acid, potato starch, and polycaprolactone in the development of pH and temperature-responsive fertilizer for eco-resilient agriculture system, Flinders University, College of Medicine and Public Health
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Controlled released fertilizer has been a popular strategy throughout the world to mitigate nutrient loss. However, the petroleum-derived non-biodegradable polymers used for coating CRFs result in the exhaustion of fossil fuel coupled with white pollution due to the deposition of polymers on the soil especially after release. Herein, this study aimed to investigate the efficacy of stearic acid (SA), potato starch (PS), and polycaprolactone (PCL) in the development of pH and temperature-responsive fertilizer by emphasing the concept of sustainable agriculture and circular economy. Multiple simulation studies were performed to find appropriate polymers for this study. The characterization of coated granules was performed (crushing strength test, surface hydrophobicity, Fourier transform infrared spectroscopy, and scanning electron microscopy) to identify their hardness, hydrophobicity, functional groups, and uniformity. Further, the nutrient release test was performed to identify the release rate and pattern of different formulations at different parameters which was followed by a granule’s stability test. Finally, this study brings together the concept of agricultural biotechnology and microbiology by analysing biofilm studies.
The fertilizer encapsulated using stearic acid (8% w/v) and potato starch (1% w/v), stands out as an effective CRF. Consistent with this finding, a slower release of nutrients was exhibited by this CRF when compared with other coating formulations. The cumulative release rate and pattern of the coated fertilizer at different temperatures and different pH reveals that the release is temperature and pH dependent with the longevity of release at lower temperatures and acidic pH. Likewise, the most significant finding of the study that aligns with the release study was the ability of CRF 1B to maintain stability even within different treatments which was confirmed under SEM. Besides, it also has the ability for consistent accumulation of soil bacteria in the form of biofilm production. Therefore, the obtained CRF made by coating (8% w/v) and potato starch (1% w/v), with 8%stearic acid and potato starch shows potential avenues for application in real agriculture practice. Nevertheless, the experiment should be designed to study the release for an extended time, at least a month with a particular focus on the synchronization of nutrient release with the needs of the plants, before implementing this finding in real agriculture practices.
Keywords: Controlled released fertilizer, stearic acid, Polycaprolactone, potato starch, coating, fertilizer, biofilm.
Subject: Medical Biotechnology thesis
Thesis type: Masters
Completed: 2024
School: College of Medicine and Public Health
Supervisor: Vi Khanh Truong