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Improve biochar-based controlled release fertilizer’s performance by coating multiple layers of polylactic acid

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2021 ASABE Annual International Virtual Meeting  2100092.(doi:10.13031/aim.202100092)
Authors:   Robiul Islam Rubel, Lin Wei
Keywords:   nitrogen fertilizer, polylactic acid, coating, controlled release, nitrogen use efficiency


Crop‘s nutrition demand varies at its different growth stages. Conventional fertilizer applied for yield improvement dissolve in the soil quickly leading to losses and serious ecological problem without being consumed by the plant‘s roots. Thus, synchronizing between fertilizer application and crop nutrients uptakes is a key to get a good yield of the crops. Impeding the diffusion of the fertilizer into the soil by a physical method like mixing and coating can expand the nutrients uptake times of the crops and curbing the losses. This research intends to develop a polylactic acid (PLA) coated biochar-based controlled release nitrogenous fertilizer (BCRNF) to control N release to synchronize the N demand of the corn in different stages to improve the yield. Powder ammonium sulfate (AS) has impregnated into pre-prepared biochar produced by pyrolysis of corn stover and mixed with three different percent of bentonite (0%, 5%, and 10%) to make BCRNFs. Later the oven dried BCRNFs samples were coated with 5 wt% of PLA solution in chloroform. Samples have coated with single, double, and triple layers of PLA and the expected controlled N release has been observed through NH4+ ion release in distilled water for a different layer of BCRNFs samples. The results demonstrated controlled N release in water by the increasing %wt of the bentonite in the samples and an increasing number of PLA coating layers of the samples. Up to 18 days of controlled N release can easily be expected from this anticipated method that will last longer in the soil if a good coating layer is provided. The main challenge found for this experiment is to provide a uniform and good coating layer over the fertilizer particles that should go for further research.

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