Formulation and characterization of water retention and slow-release urea fertilizer based on Borassus aethiopum starch and Maesopsis eminii hydrogels
D. T. Gungula, Fartisincha P. Andrew, Japari Joseph, Semiu Adebayo Kareem, J. T. Barminas, Elizabeth F. Adebayo, A. M. Saddiq, Vadlya T. Tame, Idayatu Dere, Wamarhyel J. Ahinda, Reuben Ator
Abstract
Environmentally friendly slow-release fertilizers (SRF) based on Borassus aethiopum starch (BAS-SRF) and Maesopsis eminii (ME-SRF) hydrogels were formulated by encapsulating urea into biomaterials using borax as a binder. The SRFs were characterized by FT-IR, SEM and XRD techniques. The gel ratios of the hydrogels were found to be 71.27 ± 0.31 and 57.43 ± 2.27 for BAS-SRF and ME-SRF respectively. Swelling and water retention capacity of the SRFs in distilled water, NaCl, CaCl2, and FeCl3 solutions were evaluated. The water retention ratio at 4 days was similar 14.76% for both BAS-SRF and ME-SRF in soil and 4.67% for soil without the SRFs. The swelling ratio of the SRFs in solution, followed the order Water > NaCl > CaCl2>FeCl3. The swelling kinetics fitted with Scott's second order swelling kinetic model. The fertilizer release of the standard urea (un-capsulated) in distilled water revealed a cumulative release of about 97% within an hour. Whereas the formulated BAS-SRF and ME-SRF (encapsulated) had a cumulative release of 76% and 68% at 24 h and 96 h respectively. Interestingly, a sustained cumulative urea release was observed in soil; about 95% and 92% at 36 days for BAS-SRF and ME-SRF respectively.