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The slow release urea fertilizer was prepared by the boric acid crosslinked starch/polyvinyl alcohol (SPB) matrix as biodegradable carrier material. Using a two level factorial design of experiment, a comprehensive understanding of the concentration of boric acid, reaction time and heating temperature in the preparation of SPB matrix was obtained. The swelling ratio, release profile of urea in water, and crushing strength were selected as the response. The interaction between the variables and response was analyzed using the ANOVA model. The system was confirmed using the constant determination, R2 with values above 0.99. The high concentration of boric acid with a prolonged reaction time at high temperature gave relative good results of swelling ratio, dissolution rate of urea and crushing strength. In the 28-day soil incubation experiment, the retention of exchangeable ammonium ion ${\rm{(NH}}_4^ + )$ was significant higher in SPB urea as compared to pure urea. There was a potential for SPB matrix to improve nitrogen efficiency by increasing the accumulation of exchangeable ${\rm{NH}}_4^ + $ and decreasing the dissolution rate of urea in the flooded condition.

Plant growth rate is significantly dependent on application of nitrogenous fertilizer which mainly contributed by urea fertilizer (UF). Nanotechnology advancements in nutrition strategies for plants have attempted to assist plant nutrition for efficient plant growth. The development of carbon nanomaterials (NMs) including Multi-walled carbon nanotubes (MWNTs) in conjunction with the advancement in biotechnology has expanded their application area of in the field of agriculture. The aim of the work is to identify the significant process parameters to attach urea fertilizer (UF) onto MWNTs. The UF-MWNTs was than characterized optically and chemically to confirm their bonding. Comparison study was also conducted between UF-MWNTs and UF-functionalized MWNTs on total N content bonding to the MWNTs. The surface functional groups produced from functionalization process are essential for further modification of MWNTs and facilitate the separation of nanotube bundles into individual tubes. Optical, vibrational spectroscopy and chemical characterization were conducted on the samples using TEM, FT-IR and total N analysis confirmed the successful bonding of urea onto MWNTs. Plackett-Burman Experimental Design showed, two out of nine investigated parameters (amount of functionalized MWNTs and percentage of functionalization) were found significant in producing successful attachment of UF onto functionalized MWNTs (fMWNTs).