The research with the title usage of zeolite and chitosan composites as slow release fertilizer had been done. In this research, fertilizer was made by mixing zeolite with NaNO 3 as a source of macro nutrients (nitrogen) and chitosan as a crosslinks which will later be used to provide slow release function in fertilizers. The slow release fertilizer was made by impregnating zeolite on NaNO 3 and chitosan solution. Initial characterization of slow release fertilizer functional groups was identified using FTIR instruments. The results of the characterization of slow-release fertilizer functional group are known to have shifted the zeolite characteristic peaks namely Si-O and Al-O groups which indicate the presence of Nitrogen got into the fertilizer. Nitrogen release rates were identified by UV-VIS spectrophotometer. The slowest Nitrogen release rate is zeolite-chitosan fertilizer with the ratio of zeolite and chitosan is 1:1 (%w/w), while the fastest Nitrogen release produced by zeolite fertilizer.

Research with the title of the use of silica chitosan with glutaraldehyde crosslinking agents as a matrix in the making of slow release urea fertilizer has been done. The purpose of this research was to determine the physical and chemical properties of slow release fertilizer coated with chitosan-silica matrix and also glutaraldehyde with a concentration of 1%, 1.5% and also 2% (v/v). Physical properties are known by SEM where it has been seen that the matrix has covered the fertilizer, for the chemical properties of slow release fertilizer can be analyzed from functional groups by FTIR to see the interaction between fertilizer, matrix and glutaraldehyde crosslinking agents. Slow release fertilizer has also been tested for nitrogen release levels. From the test, the composition of slow release urea fertilizer with chitosan-silica matrix and glutaraldehyde 1% (v / v) is more stable than the matrix with glutaraldehyde 1.5% and 2% (v / v).

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