Slow release fertilizer (SRF) that consist of rice straw (RS) and urea coated with natural rubber (NR) and salt abbreviated as RS/Urea beads coated with NR/salt composites were prepared. RS was sieved in two different sizes which were 500 μm and 1 mm. Both of the RS sizes were treated with sodium hydroxide to expand the fibre capacity in order to store more urea. The RS/urea beads were then coated with NR/salt composite. Two concentrations of the salts prepared which were 5 % and 10 % towards the weight of the NR while 0 % salt act as a control. The role of salt is to introduce pore to the NR which allow urea to pass through its coating when soaked in the water. All SRF samples were analysed using FTIR and UV-Vis technique.
