In this study, chitosans was deacetylated with 45% sodium hydroxide under air atmosphere at 80 °C for up to 3 hour, to obtain deacetylated chitosan DDA measure by potentiometer titration method. Deacylated chitosan polymerizing methacrylic acid (DDCSPMAA) nanoparticle is an interesting material for use in controlled release for K fertilizers. In this work chitosan nanoparticles were obtained by polymerizing methacrylic acid for the incorporation of potassium chloride for potassium(K) fertilizers. The interaction and stability of chitosan nanoparticle suspensions containing K was evaluated by SEM. The SEM results indicated the existence of electrostatic interactions between chitosan nanoparticles and the elements K. The stability of the DDCS-PMAA colloidal suspension was higher with the addition of potassium due to the higher anion charge of potassium chloride. The use of slow release fertilizer has become a new trend to save fertilizer consumption and to minimize environmental pollution. Due to its polymeric cationic, biodegradable, bioabsorbable, and bactericidal characteristics.