Production and characterization of slow-release urea fertilizer using modified starch/bentonite clay coating materials

The fast nutrient release behavior of chemical fertilizer is becoming a pressing issue in the environment and causes a decrease in agricultural land productivity. This study presents the development of slow-release urea fertilizer (SRUF) using bentonite-starch coating materials as a response to the weak utilization efficiency of conventional urea fertilizer. Production and characterization of SRUF have been carried out using bentonite-starch coating materials at different combination stages. The two-way ANOVA without replication was examined using Microsoft Excel for statistical data analysis to see the significance of the effect of affecting parameters on the response parameters. The SRUF product sample was characterized in terms of water swelling capacity, water retention capacity, strength, and nutrient release in static water. The result has shown, water swelling (%WS) to be in the range of (55.1–89.7%), water retention (%WR) (4.45–93.2%), crushing strength (87.74–99.02%), and nutrient release in static water (8.92-89.00%). The effect of bentonite, starch, and urea particle size on the quality of the SRUF has been discussed in this research study. ANOVA analysis showed that affecting parameters had a significant effect on the response parameters (P value < 0.05). From the experiment carried out, the SRUF sample with 25% bentonite and 10% starch achieved a better-quality product. Additionally, the SRUF sample was subjected to the SEM and FT-IR analysis and revealed, the produced SRUF sample has a better water and nutrient retaining behavior. Generally, the study demonstrates the efficiency of bentonite clay and starch for urea fertilizer coating purposes, and the materials were found to be the best candidates for coating purposes to solve problems associated with the use of chemical fertilizers.