Nitrate and Potassium Release Patterns from Different Zeolite/Biopolymer Matrices as Model Slow-Release Fertilizer Systems

The supply of mineral elements for plant growth is of great importance in agricultural production. The development of slow-release fertilizers is one of the effective methods for overcoming problems caused by the uncontrolled use of chemical fertilizers in agricultural lands. Biopolymers are among the most suitable natural compounds for the synthesis of slow-release fertilizer systems. In the present research, alginate, rosin gum, and combination of wheat straw and the gum together with zeolite in the mass ratios of 1:2, 1:4, and 1:8 were used to produce slow-release systems of nitrate and potassium. The extents of nitrate and potassium release were measured 1, 3, 5, 10, 15, 20, 25, and 30 days after slow-release fertilizers applications. The highest percentages of potassium and nitrate release were recorded during the first 24 hours. The results showed that the highest percentages of potassium release were recorded for the systems made from wheat straw in combination with gum rosin and zeolite while the lowest release percentages were observed for the 1:8 zeolite:rosin gum system. In general, it may be concluded that the slow-release systems made based on rosin gum:zeolite were suitable candidates for the preparation of slow-release nitrate and potassium fertilizers.