Assessing the performance of clinoptilolite for controlling and releasing ammonium in agricultural applications

To develop soil holding capacity of NH4+ and reduce the energy consumption of industrial fertilizer production, different dosages of clinoptilolite mixed with soil were used to absorb NH4+, which was also simulated using Freundlich and Langmuir equation under different conditions. The results showed that NH4+ adsorption of clinoptilolite-amended soil changed from multilayer adsorption to single-layer adsorption with the increase in clinoptilolite application rates. The optimal ratio of clinoptilolite applied to the soil for high adsorption efficiency was 0.01g 10g−1. The co-existence of Na+ and K+ increased the NH4+ adsorption capacity of clinoptilolite-amended soil relative to the existence of single Na+. This showed that K+ was less competitive towards NH4+ than Na+. Decreasing water quantity, which increased the total soil adsorption capacity by a factor of 2 to 3, had the most significant effect and helped regulate the release of nitrogen in clinoptilolite-amended soil. In sum, clinoptilolite can enhance soil nitrogen holding capacity, which shows great potentials to reduce the energy consumption of industrial urea production.