Wheat (Triticum aestivum L.) performance and nitrogen dynamics in soil amended with ammonium-enriched zeolite from real treated wastewater

In this study, the effect of ammonium-enriched zeolite (NH4+) as a slow-release fertilizer for wheat grown was evaluated. Zeolites were enriched in filter columns located in a wastewater treatment pilot plant using real wastewater from the Water Resource Recovery Facility of Palermo University. Two zeolites, ZCS and ZCL, with the same mineralogical composition but with different particle diameters (ø 0.5-1.5 mm and ø 2-5 mm, respectively) were used. The experimental design involved the use of two different soils to evaluate the effect of enriched zeolite compared to N-fertilizer. Four treatments were set up: control (no nitrogen), soil fertilised with 30 mg of N per plant applied in the form of ammonium sulphate, [NH₄)₂SO₄], ZCS and ZCL treatments, where zeolite with small and large particle diameter respectively, were applied to add 30 mg of N per plant. The four treatments were replicated in four blocks for the two soils, resulting in a total of 32 experimental units. The entire experiment was conducted in a growth chamber. Wheat (Triticum aestivum L.) plants were irrigated daily with 20 mL of nitrogen-free Hoagland nutrient solution. Wheat was chosen as test plant due to its high nitrogen requirement and rapid hazard of nutritional deficiencies. Before starting the experiment, both zeolites were analysed to determine cation exchange capacity, and exchangeable cations, included NH4+, total carbon, nitrogen, sulphur, mineralogy, and FTIR spectra. At the end of the growth experiment lasted 88 days, plants were harvested and stored for further analyses. Soil analyses included the determination of available NO3-, NH4+ and β-glucosidase. Plant samples were analysed for total nitrogen concentrations in roots, stems, glumes, and grains. Moreover, biometric parameters such as fresh weight, dry weight, number of ears per plant, grain weight, and glume weight were determined. Nitrogen Use Efficiency (NUE) and Nitrogen Fertilizer Replacement Value (NFRV) were evaluated.