Synthesis and characterization of nano-micronutrient fertilizer and its effect on nutrient availability and maize (Zea Mays L.) productivity in calcareous soils

Agriculture in calcareous soil faces challenges such as high calcium carbonate content, low organic matter, and poor availability of nutrients. Therefore, a field experiment was done during the summer seasons of 2022 and 2023 at the Nubaria Research Station in Egypt to study the effect of nano-fertilizers (NFs) on maize productivity and nutrient availability. The field experiment was done through a randomized completely block design with treatments: Control, Nano-Zn 20 mg/L, Nano-Zn 40 mg/L, Zn-chelate 2 g/L, Nano-Mn 20 mg/L, Nano-Mn 40 mg/L, Mn-chelate 2 g/L, Nano-Mo 20 mg/L, Nano-Mo 40 mg/L and ammonium molybdate (AMo) 250 mg/L. The synthesized nano-micronutrient fertilizers were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that 40 mg/L of NFs was the most effective treatment for most studied traits. The highest maize grain weight per plant (239.4 g), 100-grain weight (40.7 g), and yield (15.1 ton/ha) were obtained with 40 mg/L of Nano-Mo, Zn, and Mn, respectively. The maximum leaves nutrient contents of P (0.98%), K (1.0%), Fe (268 mg/kg), Zn (79 mg/kg), and Cu (24.3 mg/kg) were found in plants treated with Nano-Zn 40 mg/L. While, the highest concentrations of Mn (271.7 mg/kg) and N (3.96%) on the leaves were obtained with 40 mg/L of Nano-Mn and Mo, respectively. When compared to traditional fertilizers, NFs showed better plant growth traits, productivity, and nutrient levels.