Enhancing Micronutrient Availability Through Humic Substances and Vermicompost While Growing Artichoke Plants in Calcareous Soil: Insights from a Two-Year Field Study

Calcareous soil poses challenges for crop production due to the limited availability of micronutrients in insoluble forms. This study evaluated various organic and biological treatments for managing deficiencies in iron, zinc, and manganese in artichoke (<i>Cynara scolymus</i> L.) grown in calcareous soil over two seasons (2023 and 2024). A randomized complete block design (RCBD) was employed, with 24 plots (5 × 8 m² each) receiving the following five treatments: mineral fertilizer, humic substances, ALCRI-anti chlorosis, ALCRI-vermicompost, and ALCRI-bio-help. Each treatment was replicated three times. In the 2023 season, significant increases in micronutrient levels were observed following the application of the organic and biological treatments, particularly ALCRI-vermicompost and humic substances. Compared to the control group, the iron content (Fe²⁺) increased by 57.1%, reaching 715.6%. Zinc (Zn²⁺) rose by 66.1% to 686.4%, while manganese (Mn²⁺) and copper (Cu²⁺) increased by 56.9% to 685.2% and 44.9% to 673.4%, respectively. These positive trends continued into the 2024 season, with Fe²⁺ showing even greater gains of 103.4%, peaking at 824.0% in the plots treated with the ALCRI-vermicompost and humic substances. Zn²⁺ and Mn²⁺ displayed more modest increases of 36.9% and 58.0%, while Cu²⁺ exhibited a remarkable rise of 50.7%, reaching 861.2%, particularly for the ALCRI-anti chlorosis treatments. The results indicate that the application of vermicompost fertilizer, alone or in combination with humic substances, significantly enhanced the soil structure, as confirmed by the SEM examination, which revealed increased porosity and improved aggregation. These consistent improvements over two seasons strongly support the effectiveness of organic and biological treatments in enriching soil with essential micronutrients.