EDTA chelated calcium (EDTA-Ca, full name: Ethylenediaminetetraacetic Acid Calcium Disodium Salt) is a widely used chelated calcium fertilizer in agriculture. With standard CAS No. 62-33-9 and molecular formula C₁₀H₁₂CaN₂Na₂O₈·2H₂O, agricultural grade products contain ≥10% chelated calcium and appear as white crystalline powder with excellent water solubility.

Its core principle is that EDTA chelating agent molecules form a cyclic "molecular cage" structure, tightly wrapping calcium ions inside to form a stable chelate. This structure protects calcium ions from reacting with phosphate, carbonate, sulfate and other ions in soil to form insoluble precipitates, keeping calcium in a water-soluble active state that can be directly absorbed by crop roots and leaves.

Different from common inorganic calcium fertilizers, EDTA chelated calcium can exist stably in a wide soil pH range of 4.0-9.0, adapting to acidic, neutral and even weakly alkaline soils. It is widely applicable to fruit trees, vegetables, field crops and hydroponic systems, serving as an efficient calcium nutrient for preventing and correcting crop calcium deficiency.