Calcium Cyanamide as an Alternative Nitrogen Fertilizer: A Comprehensive Review of Its Agronomic and Environmental...

Calcium cyanamide (CaCN₂), commercially known as Perlka^®, is re-emerging as a multifunctional nitrogen (N) fertilizer with significant agronomic and environmental advantages. Composed of 19.8% nitrogen and 50% calcium oxide (CaO), CaCN₂ not only supplies slow-release nitrogen but also acts as a liming agent, improving soil pH and structure. Its transformation pathway: cyanamide → urea → ammonium → nitrate-ensures a gradual nitrogen release that aligns with crop demand, enhances nitrogen use efficiency, and minimizes nitrate leaching and nitrous oxide emissions. Additionally, the presence of dicyandiamide, a known nitrification inhibitor, further stabilizes nitrogen in the soil. Field studies across diverse cropping systems, including curly endive and short-day onions, have demonstrated that CaCN₂ improves yield, crop quality, and soil health. In onions, preplant application of 80 kg ha^-1 N from CaCN₂ increased bulb yield by up to 18%, enhanced phytochemical content (e.g., phenolics and flavonoids), and reduced nitrate leaching by over 40% compared to urea and limestone ammonium nitrate (LAN). In curly endive, CaCN₂ significantly improved ascorbic acid, total soluble solids, and phenolic content, particularly in fall-grown crops, while reducing nitrate accumulation and improving physiological and recovery efficiency of applied nitrogen. Beyond its role as a nutrient supplier, CaCN₂ exhibits biocidal properties that suppress soil-borne pathogens such as Sclerotinia and Plasmodiophora brassicae, reduce weed pressure, and stimulate beneficial microbial activity. Its high calcium content also addresses physiological disorders linked to calcium deficiency, such as tip-burn and blossom-end rot. However, proper application timing and dosage are critical to avoid phytotoxicity, especially in sensitive crops. This review synthesizes current knowledge on CaCN₂'s chemical behavior, agronomic performance, and environmental implications, and identifies research gaps to guide its optimized use in climate-smart and resource-efficient agriculture.