Abstract:

This study aimed to clarify the distribution characteristics of soil chloride ions in major tobacco-growing areas of Chifeng, explore the regulatory effects of fertilizer types, fertilization methods, and irrigation water purification on chloride ion content in tobacco leaves, and provide theoretical basis and technical support for precise management of chloride ions in tobacco areas. A survey was conducted on chloride ion contents in 80 tobacco-planting soil samples from Aohan Banner, Harqin Banner, Ningcheng County, and Songshan District of Chifeng. Combined with field experiments (different compound fertilizers, fertilization methods, and irrigation water treatments), chloride ion contents were determined by silver nitrate titration, and conventional chemical components in tobacco leaves were analyzed by near-infrared spectroscopy. Significant regional differences were observed in soil chloride ion contents in Chifeng tobacco areas, which were significantly affected by previous crops. In Aohan Banner (previous crop: maize), most soil samples had chloride contents <45 mg/kg (optimum range). In Harqin Banner and Ningcheng County (previous crop: tobacco), 75% of soil samples had chloride contents >50 mg/kg (suboptimal range). In Songshan District (previous crop: maize), soil chloride contents ranged from 30 to 50 mg/kg (suboptimal range). Field experiments showed that low-chloride and high-potassium ternary compound fertilizers reduced chloride content in tobacco leaves by 0.03-0.16 percentage points (most significant effect on lower leaves), while the ‘big ternary’ integrated fertilizer achieved an average reduction of 0.13%. Potassium chloride-based fertilizers significantly increased leaf chloride content (average increase of 0.11-0.13 percentage points). Among fertilization methods, applying potassium chloride as topdressing had the greatest impact on lower leaves ( chloride increase by 0.28%), whereas using potassium chloride as base fertilizer combined with potassium sulfate as topdressing reduced chloride content in middle leaves by 0.11%. Irrigation water purification decreased chloride contents in upper, middle, and lower leaves by 0.44, 0.50, and 0.59 percentage points respectively, with all treated leaves showing chloride contents <0.80%. This study revealed the distribution pattern of chloride ions and multi-dimensional management technologies in Chifeng tobacco areas, providing scientific support for improving tobacco leaf quality.

Key words: chloride ion, tobacco, fertilizer, fertilization method, irrigation water, previous crop, potassium-chlorine ratio, tobacco leaf quality