Abstract: The objective of this paper is to study the districts, soils and crops suitable for chlorine (Cl) containing fertilizers and the safe and high efficient fertilizer application techniques. Ammonium chloride and double Cl fertilizers were used as the main materials and the chloride ion was taken as the key point of study. The content of Cl of the soils in China is low and the average content is 59.6 mg·kg-1. The content of Cl of the soils in northwest is high and the average content is 126.0 mg·kg-1. The soil with high Cl content is a salt soil and the average content is 607.0 mg·kg-1. Geographic characters are obvious in soil Cl accumulation and soil acidification resulted from application of Cl -containing fertilizers. The accumulated Cl in the dryland soils in northwest China is 50%-100% while that in southwest China and south China is zero. Soil acidification is only occurred in the neutral and acid soils. Thirty three crops were classified as high tolerant crops to Cl (＞600 mg·kg-1), medium tolerant crops to Cl (300-600 mg·kg-1), and low tolerant crops to Cl (＜300 mg·kg-1) according to critical concentration of Cl tolerance. The safe and high efficient application techniques of Cl-containing fertilizers were proposed. The results of study can be used as a reference for Cl-containing agriculture and allocation planning of combined-soda industry.

Key words: Chlorine-containing fertilizer, Chlorine content, Chlorine ion, Chlorine tolerance, Fertilizer application technique