Abstract:In order to clarify the correlation between exchangeable calcium (Ca2+) and magnesium (Mg2+) contents with other soil properties in the northeastern Chongqing tobacco-growing region, and provide reference basis for nutrient management in tobatacco planting areas, 1 092 typical soil samples were collected from Wuxi, Wushan, Fengjie, Wanzhou, Fuling and Fengdu using GPS positioning technology, and Ca2+ and Mg2+ contents and their correlation with other soil properties were analyzed. The results show that the average contents of Ca2+ and Mg2+ are 10.85 cmol/kg and 1.79 cmol/kg, respectively, but there are also deficiencies and uneven regional distribution, 28.30% and 42.75% of the samples are deficient in Ca2+ (<6 cmol/kg) and Mg2+ (<1.0 cmol/kg), respectively. Ca2+ and Mg2+ deficiencies are most severe in Fuling and Fengdu counties, accounting for 40.00% and 55.00%, respectively. Fengdu County and Wanzhou District have the most suitable Ca2+ and Mg2+ contents, with 42.00% and 36.61% respectively. The parent material is an important factor influencing Ca2+ and Mg2+ contents, which are high in soils derived from Permian marl but low in soils derived from Jurassic purple sandstone. Ca2+ and Mg2+ are significantly positively correlated with soil pH and cation exchange, whereas significantly negatively correlated with total soil exchangeable acid. Deficiencies in Ca2+ and Mg2+ are the main cause of soil acidification in tobacco-planting fields. 1 ~ 2 mm and <0.25 mm aggregates are the key factors causing Ca2+ and Mg2+ differentiation, and the formation of large soil aggregates (>2 mm) should be promoted to prevent soil acidification. This study can guide the management of soil Ca2+and Mg2+ nutrients in tobacco-planting fields in the northeastern part of Chongqing.