Soil Fertility and Its Relationship with Soil Salinity in Tobacco-planting Areas of Luoyang, Henan Province

Tobacco-planting soils in 20 typical farmlands in Luoyang of Henan Province were taken as the study objects, and the conventional statistical method and redundancy analysis method were applied to disclose soil basic fertility and total salinity in 0-20 cm, 20-40 cm, 40-60 cm, 60-80 cm, 80-100 cm depths, and the relationship between soil fertility and salt ions was explored. The results showed that:(1) The contents of organic matter (OM), alkali-dissolved nitrogen (AN), available phosphorus (AP) and potassium (AK) were all the highest in the 0-20 cm layer, and among them, OM and AK gradually decreased with the deepening of soil, while AN and AP decreased first and then increased. Most soils were alkaline, and pH was the minimal in the 0-20 cm layer. As AN and AP, the total salt content also decreased first and then increased from top to bottom; (2) Redundancy analysis showed that OM had a significant correlation with K⁺, Na⁺, Ca²⁺ and SO₄^2- with 0-100 cm depth; AN had a positive correlation with K⁺ and a negative correlation with Na⁺ in the 0-40 cm layer; AP was greatly affected by K⁺ within 0-80 cm depth and had a significant correlation with Ca²⁺ and SO₄^2- in 0-100 cm depth; AK had different correlations with salt ions in different layers; pH had a significant correlation with HCO₃^-. Considering comprehensively, the surface soil fertility of typical tobacco planting soil in Luoyang is higher, and the salt content is more concentrated in the surface layer and the bottom layer soil. K⁺ has a greater impact on the fertility index, while Cl^- has enhanced influence on the fertility index with the deepening of the soil layer. There is no obvious regularity in the performance of each ion and fertility.