Study on the Relationship between pH and Organic Matter Components, Ion Content in Baoshan Tobacco-planting Soil

PurposeTo study the correlation between pH and organic matter and its components, exchangeable acid (total), exchangeable base, ion content of tobacco-planting soil in Baoshan, and to evaluate the influence of those factors on soil pH.

MethodTaking Baoshan tobacco planting topsoil as the research object, Pearson correlation method was used for correlation analysis, and partial least-squares regression (PLS) method was used for modeling analysis.

Results1) The contents of organic matter and its components, exchangeable acid (total), NO₃⁻, SO₄²⁻ and so on in Baoshan acid soil were high; the contents of exchangeable Ca²⁺, exchangeable Mg²⁺, HCO₃⁻, Ca²⁺ and Mg²⁺ in alkaline soil were high. 2) Correlation analysis showed that soil pH was extremely significant negative correlation with organic matter and its components, exchangeable acid (total), NO₃⁻, SO₄²⁻ (P<0.01), and extremely significant positive correlation with cation exchange capacty (CEC), exchangeable Ca²⁺, exchangeable Mg²⁺, HCO₃⁻, Ca²⁺, Mg²⁺ (P<0.01), and significant positive correlation with humic acid (P<0.05). 3) The PLS regression analysis showed that the important indexes affecting soil pH in Baoshan were the contents of exchangeable H⁺, HCO₃⁻, exchangeable Ca²⁺, Ca²⁺, humic acid, exchangeable acid (total), exchangeable Mg²⁺, SO₄²⁻, exchangeable Al³⁺ and Mg²⁺. The contents of K⁺, exchangeable K⁺, fulvic acid, exchangeable Na⁺, Na⁺, CEC were not important indexes.

ConclusionThe determination factors of acidity of tobacco planting soil in Baoshan were the contents of exchangeable H⁺, humic acid, exchangeable acid (total), SO₄²⁻, exchangeable Al³⁺; the determining factors of alkalinity were the contents of HCO₃⁻, exchangeable Ca²⁺, Ca²⁺, exchangeable Mg²⁺ and Mg²⁺.