%0 Journal Article %T A Brief Study on Using pHH2O to Predict pHKCl for Acid Soils %A Anqi Wang %A Decheng Li %A Biao Huang %A Yin Lu %J Agricultural Sciences %P 142-149 %@ 2156-8561 %D 2019 %I Scientific Research Publishing %R 10.4236/as.2019.102012 %X pH_KCl and pH_H₂O are two basic necessary indexes to reflect the acidity of asoil. Predicting pH_KCldirectly from pH_H₂Ocould save the cost of laboratory work. In this study, the values of pHKCl and of 442 and 310 horizon samples from 126 and 98 soil profiles (0 - 120 cm in depth) surveyed from 2014 to 2015 in Guangxi and Yunnan were used to establish the optimal correlation model between pH_KCl and pH_H₂O. The results showed that: 1) pH_KCl is lower than pH_H₂O, pH_KClwas 0.07 - 1.99 units with a mean of 0.99 units lower than for Guangxi, while 0.03 - 1.90 units with a mean of 0.89 lower than pH_H₂Ofor Yunan. 2) There is significant positive correlation between pH_KCl and pH_H₂O, the optimal correlation models between pH_KCl(y) and pH_H₂O(x) for Guangxi and Yunnan are y = 0.1963x² − 1.0512x + 4.338, R2 = 0.836, p < 0.01 and y = 1.5882e^0.1859x, R2 = 0.769, p < 0.01, respectively, and the values of MAE and RSME of the models are 0.13 and 0.36 for Guangxi, 0.08 and 0.28 for Yunnan, respectively. There are significant negative correlations between pH_KClwith exchangeable H⁺and Al³⁺ (R2 = 0.487, 0.716, p < 0.01), and pH