pHKCl and pHH2O are two basic necessary indexes to reflect the acidity of asoil. Predicting pHKCl？directly from pHH2O？could 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 pHKCl and pHH2O. The results showed that: 1) pHKCl is lower than pHH2O, pHKCl？was 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 pHH2O？for Yunan. 2) There is significant positive correlation between pHKCl？and pHH2O, the optimal correlation models between pHKCl？(y) and pHH2O？(x) for Guangxi and Yunnan are y = 0.1963x2− 1.0512x + 4.338, R2 = 0.836, p < 0.01 and y = 1.5882e0.1859x, 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 pHKCl？with exchangeable H+ and Al3+ (R2 = 0.487, 0.716, p < 0.01), and pH
Deng, X.H., Li, Y.H., Zhou, M.L., et al. (2018) Acidity Characteristics and Influencing Factors of Tobacco-Planting Soils in Wuling Mountains—A Case Study in Xiangxi Autonomic Prefectural, Hunan Province. Journal of Soil and Water Conservation, 32, 304-309. (In Chinese)
Wu, Z.D., Jiang, F.Y., You, Z.M., et al. (2016) Acidic Characteristics of Subtropical Tea Garden Soil: A Case Study in Wuyishan City, Fujian Province, Southeast China. China Environmental Science, 36, 181-189. (In Chinese)
Xu, R.K., Coventry, D.R., Farhoodi, A., et al. (2002) Soil Acidification as Influenced by Crop Rotations, Stubble Management, and Application of Nitrogenous Fertiliser, Tarlee, South Australia. Australian Journal of Soil Research, 40, 483-496.
Schroder, J.L., Zhang, H.L., Girma, K., et al. (2011) Soil Acidification from Long-Term Use of Nitrogen Fertilizers on Winter Wheat. Soil Science Society of America Journal, 75, 957-964. https://doi.org/10.2136/sssaj2010.0187