[Study of using digital photography to measure soil pH]

Soil saline-alkalization is one of the most important problems of land degradation and the basic environmental problem in arid and semi-arid regions. The digital photography technology can rapidly and timely provide the information about properties, geographical distribution and extent of soil saline-alkalization. For verifying use digital photography assess degrees of sodality promptly and accurately, based on the monitored data of soil pH and measured VIS-NIR reflectance and photographs on given spots, The correlation were analyzed between soil pH and color space model parameters, Partial least squares Regression (PISR) was employed to build predicting model of pH value and the different between two Kinds of data were compared. The results showed that most of parameters with significant correlation While the CIEL * a * b * color model was the best, and it is the best model to assess soil pH (R2 = 0.795, RMSEcv = 0. 084). Prediction set has also seen it was accurate and stability (R2 =0.781, RMSE p = 0.158). The prediction had no significant difference between the digital photography and VIS-NIR reflectance data. The digital image color analysis method showed the potential of being used in soil pH value assessing in the future.