Prediction of pH value change during flooding and draining of paddy soil in China

[ China Instrument Network Instrument Development ] The pH value of paddy soil will tend to be neutral under flooding and reducing conditions, but will show the opposite trend during draining. Accurate measurement and characterization of soil acidity is an important basis for studying biogeochemical processes such as organic matter decomposition, element migration and microbial activity.

pH change during flooding and drainage of 20 paddy soils in China

The air activity of soil samples changes the ion activity of calcium, magnesium, aluminum, phosphate, etc. and the number of protons closely related to organic matter. Therefore, the pH value of soil air-dried samples measured by laboratory does not reflect the real situation in the field. Dynamic monitoring of in situ pH is time consuming and labor intensive. If the physical and chemical properties of air-dried samples can be used to predict the change of in-situ pH value during paddy and draining of paddy soil, this problem can be solved better.

Wang Xingxiang, a researcher at the Institute of Soil Science of the Chinese Academy of Sciences, found that the pH, organic matter, cation exchange capacity, and flooding or draining time of soil air-dried samples can be used to predict the in-situ pH of paddy soil during flooding or draining. The established prediction model is as follows:

The researchers further collected literature data to verify the reliability of the predictive model. This is of great significance for predicting the availability of nutrients and heavy metal elements in the process of flooding and drying of paddy soils, and guiding the water management of heavy metals in the southern China. Related results were recently published in Geoderma (2019, 337: 511-513).

The above research was funded by the National Natural Science Foundation of China, the Natural Science Foundation of Jiangsu Province, the National Key Research and Development Program, and the Frontier Project of the Nanjing Soil Institute.

(Original title: Progress in the prediction of pH change during flooding and draining of paddy soil in Nanjing soil)