Soil Initial Available Phosphorus and Exchangeable Magnesium Shaping the Response of Wheat Growth to pH.

The critical pH was the target pH for soil acidity improvement, which has important guiding significance for agricultural production and sustainable development. A pot experiment was conducted to investigate the effect of soil initial properties affecting the response of wheat growth to pH. 5 soils derived from plate shale, quaternary red earth, river alluvium, tertiary red sandstone, and granite were used in this study. The results showed that the maximum shoot biomasses of wheat were 2.71, 1.17, 2.06, 1.57 and 1.70 g⋅pot^-1 for soils derived from plate shale, quaternary red earth, river alluvium, granite, and tertiary red sandstone, respectively. The critical values of pH9_5%, pH_50%, or pH_5% were defined as shoot biomass reaching to 95%, 50%, or 5% of maximum values. The pH_95%, pH_50%, or pH_5% were 5.31, 4.42, and 3.53 for soil derived from plate shale, 5.79, 4.79, and 3.80 for quaternary red earth, 5.25, 4.71, and 4.16 for river alluvium, 4.94, 4.61, and 4.29 for tertiary red sandstone granite, and 5.72, 4.66, and 3.59 for granite, respectively. The maximum values of shoot biomass had significant positive correlations with soil initial pH, available P, exchangeable Mg and exchangeable Ca. The pH_50% of wheat shoot biomass was negatively correlated with soil initial available P; and the pH_50%of wheat height was negatively correlated with soil initial available P and exchangeable Mg. The data indicated that soil initial available P and exchangeable Mg shaped the response of wheat growth to pH and the maximum values of crop biomass were determined by both soil nutrient status and acidity. Therefore, we recommend that co-amelioration of soil fertility and acidity was a practical method to reach a best condition for plant growth. [ABSTRACT FROM AUTHOR]