Effect of Moisture Deficiency and Increased Salt Content on Silicon State of Some Soils of European Part of Russia and Central China

Soluble forms of silicon affect a number of physical, chemical, and biological soil properties. Optimization of silicon nutrition enhances plant tolerance to biotic and abiotic stresses. Current climate change and anthropogenic impacts can alter the soil silicon state. Model laboratory experiments conducted with upper horizons of sod-podzolic soil, gray forest soil under different plant associations, chernozem, paddy soil, and red subtropical soil showed that insufficient soil moistening led to a reduction in soil monosilicic acid by 15 to 36% and simultaneous increases in polysilicic acid by 9 to 45%. Soil cultivation resulted in a decrease in plant-available soil silicon. An increase in NaCl concentration in the soil caused an increase in both monomers and polymers of silicic acid by 6 to 79%. The mobile equilibrium and lability of the numerical values of the parameters of the silicon state of the soil–plant system are revealed. These factors should be taken into account when implementing the 4R-STRATEGY for optimizing mineral nutrition in agricultural crops.