Effect of Silicon and Phosphorus Additions and Their Interactions on Wheat Plants Grown on a Clay Soil

A pot experiment was conducted in clay soil collected from Agricultural Research Center farm, Giza governorate, Egypt. Wheat grains (Triticum aestivum L., Giza 168) were cultivated to study the effect of silicate and phosphate ions as well as their interactions on the growth and nutritional status of the growing plants, beside their availability in the studied soil. Silicon (Si) in the form of sodium meta-silicate penta-hydrate (Na2SiO3.5H2O) was added at a rate of 0, 200, 300 and 400 mg Si kg-1 soil, and phosphorus (P) in the form of calcium super phosphate was given at a rate of 0, 3.5, 7.0, 10.0 and 13.0 mg P kg-1 soil to represent 0, 25, 50, 75 and 100% of the recommended rate of P fertilization by the Egyptian Ministry of Agriculture for wheat cultivation. Also, the experiment included combinations between all these concentrations of Si and P. Obtained results showed that Si and P availability increased in the studied soil with increasing either Si or P concentrations added. This means that P availability in soil as an essential element for plant growth can be improved by addition of Si. Also, Si increased in plant with increasing applied Si concentrations. Interaction between Si and P generally increased all parameters of plant growth; such responses were significant for fresh and dry weights of wheat plants at booting stage. It could be recommended that selecting good P fertilization design, including time and rate of addition, goes along with values of available Si in the soil.