Silicon in Soil, Plants, and Environment

Silicon (Si) is the most abundant element after oxygen on the earth's crust and silicate minerals make up a large portion of soil minerals. The Si is quasi-essential element for plant growth and is beneficial to reduce biotic and abiotic stress such as metal toxicity, salinity, water stress, extreme temperature, drought, pest attack, and plant diseases. Despite being that abundant element, the bioavailability of Si (available to plants for uptake) is limited and mostly residing in upper soil. Major sources of silicon in soil are silicate minerals, plagioclase, orthoclase, feldspars, plant residues, rice hulls, sugar cane bagasse, calcium silicate slag, magnesium silicate, silicic acid, and Si nanoparticles. In agriculture, silicon is also being used as fertilizer for enhancing crop growth and mitigating abiotic and biotic stresses. Silicon plays an essential part in plant nutrient uptake, increasing crop yield, improving crop quality, enhancing crop biomass, crop growth, and antioxidant enzyme activities. Silicon possesses distinctive physiological effects in plants, which enable them to tolerate biotic and abiotic stresses. This chapter addresses silicon usages and the role of silicon in plant nutrition in the soil plant and environment, the way in which plants take up silicon from soil. Additionally, the role of Si in plant biotic and abiotic stress reduction, the effect of silicon on the environment, and the role of silicon sources in stress management are addressed.