19 Silicon Silicon (Si) is the second-most abundant element of the Earth’s surface. Beginning in 1840, numerous laboratory, greenhouse, and field experiments have shown benefits of application of silicon fertilizer for rice (Oryza sativa L.), corn (Zea mays L.), wheat (Triticum aestivum L.). | 7 14 2006 12 16 PM Page 55 19 Sil icon George H. Snyder University of Florida IFAS Belle Glade Florida Vladimir V. Matichenkov Russian Academy of Sciences Pushchino Russia Lawrence E. Datnoff University of Florida IFAS Gainesville Florida CONTENTS Historical Perspectives .552 Silicon in Plants .553 Plant Absorption of Forms of Silicon in Biochemical Reactions with Beneficial Effects of Silicon in Plant Nutrition .554 Effect of Silicon on Biotic Effect of Silicon on Abiotic Effect of Silicon on Plant Growth and Effect of Silicon on Root Development .557 Effect of Silicon on Fruit Effect of Silicon on Crop Silicon in Forms of Silicon in Soil Tests. .561 Silicon Fertilizers .562 Silicon in Animal INTRODUCTION Silicon Si is the second-most abundant element of the Earth s surface. Beginning in 1840 numerous laboratory greenhouse and field experiments have shown benefits of application of silicon fertilizer for rice Oryza sativa L. corn Zea mays L. wheat Triticum aestivum L. barley 551 7 14 2006 12 16 PM Page 55 552 Handbook of Plant Nutrition Hordeum vulgare L. and sugar cane Saccharum officinarum L. . Silicon fertilizer has a double effect on the soil-plant system. First improved plant-silicon nutrition reinforces plant-protective properties against diseases insect attack and unfavorable climatic conditions. Second soil treatment with biogeochemically active silicon substances optimizes soil fertility through improved water physical and chemical soil properties and maintenance of nutrients in plant-available forms. HISTORICAL PERSPECTIVES In 1819 Sir Humphrey Davy wrote The siliceous epidermis of plants serves as support protects the bark from the