Silicon Management of Blast in Upland and Irrigated Rice Ecosystems

Abstract

Silicon (Si) is one of the most abundant elements in the earth’s crust, and most soils contain considerable quantities of the element (Savant et al, 1997a). However, repeated cropping can reduce the levels of plant-available Si to the point that supplemental Si fertilization is required for maximum production, and some soils contain little plant-available Si in their native state (Savant et al, 1997a; Savant et al, 1997b). Low-Si soils are typically highly weathered, leached, acidic and low in base saturation. Thus, highly weathered soils such as Oxisols and Ultisols can be quite low in soluble·Si. Highly-organic Histosols that contain little mineral matter may contain little Si. Interestingly, soils comprised mainly of quartz sand (Si0₂) such as sandy Entisols also may be very low in plant-available Si. These conditions are found in many crop producing areas of Africa, Asia, Latin America and the southeastern USA.