Crop Protection 20 (2001) 43 } 48 The economic potential of silicon for integrated management and sustainable rice production  Jose Alvarez, Lawrence E. Datno! * University of Florida-IFAS, Everglades Research and Education Center, Belle Glade, FL 33430 USA Received 21 September 1999; received in revised form 5 April 2000; accepted 7 April 2000 Abstract The bene"cial e!ects of silicon fertilization on rice culture has been described and quanti"ed in numerous literature citations. They include yield increases, improved disease, insect, and fertility management, and other bene"ts. Despite the scienti"c evidence, widespread silicon use is hindered by the high cost of the material and its application. The bene"cial e!ects of silicon application on world rice production have been translated to monetary values using a yield and cost-price structure in the Everglades Agricultural Area of southern Florida and later changed to re#ect conditions in other countries. The analysis of yield increases in the three scenarios analyzed provide savings of $271.85, $135.91, and $50.22/ha/yr for the 1996 crop season, respectively. The analysis of the remaining bene"ts also shows additional savings of $73.54, $52.32, and $6.43/ha/yr in the 1996 crop season. Assuming only an additional increase of 0.5 metric tons/ha in rice yields during the 1996}2010 period, land use would be reduced by 22.2 million ha and still satisfy consumption requirements in 2010. Consequently, land would be liberated for the production of non-traditional, export-oriented crops. This would be an important accomplishment, since production increases in the past and forthcoming decades have, and will, come from yield increases because of lack of available land. The additional bene"ts from silicon application may outweigh its cost in most rice-producing countries.  2001 Elsevier Science Ltd. All rights reserved. Keywords: Bene"t/cost; Consumption; Rice diseases; Fertility; Grain discoloration; Growth rate; Insect; Management; Present value; Production; Yield 1. Introduction Rice is an important staple food that is produced throughout most of the world, accounting for over 22% of global caloric intake (Wailes et al., 1997). Total utiliz- ation of rice is projected to increase from 376 million metric tons (MT) in 1996 to 435 MT by 2010 (Wailes et al., 1997). There are several di!erent types of ecosystems or growing environments for rice production throughout the world, including upland and lowland. Soils in parts of Asia, Africa, and Central and South America could be limiting in plant available silicon (Si), and this would be a constraint to optimal rice production (Savant et al., 1997a, b).  Florida Agricultural Experiment Station Journal Series No. R- 06717. * Corresponding author. Tel.: #1-561-993-1531; fax: #1-561-993- 1582. E-mail address: leda@gnv.ifas.u#.edu (L.E. Datno!). Some soils cropped to rice in the tropics have been shown to be particularly poor in plant-available Si; these soils are classi"ed in the order of sandy Entisols, Oxisols and Ultisols (Brady, 1992; IRRI, 1978). Histosols (or- ganic soils) also belong in that group (Snyder et al., 1986). Oxisols and Ultisols account for 34% of the area of major soil orders in the tropics, including Africa, America and Asia (Sanchez, 1976), which translates into about 1666 million hectares. Research conducted on Oxisols, Ultisols, Histosols and others has shown Si to be a functional element for either #ooded or upland rice (Jones and Handreck, 1967; Lian, 1976; Okuda and Takahashi, 1964). The bene"ts include dramatic increases in rice yields, prevention of Fe and Mn toxicity, and better uptake of P. Furthermore, Savant et al. (1997b) have conducted an extensive review of the literature documenting the positive impact of Si applications on rice yields under subtropical to tropical conditions, while Lian (1976) and Elawad and Green (1979) have done so for temperate countries of the world. The phenomenon of yield decline in di!erent rice eco- systems from many parts of the world has been reported 0261-2194/01/$ - see front matter  2001 Elsevier Science Ltd. All rights reserved. PII: S 0 2 6 1 - 2 1 9 4 ( 0 0 ) 0 0 0 5 1 - X