The objective of this work was to evaluate the

effect of silicon on the soil fertility, the incidence of diseases

and insect pests, the yield and quality of rice grains, variety

CR 4477. The study was conducted in La Vega, Florencia,

San Carlos, Costa Rica between May and Octuber in 2010

and 2011 in the same field. Five treatments were established:

silicon to soil, silicon to soil plus pesticides (chemical alternatives),

silicon to foliage, silicon to foliage plus pesticides

and a commercial control. Sources were silicon powder at

70% of SiO2 applied 15 days before sowing at a dose of 100

kg SiO2/ha and 40% SiO2 and 36% MgO concentrated liquid

applied to the foliage at a dose of 4 l/ha at 17 and 30 days

after planting. The soil was an alluvial formation inceptisol

order, and at the beginning of the experiment had a pH of

4.9, P and Si values of 29 and 44.7 ppm respectively, exchangeable

acidity 1.2 cmol(+)/l and base sum 19.11 cmol(+)/l.

The results showed no effect of silicon in soil fertility, the incidence

of pests and diseases, and milling quality, except that

the combination of silicon applied at soil and the pesticides

used increased the zinc and copper content in the soil, also

the zinc and magnesium in the leaves of rice, but this effect

did not result in yield and grain quality. Results also suggest

that the use of pesticides positively influenced weight and

paddy yield (p ≤ 0.05).

Keywords: Oryza sativa, soil acidity, silicon applied to soil, zinc in rice leaves.