Calibration of soil and plant silicon analysis for rice production

Calibration of field crop response to nutrient availability is the bases fo r making a fertilizer recommendation from soil and tissue analyses. The pur pose of this study was to evaluate and summarize results from a series of e xperiments on silicon (Si) fertilization of rice in the Everglades Agricult ure Area. Twenty-eight rice field experiments were conducted from 1992 thro ugh 1996. The experiments consisted of 2 to 5 rates of calcium silicate app lied to soils (HistosoIs) of varying Si soil-test values. Soil samples were taken before planting and analyzed for acetic acid (0.5 mol L-1), extracta ble Si. Straw samples were collected at harvest and analyzed for total Si. Grain yield was determined. The "critical" levels for Si in the soil (point below which response to Si fertilizer is expected) calculated by the Gate & Nelson procedure was 19 mg Si L-1 soil. The amount of silicon to correct Si deficiency in the soil and to obtain optimum rice yield was 1500, 1120 a nd 0 kg ha(-1) for low (<6 mg L-1), medium (6 to 24 mg L-1), and high (> 24 mg L-1) level of soil Si, respectively. Silicon in the straw was classifie d as high when Si concentration was > 34 g kg(-1), medium when in between 1 7 and 34, and low when < 17g kg(-1) (3.4 and 1.7%, respectively).