Evaluation of soil test procedures for determining rice-available silicon

Document Type

Article

Publication Date

1-1-2001

Abstract

Soil testing for silicon (Si) in the predominantly organic soils of the Everglades Agricultural Area has not been sufficiently investigated. The objective of this study was to identify a suitable Si extraction method for these soils for rice (Oryza sativa L.). Twenty-two surface soil samples were collected from 10 farms. Of these 22, 10 samples were from fields that had received Si fertilization at some time in the past, and 12 were from fields that had not received Si fertilization. Rice was grown for 80 days in each soil in the greenhouse. Subsequently, the straw and immature panicles were harvested, dried, weighed, and analyzed for Si. In the laboratory, seven different methods were used for extracting Si from the soils. The methods were: (1) 0.5 M acetic acid extract, 10:25 (soil:extract, v/v ratio), (2) citric acid 1%, 1:10, (3) demineralized water, 1:10, (4) TRIS buffer pH 7.0, 1:10, (5) water-bath shaking (Batch method) 1:10 v/v ratio plus cation exchange resin (Amberlite IRC-50 H type), (6) soil incubated with water for 1 week at 40°C, 1:6 (Incubation method), and (7) soil incubated with water for 4 weeks at 30°C, 1:4 (Extended Incubation method). The concentration of dissolved Si in soil extracts from all methods was determined colorimetrically. Soil Si values were correlated with straw Si and panicle Si content. Among the methods studied, extraction with 0.5 M acetic acid appeared most suitable for evaluating Si availability, followed by extraction with citric acid at 1%. These methods provided the best correlations with rice straw and panicle Si percentage (r2 = 0.899***, r2 = 0.768***, and r2 = 0.839***, r2 = 0.774***, respectively). These methods, being rapid and effective in extracting Si in comparison to other methods, appear to be the most suitable for routine soil testing for Si in the Everglades Agricultural Area in South Florida.

Publication Source (Journal or Book title)

Communications in Soil Science and Plant Analysis

First Page

1779

Last Page

1792

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