EXTRACTION OF SILICON IN SOILS FERTILIZED WITH PHOSPHATE AND SILICATE

Abstract

The objective of this study was to evaluate the levels of silicon (Si) extracted by using calcium chloride and acetic acid solutions, in Haplortox soil samples fertilized with phosphate and silicate. The experimental design was completely randomized, in a 5x2 factorial scheme, consisting of five doses of phosphorus (P) (0 mg dm^-3, 96 mg dm^-3, 192 mg dm^-3, 288 mg dm^-3, and 480 mg dm^-3), in the absence and presence of 300 mg dm^-3 of Si. The experimental units were submitted to two incubation periods, the first with silicate (half of the portions) and the second with limestone (remaining of the portions). After incubation, the soil samples received the P doses and were cultivated with corn plants. The Si level in the soil, measured by using extracting solutions, and the Si and P contents in the dry matter of the aerial part were evaluated. Significant effect was observed for Si, phosphate levels, and for the interaction Si x phosphate doses, in relation to the Si content extracted from the soil. The acetic acid solution extracted more Si than the calcium chloride solution, independently of the slag fertilization.

KEY-WORDS: Zea mays L.; slag; phosphorus; extractors.