Abstract
Based on the assumption that silicate application can raise soil P availability for crops, the aim of this research was to compare the effect of silicate application on soil P desorption with that of liming, in evaluations based on two extractors and plant growth. The experiment was carried out in randomized blocks with four replications, in a 3 × 3 × 5 factorial design, in which three soil types, three P rates, and four soil acidity correctives were evaluated in 180 experimental plots. Trials were performed in a greenhouse using corn plants in 20-dm³ pots. Three P rates (0, 50 and 150 mg dm-3) were applied in the form of powder triple superphosphate and the soil was incubated for 90 days. After this period, soil samples were collected for routine chemical analysis and P content determination by the extraction methods resin, Mehlich-1 and remaining P. Based on the results, acidity correctives were applied at rates calculated for base saturation increased to 70 %, with subsequent incubation for 60 more days, when P content was determined again. The acidity correctives consisted of: dolomitic lime, steelmaking slag, ladle furnace slag, and wollastonite. Therefore, our results showed that slags raised the soil P content more than lime, suggesting a positive correlation between P and Si in soil. Silicon did not affect the extractor choice since both Mehlich-1 and resin had the same behavior regarding extracted P when silicon was applied to the soil. For all evaluated plant parameters, there was significant interaction between P rates and correctives; highest values were obtained with silicate.
Highlights
The reaction of phosphate ion adsorption to soil colloids is directly related to the reaction conditions of soil, since with a rise of pH the solubility of iron and aluminum phosphates is increased with reduction of phosphate anion adsorption to the soil solid phase
The lime and ladle furnace slag had a similar behavior, which can be explained by the similarity in reactivity and RPTN of these products
The same was not true for steelmaking slag, which had lower pH values than the other correctives; this fact can be explained by the larger grain size and, the longer time required for reaction (Table 3)
Summary
The reaction of phosphate ion adsorption to soil colloids is directly related to the reaction conditions of soil, since with a rise of pH the solubility of iron and aluminum phosphates is increased with reduction of phosphate anion adsorption to the soil solid phase. The extractor Mehlich-1, widely used in routine laboratory analyses across the country, may overestimate available P contents in soils treated with rock phosphate, or in situations where inorganic CaP contents are higher due to low weathering (Novelino et al, 1985). This extractor may underestimate available P in soils with high clay content, due to the resulting extractor wear (Novais & Kamprath, 1979, Muniz et al, 1987). The resin method is questionable due to the likely underestimation of labile
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
