Solubilidade do silício em solos: influência do calcário e ácido silícico aplicados

Abstract

) RESUMOO silício tem sido muito utilizado na agricultura brasileira, especialmente após sua inclusão na legislação de fertilizantes e corretivos. Poucos são os estudos, no entanto, sobre sua solubilidade em solos tropicais, que é importante para sua utilização. Foi avaliado silício solúvel de solos de cerrado muito argilosos (LVd, LVAd, NVef), de textura média (PVAe, LVd, LVAd) e arenoso (RQo) incubados com calcário (0, 2, 4 e 6 Mg ha -1 ) e ácido silícico (0 e 400 mg kgSi) e quatro repetições. As amostras dos solos foram secas, passadas em peneira ABNT 50 (0.297 mm) acondicionadas em potes (250 g) com os tratamentos e incubados por 90 dias (80 % da capacidade de campo). O ácido acético 0,5 mol L -1 (AA) extraiu mais silício em relação à água (A) e CaCl 2 0,01 mol L -1 (CC). Os teores de Si foram maiores nos solos muito argilosos seguidos daqueles de textura média e arenoso e maiores no horizonte B que no horizonte A dos latossolos. Houve efeito apenas das doses de calcário que reduziram a acidez potencial, aumentaram o pH (CaCl 2 ) e os teores de Ca e silício extraível em AA para todos os solos. Houve aumento nos teres de silício extraível por CC e A nos solos de textura média e arenoso e diminuição nos solos muito argilosos por efeito da calagem. Verifica-se a necessidade de estudos com plantas para seleção de extratores adequados para avaliar a disponibilidade de silício, especialmente em solos oxídicos, onde o aumento de pH tem efeito negativo sobre a solubilidade de silício.Palavras-chave: extratores, pH, ácido acético, cloreto de cálcio. ABSTRACT SOLUBILITY OF SILICON IN SOILS: EFFECT OF LIME AND SILICIC ACID APPLIEDSilicon has been utilized in brazilian agriculture, specially after its inclusion in regulations concerning fertilizers. However, there are few studies on Si solubility in tropical soils, which is important for silicate fertilization. Soluble silicon was evaluated in clayey (LVd, LVAd, NVef), loamy (PVAe, LVd, LVAd) and sandy soils (RQo) treated with lime (0, 2, 4 e 6 Mg ha -1 ) and silicic acid (0 e 400 mg kg -1 ), with 4 replications. The soil samples were dried and passed through sieve (50 mesh), placed in pots (250 g) with the treatments and incubated during 90 days (80 % of holding moisture capacity). The 0.5 mol L -1 acetic acid (AA) extracted more silicon than water (A) and 0.01 mol L -1 CaCl 2 (CC). Si contents were higher in clayey than in loamy and sandy soils and B horizon had more silicon than A horizon in latosols. There was effect of lime decreasing potencial acidity and increasing pH(CaCl 2 ), Ca, and AA extractable silicon contents in all soils. CC and A extractable Si increased in loamy and sandy soils and decreased clayey soils. Studies with plants to determinate suitable extractants for available Si are needed, especially in oxidic soils, where increasing pH decreases Si solubility.

Silicon fertilization improve yield and quality of rice and pearl millet in cerrado soils

“…Soluble Si content was greater in LV than in RQ (Figures 1 and 2), and was classified as medium and low, respectively (KORNDÖRFER et al, 2001). Higher values for the loamy sandy soil make sense given its higher clay content which is a source of soluble Si, in agreement with Raij;Camargo (1973), Camargo et al, (2007a), Camargo et al (2007b), and Pereira et al(2010).…”

“…These results confirm that the materials were reactive, given that Si was available for rice and pearl millet since sowing. Silicic acid was not reactive due to its low solubility, which was confirmed by Benedito (2004) and Camargo et al(2007a). Soluble Si content was greater in LV than in RQ (Figures 1 and 2), and was classified as medium and low, respectively (KORNDÖRFER et al, 2001).…”

“…However, they focused on the evaluation of the acidity correction and Ca, Mg, and Si supply under field conditions (BARBOSA FILHO et al, 2001;KORNDÖRFER et al,2001;CARVALHO-PUPPATTO et al,2003) and pots (PEREIRA et al,2004;KORNDORFER et al, 1999;CAMARGO et al, 2007b) and only a few studies (RAMOS et al, 2008) have evaluated the benefits of Si supply for the rice crops on its uptake, yield and quality without the additional effects (increasing on pH and Ca and Mg content in soils) of silicate applied in tropical soils. The Ca and Mg levels in soil had to be used in the same quantities when different silicate rates were applied in soil, as already done in incubation studies of Si sources and rates (CAMARGO et al, 2007a;PEREIRA et al, , 2010.…”

Application of silicon sources in yam (Dioscorea spp.) micropropagation

“…Si indirectly increases photosynthetic capacity, decreases transpiration, and improves mechanical resistance of the cell (Camargo et al, 2007). Additionally, Si produces more erect plants, increases pest resistance, decreases toxic effects of B, Mn, and Fe, among other elements, and increases nutrient absorption and metabolism (Lana et al, 2003;Gunes et al, 2007).…”

Fontes de silício na micropropagação de orquídea do grupo Cattleya

“…Essas espécies podem ser propagadas tanto por meio de sementes como vegetativamente, e se utiliza a cultura de tecidos para a obtenção de grande quantidade de mudas em curto espaço de tempo e esta técnica tem sido utilizada para estudos de propagação in vitro, fitopatologia e nutrição mineral (SOARES et al, 2008 (CAMARGO et al, 2007). A sílica solúvel tem sido pouco estudada, principalmente pelo fato do silício não ser elemento essencial às plantas.…”