Extração do Si e efeitos da fertilização silicatada na cana-de-açúcar, cultivada em solo arenoso

Abstract

Sugarcane is a crop of economic importance in Brazil, and adequate fertilization is indispensable to obtain expected yields. Si plays a key role in the development of this culture and is absorbed in large quantities. The efficient evaluation of Si availability to the plants is fundamental to adjust the recommendations of silicate fertilization. The objective of this work was to determine the efficiency of 4 extractors (acetic acid 0.5 mol L -1, CaCl2 0.01 mol L -1, KCl 1 mol L -1 and distilled water) in the evaluation of Si availability in soil, besides evaluating the effect of diatomite fertilization on soil chemical characteristics, the nutrition, productivity and technological characteristics of sugarcane. For that, samples of soils and diagnostic leaves were collected in different areas of sugarcane cultivation between the states of Pernambuco and Paraíba. The levels of Si were determined on each extractor and on the leaf. Subsequently, a greenhouse experiment was carried out using a Arenosol, which was submitted to Si doses (0, 75, 150, 225, 300 and 375 kg ha-1) in the form of a diatomite granulated fertilizer. The chemical characteristics of the soil, biomass and nutrient accumulation and Si in the plant were evaluated. Another experiment was carried out in a field of sugarcane cultivation in the State of Paraíba, under a Arenosol. In this work, diatomite doses were applied (0, 125, 250, 500 and 750 kg ha-1) in the annual crop cultivation. The results showed that acetic acid extracted larger amounts of available Si, but CaCl2 was the one that obtained better correlations with Si absorbed by the plant for the majority of evaluated soils. There was a positive correlation between sugarcane biomass and Si accumulation. Silicate fertilization increased the availability of P, K, Mn and Cu in the soil. The uptake of Si increased the N, P, S, Mn and Zn contents in the aerial part of the sugarcane. The application of diatomite in field cultivation increased the biometric characteristics, the absorption of macro and micronutrients and significantly reduced the damage caused by the sugarcane borer (Diatraea saccharalis). These results were decisive for the significant increase in productivity and technological characteristics of sugarcane. Therefore, the integration of an efficient methodology for the evaluation of Si available in soil associated with the management of the fertilization of sugarcane with silicon can be a viable alternative to obtain higher yields for sugarcane cultivated in sandy soils.