Extração e determinação de Mo em três argissolos do nordeste cultivados com cana-de-açúcar.

Abstract

The Mo is a micronutrient essential important to the development of plants. This element is found in the soil in small quantities. In the anion adsorption processes MoO4 2- is connected to Fe oxides and hydroxides and Al, interfering with the availability of Mo no soil, as well as quantity and quality , organic matter, interaction with other nutrients and the source material. The Mo is important for plant systems therefore participates in the activity of nitrate reductase in plants, and of nitrogenase in diazotrophic bacteria. Therefore, this work had as objectives: adapting a more operational methodology for extraction and determination of Mo in different soils; using 4 extractors as chemical Mehlich 1, Mehlich-3, ammonium acetate and hot water to assess the levels of Mo recovered in 3 different soil types in the Northeast region, and correlate the contents of recovered by different extractors used Mo with Mo certain levels in plants of sugar cane. According to adaptations in existing methodology, which accounted for 4 assessment of reaction times (KI + H2O2), read in colorimeter in 2 wave length: 350 and 420 nm. Thus, it is suggested to increase the contact time reagents of work up to 120 minutes, this reading is performed with wavelength of 420 nm.Treatments evaluated the Mo recovered according to the applied consisted of 5 doses of Mo applied on the soil types 3 and 4 repetitions. We analyzed the Mo recovered in function of the applied using the average method and reaction of KIH2O2 with wavelength of 350 nm, without reaction time of 10 minutes after the addition of the reagents. There was a maximum capacity of adsorption (CMAMo) higher in clay soils and weathered in method for determining proficiency of Mo in soils with clay levels above 200 g kg-1. Obtained a descending sequence of extraction: ammonium acetate, Melhich-3, Melhich-1, Water hot; ammonium acetate was more efficient in extracting Mo in clay soils and the best correlated contents of Mo in the plant.