Interação nitrogênio níquel em feijoeiro comum

Abstract

The bean (Phaseolus vulgaris L.) is a crop of great economic importance and nutrition, it has also highlighted the relevance of social perspective in Brazil. Nickel (Ni) is an essential element for plants to be structural component of urease enzyme, whose main function is to allow organizations the use of external urea or generated internally, as a nitrogen (N) source, however, there are few studies on its effect on bean crop. There are no criteria for fertilization with Ni and information is scarce on it is availability in the soil. Understanding the dynamics of phenomena nickel in the soil is important for decision-making on the need to add and to define the dose and application of nickel-enriched fertilizers. Thus, the objective was to determine the response of plants of common beans to N and Ni through soil fraction assessments where Ni is connected in larger quantities before and after cultivation of the common bean , determining the availability of Ni by Mehlich -1 extractor and compare the levels of soluble + exchangeable fraction fractionation before and after the common bean cultivation , the activity of urease enzymes and nitrate reductase according to the N doses and Ni applied and interaction N and Ni by ratio N / Ni. Two soil types were used, collected in depth 0-20 cm, classified as Dystrophic Red Latossol and Entisol Quartzipsamment. We are done two experiments conducted in a completely randomized design with three replications in a 2x5 factorial scheme, two rates of N (50 and 100 mg dm -3 ) and 5 rates of Ni (0, 1, 2, 4, 8 mg dm -3 ) applied in two contrasting, totaling 60 plots. The Ni and N source used was nickel sulfate and urea. Physical and chemical properties of soils influenced the responses of the studied variables. The one with the largest content of Ni available in the soil, providing toxic effect already at a lower level, however, the Dystrophic Red Latossol had this delayed effect by nickel adsorb a greater extent due to its high content of clay and organic matter. The highest activities of urease enzyme and nitrate reductase occur with the highest dose of nitrogen in both soils. The urease activity had small increase in smaller doses in Ni Dystrophic Red Latossol. All the variables analyzed showed higher values at the highest dose of N applied.