Efeitos da aplicação de manipueira nos atributos de um solo e na produção de alface Lactuca sativa L

Abstract

The cassava (Manihot esculenta Crantz) crop is an important economic activity nationally and globally. Industrial processing of its various products are obtained, between the starch and flour table, which generates a residual effluent of industrial processing of cassava, the called cassava wastewater. This effluent has high organic load and high concentration of nutrients, so if applied at high doses in the soil can contaminate ground water bringing serious damage to the environment. The objective of this study was to evaluate changes in physical and chemical characteristics of soil treated with cassava wastewater and the phenological characteristics of lettuce. The experiment was conducted in a greenhouse in a completely randomized design with six treatments composed of the following doses: 0, 5, 15, 25, 45, 65 m3 ha-1 and four replicates. We used the lettuce cultivar Regina 2000, offering one plant per pot of 4 L. To achieve the proposed objective, were determined as a function of the applied doses, the following parameters: flocculation, water dispersible clay, electrical conductivity of saturation extract of soil, pH and concentration of P, Na, K, Ca and Mg and soil, leaf area, plant height, leaf number, fresh and dry lettuce. At the end of the experiment it was found that the dose of 45 m3 ha-1 was the one that provided the largest gain in plant height, leaf area and, consequently, also increased production of fresh and dry. Moreover, in general, it was observed that the incorporation of manipueira soil caused a significant increase in all studied variables, primarily the pH and the cations and anions of the soil, however was not observed risk of salinization or the sodification soil. Thus, the use of cassava wastewater served as the source of fertilizers for the cultivation of lettuce, depending on the applied dose.