Caracterização da manipueira e sua utilização para a produção do coentro 'verdão' e da pimenta 'biquinho'

Abstract

The cassava crop has high socioeconomic and food importance, especially for family-based farmers who use the most of their production for flour manufacture. This activity causes several inconveniences, due to the residues generated during the root processing. The liquid residue, called manipueira, is configured as the main problem of the cassava production chain, due to its high organic load and the presence of environment toxic cyanide acid (HCN). The manipueira composition varies with the root HCN content, cassava cultivar, different growth conditions, processing scales, and extraction methods. In this context, the present work aimed to characterize the manipueira according to the cassava cultivars and the soil cultivation conditions. Then, the potential for its use in the production of 'Verdão' coriander and 'Biquinho' pepper, as a substitute for bovine manure or mineral fertilization, was evaluated. For this purpose, the main cassava cultivars used for flour production by farmers in the municipality of São Felipe, Bahia, Brazil, were selected ('Salangó Preta', 'Cigana', 'Platina', 'Eucalipto', 'Graveto', 'Milagrosa', 'Cidade Rica', and 'Correnteza'), in addition to cultivars developed by Embrapa Cassava & Fruits ('Kiriris', 'Formosa', and 'Poti Branca'). Next, root samples of these cultivars were collected to characterize the manipueira, and, at the same time, soil samples to perform physical and chemical analysis. Subsequently, 'Verdão' coriander and 'Biquinho' pepper were grown to evaluate the promising potential of this effluent in crop yield, in a greenhouse at the Water and Soil Engineering Center of the Federal University of Recôncavo da Bahia, in Cruz das Almas, Bahia, Brazil. The results obtained were submitted to descriptive, univariate, and multivariate statistical analysis. The manipueira attributes of different cassava cultivars showed low and medium variability. High quality manipueira was obtained from the cultivars 'Graveto' and 'Eucalipto'; medium quality from 'Salangó Preta', 'Platina', 'Milagrosa', 'Correnteza', 'Cidade Rica', and 'Formosa'; and low quality from 'Cigana', 'Kiriris', and 'Poti Branca'. Electrical conductivity proved to be a nutritional quality indicator of the manipueira from different origins in the region. High or very high variability of soil chemical attributes occurred in areas of cassava production under different managements. The different cultivation conditions and soil chemical fertility were not determinants of the manipueira quality. The highest yields of 'Verdão' coriander were obtained with the manipueira application together with bovine manure. The application of 45 m3 ha-1 of manipueira, in the presence of bovine manure, provided greater leaf area, fresh mass of the aerial part, and succulence of the 'Verdão' coriander aerial part. The isolated manipueira application, at the dose of 150 m3 ha-1, provided 'Biquinho' pepper productivity equivalent to that obtained with the application of 100 % of the mineral fertilizer recommended for this crop, thus allowing the partial or total replacement of this fertilization by the manipueira.