The agricultural farming activities generate organic waste whose indiscriminate deposition can be prejudicial to the environment. However, careful application of these wastes as organic fertilizers it is a possibility to improve soil fertility. This study aimed to confirm the hypotheses that organic wastes produced in various production chains in the semi-arid region of Ceará have contents of nutrients that give them potential as organic fertilizers and, since they are used as organic fertilizers, these residues improve the chemical soil attributes. Nutrient contents were determined at the laboratory and then the wastes were placed in decomposition bags and applied in a Fluvic Neosol. Soil samples were collected in the 0-0.10 m layer 90 days after wastes were applied. The residues presented nutrient contents that allow their use as organic fertilizers, except the shrimp farming residue that presented sodium content above that allowed by legislation, resulting also in higher element contents in the soil. In addition, the shrimp farming showed the lowest organic carbon content in relation to others chemical elements. The residues of the poultry industry and the compound made with residues of small ruminants presented the highest of nitrogen and phosphorus levels. The carnauba residue was associated with phosphorus immobilization because it presented C/P ratio higher than 300.

Soil pollution by heavy metals is mainly caused by poor management of tailings generated by mining during exploration and processing of metals. Given the concern about the soil environment, this study aimed to evaluate the tolerance and effectiveness of isolates of rhizobium strains native to soils of Mn2+-mining areas in association with Mimosa caesalpiniaefolia (Benth.) cultivated under increasing concentrations of Mn2+. Isolates of rhizobium strains, obtained from Mn-mining area, were authenticated and morphologically characterized. Effect of Mn2+ on the growth and nodulation of M. caesalpiniaefolia was subsequently evaluated. We obtained 14 isolates which were similar, differing only in the form of colonies. Mn2+ did not inhibit the symbiotic process between isolates and plant species. The isolates from mining area showed higher efficiency than native strains. All isolates are Mn2+-tolerant, and those from mining area can increase the tolerance of M. caesalpiniaefolia to excess Mn2+ in the soil.

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Tolerância e eficiência de rizóbios nativos de área de mineração de manganês no desenvolvimento de Vigna unguiculata L. (Walp.) Tolerance and efficiency of native rhizobia from the manganese mining area in the development of Vigna unguiculata L. (Walp.

IntroduçãoO desmatamento, somado ao cultivo intensivo das terras sem adoção de práticas conservacionistas, resulta no declínio da fertilidade dos solos. A utilização de fertilizantes orgânicos e a adoção de praticas visando aumentar os teores de matéria orgânica no solo são fundamentais na melhoria dessa fertilidade.Com o aumento nos custos dos fertilizantes minerais os crescentes níveis de poluição ambiental, a utilização adequada de resíduos orgânicos é uma alternativa para o suprimento de nutrientes como nitrogênio e fósforo em áreas de agricultura familiar no semiárido brasileiro. A reciclagem de resíduos oriundos das diversas cadeias produtivas, cuja deposição indevida pode causar impactos negativos ao ambiente, apresenta-se como importante alternativa para o uso de fertilizantes orgânicos.Para recuperar solos degradados, uma prática promissora é a adição de resíduos orgânicos que trazem benefícios aos atributos físicos, químicos e biológicos. É importante que seja conhecida a composição desses resíduos, bem como seu potencial de liberação de nutrientes ao solo. No nordeste brasileiro são gerados resíduos como resíduos da agroindústria aviária, resíduo orgânico provenientes da produção e abate de pequenos ruminantes e resíduo da agroindústria processadora de goiabas.O estudo parte da hipótese de que os resíduos anteriormente mencionados apresentam teores