Caracterização física, química e microbiológica de compostagem enriquecida com pó de rocha silicatada e avaliação da utilização do composto orgânico na cultura do arroz (Oryza sativa)

Abstract

Mineral enrichment is an alternative that can favor the higher nutritional quality of organic compounds, by increasing the content of nutrients present, as well as making them more readily bioavailable for crops. This can be done by incorporating low-cost materials such as silicate rock powder, which has beneficial effects for cultures capable of bioaccumulating silicon in their tissues, such as rice. This cereal has great importance for food security, since more than half of the world population has in it their primary source of calories and the main disease that affects this crop is Rice-Blast, caused by the fungus Pyricularia oryzae. Therefore, the objective of the present work was to evaluate the dynamics of the total contents of macronutrients and silicon in two compost heaps with and without addition of magnesium silicate, and characterize physical, chemical and microbiological parameters along with the enzymatic dynamics throughout of the process. The impact of the application of these bioproducts on the productivity of cultivars BRS Esmeralda and BRS Caçula under field conditions was also evaluated. In addition, the isolation and characterization of bacteria from the obtained organic compounds regarding their ability to antagonize Pyricularia oryzae was also carried out. As general results, the Carbon/Nitrogen ratio decreased at the end of composting for both treatments, and the nutrient, pH and humic substances content increased. Amylase activity was higher in the initial stages of composting, while cellulase activity was more pronounced at the end of the process. The incorporation of magnesium silicate did not change the bacterial community profile, nor did it significantly interfere in the dynamics of the analyzed physical and chemical parameters, except for the element magnesium. Temperature was the factor that most influenced the way the microbial communities were organized along the composting, with the most abundant phylum in both treatments being Firmicutes, followed by Proteobcteria, Actinobacteria and Bacteriodetes. Seven bacterial isolates of organic compounds (BAC 8, BAC 9, BAC 10, BAC 11, S8, S13 and 5.1) demonstrated a percentage of inhibition above 50% against Pirycularia orizae. Fertilization via organic compost with silicate enabled an increase in the productivity of the cultivar BRS Caçula, totaling 41.6 sc/ha, compared to 37.7 sc/ha in the control treatment with chemical fertilization.