Agronomic potential of different fermented organic composts based on agro-industrial plant waste

• Published in: Environmental monitoring and assessment 2024-09, Vol.196 (9), p.863, Article 863
• Main Authors: dos Santos Cordeiro, Ana Amélia, de Sousa Antunes, Luiz Fernando, da Costa Rodrigues dos Santos, Giulia, Guerra, José Guilherme Marinho, Berbara, Ricardo Luiz Louro, da Silva Araújo, Ednaldo, Espindola, José Antonio Azevedo
• Format: Article
• Language: English
• Subjects: Agricultural wastes; Agriculture - methods; Ammonium; Ammonium compounds; Ammonium nitrate; Atmospheric Protection/Air Quality Control/Air Pollution; Availability; Beans; Bio-assays; Bioassays; Brazil; Carbon-nitrogen ratio; Composting; Composts; Cost analysis; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Fermentation; Formulations; Greenhouses; Indicator organisms; Indicator species; Industrial plants; Industrial Waste; Inoculation; Mass production; Microorganisms; Monitoring/Environmental Analysis; Nitrates; Nitrogen; Nitrogen - analysis; Organic soils; Passion fruit; Plant tissues; Raw materials; Rice bran; Ricinus communis; Soil - chemistry; Soil characteristics; Soil improvement; Soil microorganisms; Soil mixtures; Sorghum; Sustainable use; Wheat; Wheat bran
• ISSN: 0167-6369; 1573-2959; 1573-2959
• DOI: 10.1007/s10661-024-12983-7

Organic composts such as "bokashi", obtained from the fermentation of bran mixtures and inoculated with microorganisms, improve soil characteristics. In Brazil, the most widely used formulation for the production of this compost is obtained from a mixture of wheat and castor bean bran, but both have a high monetary cost. Replacing these components with regionally available sources represents the possibility of reducing costs and making more sustainable use of this waste. The aim of this study was to analyze the chemical characteristics and determine the availability of nitrogen for the plants. The study was divided into two stages, consisting of an incubation test in the laboratory and a bioassay in the greenhouse using forage sorghum as an indicator species. In the laboratory trial, the treatments consisted of two raw material sources with a low C/N ratio (castor bean bran—CAB and cottonseed bran—COB), corresponding to 40% of the mixture; three sources with a high C/N ratio (wheat bran—WHB or rice bran—RIB), gradually replaced by passion fruit peel bran—PFPB), corresponding to 60% of the mixture. The materials were mixed, moistened, inoculated with microorganisms (Embiotic ® ) and kept in sealed containers with a capacity of 620 cm 3 for 21 days. In the greenhouse, in addition to the aforementioned treatments, seven controls were included: no addition of organic and synthetic N sources; ammonium nitrate; CAB; COB; WHB; RIB and PFPB. In the second stage, dry mass production and N content in sorghum plant tissues were determined, and the rates of N availability were estimated. It was found that the pH of the standard compost was 4.75, and in the other formulations it ranged from 4.62 to 5.3, the highest values being observed when WHB was fully replaced by RIB There was a significant difference in the EC values, but all were well below the value considered adequate. Replacing CAB with COB and WHB with RIB and PFPB resulted in a reduction in N content and an increase in the C:N ratio. Replacing WHB with PFPB led to an increase in K content and a reduction in P and Mg content. In the bioassay, the highest biomass production was in the treatments with the fermented composts, and the highest biological recovery of N was obtained in the ammonium nitrate treatment, followed by the CAB, COB and WHB treatments.