Circular economy in coffee waste management and its effects on the soil-plant system
carbon sequestration; greenhouse effect; soil quality
The increase in the generation of agricultural, industrial, and domestic solid waste is a global problem that significantly contributes to environmental pollution. The coffee industry generates large volumes of waste which, if not properly treated, can cause serious environmental impacts. Transitioning to a circular economy approach is crucial for developing sustainable solutions that make coffee production cleaner, maximizing the reuse, recycling, and recovery of resources throughout the production cycle. Methods such as composting, Bokashi use, and biochar transformation are examples of how these wastes can be valorized to improve soil fertility and reduce environmental pollution. The objective of this study was to compare the conditioning effect of products from different processes of transforming coffee industry organic waste on soil fertility and health. The experiment was conducted on two properties in Santo Antônio do Amparo, Minas Gerais, during the 2021/2022 and 2022/2023 agricultural years. Experimental area 1, located on a 2,000-hectare property with fully mechanized management, used the Acaiá variety. Experimental area 2, on a 30-hectare property with semi-mechanized management, used the Mundo Novo variety. The evaluated treatments were: coffee husk, organic compost, Bokashi, biochar (coffee husk and wood), COMBI (compost + biochar), organomineral, and conventional fertilizer. The experiment was conducted in a randomized block design with four replications. Soil analyses, biological soil indicators, and analyses of income, yield, and coffee productivity were performed. In area 1, there was a significant effect on pH, Ca, Mg, V%, organic matter, remaining P, H+Al, and CEC pH 7.0. In area 2, the significant effects were on P, K, Mg, V%, organic matter, remaining P, H+Al, and CEC pH 7.0. Biological indicators responded to the application of soil conditioners, showing significant effects on microbial biomass carbon, basal respiration, β-glucosidase, acid phosphatase, and urease.