Biological control of soil-borne phytopathogenic fungi through onion waste composting: implications for circular economy perspective

Abstract

The production of onion waste derived mainly from bulbs affected by fungal diseases, during onion classification and storage presents an important agro-environmental issue in onion production regions. Composting is an environmentally friendly strategy to recycle agricultural waste and produce organic fertilizers. Modifications of the microbial community in soil can affect the ability of pathogen propagules to survive, germinate and infect plant roots. Hence, the main objective of this work was to exploring the mechanisms involved on the presence of three soil-borne phytopathogenic fungi during the composting process of onion waste under the hypothesis if that the resulting compost effectively prevents or minimizes the dispersion of phytopathogenic fungi. To this end, three composting piles of 60 tonnes each were built by layering onion waste affected by phytopathogenic fungi and cow dung at 1:1 ratio. Temperature, moisture, pH, electrical conductivity (EC) and Aspergillus niger, Penicillium sp. and Fusarium sp. growth were monitored for 100 days. During the first 28 days of composting, the presence of phytopathogenic fungi increased significantly showing thereafter a downward trend. Final estimations of fungal populations densities indicated a predominance of A. niger and an effective reduction in the abundance of Fusarium sp. This pilot-scale work demonstrates the feasibility of composting onion waste contaminated with phytopathogenic fungi and highlights the positive environmental impact associated with this practice. Therefore, the composting of onion waste and cow dung is a feasible and sustainable procedure to recycle onion waste and to promote circular economy in onion production regions.

Insights into Circular Horticulture: Knowledge Diffusion, Resource Circulation, One Health Approach, and Greenhouse Technologies

“…Biowastes based on alfalfa, lupine meal, castor cake, tomato, tea, fish, algae, cow horn shavings, and cattle and chicken manure are raw materials that demonstrate their biofertilizer potential for both agricultural production and the maintenance of soil health [34][35][36]. Various works have shown that the enrichment of biowaste with microbial biostimulants, biological controllers, and plant extracts is a promising practice to stabilize certain conditions of the biowaste as well as to improve seedling growth further, mitigate abiotic stress, and control pests [37][38][39]. We identified that studies focused on biowaste management are associated with its conditioning, characterization, and application effect in crop production.…”

Use of Onion Waste as Fuel for the Generation of Bioelectricity

“…It is expected that in 2025, an increase of 88.6-92.8% of waste generated by this vegetable will occur, with the implementation of strategies to minimize contamination due to this product being of vital importance [26]. The accelerated increase in waste affects the environment, emphasising the need to design adequate strategies to minimize the social and environmental impacts on future generations [27]. In general, a 70% increase in the generation of urban solid waste is expected by 2050, which will occur if there are no changes in consumer habits in the process of disposing waste.…”