Recycling of leather waste industry as phosphorous based fertilizers

In a context of sustainable agriculture, the use of leather waste as fertilizer is part of the concept of the circular economy, which is being promoted by the European Union to enhance the reuse and recycling of materials. Leather industries produce a large amount of waste products that, if treated with the eco-friendly vegetable tanning method (Cr (VI) free), can be used as organic fertilizers as they are rich in organic N and C compared to manure and compost. We studied the agronomic performances of a fertilizer (Vegetable Tanned Leather Waste-VTLW) obtained by hydrolysing vegetable tanned leather scrap with sulphuric acid and then solidified by adding natural soft rock phosphate. Performance of VTLW was evaluated against other mineral, organic and inorganic fertilizers in pot experiment on six vegetable crops: brown-mustard (Brassica oleracea L.), chick pea (Cicer arietinum L.), chicory (Cichorium intybus L.), pea (Pisum sativum L.), tomato (Solanum Licopersicum L.), fava bean (Vicia faba L.). Periodically, morphological data were measured with the aim of monitoring the development of the plants. At the end of the crop cycle production, yield was determined. This study showed that VTLW fertilizer enabled good plant growth and production and a slow release of nutrients with a positive effect on soil chemical properties. The results suggest that VTLW could be used as organic fertilizer in agricultural systems to assist with sustaining healthy soils. This research was supported by the project “AgrinMec - Produzione di fertilizzante per AGRicoltura biologica: automazione del ciclo tramite Innovative parti MECcaniche” and was co-financed under Tuscany ERDF ROP 2014 - 2020 - POR-CReO FESR 2014 – 2020 RD&I Call 2.