Hydrochars Derived from Spent Coffee Grounds as Zn Bio-Chelates for Agronomic Biofortification
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AuthorLara-Ramos, Leslie; Cervera Mata, Ana Gloria; Fernández Bayo, Jesús Dionisio; Navarro Alarcón, Miguel; Delgado Calvo-Flores, Gabriel; Fernández Arteaga, Alejandro
Hydrothermal carbonizationMicronutrientsBio-chelatesHidden hungerAgricultural soilSpent coffee groundsBiofortification
Lara-Ramos, L.; Cervera-Mata, A.; Fernández-Bayo, J.; Navarro-Alarcón, M.; Delgado, G.; Fernández-Arteaga, A. Hydrochars Derived from Spent Coffee Grounds as Zn Bio-Chelates for Agronomic Biofortification. Sustainability 2023, 15, 10700. [https://doi.org/10.3390/ su151310700]
SponsorshipPY20_00585 from FEDER and RDPTC-2018 (AT17_6096_OTRI UGR) from the Andalusia n Ministry of Economic Transformation, Knowledge, Industry and Universities.
Previous studies have attributed both phytotoxicity and the capacity to mobilize nutrient elements to the presence of polyphenols and melanoidins in spent coffee grounds (SCG) and SCG-hydrochars obtained through hydrothermal carbonization (HTC). This work aimed to evaluate SCG and two SCG-hydrochars obtained at 160 and 200 °C that were functionalized with Zn salts (bio-chelates), to achieve the in vitro biofortification of lettuce. Two application modes were established: (1) a fixed Zn concentration of 10 mg kg−1 of soil and (2) a fixed dose of 0.5% bio-product. Soil alone (control A) and commercial chelates (control B) were used as controls. Outcomes showed that SCG-hydrochars retain the capacity to mobilize Zn compared to SCG. However, the chelating capacity was reduced (Zn: 94%) and the toxicity was significantly increased (p < 0.05) with higher temperatures of HTC (200 °C). Both fresh and dry lettuce weights were less affected at doses of 0.5% of bio-product and registered a maximum increase of 136% of Zn in the plant content. The present study approaches the possibility of using these by-products as bioinorganic fertilizers at subtoxic doses, although more research is needed