Humic-like Substances Extracted from Hydrochar as an Additive for Foliar Fertilization in Tomato Plants.

Area of Science:

• Agricultural Science
• Biotechnology
• Environmental Science

Background:

• Biomass reuse and advanced fertilization are key to boosting agricultural output.
• Humic-like substances (HLS), derived from hydrochars, offer rich organic compounds and nutrient complexation beneficial for plant stimulation.
• Limited research exists on HLS application as a foliar fertilizer.

Purpose of the Study:

• To extract and characterize HLS from sugar cane bagasse and vinasse hydrochars.
• To evaluate the efficacy of HLS as a foliar fertilizer on tomato plants (Solanum lycopersicum L.).
• To assess the impact of HLS on plant growth, chlorophyll content, and root development.

Main Methods:

• HLS were extracted from hydrochars using additive H3PO4 (HLS_A) and KOH (HLS_B).
• HLS were applied via foliar spray at varying concentrations (50, 100, 300 mg TOC L-1) with and without fertilizer.
• Plant growth, chlorophyll index, and root micromorphology were monitored over 35 days.

Main Results:

• HLS_A (100 mg TOC L-1) with fertilizer increased shoot length, dry biomass, and chlorophyll by 18%, 20%, and 13.9%, respectively.
• HLS_B (300 mg TOC L-1) enhanced shoot length (17.4%), dry biomass (15%), and chlorophyll index (28.2%).
• HLS_B also significantly increased root length and dry weight by 25%, with no observed cellular damage.

Conclusions:

• Both HLS demonstrated intrinsic plant-growth-stimulating effects, validating their use as foliar fertilizers.
• HLS derived from sugar-energy industry residues represent a sustainable approach to enhance crop productivity.
• The study supports the reuse of industrial biomass residues for agricultural applications.