# Novel Polysaccharide Hydrogels Enriched with Humic Acid for Sustainable Agricultural Applications

## TL;DR

This paper introduces a new type of biodegradable hydrogel enriched with humic acid to improve soil moisture and plant growth in agriculture.

## Contribution

The novel contribution is the development of sustainable, HA-enriched hydrogels using gellan gum and karaya gum for agricultural use.

## Key findings

- GG/HA and GG/KG/HA hydrogels retained more soil moisture than commercial polyacrylate hydrogels.
- The hydrogels showed no phytotoxicity and even promoted plant growth in wheat cultivation trials.
- The biopolymer hydrogels biodegraded significantly after 30 days in soil extract.

## Abstract

This study deals with the development of humic acid (HA)-enriched
hydrogels aimed at enhancing water retention and promoting plant growth
for agricultural applications. A set of hydrogels based on spermidine
(SPD)-ionotropically cross-linked gellan gum (GG) were formulated
with and without the addition of karaya gum (KG). The hydrogels were
structurally characterized by Fourier transform infrared spectroscopy,
thermogravimetric analysis, mechanical assays, scanning electron microscopy,
and swelling kinetic measurements. Water retention tests indicated
that both GG/HA and GG/KG/HA hydrogels preserve higher soil moisture
levels compared to commercial polyacrylate hydrogels. Biodegradation
studies showed that the biopolymer hydrogels lost more than one-third
of their weight after 30 days of immersion in a soil aqueous extract.
Both GG/HA and GG/KG/HA hydrogels exhibited no phytotoxicity on cultivation
trials of Triticum aestivum L. var.
Borlaug 100, but the plant growth was promoted with the GG/KG/HA network
compared to GG/HA sample. The overall results support the potential
use of GG/KG-based hydrogels enriched with HA as sustainable materials
for improving soil quality and crop productivity in agricultural systems.