Functional Hydrogels for Agricultural Application.

Area of Science:

• Materials Science
• Soil Science
• Polymer Chemistry

Background:

• Hydrogels are increasingly explored for soil amendment applications due to their water retention capabilities.
• Optimizing hydrogel composition is crucial for enhancing soil properties and fertilizer delivery.
• Understanding the stability of hydrogels under environmental stresses like drying, re-swelling, and freezing is vital for practical use.

Purpose of the Study:

• To characterize ten different hydrogels formulated with varying amounts of NPK mineral fertilizer and lignohumate.
• To evaluate the stability and utility properties of these hydrogels for soil applications, focusing on drying/re-swelling cycles and freezing.
• To assess the impact of lignohumate and NPK on hydrogel swelling, morphology, and rheological behavior.

Main Methods:

• Preparation and characterization of ten distinct hydrogel formulations.
• Analysis using Fourier Transform Infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) for morphology, swelling tests, and rheological property measurements.
• Assessment of hydrogel stability through repeated drying/re-swelling cycles and freeze-thaw cycles.

Main Results:

• Lignohumate addition enhanced water absorbency, while NPK fertilizer negatively impacted it and decreased pore sizes.
• Lignohumate created a more heterogeneous porous structure, whereas NPK increased the elastic character of the hydrogels.
• Hydrogels containing only NPK or lignohumate exhibited the highest stability; repeated cycles and freezing generally increased elastic character due to fertilizer release, with exceptions for high-NPK samples without lignohumate.

Conclusions:

• Hydrogel formulations require careful balancing of lignohumate and NPK for optimal soil application performance.
• Lignohumate positively influences water retention and structural diversity, while NPK affects mechanical properties and pore structure.
• Single-component fertilizer hydrogels demonstrate superior stability under repeated environmental stress compared to combined formulations.