Hydrogel materials in agriculture: A review

Abstract

Hydrogel, as a typical representative of functional materials, constructs a three-dimensional network structure through physical or chemical cross-linking of hydrophilic polymer chains, which are rich in hydrophilic groups such as hydroxyl (-OH), carboxyl (-COOH), and amino (-NH₂) on the molecular chain and exhibit excellent high water absorption (water absorption multiplication rate of 10–20 times and up to more than 500 times after nanocomposite modification). Studies have shown that the modified hydrogel removes more than 95 % of heavy metal ions (e.g., Pb^2⁺, Cr^3⁺) and possesses pH and temperature responsive swelling behavior. In response to the pressing problems faced by global agriculture, such as water scarcity, low fertilizer utilization, and soil heavy metal pollution, hydrogels show great potential for application in precision controlled release of fertilizers, water and moisture conservation, and pollution remediation. In this paper, we systematically review the performance characteristics of hydrogel, optimization strategies, and preparation methods, focusing on its innovative applications in agriculture and mechanistic role based on the environmental response mechanism to achieve the synergistic management of nutrients, water, and pollutants, which provides significant technological support for the development of sustainable agriculture.