Hydrogels as water and nutrient reservoirs in agricultural soil: a comprehensive review of classification, performance, and economic advantages

Rational Design of a Multifunctional Hydrogel Trap for Water and Fertilizer Capture: A Review

“…Furthermore, the water absorption capacity of hydrogels increases proportionally with the number of hydrophilic groups. 96 Zhou et al 97 synthesized a superabsorbent hydrogel by incorporating carboxycellulose nanofibers (CCNFs) into carboxymethyl cellulose-g-poly-(acrylate-acrylamide), resulting in a remarkable enhancement of the hydrogel swelling rate due to the abundant presence of hydrophilic carboxylic acid groups on the surface of CCNFs. After incorporating 2.5 wt % of CCNFs, the swelling rate of the material in distilled water increased from 245.8 to 458.7 g/g.…”

“…91 The absorption of fertilizers into a hydrogel primarily occurs through two mechanisms: hydrophilic group adsorption and swelling absorption. 96 On one hand, hydrogels possess numerous hydrophilic functional groups, such as −OH, −COOH, and amine groups, which can effectively retain and adsorb K + , NH 4 + , NO 3 − , H 2 PO 4 − and other cations/ anions in soil through mechanisms like electrostatic attraction and van der Waals force. Additionally, they also exhibit a certain fixation effect on small organic molecules like urea.…”

“…The swelling absorption properties of hydrogels enable the capture and gradual release of K in soil. 96 The impact of poly(acrylic acid) hydrogel on K release behavior in soil was investigated by Wu et al, 139 who observed a significant reduction in the release rate compared to soil without hydrogel. Specifically, after 10 days, the residual amount of K in the soil increased nearly twice.…”

“…In terms of fertilizer retention, hydrogels can enhance the fixation of fertilizers in the soil through absorption by hydrophilic groups and swelling, thereby reducing fertilizer loss and improving soil's capacity to retain fertilizers. 96 Zhao et al 142 investigated the impact of hydrogel on nutrient retention characteristics in saline soils within the Yellow River Basin in China. They discovered that compared to soils without hydrogel, those with added hydrogel exhibited a decrease in leaching rates for nitrogen (49.2−65.0%), phosphorus (52.62− 68.1%), and potassium (15.2−63.8%).…”

An Overview of Polymeric Hydrogel Applications for Sustainable Agriculture

“…The consideration of these environmental issues (i.e., the biodegradability of polymeric waste and the long-term impact of the hydrogel on the soil ecosystem) is a critical point for the widespread use of hydrogel films. To this end, researchers are exploring hydrogels based on natural biopolymers, which are advantageous due to their biodegradability, minimizing negative environmental impacts [126,127].…”