Eco‐friendly three‐dimensional hydrogels for sustainable agricultural applications: Current and future scenarios

Abstract

Modern world is searching for water efficient agriculture techniques as irrigation is becoming scarce. Limited water resources and more food demand are the two key challenges in agriculture. Hydrogels which can respond intelligently by pH, temperature, light, ionic strength, osmotic pressure, magnetic or electric field changes are termed as intelligent or smart hydrogels which are analogous to conventional hydrogels in preparatory methods and features. Lag phase, constant release and decay phase are three steps involved in release of nutrients from polymeric hydrogels. In fact, hydrogels act as little reservoirs of water and dissolve nutrients that are released in controlled manner anchored by plant roots via capillary action. Hydrogels also sustain optimum amount of water in water stress conditions and reabsorb water in moist conditions which ultimately increases seedling, seed germination, plant growth and crop yield. Fertilizer and salt release are majorly dependent upon pH and temperature followed by diffusion‐controlled mechanism. Cross‐linkers, binders and fillers play pivotal role in determining properties, architecture and hydrogel pores. In comparison to potassium (K+) and phosphate (PO4−3) ions, nitrates (NO3−1) and ammonium (NH4+1) ions exhibited faster release rate. This review spotlights application prospects of three dimensional hydrogel in agriculture. Initially, properties of hydrogels, their classification, preparatory methods, effect of natural‐synthetic‐polymer blending and role of fillers are stated. Afterward, hydrogel functioning, significance, advantages, mechanism of fertilizer release and agriculture specific applications of hydrogels are comprehensively described. In conclusion, extraordinary biocompatible, cheaper, stable, biodegradable, durable, non‐toxic and re‐wettable characteristics of hydrogel systems motivated their utilization in agronomical applications.

Assessment of energy cane bagasse-derived cellulosic microfiber hydrogels on the growth of potted chili peppers

“…Sasmal and Patra (2020) [ 41 ] reported that the quantity of water retained in the soil increased significantly with CMH inclusion, resulting in controlled water release under dry conditions. This observation aligns with Azeem et al (2023) [ 42 ], who attributed plant growth to CMH's effective water retention and gradual release capabilities, ensuring a consistent and controlled moisture supply to plant roots. Similarly, Prisa and Guerrini (2022) [ 43 ] reported increased Solanum lycopersicum plant height, vegetative growth, seed germination, and microbial colonization of the substrate with two or three hydrogel (Hydro Start) capsules under drip irrigation.…”

Polymer Composites in 3D/4D Printing: Materials, Advances, and Prospects

“…Smart hydrogel composites, with their ability to swell upon water immersion while maintaining structural integrity, hold significant promise as smart materials. Their applications span diverse fields, from biomedicine including drug delivery devices [ 89 ], artificial organs, and tissue engineering [ 19 , 90 ], to agriculture [ 91 , 92 ]. In 4D printing, these hydrogel composites present an innovative method for various applications such as custom-designed sensors and robotics [ 19 , 85 , 86 ].…”

Functional Hydrogels for Agricultural Application

“…Smart hydrogels for agricultural applications were recently developed and investigated [14,15]. Obtained results and characteristics were described in several reviews [16][17][18][19]. Zhang et al [14] developed new multifunctional smart soils with double-layer structures consisting of zwitterionic, thermo-responsive poly(NIPAM-co-VPES), and poly(NIPAM-co-SBAA) aerogels doped in the upper layer and the bottom bed of the soils, respectively.…”

“…Another review encompassed the latest developments in the field of smart hydrogel synthesis based on their unique features and different aspects of their responsive behaviors was published by Sikdar et al [17]. Azeem et al [18] published the review that spotlighted application prospects of three-dimensional hydrogel in agriculture. Hydrogel functioning, significance, advantages, mechanism of fertilizer release, and agriculture-specific applications were comprehensively described.…”