Next Generation NPK Slow Release Hydrogel Fertilizers: A Critical Review of Material Design, Performance, and Field Translation
4 affiliations
- 1Department of Chemical Engineering
- 2Bangladesh University of Engineering and Technology (BUET
- 3Department of Chemical and Biomolecular Engineering
- 4University of Nebraska–Lincoln
Abstract
Climate variability, water scarcity, declining soil quality, and inefficient fertilizer use are increasing the need for nutrient-delivery systems that support climate-resilient agriculture. Slow-release fertilizer hydrogels (SRFHs) are promising because they can retain water and control nutrient transport. This critical review examines SRFHs within conventional and enhanced-efficiency fertilizer strategies. It covers matrix, coated reservoir, and multilayer systems, along with their preparation methods and functional properties. The available evidence shows that polymer composition, crosslink density, pore structure, particle size, fertilizer loading, and environmental conditions affect swelling, mechanical behavior, and nutrient release. Important environmental factors include soil confinement, pH, ionic strength, and temperature. Kinetic models and response surface methodology can help explain release mechanisms and formulation trade-offs. Moisture-, pH-, and temperature-responsive systems may also support more adaptive nutrient delivery. However, high swelling or prolonged release in deionized water does not demonstrate improved nutrient uptake, crop yield, water-use efficiency, reduced nutrient loss, or environmental safety under field conditions. Translation is limited by inconsistent protocols, inadequate dose-matched controls, few multi-season trials, and limited evidence on degradation, residual materials, batch reproducibility, scale-up, and farm-level value. To address these gaps, this review proposes a target product profile that links crop, soil, and climate conditions with nutrient-specific release, mechanical service life, environmental fate, manufacturability, and economic performance. Model-guided responsive formulations could eventually be combined with sensor- and IoT-enabled monitoring for precision agriculture. However, this remains a prospective rather than field-validated approach. SRFHs should therefore be judged by reproducible and context-specific agronomic and environmental performance rather than maximum laboratory performance alone.
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BibTeX
@misc{kawsar2026next,
title = {{Next Generation NPK Slow Release Hydrogel Fertilizers: A Critical Review of Material Design, Performance, and Field Translation}},
author = {Sayem Kawsar and Ahasan Chowdhury Mridul and Khondoker Kabbyo Shariar and Nafisa Islam and Ahasan Chowdhury Mridul},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010237/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010237/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Next Generation NPK Slow Release Hydrogel Fertilizers: A Critical Review of Material Design, Performance, and Field Translation
AU - Sayem Kawsar
AU - Ahasan Chowdhury Mridul
AU - Khondoker Kabbyo Shariar
AU - Nafisa Islam
AU - Ahasan Chowdhury Mridul
PY - 2026
DA - 2026/10/11
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010237/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010237/v1
AB - Climate variability, water scarcity, declining soil quality, and inefficient fertilizer use are increasing the need for nutrient-delivery systems that support climate-resilient agriculture. Slow-release fertilizer hydrogels (SRFHs) are promising because they can retain water and control nutrient transport. This critical review examines SRFHs within conventional and enhanced-efficiency fertilizer strategies. It covers matrix, coated reservoir, and multilayer systems, along with their preparation methods and functional properties. The available evidence shows that polymer composition, crosslink density, pore structure, particle size, fertilizer loading, and environmental conditions affect swelling, mechanical behavior, and nutrient release. Important environmental factors include soil confinement, pH, ionic strength, and temperature. Kinetic models and response surface methodology can help explain release mechanisms and formulation trade-offs. Moisture-, pH-, and temperature-responsive systems may also support more adaptive nutrient delivery. However, high swelling or prolonged release in deionized water does not demonstrate improved nutrient uptake, crop yield, water-use efficiency, reduced nutrient loss, or environmental safety under field conditions. Translation is limited by inconsistent protocols, inadequate dose-matched controls, few multi-season trials, and limited evidence on degradation, residual materials, batch reproducibility, scale-up, and farm-level value. To address these gaps, this review proposes a target product profile that links crop, soil, and climate conditions with nutrient-specific release, mechanical service life, environmental fate, manufacturability, and economic performance. Model-guided responsive formulations could eventually be combined with sensor- and IoT-enabled monitoring for precision agriculture. However, this remains a prospective rather than field-validated approach. SRFHs should therefore be judged by reproducible and context-specific agronomic and environmental performance rather than maximum laboratory performance alone.
ER -