Ethyl cellulose-alginate/poly(vinyl alcohol) dual-layer coating incorporating biochar-immobilized PGPR for controlled urea release, water retention, and plant stress resilience.

Authors

Siqi Guo, Xiaoyan Qian, Shengnan Zhang, Desheng Wang, Mukkram Ali Tahir, Chong Liu, Fayong Li

Published in

International journal of biological macromolecules. Pages 154873. Oct 16, 2026. Epub Oct 16, 2026.

Abstract

Coated controlled-release fertilizers can synchronize nutrient supply with crop demand, yet single-layer systems are often limited by poor structural integrity and restricted functionality. Here, salt-tolerant plant growth-promoting rhizobacteria (PGPR) were immobilized on biochar and embedded in a dually crosslinked poly(vinyl alcohol)/sodium alginate hydrogel (PSBP). A dual-layer controlled-release urea fertilizer (PSBPEU-CRF) was fabricated using an ethyl cellulose inner diffusion barrier and a PSBP outer hydrogel coating. PSBPEU-CRF enabled sustained viable-cell release and improved bacterial immobilization stability. PSBP hydrogel reached an equilibrium swelling ratio of 424%, improved soil water retention and showed 70.65% mass loss after 28 d. At 2% (w/w), soil water retention remained 20.96% on day 10, compared with 2.35% in unamended soil. PSBPEU-CRF markedly retarded urea release in water and soil; the release profiles fitted the Korsmeyer-Peppas model, indicating anomalous transport governed by diffusion and polymer-network swelling/relaxation. In saline-alkali pakchoi pots, PSBPEU-CRF increased chlorophyll accumulation and antioxidant enzyme activities while reducing lipid peroxidation and the Na⁺/K⁺ ratio. Overall, the integration of controlled nutrient release, soil water retention, and rhizosphere functional regulation provided by the PSBP hydrogel layer offers a promising approach for developing multifunctional fertilizers for salt-affected soils. Nevertheless, its long-term field performance, manufacturing scalability, and economic feasibility require further evaluation.

PMID:
42887746
Bibliographic data and abstract were imported from PubMed on 17 Oct 2026.

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