Lignin-based cryogels for advancing sustainable crop production via enhanced nutrient accessibility and growth...

Sustainable lignin-based materials are becoming increasingly valuable in agriculture, where climate change and nutrient deficiencies threaten crop productivity. We developed lignin-derived cryogels using waste biomass to improve soil nutrients, seed germination, water retention, and photosynthetic pigment levels. These cryogels were synthesized with gum Arabic (GA), keratin (K), and N-vinylpyrrolidone at lignin concentrations of 0.02 wt% (LbC₁), and 0.1 wt% (LbC₂), along with a control (NLC), through low-temperature polymerization at -20 °C. The cryogels exhibited high thermal stability and water retention, exceeding 170 %, due to their network structure. Functional groups like carboxyl and hydroxyl enhanced nutrient assimilation, accelerating germination and plant growth, with keratin providing bioavailable amino acids through microbial degradation. After 5 days, the cryogel treatments significantly improved early germination rates (100 %, 100 %, and 99 % for wheat, maize, and rapeseed, respectively), while boosting chlorophyll (a, b, and total), sugar, and soluble protein levels. Treated plants showed increased leaf numbers, plant height, and root length, with a 98.4 % improvement in water uptake compared to controls, mitigating the effect of soil salinity. LbC₁ and LbC₂ also notably increased chlorophyll pigments, soluble sugars, and total protein across all crops compared to the NLC. Additionally, the cryogel exhibited a 33 % biodegradation rate after 130 days in soil, confirming their environmental compatibility. In conclusion, the developed lignin-based cryogels represent a sustainable, effective solution to enhance nutrient availability and resilience in agriculture, repurposing industrial lignin waste to address climate-driven challenges in crop production.