Restoring dryland soils functionality through synergism between biocrust-forming cyanobacteria and paper waste amendment

Organic amendments and microbial inoculants are widely applied to improve soil properties. However, their combined application remains underexplored in both soil restoration and sustainable agriculture. This study explores the synergistic potential of paper waste and biocrust-forming cyanobacteria as a combined strategy to enhance soil functions in drylands. Specifically, we assessed (i) whether paper waste can support long-term cyanobacterial survival and establishment in soil, and (ii) the effects of their combined application on soil functions and microbial community structure. In a mesocosm experiment, two forms of paper waste, shredded paper and paper pulp, were applied alone or with a native cyanobacterial consortium to natural and agricultural soils. Results showed that cyanobacteria remained viable on paper waste for three months. Redundancy Analysis (RDA) revealed strong association between treatments and shifts in key indicators of soil functions. The combination of paper waste and cyanobacteria significantly improved SOC (up to 979%), total nitrogen (30%), aggregate stability (500%), and water retention (86%), compared to untreated soil. A complementary field experiment confirmed this synergism and revealed partial inoculum transfer to the underlying soil, resulting in increased chlorophyll- a , aggregate stability and nitrogen concentration. Functional potential predictions of microbial communities (PICRUSt2 and FungalTraits) indicated that microbial taxa most strongly related to nutrient changes following amendment were linked to nutrient cycling pathways, particularly carbon and nitrogen metabolism. Despite functional shifts, occurring mainly in the paper layer, overall soil microbial diversity and nutrient balance were preserved, supporting this strategy as a sustainable tool for enhancing key soil functions in drylands. • Paper waste promoted long-term survival of native cyanobacteria in dryland soils • Combined application of cyanobacteria and paper waste improved key soil functions • The combined application preserved native microbial community composition • The combined strategy enhanced microbial functional potential for nutrient cycling