ABSTRACT

Microalgal and cyanobacterial biofertilizers present a transformative pathway for climate-smart smallholder agriculture by simultaneously enhancing nutrient use efficiency, bolstering crop resilience to abiotic stress, and promoting soil carbon sequestration. This review critically evaluates the bioprocessing, agronomic deployment, and commercialization trajectories of these biological inputs. While laboratory and pilot-scale studies demonstrate significant yield stabilization and greenhouse gas mitigation potential, large-scale adoption remains constrained by energy-intensive harvesting, formulation instability, field heterogeneity, and fragmented regulatory frameworks. We synthesize recent techno-economic and life cycle assessment data to identify key optimization nodes, emphasizing AI-driven bioprocess control, low-cost circular feedstocks, and climate-resilient carrier matrices. Furthermore, the analysis highlights the socio-technical and policy barriers to rural-to-global market integration, including subsidy imbalances, gaps in quality standardization, and limited extension capacity. To bridge the laboratory-to-field divide, we propose a coordinated roadmap that prioritizes decentralized production models, harmonized biosafety protocols, and alignment with climate finance. By integrating synthetic biology, participatory innovation, and adaptive governance, microalgal and cyanobacterial biofertilizers can transition from niche biostimulants to foundational, equitable components of sustainable smallholder farming systems, ultimately decoupling agricultural productivity from reliance on synthetic inputs while advancing global climate resilience targets.

Keywords: Biological nitrogen fixation; Soil microbiome engineering; Techno-economic assessment; Circular bioeconomy; Regulatory harmonization; Participatory innovation.

INTRODUCTION

Global agriculture faces unprecedented pressure from climate volatility, soil degradation, and rising input costs, disproportionately affecting smallholder farmers who cultivate the majority of the world’s arable land yet operate under severe resource constraints (Lowder et al., 2016). Climate-smart agriculture (CSA) has emerged as a strategic paradigm to simultaneously enhance productivity, build systemic resilience, and reduce greenhouse gas emissions, yet its adoption remains constrained by the financial and technical barriers inherent in conventional agrochemical dependency (Lipper et al., 2014; Campbell et al., 2017). Synthetic nitrogen fertilizers, while historically instrumental in yield intensification, now contribute significantly to nitrous oxide emissions, aquatic eutrophication, and soil microbiome depletion, rendering them increasingly incompatible with long-term agronomic sustainability (Zhang et al., 2015). Consequently, there is an urgent imperative to transition toward ecologically integrated nutrient management systems that align with the socioeconomic realities of smallholder contexts while advancing climate adaptation and mitigation targets.

Microalgae and cyanobacteria have garnered substantial attention as next-generation biofertilizers due to their multifunctional agronomic properties and low environmental footprint. These photoautotrophic microorganisms not only fix atmospheric nitrogen and solubilize recalcitrant phosphorus but also secrete phytohormones, exopolysaccharides, and siderophores that enhance seed germination, root architecture, and plant tolerance to drought, salinity, and thermal stress (Braun and Colla, 2023; Sun et al., 2025). Unlike conventional microbial inoculants, algal-based consortia can actively modulate soil physicochemical properties, improve aggregate stability, and promote long-term carbon sequestration, thereby addressing both productivity and climate resilience dimensions of CSA (Ramakrishnan et al., 2023; Swami et al., 2025). Furthermore, their cultivation can be integrated with wastewater remediation and flue gas CO₂ utilization, positioning them within circular bioeconomy frameworks that minimize dependency on external inputs while generating value from waste streams (Leong et al., 2021; Deprá et al., 2026). Despite this promise, the transition from laboratory validation to widespread field deployment remains hampered by unresolved bioprocessing inefficiencies, formulation instability, and fragmented commercial pathways.

This review critically synthesizes current advances and persistent bottlenecks in the development, optimization, and commercialization of microalgal and cyanobacterial biofertilizers for climate-smart smallholder agriculture. Drawing on peer-reviewed literature, techno-economic assessments, and market analyses published between 2015 and 2025, we evaluate strain selection criteria, cultivation architectures, downstream processing, and field application protocols through an integrated agronomic and systems-engineering lens. Special emphasis is placed on identifying scalability constraints, including energy-intensive harvesting, shelf-life decay, contamination risks, and socio-technical adoption barriers that limit rural uptake. Furthermore, we examine the evolving regulatory landscape, quality standardization efforts, and rural-to-global value chain dynamics, highlighting how decentralized production models, digital extension networks, and climate finance mechanisms can accelerate market penetration. By bridging bioprocessing innovation with socio-economic implementation frameworks, this review delineates actionable research priorities and policy interventions required to translate algal bioinput potential into resilient, equitable, and commercially viable smallholder farming systems.

BIOLOGICAL MECHANISMS AND AGRONOMIC VALUE IN CLIMATE-SMART SYSTEMS

Biological nitrogen fixation, phosphorus solubilization, and micronutrient mobilization

Heterocystous cyanobacteria, particularly Nostoc, Anabaena, and Calothrix spp., possess specialized nitrogenase complexes that catalyze atmospheric N₂ fixation under micro-oxic conditions, directly supplementing soil nitrogen pools without synthetic inputs (Pathak et al., 2018). Concurrently, diverse microalgal and cyanobacterial strains secrete organic acids and extracellular phosphatases that solubilize recalcitrant calcium- and iron-bound phosphorus complexes, significantly enhancing plant-available P (Abinandan et al., 2019). These photoautotrophs also synthesize high-affinity siderophores and low-molecular-weight chelators that mobilize essential micronutrients, such as Fe, Zn, and Cu, from mineral matrices, addressing widespread micronutrient deficiencies in intensively cropped smallholder soils. The synergistic nutrient provisioning reduces fertilizer dependency while maintaining yield stability under low-input management regimes, a critical advantage given the persistent constraints on synthetic fertilizer affordability and supply chain reliability.

Phytohormone secretion, ROS scavenging, and abiotic/biotic stress resilience

Beyond macronutrient cycling, microalgae and cyanobacteria function as potent biostimulants through the continuous exudation of phytohormones, including indole-3-acetic acid, cytokinins, and gibberellins, which regulate root architecture, enhance water uptake efficiency, and delay leaf senescence (Wang et al., 2021). Under climate-induced stressors, these microbial consortia upregulate antioxidant enzyme systems and synthesize osmoprotectants such as proline, glycine betaine, and trehalose, effectively scavenging reactive oxygen species and preserving cellular membrane integrity in host plants (Coulombier et al., 2021; Vangenechten et al., 2025). This biochemical buffering substantially improves crop resilience to drought, salinity, and thermal extremes. Additionally, competitive rhizosphere colonization and the secretion of antimicrobial secondary metabolites suppress soil-borne phytopathogens, offering an integrated disease management strategy that aligns with agrochemical reduction targets. Consequently, algal-mediated stress priming offers a scalable, low-cost adaptation pathway for rainfed and marginal agroecosystems.

Soil microbiome modulation, aggregate stability, and carbon sequestration potential

The field application of algal biofertilizers induces profound shifts in the rhizosphere microbiome, fostering beneficial bacterial and fungal networks that amplify nutrient cycling and plant health signaling cascades (Pathak et al., 2018; Abinandan et al., 2019). A critical mechanism is the abundant secretion of extracellular polymeric substances (EPS), which act as biological glues that bind mineral and organic particles into stable macroaggregates, thereby improving soil porosity, water-holding capacity, and resistance to wind and water erosion (Wang et al., 2021; Ramakrishnan et al., 2023; Swami et al., 2025). Furthermore, recalcitrant polysaccharides, lipids, and microbial necromass derived from algal biomass contribute to long-term soil organic carbon accumulation, directly mitigating greenhouse gas emissions by enhancing carbon drawdown and reducing N₂O fluxes from synthetic fertilizer replacement (Hoque et al., 2025). By simultaneously enhancing productivity, buffering climatic extremes, and promoting carbon sequestration, these interconnected biological processes directly operationalize the three foundational pillars of climate-smart agriculture for resource-constrained farming systems (Figure 1).

PRODUCTION SYSTEMS AND DOWNSTREAM PROCESSING

Strain selection, genomic profiling, and cultivation architectures (open vs. closed)

Strain selection represents the foundational determinant of biofertilizer efficacy, requiring rigorous screening for nitrogen-fixation capacity, phytohormone secretion profiles, stress tolerance, and compatibility with target crops and soil types. Modern genomic and transcriptomic tools, including whole-genome sequencing and CRISPR-based functional annotation, enable precise identification of biosynthetic gene clusters responsible for exopolysaccharide production, siderophore synthesis, and phytohormone pathways (O’Neill 2020; Hassanien et al., 2023). Genomic profiling further facilitates the detection of toxin genes and antibiotic resistance markers, ensuring biosafety compliance for field deployment. Cultivation architecture selection involves trade-offs between cost, contamination risk, and biomass productivity. Open raceway ponds offer low capital expenditure and operational simplicity, making them suitable for decentralized smallholder contexts, yet they suffer from evaporative losses, predator invasion, and inconsistent biomass quality (Johnson et al., 2018). Conversely, closed photobioreactors (tubular, flat-panel, or vertical column systems) provide superior environmental control, higher cell densities, and year-round production but entail 3–5-fold higher capital costs and energy inputs for mixing and temperature regulation (Narala et al., 2016). Hybrid systems combining open ponds for bulk biomass production with closed systems for inoculum multiplication are emerging as economically viable compromises for regional-scale operations.

Harvesting, dewatering, and preservation: energy, water, and cost trade-offs

Harvesting and dewatering constitute the most energy-intensive stages of algal biofertilizer production, accounting for 20–30% of total operational costs and representing a critical bottleneck for commercial viability (Kendler et al., 2025). Conventional methods such as centrifugation achieve high biomass recovery (>90%) but demand prohibitive electrical inputs (0.5–1.5 kWh m⁻³), rendering them unsuitable for low-resource settings. Flocculation using chemical coagulants (alum, ferric chloride) or bioflocculants (chitosan, microbial EPS) reduces energy requirements substantially but introduces chemical residues that may compromise soil microbiome integrity and regulatory approval (McGrath et al., 2024). Emerging low-cost alternatives include gravity sedimentation enhanced by pH modulation, electrocoagulation powered by renewable energy, and membrane filtration using locally fabricated ceramic filters, though these methods often entail slower throughput or lower concentration factors. Post-harvest preservation via spray-drying, freeze-drying, or encapsulation in protective matrices is essential for extending shelf-life beyond 6–12 months, yet thermal degradation of bioactive metabolites during drying remains a persistent challenge. Liquid formulations stabilized with cryoprotectants (trehalose, glycerol) offer superior retention of viability but incur higher transportation costs and require refrigeration, limiting their applicability in off-grid rural areas (Waghmare et al., 2022).

Formulation engineering: carrier matrices, stabilizers, and shelf-life extension

Formulation engineering determines field applicability, ease of application, and long-term stability of viable cell counts and bioactive compounds. Solid carriers such as lignite, peat, biochar, vermiculite, and agricultural residues (rice husk, sugarcane bagasse) provide porous matrices that protect cells from desiccation and UV radiation while facilitating slow nutrient release (Miranda et al., 2024). Biochar-based carriers, derived from pyrolyzed crop residues, offer dual benefits of enhanced water retention and soil carbon amendment, aligning with circular economy principles. Liquid formulations incorporating natural polymers (alginate, xanthan gum, carboxymethyl cellulose) improve adhesion to seeds and soil particles, enabling uniform distribution and prolonged rhizosphere colonization. Advanced encapsulation techniques, including microencapsulation in alginate-chitosan beads and nanoemulsion-based delivery systems, shield sensitive metabolites from environmental degradation and enable controlled-release kinetics synchronized with crop growth stages (Pathak et al., 2018; Miranda et al., 2024). However, scaling these technologies while maintaining cost-effectiveness for smallholder markets remains an unresolved challenge. Shelf-life extension beyond 12 months requires optimizing storage conditions (temperature, humidity, light exposure) and incorporating antioxidants, antimicrobial agents, and osmoprotectants that preserve cellular integrity without causing phytotoxicity (Table 1).

OPTIMIZATION PATHWAYS AND IMPLEMENTATION CHALLENGES

Techno-economic and life cycle assessment (LCA) insights

Techno-economic analyses (TEA) consistently identify downstream processing as the primary cost driver in algal biofertilizer production, with harvesting, dewatering, and stabilization accounting for 40–60% of total operational expenditures (Fasaei et al., 2018; Romero-García et al., 2022). At current technology maturity levels, production costs range from $2.0 to $9.0 kg⁻¹ of dry biomass, rendering algal inputs economically competitive only when integrated into circular resource loops or positioned as premium biostimulants rather than bulk fertilizer substitutes (Zabochnicka et al., 2022; Parmar et al., 2023). Life cycle assessments (LCAs) demonstrate that microalgal and cyanobacterial formulations can reduce cradle-to-gate greenhouse gas emissions by 30–70% relative to synthetic urea, primarily by avoiding Haber-Bosch energy consumption and enhancing soil carbon sequestration (Osorio-Reyes et al., 2023; Rafiq et al., 2025). However, LCA outcomes remain highly sensitive to system boundaries, energy mix assumptions, and allocation methodologies. Fossil-dependent drying and refrigerated logistics can inadvertently offset mitigation benefits, underscoring the necessity of renewable energy integration and low-energy preservation strategies. Economically viable scaling requires hybrid value chains that couple biofertilizer production with wastewater remediation, agro-industrial effluent treatment, or biogas upgrading, thereby converting waste streams into low-cost nutrient media while generating ancillary environmental credits (Rafiq et al., 2025).

Process intensification, AI-driven bioprocess control, and contamination management

Achieving consistent, high-yield production demands a paradigm shift from empirical batch cultivation to intensified, data-informed bioprocessing. Continuous and semi-continuous cultivation architectures, coupled with automated nutrient dosing and light-dark cycling, have demonstrated 2–3-fold  increases in productivity in pilot-scale trials (Penloglou et al., 2018). The integration of low-cost Internet of Things (IoT) sensors with machine learning algorithms enables real-time monitoring of dissolved oxygen, pH, turbidity, and chlorophyll fluorescence, facilitating predictive harvest scheduling and early anomaly detection (Lim et al., 2022). AI-driven process control optimizes resource allocation, minimizes energy waste, and dynamically adjusts operational parameters to maintain strain-specific physiological optima (Wu et al., 2025). Contamination by protozoan grazers, competing phytoplankton, and filamentous fungi remains a pervasive risk, particularly in open systems where environmental filtering is minimal (Lam et al., 2018). Mitigation strategies include strategic pH oscillation, pulsal nutrient limitation, selective salinity modulation, and the deployment of extremotolerant or fast-colonizing consortia engineered for competitive exclusion. For decentralized, smallholder-adjacent production, simplified contamination monitoring protocols and community-based quality assurance frameworks are essential to prevent culture collapse and ensure product consistency (Tenzin et al., 2026).

Field variability, application protocols, and socio-technical adoption barriers

Translating controlled-environment efficacy to reliable field performance is constrained by agroecological heterogeneity and suboptimal application practices. Biofertilizer viability, rhizosphere colonization, and metabolic activity are highly sensitive to soil moisture regimes, temperature fluctuations, UV exposure, and native microbial competition (Kumar et al., 2022). Standardized, context-specific application protocols—encompassing seed priming, root dipping, soil incorporation, or foliar spraying aligned with critical phenological stages—are required to maximize nutrient delivery and plant-microbe synergies (Khan et al., 2023). Socio-technical adoption barriers further impede commercialization. Smallholder farmers frequently perceive microbial inputs as unreliable due to inconsistent field outcomes, inadequate storage infrastructure, and limited extension support. Trust deficits, gender-disparate access to training, and upfront liquidity constraints necessitate innovative dissemination models, including demonstration plots, microfinance-linked input credit, and participatory co-development programs. Digital extension platforms, mobile-based agronomic advisories, and farmer-to-farmer knowledge networks have shown promise in accelerating adoption by contextualizing technical guidelines and providing real-time troubleshooting (Rezaee Danesh, 2025). As illustrated in Figure 2, bridging the lab-to-field gap requires synchronized optimization across bioprocessing, formulation stability, precision application, and socio-institutional enablement.

MARKET DYNAMICS AND RURAL-TO-GLOBAL COMMERCIALIZATION

Decentralized village-scale vs. centralized industrial production models

The commercialization trajectory of microalgal and cyanobacterial biofertilizers is fundamentally shaped by the operational and economic trade-offs between decentralized village-scale production and centralized industrial manufacturing (Stoklosa et al., 2017; Slegers et al., 2020). Decentralized models, typically organized around farmer cooperatives or rural micro-enterprises, utilize locally available feedstocks, wastewater streams, and ambient sunlight to cultivate biomass in low-cost raceway ponds or simple photobioreactors. This approach minimizes capital expenditure, reduces transportation emissions, and generates rural employment while embedding circular resource utilization into local agronomic practices (Bhooshan et al., 2020). However, decentralized systems frequently encounter challenges related to batch-to-batch variability, limited technical capacity, and constrained quality control, which can undermine regulatory compliance and farmer trust (Xue et al., 2026). Conversely, centralized industrial facilities benefit from economies of scale, automated environmental control, standardized downstream processing, and rigorous quality assurance protocols that ensure consistent viable cell densities and metabolite profiles (Xue et al., 2026). While these advantages facilitate large-scale market penetration and export readiness, high capital requirements, energy-intensive infrastructure, and complex logistics often render industrial models less accessible to remote smallholder regions. A hybrid tiered architecture—where centralized hubs produce certified starter cultures and premium formulations while decentralized nodes manage local cultivation, formulation, and last-mile distribution—emerges as a pragmatic pathway to reconcile quality assurance with rural inclusivity (Rahman et al., 2025).

Supply chain logistics, quality standardization, and traceability systems

Scaling algal biofertilizers from regional pilots to national markets necessitates robust supply chain logistics, stringent quality standardization, and transparent traceability mechanisms. Unlike inert synthetic inputs, microbial biofertilizers are living products that require controlled storage conditions to preserve viability, typically maintained at 4–25°C with strict protection from desiccation and UV radiation (Xue et al., 2026). Inadequate cold-chain infrastructure and prolonged transit times in developing economies frequently result in significant viability losses before field application, necessitating climate-resilient carrier matrices and decentralized buffer hubs. Quality standardization remains fragmented across jurisdictions, with divergent regulatory requirements for colony-forming unit thresholds, contaminant limits, and shelf-life validation. Harmonized testing protocols, aligned with emerging international biofertilizer guidelines, are critical for establishing market credibility and enabling cross-regional trade (Kanishka et al., 2025). Concurrently, digital traceability systems leveraging QR coding, blockchain ledgers, and cloud-based batch tracking are increasingly deployed to verify product authenticity, monitor storage conditions, and provide farmers with contextualized application advisories. These technologies mitigate counterfeit risks while generating agronomic feedback loops that inform continuous product refinement (Rezaee Danesh, 2025).

Business models, digital marketplaces, and cross-border trade integration

Commercial viability is increasingly contingent on innovative business models that transcend traditional input distribution channels. Cooperative-led franchising, pay-for-performance contracts, and input-output linkage schemes have demonstrated success in de-risking adoption for resource-constrained farmers by aligning upfront costs with measurable yield or soil health outcomes (Wei et al., 2022). Digital agritech marketplaces further accelerate market penetration by connecting producers directly with smallholder networks, aggregating fragmented demand, and integrating microfinancing or ecosystem service monetization into purchasing decisions. These platforms leverage mobile payment ecosystems and AI-driven recommendation engines to contextualize product selection based on crop typology, soil diagnostics, and localized climate forecasts (Rezaee Danesh, 2025). Cross-border trade integration remains constrained by divergent regulatory frameworks, phytosanitary requirements, and biosafety protocols, yet growing international demand for sustainable inputs is catalyzing mutual recognition agreements and harmonized certification pathways. Strategic public-private partnerships, coupled with climate finance instruments such as green bonds and verified carbon standards, are progressively de-risking private investment and enabling the transition from niche biostimulant markets to mainstream agricultural input supply chains (Kacprzak and Ferri, 2025). As depicted in Figure 3, the evolution of a resilient rural-to-global value chain requires synchronized alignment of production architecture, quality governance, digital commerce, and policy enablement.

FUTURE PERSPECTIVES AND RESEARCH PRIORITIES

Synthetic biology, engineered consortia, and multi-trophic synergies

The next frontier in algal biofertilizer development lies in precision strain engineering and the rational design of synthetic microbial consortia. Advances in CRISPR-Cas genome editing, multi-omics integration, and metabolic pathway reconstruction enable targeted enhancement of nitrogenase efficiency, phytohormone biosynthesis, and stress-responsive gene expression while preserving ecological safety (Dhokane et al., 2023; Sadvakasova et al., 2023). Engineered cyanobacterial strains with optimized carbon-concentrating mechanisms or amplified exopolysaccharide secretion demonstrate superior rhizosphere colonization, nutrient mobilization, and soil aggregation under abiotic stress. Beyond single-strain optimization, the development of multi-trophic synthetic consortia—strategically pairing nitrogen-fixing cyanobacteria, phosphate-solubilizing microalgae, and plant growth-promoting rhizobacteria—creates functional redundancy that buffers against environmental fluctuations, pathogen pressure, and native microbial competition (Llamas et al., 2025; Sun et al., 2025). However, translating engineered consortia from controlled bioreactors to heterogeneous field soils requires rigorous ecological risk assessment, monitoring of horizontal gene transfer, and longitudinal tracking of strain persistence. Emerging biocontainment strategies, including inducible kill switches, auxotrophic dependencies, and synthetic auxin-regulated population control, offer promising pathways to mitigate unintended ecological dispersal (Lensch et al., 2024). Future research must prioritize field-realistic validation of synthetic communities, standardized biosafety frameworks for environmental release, and predictive ecological modeling that captures plant-microbe-soil feedbacks under compounding climate stressors (Pei et al., 2023). Integrating machine learning with metagenomic and metabolomic datasets will further enable dynamic consortia tuning, allowing formulations to be algorithmically matched to specific soil microbiomes, crop phenotypes, and regional climate projections. Establishing open-access benchmarking platforms for synthetic bioinput performance will accelerate cross-laboratory reproducibility and reduce the translational gap between molecular design and agronomic deployment (Folorunso et al., 2026).

Circular economy integration: wastewater, agro-residues, and CO₂ valorization

Scaling algal biofertilizer production sustainably demands seamless integration within circular bioeconomy architectures that convert waste streams into low-cost nutrient media and carbon feedstocks. Municipal, industrial, and agricultural effluents rich in nitrogen, phosphorus, and dissolved organics can simultaneously support high-density algal cultivation and achieve >80% nutrient recovery, effectively coupling bioinput production with environmental remediation (Behera et al., 2022; Alavianghavanini et al., 2024). Agro-residue hydrolysates, lignocellulosic byproducts, and food processing streams further reduce medium formulation costs while enabling heterotrophic or mixotrophic cultivation modes that circumvent photolimitation bottlenecks. Concurrently, coupling photobioreactors with industrial flue gas or biogas upgrading streams enables direct CO₂ valorization, enhancing biomass productivity while decarbonizing emission-intensive sectors. Life cycle assessments confirm that circular integration can reduce production costs by 30–50% and lower cradle-to-gate carbon footprints by up to 60% relative to conventional fertilizer synthesis (Kumar et al., 2023). Nevertheless, operational challenges persist, including heavy metal accumulation, pathogen carryover, and seasonal variability in waste stream composition. Standardized pre-treatment protocols, robust contaminant monitoring, and adaptive strain selection will be critical to ensuring product safety, regulatory compliance, and consistent field performance in waste-fed production systems (Santos et al., 2025). Future research should focus on developing dynamic feedstock-adaptation algorithms, modular, integrated biorefinery designs, and closed-loop nutrient-recovery systems that maintain formulation purity without compromising economic viability. Additionally, policy frameworks must incentivize cross-sectoral synergies by establishing clear regulatory pathways for waste-to-bioinput valorization, harmonizing environmental compliance standards, and creating market mechanisms that recognize the dual climate-mitigation and circular-economy benefits of algal production systems.

Participatory innovation, open-source platforms, and climate-adaptive scaling

Technological advancement alone cannot guarantee equitable adoption; successful commercialization requires institutionalizing participatory innovation models that center smallholder knowledge, contextual agronomy, and localized capacity building. Co-designing biofertilizer formulations with farming communities—through iterative on-farm trials, feedback-driven carrier optimization, and culturally appropriate application training—significantly improves trust, usability, and long-term retention (Adeniji et al., 2024; Nygymetova et al., 2025). Open-source platforms that democratize access to validated strain libraries, low-cost cultivation protocols, and modular formulation recipes can accelerate decentralized production while reducing proprietary bottlenecks that stifle rural entrepreneurship. Digital infrastructure, including climate-adaptive decision-support systems, remote-sensing-guided soil diagnostics, and AI-driven phenotyping networks, will enable dynamic matching of biofertilizer consortia to microclimatic conditions, crop phenology, and site-specific degradation profiles (Schweng et al., 2026; Vedamurthy et al., 2026). Climate-adaptive scaling further necessitates flexible regulatory pathways that accommodate region-specific strain deployment, modular certification frameworks, and climate finance mechanisms that reward verifiable soil health improvements and emission reductions. Crucially, participatory innovation must address structural inequities by integrating gender-responsive extension models, safeguarding indigenous agricultural knowledge, and establishing community-owned data governance frameworks (Makkar et al., 2023; Sahoo et al., 2025). Future research priorities should include longitudinal socio-technical adoption studies, scalable open-source certification protocols, and interoperable digital platforms that link smallholder field data to carbon market MRV systems. By aligning synthetic biology, circular resource flows, and participatory governance, the next generation of algal biofertilizer systems can transition from niche biostimulants to foundational, equity-driven components of resilient smallholder agriculture, ultimately fostering a decentralized, climate-smart bioeconomy that empowers rural producers while advancing global sustainability targets.

CONCLUSIONS

Microalgal and cyanobacterial biofertilizers represent a transformative pathway toward climate-resilient smallholder agriculture, offering integrated nutrient provisioning, stress mitigation, and soil carbon enhancement. Despite their agronomic promise, widespread adoption remains constrained by energy-intensive downstream processing, formulation instability, regulatory fragmentation, and socio-technical barriers that limit rural uptake. This review underscores that realizing the full potential of microbial bioinputs demands integrated techno-economic modeling, context-specific application protocols, and harmonized quality standards. Bridging the gap between laboratory validation and field-scale deployment requires a coordinated, multi-stakeholder strategy that prioritizes both technological optimization and institutional enablement. Researchers must prioritize low-energy bioprocessing, robust multi-strain consortia, and longitudinal field trials that capture real-world agroecological variability, while advancing open-source strain libraries and predictive ecological models. Industry should pivot toward decentralized, circular production architectures, standardized climate-resilient formulations, and digital traceability networks that ensure quality assurance and supply chain transparency. Concurrently, policymakers must harmonize registration frameworks, integrate microbial inputs into national subsidy and carbon finance mechanisms, and strengthen participatory extension systems that empower smallholders as co-developers rather than passive recipients. By aligning synthetic biology, circular resource flows, and adaptive governance, the agricultural sector can convert algal bioinputs from experimental promise into scalable, equitable, and commercially viable foundations for climate-smart food systems, ultimately decoupling smallholder productivity from synthetic input dependency while advancing global sustainability targets.                                                                                                               

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