Agriculture today faces unprecedented challenges. With a global population expected to reach 9.7 billion by 2050 and climate change causing more frequent droughts, floods, and soil degradation, traditional farming methods are struggling to keep up.
Chemical fertilizers and pesticides, while effective in boosting short-term yields, have contributed to the degradation of 33% of the world’s topsoil and polluted critical water sources. In response, scientists and farmers are turning to biostimulants—a diverse group of natural or synthetic substances that enhance plant growth, resilience, and nutrient efficiency without the environmental harm caused by conventional inputs.
What Are Biostimulants and How Do They Work
Biostimulants are defined by the European Union as products that stimulate natural processes in plants or soil to improve nutrient uptake, stress tolerance, or crop quality. Unlike fertilizers, they do not directly provide nutrients but enhance the plant’s ability to absorb and use them.
- Certain biostimulants can increase nitrogen absorption by up to 40%, reducing the need for synthetic fertilizers.
They also help plants withstand environmental stresses like drought, salinity, or extreme temperatures. The global biostimulant market is growing rapidly, with projections suggesting it will reach $6.5 billion by 2030, driven by demand in Europe, Asia-Pacific, and North America.
The concept of biostimulants is not entirely new. Ancient farming practices, such as applying seaweed or animal manure to crops, relied on similar principles. However, modern science has expanded our understanding of how these substances work.
For instance, seaweed extracts are now known to contain over 70 bioactive compounds, including plant hormones like auxins and cytokinins, which promote root growth and delay leaf aging. Auxins are hormones that regulate cell elongation and root development, while cytokinins control cell division and delay senescence (aging) in plants.
Similarly, microbial inoculants like Rhizobia bacteria form symbiotic relationships with legumes, converting atmospheric nitrogen into a form plants can use, reducing synthetic fertilizer dependency by 40–60%.
The History and Evolution of Biostimulants in Farming
The use of biostimulants dates back centuries, though their scientific validation is a recent development. Early farmers observed that crops grown near coastlines, where seaweed washed ashore, yielded better harvests. By the 18th century, coastal communities in Europe and Asia were deliberately applying seaweed to fields.
Animal manure and compost were also staples in ancient Mesopotamia and China, where farmers recognized their ability to enrich soil fertility.
- Compost, a mixture of decomposed organic matter, improves soil structure by increasing its water-holding capacity and microbial activity.
The 20th century marked a turning point. In the 1930s, researchers identified auxins—a class of plant hormones—in seaweed extracts, explaining their growth-promoting effects. By the 1980s, studies revealed how humic acids, derived from decomposed organic matter, improved soil structure and nutrient retention.
Humic acids are large molecules formed during the breakdown of plant and animal residues; they enhance soil’s cation exchange capacity (CEC), a measure of its ability to hold positively charged nutrients like calcium and magnesium.
The 2000s saw breakthroughs in microbial inoculants, with species like Azospirillum and Pseudomonas gaining attention for their roles in nitrogen fixation and phosphate solubilization. Nitrogen fixation is the process by which certain bacteria convert atmospheric nitrogen (N₂) into ammonia (NH₃), a form plants can absorb.
A major milestone came in 2019 when the European Union introduced the Fertilizing Products Regulation (FPR), formally recognizing biostimulants and establishing safety and efficacy standards.
This regulation paved the way for innovations like nano-biostimulants, which use tiny particles to deliver nutrients directly to plant cells, and CRISPR-edited microbes designed to enhance stress tolerance. CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a gene-editing technology that allows scientists to modify DNA sequences in organisms, enabling the creation of microbes with tailored traits, such as heat resistance.
Key Types of Biostimulants Enhancing Crop Productivity
Biostimulants are categorized based on their origin and function. Microbial inoculants, such as Rhizobia and Trichoderma, form symbiotic relationships with plants. For example, Rhizobia bacteria infect the roots of legumes like soybeans, forming nodules where they convert atmospheric nitrogen into ammonia, a usable form for the plant.
This process reduces the need for synthetic nitrogen fertilizers by 40–60%. In drought-prone regions, inoculating corn with Azospirillum brasilense has increased root biomass by 25% and yields by 15%, according to a 2023 study.Humic and fulvic acids, derived from decomposed plant and animal matter, improve soil health.
Humic acids enhance the soil’s cation exchange capacity (CEC), allowing it to retain more nutrients like calcium and magnesium. CEC is a critical soil property that determines its fertility; soils with high CEC can hold more nutrients, reducing leaching and waste.
Fulvic acids, smaller molecules, help plants absorb iron and other micronutrients, particularly in alkaline soils.Trials on tomato crops in 2024 showed that humic acid applications increased fruit weight by 18% and vitamin C content by 12%.
Seaweed extracts are rich in natural growth hormones, vitamins, and minerals. For instance, auxins in seaweed promote root development, while cytokinins delay leaf senescence, extending the plant’s photosynthetic activity.
Photosynthesis is the process by which plants convert sunlight into energy, and prolonged leaf activity directly boosts yield. In California’s almond orchards, seaweed-based biostimulants reduced irrigation needs by 20% during droughts by improving the trees’ water retention.
Amino acids and peptides, the building blocks of proteins, act as signaling molecules during stress. Proline, an amino acid, accumulates in plant cells under drought conditions, protecting proteins and cell membranes from damage.
Cell membranes are vital for maintaining cell structure and regulating nutrient uptake; proline stabilizes them under stress. In strawberry farms, foliar sprays of amino acids raised yields by 22% in 2023 trials by enhancing nitrogen metabolism and chlorophyll production.
Chlorophyll is the green pigment in plants essential for photosynthesis; higher levels mean more energy production.
Emerging biostimulants include chitosan, derived from crustacean shells, which strengthens plant immunity against fungal infections. Field trials in rice paddies showed a 60% reduction in fungal diseases after chitosan application.
Silicon, though not essential for most plants, reinforces cell walls, reducing pest damage. Sugarcane treated with silicon saw a 35% drop in insect-related losses.
Nano-biostimulants, which encapsulate nutrients in microscopic particles, have improved nutrient use efficiency (NUE) by 50% in lettuce crops, minimizing waste and environmental runoff. NUE measures how effectively plants convert applied nutrients into biomass; higher NUE means less fertilizer is needed.
Effective Application Strategies for Biostimulants in Agriculture
The effectiveness of biostimulants depends heavily on timing and method. During seed treatment, coating seeds with humic acids or microbial inoculants can boost germination rates by 20–30%. At the seedling stage, soil drenches containing beneficial microbes like Pseudomonas enhance root growth, increasing biomass by 25–40%.
As plants enter the vegetative growth phase, seaweed extracts applied through irrigation systems (fertigation) promote leaf and stem development, raising biomass by 15–25%. Fertigation is the process of delivering fertilizers or biostimulants through irrigation water, ensuring even distribution.
During flowering and fruiting, foliar sprays of cytokinins improve pollination and fruit set. For example, tomato plants treated with cytokinins produced 30–50% more flowers that developed into mature fruits.
Foliar sprays are liquid solutions applied directly to plant leaves, allowing rapid nutrient absorption.
Pre-harvest applications of chitosan or silicon protect crops from mold and pests, extending shelf life by 10–14 days. These strategies highlight the importance of aligning biostimulant use with the plant’s growth cycle.
Challenges and Limitations of Using Biostimulants Today
Despite their potential, biostimulants face significant hurdles. Variable efficacy is a major issue, as their performance depends on soil type, climate, and crop species. For instance, microbial inoculants often fail in highly acidic (pH <5.5) or alkaline (pH >8.0) soils. A 2025 meta-analysis of 150 field trials found a 40% variability in results, underscoring the need for tailored solutions.
Regulatory fragmentation further complicates adoption. While the EU’s FPR requires rigorous safety and efficacy testing, taking 2–3 years for approval, the U.S. lacks a unified framework, treating biostimulants as fertilizers or pesticides. In Asia, countries like India and China have yet to establish clear policies, slowing market growth.
High costs also deter farmers. Developing a new microbial inoculant can cost $2–5 million, and nano-encapsulated products are 3–5 times pricier than conventional options. Smallholder farmers, particularly in developing regions, struggle to afford these innovations without subsidies or financing.
Environmental constraints pose another challenge. Extreme conditions, such as temperatures above 40°C or prolonged drought, can reduce biostimulant efficacy by 50%. In saline soils, humic acids lose 30% of their effectiveness due to high sodium levels. Saline soils contain excessive salts that hinder plant growth by disrupting water uptake and nutrient balance.
Future Innovations in Biostimulant Technology and Research
The future of biostimulants lies in addressing these challenges through innovation and collaboration. Regulatory harmonization is critical. The proposed International Biostimulant Impact Model (IBIM), set to launch in 2025, aims to standardize testing protocols across 50+ countries by 2030, ensuring consistent quality and safety.
Technological advancements are also paving the way. CRISPR-Cas9 gene editing is being used to engineer microbes with enhanced nitrogen-fixing capabilities. In Brazil, Rhizobia 2.0—a genetically modified strain—increased soybean yields by 20% while cutting synthetic fertilizer use by half.
IoT sensors, which monitor soil moisture and nutrient levels in real time, allow farmers to optimize biostimulant dosing, reducing waste by 20%. IoT (Internet of Things) refers to interconnected devices that collect and share data, enabling precision agriculture.Climate-resilient formulations are another focus.
Heat-tolerant Bacillus subtilis strains, which survive temperatures up to 45°C, are protecting crops in regions like India’s Punjab, where heatwaves have reduced wheat yields by 15% in recent years. Salt-tolerant seaweed extracts, tested in Bangladesh’s coastal farms, lowered sodium uptake in rice by 40%, reviving productivity in saline soils.
The circular economy offers additional opportunities. Converting food waste into biostimulants not only reduces landfill costs by 200pertonbutalsoprovidesfarmerswithaffordableorganicinputs.Circulareconomy is a model that minimizes waste by reusing resources in a closed loop system.
In Norway, shrimp processing waste is being repurposed into chitosan, generating 500 per ton in revenue while reducing marine pollution.
Farmer education and subsidies are equally vital. In Kenya, government-funded workshops increased biostimulant adoption by 60% among smallholders, improving maize yields by 25%. India’s 2024 subsidy program cut prices by 30% for organic farmers, encouraging a shift away from chemical inputs.
Real-World Success Stories of Biostimulant Implementation
The impact of biostimulants is already visible worldwide. In Morocco’s arid argan orchards, a combination of humic acids and drought-tolerant microbes raised yields by 35% over three years, while soil organic matter increased from 1.2% to 2.8%.
Soil organic matter refers to decomposed plant and animal residues that improve soil fertility and structure. In Brazil, soybean farmers using Azospirillum inoculants reduced nitrogen fertilizer use by 50%, saving $120 per hectare annually. California’s almond growers, battling persistent droughts, cut water usage by 25% in 2023 by applying seaweed extracts that improved tree resilience.
Conclusion
Biostimulants represent a transformative shift in agriculture, offering a way to boost productivity while healing ecosystems. By reducing synthetic fertilizer use by 30%, cutting greenhouse gas emissions by 15%, and improving farmer incomes by 20%, they align closely with the United Nations’ Sustainable Development Goals (SDGs).
As the world grapples with feeding a growing population under worsening climate conditions, biostimulants offer a beacon of hope. With continued investment and collaboration, they could help build a future where agriculture thrives in harmony with nature—producing enough food for all without compromising the planet’s health.
Power Terms
Biostimulants: Substances applied to plants, seeds, or soil to enhance natural processes like nutrient uptake or stress resistance. They do not act as fertilizers but improve plant efficiency. Examples include seaweed extracts and microbial inoculants. Importance lies in reducing synthetic fertilizer use and boosting crop resilience. Used in sustainable farming to improve yields and soil health.
Microbial Inoculants: Beneficial bacteria or fungi (e.g., Rhizobia, Pseudomonas) that form partnerships with plants. They help fix nitrogen, solubilize phosphorus, or protect against diseases. Critical for reducing fertilizer dependency. Applied as seed coatings or soil treatments. Example: Rhizobia in soybean fields.
Rhizobia: Nitrogen-fixing bacteria living in legume roots. Convert atmospheric nitrogen (N₂) into ammonia (NH₃), a plant-usable form. Vital for enriching soil nitrogen naturally. Formula: N₂ + 8H⁺ → 2NH₃ + H₂. Used in crops like peas and lentils.
Humic Acids: Large organic molecules from decomposed plant/animal matter. Improve soil’s ability to retain nutrients (CEC) and water. Important for soil fertility. Applied as soil amendments. Example: Adding humic acids to tomato fields increases fruit weight.
Fulvic Acids: Smaller organic molecules than humic acids. Help plants absorb micronutrients like iron. Vital in alkaline soils where nutrients are less available. Used in foliar sprays. Example: Boosting iron uptake in citrus trees.
Seaweed Extracts: Liquid solutions from seaweed (e.g., Ascophyllum nodosum). Rich in auxins, cytokinins, and trace minerals. Promote root growth and stress tolerance. Used in drought-prone regions. Example: Almond orchards in California use seaweed sprays to reduce water needs.
Auxins: Plant hormones regulating root development and cell elongation. Found in seaweed or synthetic forms. Applied during seedling stages. Example: Auxin-rich sprays improve root growth in corn.
Cytokinins: Hormones delaying leaf aging and promoting cell division. Extend photosynthesis duration, boosting yields. Example: Tomato plants sprayed with cytokinins produce more flowers.
Proline: Amino acid accumulating in plants under drought or salinity. Protects proteins and cell membranes. Applied as foliar sprays during stress. Example: Strawberry plants with high proline survive dry spells better.
Chitosan: Derived from crustacean shells. Strengthens plant immunity against fungi and bacteria. Used pre-harvest to extend shelf life. Example: Rice paddies treated with chitosan show fewer fungal infections.
Silicon: Non-essential nutrient that reinforces plant cell walls. Reduces pest damage and improves drought tolerance. Example: Sugarcane treated with silicon resists borer insects.
Nano-Biostimulants: Nutrients encapsulated in nanoparticles (1–100 nm). Enhance nutrient delivery and reduce waste. Formula: Nano-CaCO₃ improves calcium uptake in apples. Used in precision agriculture.
CRISPR-Cas9: Gene-editing tool to modify organisms’ DNA. Engineers microbes for better nitrogen fixation. Example: Rhizobia 2.0 increases soybean yields by 20%.
Cation Exchange Capacity (CEC): Measure of soil’s nutrient-holding ability (unit: meq/100g). High CEC soils (e.g., clay) retain more calcium, magnesium. Critical for long-term fertility.
Nutrient Use Efficiency (NUE): Ratio of nutrients absorbed by plants to those applied. Formula: NUE = (Nutrient absorbed ÷ Nutrient applied) × 100. High NUE reduces fertilizer costs.
Fertigation: Delivering fertilizers or biostimulants via irrigation systems. Ensures even distribution. Example: Drip irrigation with seaweed extracts in vegetable farms.
Photosynthesis: Process where plants convert sunlight, CO₂, and water into glucose and oxygen. Formula: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Basis of plant growth and yield.
Saline Soils: Soils with high salt content (e.g., NaCl). Hinder water uptake and nutrient balance. Biostimulants like fulvic acids help plants cope. Example: Coastal farms in Bangladesh use seaweed extracts to reduce salt stress.
Circular Economy: Reusing waste (e.g., food scraps, shrimp shells) to create biostimulants. Reduces landfill use and costs. Example: Shrimp waste converted into chitosan for rice crops.
IoT (Internet of Things): Network of sensors monitoring soil moisture, nutrients, or temperature. Enables precise biostimulant application. Example: Smart sensors in wheat fields optimize microbial inoculant doses.
Nitrogen Fixation: Converting atmospheric nitrogen (N₂) into ammonia (NH₃) via microbes. Formula: N₂ + 8H⁺ → 2NH₃ + H₂. Vital for reducing synthetic fertilizer use in legumes.
Chlorophyll: Green pigment in plants capturing sunlight for photosynthesis. Higher chlorophyll levels mean better energy production. Example: Amino acid sprays increase chlorophyll in spinach leaves.
Symbiotic Relationships: Mutually beneficial partnerships (e.g., plants and microbes). Rhizobia provide nitrogen to legumes; plants supply sugars. Basis of sustainable soil health.
Stress Tolerance: Ability to withstand drought, heat, or pests. Biostimulants like proline or silicon enhance this trait. Example: Heat-tolerant Bacillus strains protect crops in heatwaves.
Soil Organic Matter: Decomposed plant/animal residues improving soil structure and fertility. Example: Compost increases organic matter from 1.2% to 2.8% in Moroccan orchards.
Reference:
Khoulati, A., Ouahhoud, S., Taibi, M. et al. Harnessing biostimulants for sustainable agriculture: innovations, challenges, and future prospects. Discov Agric 3, 56 (2025). https://doi.org/10.1007/s44279-025-00177-9
