What are Biostimulants?
Biostimulants are substances or microorganisms applied to plants, seeds, or soil that enhance natural processes to improve nutrient uptake, increase stress tolerance, and boost growth and quality. Unlike fertilizers, they don’t supply nutrients directly but instead stimulate the plant’s own systems or improve soil biology, leading to more efficient nutrient use and better overall plant health.
Types of Biostimulants
Biostimulants are diverse in type and formulation, stimulating different responses in plants. The efficacy of a particular product may be affected by its raw materials, as well as its production, storage, and application methods.
Below are some of the most commonly used biostimulants in agricultural production.
1. Humic Acid, Natural Organic Extracts
· Humic acid and fulvic acid, tannins, phenolic compounds, compost tea
2. Seaweed and Plant Extracts
· Seaweed, algae, and plant extracts
3. Inorganic Salts
· Silicon, cobalt, phosphites (non-essential nutrients for plants)
4. Beneficial Microorganisms
· Mycorrhizae, beneficial bacteria, fungi, and their byproducts/extracts
5. Chitosan, Chitosan, and Other Biopolymers
· Shellfish extracts, synthetic polymers
6. Protein Hydrolysates, Nitrogenous Compounds
· Amino acids, peptides, organic nitrogen substances (betaine, polyamines)
Common Biostimulant Combinations
These biostimulants can be combined with each other. Common biostimulant combinations include using humic acid/fulvic acid with seaweed extracts, protein hydrolysates, or beneficial microorganisms (such as bacteria and fungi) to enhance nutrient utilization, improve root development, and increase stress resistance. Other common combinations include using microbial products (such as bacteria and fungi) with seaweed extracts to improve plant growth and yield. Examples of common combinations:
- Humic acid/fulvic acid + seaweed extract: This combination offers a wide range of benefits, including improved soil structure, enhanced nutrient uptake, and increased plant stress resistance.
- Protein hydrolysate + beneficial microorganisms: This combination provides easily absorbed amino acids while also providing the benefits of beneficial bacteria (such as Bacillus) and fungi for soil health and nutrient processing.
- Seaweed extract + beneficial microorganisms: This combination is often used to promote root development, improve plant growth, and increase yield because seaweed extracts provide beneficial compounds, while microorganisms contribute to nutrient cycling.
- Microbial Community + Nitrogen/Potassium• : Combining beneficial microorganisms with additional nutrients such as nitrogen and potassium can significantly improve plant biomass and nutrient utilization efficiency.
- Chitosan + Other Biostimulants: Chitosan can be used in combination with other biostimulants to enhance plant defense mechanisms, improve root growth, and increase stress resistance.
Today we’ll focus on the first combination: a mixture of seaweed fertilizer, humic acid, and fulvic acid.
Seaweed Fertilizer: A Plant’s “Natural Nutrient Reservoir and Endogenous Hormone Pool”
Seaweed fertilizer, especially extracts from cold-water algae such as *Sphaerocarpus sicerina* and *Klephalothorax*, is a natural biostimulant with an extremely complex composition.
- Rich Endogenous Hormones: Rich in plant endogenous hormones and signaling substances such as auxins, cytokinins, gibberellins, and betaine, it can bidirectionally regulate plant growth, promote cell division, protect flowers and fruits, and delay senescence.
- Unique Organic Nutrients: Contains seaweed polysaccharides, alginic acid, mannitol, etc. Seaweed polysaccharides can form a water-retaining film and improve soil; mannitol can scavenge free radicals in plants and enhance stress resistance.
- Highly Active Substances: Rich in polyphenols, vitamins, trace elements, etc., it comprehensively nourishes crops and improves quality.
Humic Acid: The Soil’s “Architect and Nutrient Reservoir”
As the core of soil organic matter, humic acid focuses on the fundamental improvement of the soil environment.
- Building Soil Aggregate Structure: It acts as a “universal glue” for soil, binding dispersed individual particles into loose, porous aggregates, fundamentally solving soil compaction and coordinating water, air, and heat supply.
- Fertilizer and Water Retention: Its large specific surface area allows it to absorb large amounts of nutrients and water, significantly reducing the loss of nitrogen, phosphorus, potassium, and water, and improving fertilizer utilization.
- Gentle Growth Promotion: It stimulates the reproduction of soil microorganisms and gently promotes root development.
Fulvic Acid: A “Highly Efficient Messenger and Activator” Between Soil and Plants
As the smallest molecular weight and most active component of humic acids, fulvic acid is a key bridge connecting soil improvement and plant response.
- High Physiological Activity: It significantly increases the activity of various enzymes in plants, enhances photosynthesis, and can cause partial closure of stomata during drought, resulting in extremely strong drought resistance.
- Stress Resistance Core: It can induce plants to produce stress-resistance proteins and substances, comprehensively improving crops’ resistance to drought, cold, waterlogging, salinity, and disease.
- Synergistic transport: When applied together with nutrients, it can open up plant absorption channels and act as a synergist.
Synergistic Effects: Building a Healthy Soil-Plant Ecosystem
The “Combined Punch” of Soil Improvement: Humic acid is responsible for building a loose soil physical structure, while the polysaccharides in seaweed fertilizer work together with humic acid to enhance soil water retention and biodiversity. Fulvic acid acts as a “catalyst,” activating the rhizosphere microbial community, making the improvement effect faster and deeper.
The “Two-Way Regulation” of Plant Growth: Seaweed fertilizer provides comprehensive endogenous hormones and nutrients, gently and persistently regulating the growth and development of plants throughout their entire life cycle, avoiding the risk of pesticide damage. Fulvic acid acts as an “amplifier,” rapidly transmitting and amplifying this regulatory signal, making the crop response faster and stronger.
The “Triple Protection” of Stress Resistance:
- Seaweed fertilizer provides substances such as betaine and polyphenols, directly enhancing the cell’s osmotic regulation capacity and scavenging free radicals.
- Fulvic acid activates the plant’s systemic stress-resistance genes.
- Humic acid provides a solid “rear base” for plants to resist adversity by optimizing the rhizosphere environment.
These three elements work synergistically to form a strong defense against harsh environments.
A comprehensive solution for quality improvement: The full nutrition and natural hormones of seaweed fertilizer can significantly promote uniform fruit coloring, increase sweetness and reduce acidity, and improve vitamin content. Humic acid and fulvic acid further solidify the foundation of fruit quality by promoting root absorption and transport of more micronutrients.
1. All-Purpose/Basic Care Formula
- Ratio: Seaweed fertilizer (10%-15%) + Humic acid (8%-12%) + Fulvic acid (3%-5%)
- Application Scenarios: This is the most balanced formula, suitable for the entire growth period of crops, especially the vegetative growth period. It simultaneously improves soil, promotes root development, and strengthens plants, laying a solid foundation for high yields. It is a “cure-all” choice for most field crops and fruits and vegetables.
2. Stress Resistance and Quality Improvement/Flowering and Fruiting Stage Special Formula
- Ratio: Seaweed fertilizer (15%-20%) + Fulvic acid (8%-12%) + Humic acid (3%-5%)
- Application Scenarios: Use during flowering, young fruit stage, fruit coloring stage, or before and after encountering stresses such as drought or low temperatures. Increasing the ratio of seaweed fertilizer and fulvic acid aims to maximize their physiological regulatory and stress resistance induction functions, resulting in excellent effects on flower and fruit retention, quality improvement, and stress response.
3. Soil Remediation/Replanting Problem Improvement Formula
- Ratio: Humic acid (15%-20%) + Seaweed fertilizer (5%-8%) + Fulvic acid (5%-8%)
- Application Scenarios: For soils with severe compaction, salinization, and continuous cropping problems. This formula uses humic acid as the “main force” to powerfully repair soil structure; seaweed fertilizer and fulvic acid provide “assistance,” quickly activating the soil and root system, breaking dormancy, and rebuilding a healthy soil micro-ecosystem.
The formulation of biostimulants is a sophisticated art that integrates plant physiology, soil science, and chemistry. It marks a shift in modern agriculture’s philosophy from “feeding plants” to “activating plants and healthy soil.” A deep understanding of the characteristics of each component, mastering their synergistic principles, and being able to flexibly adjust the proportions according to actual production needs will be key for agricultural technicians and large-scale growers to enhance competitiveness and achieve cost reduction and efficiency improvement in the future.