What does stability mean in biostimulants?

Stability encompasses all properties that ensure a biostimulant retains its composition and function throughout its entire lifecycle.

Important forms of stability are:

• Chemical stability (no degradation of active substances)
• Physical stability (no settling or clumping)
• Biological stability (microbial control or viability)
• Application stability (mixability in tankmix)

The impact of pH and salt stress

One of the most underestimated factors in formulation is the impact of pH stability. Many active compounds such as fulvic acids, amino acid complexes, and microbial metabolites are sensitive to pH extremes.

A pH outside the optimal range can lead to:

• faster breakdown of bioactive compounds
• precipitation of micronutrients
• loss of chelation capacity

Therefore, pH buffering is a core part of formulation technology.

Compatibility of biostimulant raw materials

Biostimulants rarely consist of a single component. Modern products combine multiple biostimulant raw materials that support different physiological pathways.

Synergy only arises when raw materials are compatible within the same matrix. Important questions are:

• Are extracts soluble in the same pH range?
• Do chelators interfere with microbial components?
• Are there unwanted salt reactions or bindings?
• Is there a risk of microbial contamination during storage?

Examples of functional combination clusters

Formulators often build around clear functional clusters:

• Fulvic chelation + micronutrients for uptake efficiency
• Protein hydrolysates + osmoprotectants for stress buffering
• Polysaccharides + elicitors for plant priming
• Microbial metabolites + humic acids for rhizosphere activation

Shelf life and storage stability

For buyers and distributors, shelf life is a direct economic factor. Biostimulants are stored under varying temperatures and logistical conditions.

The shelf life is influenced by:

• oxidation of phenols and extract components
• hydrolysis of organic compounds
• microbial growth in liquid formulations
• precipitation of salts and metals

Stable products therefore require antioxidative protection and controlled preservation.

Microbial stability: living versus non-living inputs

Microbial biostimulants bring extra complexity. Living inoculants require strict control of osmolarity, pH, and storage conditions.

Therefore, part of the market is shifting to microbial metabolites: bioactive signaling substances without the instability of living organisms.

Mixability in the spray solution (tankmix)

In practice, biostimulants are often combined with fertilizers, crop protection products, and adjuvants. Therefore, mixability is a commercial condition.

Important risks are:

• flocculation and precipitation
• pH shifts after mixing
• binding of active components

Stability as a basis for reliable market claims

New regulations require reproducibility and quality control. A biostimulant can only be credibly positioned when active components demonstrably remain stable.

Formulation and stability thus form the basis for market access, customer confidence, and long-term commercial value.

From formulation to performance: stress to yield

A stable biostimulant formulation enables plants to remain functional under stress. This translates into:

• better root activity and uptake
• more stable photosynthesis
• faster recovery after stress events
• more consistent yield and quality

Overview: stability factors in biostimulants