Improving next-generation suspension fertilisers through smart agrochemical formulation design

1. The challenge of electrolyte tolerance

Modern NPK fertilisers and suspension micronutrient formulations are pushing nutrient loading levels to well beyond expected limits. These innovative concepts are producing systems with high electrolyte content. Electrolytes can destabilise traditional surfactants and dispersants, resulting in:

• Sedimentation
• Crystal growth
• Reduced wetting and dispersancy
• Poor tank-mix compatibility
• Reduced storage stability

The impact of electrolytes can be measured using standard CIPAC testing methods appropriate for target formulation type. If an electrolyte environment is having a negative impact on formulation stability, one would expect to see an increase in viscosity or increased sedimentation in the concentrate and possibly precipitation upon dilution. It is recommended that stability testing upon dilution be completed in a representative tank mix dilution mixture to ensure all potential instabilities are reviewed before a formulation is approved.

To maintain performance in these demanding systems, formulators need technologies designed specifically for electrolyte-rich environments. Croda Agriculture's formulation approach to these high electrolyte systems combines technologies such as acrylic polymers, EO/PO block copolymers, alkoxylated alcohols, esters and phosphate esters to provide both steric and electrostatic stabilisation.

Polymers are often selected as preferred dispersing agents when looking for long-term stability. Polymers must be designed appropriately to ensure electrolyte tolerance and therefore performance in challenging systems. Electrolytes cause the electric double layer in electrostatic dispersants or the steric chains (such as PEG) in high molecular weight dispersants to collapse, reducing the effective radius of the dispersant and therefore the formulation stability.

Selecting the right chemistry is important to reduce the likelihood of electrolytes destabilising the formulation. Croda’s Atlox™ 4915 and Atlox 4917 are examples of polymeric dispersing agents designed specifically to overcome some of the challenges electrolytes may present.

In our 'Formulating in the presence of electrolytes' brochure, we discussed

How does the presence of electrolytes impact surfactant performance?

• Importance of selecting the right wetting agent
• How dispersant design can improve electrolyte tolerance
• Adjuvants for enhanced foliar wetting
• Products recommended for electrolyte tolerance

Download to learn more about designing stable, high-performance formulations in electrolyte-rich environments.

2. Improving micronutrient suspensions

Successful micronutrient formulations rely on the correct combination of wetting agents and dispersants. Dynamic wetting agents improve particle wetting and milling efficiency, while polymeric dispersants maintain long-term suspension stability and help minimise crystal growth.

Products such as Atlox 4894 and Zephrym™ PD3315 have been specifically developed to support high-performance micronutrient suspensions, particularly in electrolyte-rich systems.

3. Building better tank-mix compatibility

Tank-mix compatibility remains a major challenge for growers. Atlox 4919 was developed as an electrolyte-tolerant dispersant and compatibiliser to improve stability when crop protection formulations are mixed with concentrated fertiliser solutions.

Atlox 4919 is a nonionic dispersant designed to have both strong adhesion to organic plant protection active substances and a chemical structure which is not compromised when diluted in an environment with high salt content. These design features of Atlox 4919 mean it is a robust dispersant choice when looking for compatibility upon dilution. 

Key benefits of Atlox 4919 include the following:

• Improved concentrate and dilution stability
• Better fertiliser compatibility
• Reduced sedimentation and phase separation
• Simpler, more reliable tank mixing

4. Simplifying formulation development

Formulators are increasingly seeking multifunctional technologies that reduce complexity without compromising performance. Atlox PN-100 combines dynamic wetting and dispersancy in a single electrolyte-tolerant solution for liquid micronutrient formulations, providing:

• Faster formulation development
• Efficient milling
• High solids incorporation
• Long-term stability
• Improved glyphosate tank-mix compatibility

5. Supporting biological formulations

Biological fertilisers and biostimulants are increasingly being adopted by growers as complementary or alternative approaches to traditional nutrient programmes. While this growing interest in biologicals offers significant opportunities, it also introduces new formulation challenges, particularly around maintaining microbial viability and ensuring long-term product stability.

To address these challenges, Croda Agriculture has screened a broad range of formulation aids to evaluate their compatibility with commonly used microbial strains. Building on this expertise, we have developed Atlox BS-50, a one-pot solution for formulating microbe-containing powder products. 

As a complete wettable powder delivery system, Atlox BS-50 supports effective wetting and suspensibility while maintaining microbial viability, helping formulators reduce development time and bring products to market more efficiently.

6. Enhancing foliar performance

Formulation performance extends beyond the spray tank. Effective spreading, wetting and uptake on the leaf surface are critical for field performance. In a market under pressure to reduce application rates whilst increasing yield, boosting efficacy in application is key. 

Atlox AL-2575 LF is an electrolyte-tolerant, foliar adjuvant that provides the following:

• Rapid wetting and spreading
• Excellent foam control
• Improved uptake of systemic actives & nutrients 
• Consistent performance across different leaf surfaces

Addition of Atlox AL-2575 LF, even at low inclusion levels, can significantly boost the efficacy of a fertiliser or biostimulant formulation in the field. 

Your partner for formulation development

The future of suspension fertilisers depends on smarter formulation strategies capable of overcoming the challenges presented by concentrated electrolytes, biological actives and increasingly complex tank mixes.

Next-generation suspension fertilisers won't succeed on nutrient content alone. They need formulation strategies that hold up under concentrated electrolytes, biological actives and increasingly complex tank mixes. That's where electrolyte-tolerant technologies come in.

At Croda Agriculture, we combine formulation expertise with high-performance surfactant technologies to help our customers develop stable, effective and sustainable next-generation fertiliser systems. From micronutrient suspensions and biological formulations to advanced adjuvant technologies, our goal is to help formulators innovate with confidence.

Want the full technical detail? Stabilisation mechanisms, wetting agent selection, dispersant chemistry, and product recommendations for electrolyte-rich systems: [Download Formulating in the presence of electrolytes] and see how to build tolerance into your next formulation.