Why Water Quality Matters More Than Ever
Water is the primary carrier in most spray applications, yet it is often overlooked as a critical component of herbicide performance. Whether sourcing water from municipal systems, surface water, or on-farm wells, applicators frequently encounter variability in water quality—particularly hardness and alkalinity.
Among these factors, hard water remains one of the most common and impactful challenges affecting spray tank mixtures. Poor water quality can reduce herbicide efficacy, create compatibility issues, and increase equipment maintenance costs.
Understanding and managing water quality is essential to maximizing the return on every application.
What is Hard Water
Hard water contains dissolved minerals, primarily:
- Calcium (Ca²⁺)
- Magnesium (Mg²⁺)
These minerals are measured as calcium carbonate equivalents (CaCO₃) and classified as:
| Hardness Level | mg/L (ppm) as CaCO₃ |
|---|---|
| Soft | 0–60 |
| Moderately Hard | 61–120 |
| Hard | 121–180 |
| Very Hard | >180 |
How Hard Water Affects Spray Tank Performance
1. Reduced Herbicide Efficacy
Certain herbicides—especially weak-acid chemistries—are highly sensitive to hard water cations. Examples include: Glyphosate, 2,4-D (amine forms), Dicamba, Triclopyr, Acifluorfen
Calcium and magnesium ions bind with these herbicides to form less soluble complexes, reducing their ability to:
- Penetrate the leaf cuticle
- Translocate within the plant
This leads to weaker and less consistent weed control.
Important distinction: Herbicides like glufosinate are less sensitive to hard water and rely more on spray coverage and surfactant systems for performance.
2. Formation of Precipitates
Hard water can react with Herbicides, Fertilizers and Adjuvants. This can result in insoluble particles and sediment formation.
These materials can:
- Plug nozzles and screens
- Disrupt spray patterns
- Cause uneven application
3. Compatibility Issues
High mineral content increases the risk of:
- Layering
- Gel formation
- Separation in tank mixes
This is especially problematic in multi-product tank mixes, where interactions become more complex.
4. Equipment Wear and Scaling
Over time, mineral deposits form scale inside Tanks, Lines and Nozzles
This leads to:
- Reduced efficiency
- Increased maintenance
- Shortened equipment lifespan
5. pH-Related Performance Impacts
Hard water itself does not always change pH significantly. However, associated bicarbonates often raise pH, which can:
- Reduce stability of certain actives
- Slow herbicide uptake
- Increase degradation risk in some chemistries
Best Practices for Managing Hard Water
1. Condition Water First (AMS is Still the Standard)
Ammonium sulfate (AMS) remains the most effective tool for overcoming hard water antagonism.
How it works:
- Sulfate ions bind preferentially with Ca²⁺ and Mg²⁺
- Prevents interaction with herbicides
- Improves herbicide absorption
Typical use rates:
- Dry AMS: 8.5–17 lb per 100 gallons
- Liquid AMS substitutes: Follow label-equivalent rates
Always add AMS before herbicides to ensure proper conditioning.
2. Address Alkalinity and pH
When bicarbonates are high, consider:
- Buffering agents
- pH modifiers
Most herbicides perform best in a slightly acidic range:
- Target pH: 4.5–6.5 (verify per label)
3. Use Modern Adjuvant Systems
Today’s adjuvant technologies often combine:
- Water conditioning
- Surfactants
- Deposition aids
Selecting the right system is critical for consistent performance.
4. Conduct Jar Tests
Before mixing large spray loads:
- Simulate the mix in a small container
- Observe for Precipitation, Separation, Heat or reaction
This simple step can prevent costly field issues.
5. Follow Proper Mixing Order
Correct mixing sequence reduces compatibility problems:
- Water
- AMS or water conditioner
- Dry formulations (DF, WDG)
- Liquid formulations (SC, EC, SL)
- Adjuvants and surfactants
6. Consider Temperature and Carrier Volume
- Cold water slows solubility and mixing
- Low carrier volumes can intensify antagonism in hard water
Whenever possible:
- Use moderate water temperatures
- Adjust carrier volume based on label and conditions
7. Follow Label and Stewardship Requirements
Many modern herbicide systems (e.g., dicamba platforms) include specific water quality and adjuvant requirements.
Always:
- Follow label instructions
- Use approved adjuvants
- Document water conditioning practices
Hard water is not just a nuisance—it is a key variable that can determine application success or failure.
By understanding the roles of Hardness (calcium and magnesium), Alkalinity (bicarbonates), pH and formulation interactions
…and applying the right conditioning strategies, applicators can:
- Maximize herbicide performance
- Improve tank mix compatibility
- Reduce equipment issues
- Achieve more consistent weed control
Product Solutions
Brewer International offers a range of adjuvant technologies designed to address water quality challenges, including:
- Water conditioners
- pH modifiers
- Surfactant systems with built-in conditioning
Products such as Surfactant pH with Nitrogen, AquaBupH, and Sun Control are designed to help optimize spray solution conditions and improve herbicide performance across a range of field environments.
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