--- title: Correct chemical mixing description: Mixing spray products in the wrong order causes blockages, precipitation and spray failure. Use the WALES sequence, a step-by-step tank fill and a simple jar test. image: https://www.highlandsagsolutions.com.au/hubfs/AI-Generated%20Media/Images/Organized%20Agricultural%20Pesticide%20Mixing%20Workspace.png --- [Skip to the main content.](https://www.highlandsagsolutions.com.au/the-farm-shed/correct-chemical-mixing#main-content) [![HAS](https://www.highlandsagsolutions.com.au/hubfs/Highland%20Ag%20Solutions-Logo.svg "HAS")](https://www.highlandsagsolutions.com.au/home) [![HAS](https://www.highlandsagsolutions.com.au/hubfs/Highland%20Ag%20Solutions-Logo.svg "HAS")](https://www.highlandsagsolutions.com.au/home) - [Services](https://www.highlandsagsolutions.com.au/services) - [About us](https://www.highlandsagsolutions.com.au/about-us) - [Contact us](https://www.highlandsagsolutions.com.au/contact-highlands-ag-solutions) Search Toggle Menu Search Toggle Menu - [Services](https://www.highlandsagsolutions.com.au/services) - [About us](https://www.highlandsagsolutions.com.au/about-us) - [Contact us](https://www.highlandsagsolutions.com.au/contact-highlands-ag-solutions) [Facebook](https://www.highlandsagsolutions.com.au/the-farm-shed/correct-chemical-mixing#highlands_ag_solutions) [Instagram](https://www.highlandsagsolutions.com.au/the-farm-shed/correct-chemical-mixing#highlands_ag_solutions) [Linkedin](https://www.highlandsagsolutions.com.au/the-farm-shed/correct-chemical-mixing#highlands_ag_solutions) 4 min read # Correct chemical mixing [Will Black](https://www.highlandsagsolutions.com.au/the-farm-shed/author/will-black) : Published November 5, 2026 [Implementation](https://www.highlandsagsolutions.com.au/the-farm-shed/tag/implementation) ![Correct chemical mixing](https://www.highlandsagsolutions.com.au/hs-fs/hubfs/AI-Generated%20Media/Images/Organized%20Agricultural%20Pesticide%20Mixing%20Workspace.png?width=1536&height=1024&name=Organized%20Agricultural%20Pesticide%20Mixing%20Workspace.png) *Getting the order right every time* When filling a spray tank with multiple products, the order in which they are added is not arbitrary. Different pesticide formulations behave differently in water, and adding them in the wrong sequence can cause chemical precipitation, blocked nozzles and filters, reduced efficacy, and in some cases crop damage that cannot be undone. Correct mixing sequence takes no extra time. It simply requires knowing the order and applying it consistently. The WALES framework provides a reliable, easy-to-remember guide that covers the vast majority of spray tank situations encountered in pasture and broadacre systems. **Before mixing anything: read the label** Every product label specifies the manufacturer's mixing recommendations for that formulation. The WALES sequence covers standard mixing order, but specific products may have particular requirements or incompatibilities that override the general rule. Label directions take precedence. ## The WALES Mixing Sequence WALES is a widely used mnemonic in Australian agriculture that captures the correct order for adding different pesticide formulations to a spray tank. Each letter represents a product type or action, ordered from first to last. | Step | Product type | Why this order matters | | --- | --- | --- | | **W** | Wettable powders / WDG | Wettable powders (WP) and water-dispersible granules (WDG) — added first as they require the most agitation to disperse correctly. | | **A** | Agitate | Agitate thoroughly between each addition — not a product type, but an essential step. Never add the next product until the previous one is fully dispersed. | | **L** | Liquid suspension concentrates | Flowable and suspension concentrate (SC) formulations — already finely dispersed but still require agitation to remain stable in the tank. | | **E** | Emulsifiable concentrates | EC formulations form emulsions in water. Adding them too early can interfere with dispersion of dry products already in the tank. | | **S** | Surfactants and adjuvants | Surfactants, crop oils, penetrants, and drift control agents — added last to prevent foaming and ensure all active ingredients are fully dispersed first. | The sequence reflects the physical chemistry of different formulations in water. Dry products require sustained agitation and full dispersion before other formulation types are added. Emulsifiable concentrates, if added too early, can interfere with that dispersion. Surfactants added prematurely cause foaming that prevents the even mixing of active ingredients. ## Step-by-step tank filling process The following process applies the WALES sequence to a practical spray tank filling routine, including the water quality preparation steps covered in the companion article on water quality and pesticide performance. | # | Step | Examples | Notes | | --- | --- | --- | --- | | **1** | Fill to 30–50% capacity | — | Clean water only at this stage. Begin agitation immediately. Never add chemicals to an empty or near-empty tank. | | **2** | Add water conditioners | Ammonium sulphate (AMS), LI-700, InterLock | Must be dissolved and mixed before any pesticide is added. Critical for glyphosate and other herbicides sensitive to hard water — see companion article on water quality. | | **3** | Add wettable powders and WDG | Metsulfuron-methyl, atrazine WG, some residual herbicides | Require the strongest agitation of any formulation type. Add slowly and allow to fully disperse before proceeding. | | **4** | Add suspension concentrates (SC) | Terbuthylazine SC, simazine SC, many fungicides | Finely dispersed but still require agitation. Confirm dispersion is complete before adding the next product. | | **5** | Add soluble liquids (SL) | Glyphosate, most amine herbicides | Dissolve readily. Adding after dry formulations ensures no interference with dispersion of powders. | | **6** | Add emulsifiable concentrates (EC) | Many insecticides, some grass herbicides, some fungicides | Form emulsions in water. Added near the end to avoid disrupting dispersion of earlier products. | | **7** | Add adjuvants and surfactants | Non-ionic surfactants, crop oils, penetrants, drift retardants | Added last to prevent excessive foaming and to ensure all active ingredients are fully dispersed before surfactants alter droplet behaviour. | | **8** | Top up to final volume | — | Continue filling while maintaining agitation. Confirm all products are fully mixed and tank contents are homogenous before commencing spraying. | **The most common mistake in the sequence** Adding ammonium sulphate or water conditioners after the herbicide has already been mixed with hard water. Once calcium and magnesium ions have bound to glyphosate molecules, adding AMS cannot reverse that reaction. The conditioner must always go in first, before the herbicide. ## What can go wrong - Common mistakes and consequences Most mixing problems are predictable and preventable. The following table summarises the most common sequencing errors encountered in practice, the consequences of each, and how to prevent them. | Common mistake | Consequence | Prevention | | --- | --- | --- | | **Surfactants added too early** | Excessive foaming; other products cannot disperse properly | Add surfactants, oils, and adjuvants last, after all active ingredients are in the tank | | **EC added before WP/WDG** | EC emulsion disrupts powder dispersion; clumping or precipitation | Follow WALES sequence; fully disperse dry products before adding EC formulations | | **Water conditioner added after herbicide** | Minerals have already bound to herbicide molecules; conditioning cannot reverse this | AMS and water conditioners must be the first addition, before any pesticide | | **Products added to insufficient water volume** | Concentrated chemical contact between incompatible products in small volume | Always fill to at least 30-50% of tank capacity with water before adding any products | | **Tank left without agitation** | Formulations separate; uneven concentration when spraying; potential for incompatibility reactions | Maintain agitation throughout filling and never leave mixed spray solution static for extended periods | | **Multiple unfamiliar products mixed without jar test** | Incompatibility discovered in the paddock rather than at the shed | Conduct a jar test with small volumes before committing to a full tank mix with unfamiliar combinations | ## The Jar Test — Check before you mix When combining products that have not been mixed together before, a jar test is a simple and reliable way to check for compatibility before committing to a full tank load. The test takes a few minutes and can prevent a costly incompatibility from being discovered in the paddock. **How to conduct a jar test** - Use a clean, clear glass jar or measuring cylinder as the test vessel. - Fill with a small volume of the same water source you will use in the spray tank. - Add each product in the same proportion and sequence you intend to use in the tank. - Agitate between each addition, as you would in the spray tank. - Allow to stand for 15-30 minutes after all products have been added. - Check for signs of incompatibility: visible separation, precipitation, thick lumps, or oily residue that cannot be re-mixed by shaking. - If the mixture remains homogenous and re-mixes easily after standing, it is likely compatible in the tank. - If separation or precipitation occurs, do not proceed with that combination. Consult the product labels or seek advice. A jar test does not guarantee that a mix will perform optimally, but it will reliably identify gross incompatibilities before they cause equipment problems or spray failures. It is particularly valuable when mixing unfamiliar products, products from different manufacturers, or combinations not listed on either label. ## Pre-Spray Preparation Checklist **Before filling the spray tank** - Read the label on every product being mixed – check for specific mixing instructions and known incompatibilities. - Test water quality if the source has changed or if past spray results have been inconsistent. - Confirm sprayer filters and nozzle strainers are clean and undamaged. - Rinse measuring equipment between each product to avoid cross-contamination. - Conduct a jar test if mixing unfamiliar products or unfamiliar combinations. - Check agitation is functioning before adding any products. - Have all products measured and ready before beginning to fill – do not interrupt the mixing process to locate additional products. **Part of the HAS Spraying Best Practice Series** This article is part of a three-part series on spray best practice for Southern Highlands producers: - [Spray Rig Calibration](https://www.highlandsagsolutions.com.au/the-farm-shed/calibrating-your-spray-rig) — getting the application rate right every time - [Water Quality and Pesticide Performance](https://www.highlandsagsolutions.com.au/the-farm-shed/water-quality-and-pesticide-performance) — why what is in your tank matters - Correct Chemical Mixing Sequence — this article **How Highlands Ag Solutions can help** - Spray program design and tank mix advice - Herbicide and pesticide product selection - Water quality assessment for spray operations - Spray calibration and nozzle selection reviews - Integrated weed and pest management planning **[Book a free on-farm consultation →](https://www.highlandsagsolutions.com.au/contact-highlands-ag-solutions)** - [Tweet](https://twitter.com/share) - [Privacy Policy](https://www.highlandsagsolutions.com.au/privacy-highlands-ag-solutions-4ab17342-635a-4dfa-ab52-8dacaf65a12) - [Terms & Conditions](https://www.highlandsagsolutions.com.au/terms-conditions) Don't miss out Don't miss out Keep up to date with our latest on-farm research, agronomic advice, seasonal insights, and farm management tips. 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