Glyphosate is a widely used, non-selective herbicide, commonly recognized as the active ingredient in products like Roundup. After using any herbicide, it is important to thoroughly clean the sprayer equipment before introducing a different product. This necessary cleaning procedure prevents unintended crop injury, known as phytotoxicity. Even minute amounts of glyphosate residue left in the tank, hoses, or nozzles can severely damage sensitive plants when the sprayer is later used for fungicides or insecticides. A comprehensive clean-out prevents cross-contamination, ensuring the next application is effective and safe.
Safety Measures and Initial Preparation
Before beginning any cleaning process, protect yourself by wearing appropriate Personal Protective Equipment (PPE). This typically includes chemical-resistant gloves, protective eyewear, and long-sleeved clothing to minimize skin contact with residual herbicide, as cleaning involves handling concentrated residue and cleaning agents.
The first step involves emptying the system of the remaining glyphosate mixture. This residue should be sprayed onto an area already treated with the herbicide, or on a location listed on the product label as a safe application site; never down a drain or into a storm sewer. Once empty, a preliminary rinse with clean water helps remove loose material clinging to the tank walls and internal components.
Circulate this initial rinse water through the pump and boom for several minutes, then spray it out onto the same safe application area. This initial flush removes the bulk of the chemical product before introducing a cleaning solution.
Selecting and Applying the Primary Cleaning Solution
After the initial rinse, a chemical cleaning agent is introduced to dissolve and deactivate any remaining residue. Water alone is generally not sufficient to eliminate all residues that adhere to plastic and rubber components. Effective cleaning agents for glyphosate residue often include household ammonia, specific commercial tank cleaners, or a strong water-soluble detergent.
A 1% to 2% solution of household ammonia is a common cleaning solution, mixed at about one gallon of 3% ammonia for every 100 gallons of water. Commercial tank cleaners are also highly effective and often contain specialized ingredients designed to increase solubility and remove oil-based adjuvants. Fill the sprayer tank with clean water and add the chosen agent, allowing the tank to fill to capacity.
The solution must be circulated throughout the entire system using the sprayer’s agitation system for at least 15 minutes. This circulation ensures the cleaning agent reaches the pump, hoses, and boom lines, which are frequent spots for residue buildup. After circulation, the cleaning solution should be run out through the boom and nozzles for at least one minute to ensure the lines are saturated. Allowing the cleaning solution to soak for several hours or even overnight can significantly improve the removal of dried or hardened residues.
Detail Cleaning and Reassembly of Components
The main circulation rinse is effective for the tank and major plumbing, but smaller, intricate components require manual attention. Before spraying out the final cleaning solution, remove all nozzles, screens, end caps, and in-line filters from the boom. These parts often trap solid particles and concentrated residue, making them a primary source of contamination risk.
Place these removed components into a separate container filled with the same cleaning solution used in the main tank. Use a soft brush to scrub the screens, filters, and nozzle tips to dislodge any physical buildup. Thoroughly inspect the hoses and wands for any visible signs of buildup or scaling, paying close attention to low spots or bends where residue can accumulate.
After scrubbing, rinse all the small components thoroughly with clean water to remove any traces of the cleaning agent and dissolved herbicide. Once the main tank has completed its final rinse, these clean filters and nozzles can be reinstalled. Reassembly is the final mechanical step, ensuring all seals and caps are secured before the next application.
Handling and Disposal of Cleaning Waste
Proper handling of the waste solution, known as rinsate, is required. The cleaning solution and subsequent rinse water contain diluted herbicide and must not be poured down residential drains, into septic systems, or directly onto bare soil. Doing so risks contaminating groundwater or local water bodies.
The safest method for disposal is to spray the rinsate over a large area that was already treated with glyphosate, or on an uncropped area listed on the product label as safe for application. Spreading the waste over a large area allows the herbicide to degrade naturally without causing harm.
Following the chemical cleaning step, the sprayer must be rinsed with clean water at least two to three separate times. Repeat the process of filling, circulating, and spraying out the contents onto the designated safe application area. This final triple-rinse procedure ensures that the concentration of any remaining glyphosate is reduced to levels that pose no risk to sensitive future crops.