'Must-dos' for more efficient sprayer rinsate management

Taking steps at the start of spraying is key to minimizing rinsate in the cleanout process

Posted: June 1, 2009

As an extension specialist, Mike Hittinger has seen lots of examples of how improper rinsate management can damage a crop, but perhaps one of the most dramatic is seeing crop loss the width of the sprayer and up to a quarter-mile long, tapering in as the new herbicide takes the place of the old one. And then there are the environmental risks of rinsate potentially threatening soil, groundwater or surface water.

The problem is that the management of rinsate – the by-product of cleaning sprayer tanks, rinsing containers or cleaning up chemical spills – can be a time-consuming and cumbersome process with a wide range of decisions to make. As a result, producers may be tempted to take shortcuts. From a financial and environmental perspective, however, it's something that shouldn't be avoided.

There are some ways to make the rinsate management process more efficient, with perhaps the main one being an effort to take steps at the beginning of the spraying process to make sure there is as little rinsate to deal with at the end as possible.

The risks of rinsate

From an agronomic perspective, the most obvious risk of improper rinsate management is crop damage, the result of insufficient rinsing, says Hittinger, a conservation coordinator with the North West Alliance Conservation Initiative in Sturgeon County, Alberta.

"This is especially true with granular herbicides which, especially in sprayers with poor agitation, have a tendency to hang up in screens, boom ends, and filters, breaking loose sometimes several fields later, often on a crop that is susceptible to that herbicide."

The environmental contamination potential from crop protection products is well-documented. "Monitoring of water bodies sometimes reveals concentrations of agricultural pesticides," says Hittinger. "This can accumulate from rinsate disposal in ditches or near water bodies."

In many ways, says Hittinger, good rinsate management practices come down to being a good neighbour and fellow farmer. "A detrimental effect of improper rinsate disposal is that, if there happens to be a sensitive crop downstream from a rinse location, it can be damaged as well. For example, if a chemical washes down from a rinse site into a neighbouring pulse crop, we have seen the crop loss in the water run with tests showing the death from chemical symptoms and not drowning."

Four management tips

Like Hittinger, Jock McIntosh, chemical senior policy advisor with Alberta Environment, understands the complexities of handling rinsate at the farm level. Here are four tips from McIntosh and Hittinger to help producers reduce the risks.

1. Minimize, minimize, minimize. The first step in managing rinsate is making sure there's as little of it as possible. "Try to manage the order of spraying in a way that minimizes the need for rinsing and cleanouts," says Hittinger.

"This means making an effort to use products that not only fit into your herbicide rotation, but also may be compatible with the next crop to be sprayed. For example, this might include spraying as many cereal fields as possible before switching to oilseeds or pulses, and even within cereals, spray oats before moving to a wild oat herbicide on wheat or barley instead of the reverse. Trying to follow an order will minimize both the need for rinsing as well as the time and inconvenience involved."

Another strategy is using products with more steps in the rinsing procedure all at the same time. "For example, granular herbicides have more rinsing steps, which means more rinse water to dispose of, so if there are three fields all requiring the same granular herbicide, try to do all three fields one after the other to allow one intensive rinse instead of two or three."

McIntosh emphasizes the basics of producers mixing and using only what they need before spraying. Keeping the amount of water used in the cleanout process to a minimum is also key.

2. Reuse properly. Reuse rinsate as soon as you can, preferably over the field where the pesticide product was applied and the full value of the product can be realized, says McIntosh. "Small quantities of leftover product mixed with rinsate can be used to touch up fencelines and areas inaccessible to larger spray equipment using smaller application equipment, such as backpack or ATV sprayer units."

3. Follow label recommendations. When using collected rinsate as make-up water, remember to ensure that the pesticides in the mix are registered mixes that are specifically mentioned on the label for use on the intended application site and that it is not going to exceed the legal/label use rate, says McIntosh.

4. Avoid long-term storage. Avoid long-term storage of rinsate, says McIntosh. "If you have to store it, remember to label it with the contents and the date it was collected."