Direct injection is not new. It refers to having the spray tank full of water, or perhaps water and one chemical, and then injecting other chemicals into the mix from outside the tank. With a return to more soil-applied herbicides to get a residual down and try to stave off more weed resistance, this concept could make a comeback.
There are different types of direct injection systems. Some self-propelled sprayers offer up to three tanks with three separate pumps so you could add chemicals on the go. That could come in handy, experts say, especially if say you're spraying atrazine in the mix. It's being injected as called for by the computer monitoring the application. Since atrazine can't be used within a set number of feet of streams and water bodies, the computer could take it out of the mix when the sprayer was within the distance where atrazine was not to be applied.
Other simpler systems, often found on pull-behind sprayers, may feature one tank. You dump in each produce one at a time as you're loading the sprayer with the next batch for the field. What either of these systems can do is keep chemicals and herbicides from settling in the tank already mixed for long periods. There are settling out issues with some chemicals. That's why several reps prefer that you carry only water in the tank, and add the chemicals and herbicides you need as you prepare the batch.
It simplifies clean-up and reduces the risk of contamination if you only have water in the main tank. With the systems that inject on the go, the chemicals don't enter the main tank, thereby cutting out worries about residues in the tanks of that product.
Look for more companies to talk about these types of features as you shift toward more soil-applied herbicides in an effort to get a better handle on weed control of tough weeds.