What method places a pesticide below the soil surface and is often used for fumigants?

Soil injection is a method specifically designed for placing pesticides below the soil surface, which is particularly effective for certain types of chemicals, including fumigants. This technique involves inserting a pesticide formulation directly into the soil using specialized equipment, allowing the pesticide to be delivered to the targeted area without the volatility issues that can occur with surface applications. This method minimizes exposure to non-target organisms and helps in managing pests that reside in the soil or are associated with plant roots.

Many fumigants require soil incorporation for effective pest control due to their gaseous nature once they volatilize, making soil injection an ideal application method. It ensures the pesticide remains in contact with the pests for a longer duration and within the zone where they are active.

Other methods mentioned, like surface application, are designed for use on the top layer of soil and are not effective for fumigants that need to penetrate deeper. A root drench typically involves applying a liquid pesticide around the base of a plant to target root pathogens and is not suitable for the application depths that fumigants often require. Pulled trenching is not a standard term associated with pesticide application, making it less relevant in this context. Thus, soil injection stands out as the most suitable method for this purpose.