What does chemigation refer to?

Chemigation specifically refers to the application of chemicals, typically fertilizers or pesticides, through an irrigation system. This method allows for the precise delivery of the chemicals to the plants while they are being watered, promoting efficient use and reducing labor. The key aspect of chemigation is that it involves introducing solutions into the irrigation system, which could include emulsifiable concentrates.

The other options relate to different application methods or forms that do not pertain to the concept of using an irrigation system to distribute chemicals. For instance, using granules for soil treatment and injecting solid fumigants into the soil represent alternative methods of applying pesticides or fumigants, but they do not define chemigation. Similarly, using chemical mixtures to control surface pests indicates a different approach not linked to the irrigation system used in chemigation. Each of these methods has its own context, but they do not encapsulate the definition of chemigation.