What defines a soil fumigant?

A soil fumigant is characterized as a pesticide that can volatilize into a gas, allowing it to penetrate the soil effectively. This gaseous state enables the fumigant to disseminate throughout the soil and target pests like nematodes, weeds, and diseases, providing a comprehensive treatment before planting crops or in residential settings.

This ability to volatilize is crucial because it facilitates the active ingredient's movement through soil pores, reaching areas that might not be accessible to other types of pesticides. As a result, the soil becomes uniformly treated, which is essential for effective pest management.

In contrast, the other options do not accurately capture the definition of a soil fumigant. A solid pesticide does not possess the same chemical behavior as a fumigant, a liquid herbicide serves a different purpose in controlling plant growth, and a natural pesticide may not have the same efficacy or application methods as a fumigant.