What term is used for the time required for half of a chemical to degrade in the environment?

The term used for the time required for half of a chemical to degrade in the environment is known as "half-life." This concept is fundamental in understanding how long a substance remains active or hazardous after its application. In environmental science and chemistry, half-life describes the time it takes for the concentration of a substance to reduce to half its initial amount due to processes like degradation, metabolism, or chemical breakdown.

Understanding half-life is crucial in fields such as turf and ornamental weed management, as it helps practitioners determine the appropriate timing for reapplication of herbicides and assess their potential impact on non-target organisms and the environment. For instance, knowing the half-life of a herbicide can guide decisions regarding its application to minimize its persistence and mitigate environmental risks.

In contrast, other terms, such as decay time, decomposition time, and excretion time, do not specifically refer to the time required for half of a chemical to degrade and do not have the same specific context in environmental chemistry.