What type of herbicides kill most vegetation and may leave the soil nonproductive for one to several years?

Long-term residual (LTR) herbicides are designed to persist in the soil for extended periods, which can lead to a reduction in plant growth and difficulties in soil productivity. These herbicides typically have a chemical makeup that allows them to remain active in the environment, affecting a wide range of plants. This persistence can prevent the germination and growth of new plants for one to several years, creating challenges for land management and restoration efforts.

In contrast, short-term residual herbicides are meant to break down more quickly in the soil, meaning they are less likely to have a lasting impact on soil health or subsequent plant growth. Selective herbicides are formulated to target specific types of plants, making them less broad in their effect, and contact herbicides work by killing the vegetation they directly touch, but they do not have a residual effect on the soil. Thus, long-term residual herbicides are the choice that aligns with the condition of leaving soil nonproductive for a significant period while also killing most types of vegetation.