Which fertilizer is considered most toxic to soybean seedlings?

Anhydrous ammonia is considered the most toxic to soybean seedlings primarily due to its high concentration of ammonia gas, which can be damaging to young plants. When applied, anhydrous ammonia must be incorporated into the soil quickly to minimize injury risk. If not managed properly, the ammonia can volatilize and negatively affect seedling development.

Soybean seedlings are particularly sensitive to high levels of ammonia, which can lead to impaired root development, leaf burn, and overall stunted growth. Additionally, anhydrous ammonia's gaseous nature makes it prone to movement in the soil and can create a toxic environment for the seedlings if they are too close to the application site or if it's applied improperly.

In contrast, the other fertilizers listed, such as Monoammonium Phosphate (MAP), ammonium nitrate, and potash, have different chemical compositions and behaviors in the soil, resulting in a much lower risk of toxicity to seedlings when applied as recommended. MAP and ammonium nitrate provide nitrogen in a more stable form that is less likely to harm young plants, while potash primarily supplies potassium, which is essential for plant health but does not pose similar toxicity risks.