Which nutrient is most likely to be mobile in soil?

Nitrate is considered the most mobile nutrient in soil due to its solubility in water and its negative charge, which prevents it from strongly binding to soil particles. This characteristic allows nitrates to move easily with water during rainfall or irrigation. As a result, they can leach deeper into the soil profile, making them readily available to plants throughout their root systems. This mobility is critical for plant nutrition, especially in environments where water movement is significant.

In contrast, other nutrients listed, such as calcium and potassium, are primarily positively charged and tend to adhere more strongly to soil particles, reducing their mobility. Ammonium, while also capable of being mobile, is less so than nitrate because it can be adsorbed by soil particles, especially in certain soil types. Understanding the mobility of these nutrients is vital for effective soil management and ensuring optimal plant growth.