How is phosphorus primarily transported from fields?

Phosphorus is primarily transported from fields through runoff. This occurs when excess water from precipitation or irrigation carries phosphorus particles and dissolved phosphorus from the soil into nearby water bodies. Unlike nitrogen, which can be leached out of the soil and into groundwater, phosphorus tends to bind closely to soil particles. Therefore, when rainfall or irrigation creates surface runoff, this water can pick up phosphorus along with sediment and transport it to streams, rivers, and lakes.

In contrast, leaching refers to the downward movement of soluble substances through the soil profile, which is less significant for phosphorus due to its affinity for soil particles. Evaporation pertains to the process of water turning into vapor and does not play a role in phosphorus transport. Infiltration involves the movement of water into the soil and while it can influence nutrient movement within the soil, it does not directly lead to the transport of phosphorus away from fields. Hence, runoff is the key mechanism for phosphorus loss from agricultural land.