Most nitrogen enters corn roots through which process?

The correct choice, mass flow, describes the primary mechanism by which nitrogen is absorbed by corn roots, particularly in the form of nitrate. In mass flow, water movement through the soil carries dissolved nutrients, including nitrogen, toward the roots of plants. As roots take up water to meet their hydration needs, they also absorb the nitrogen that is naturally present in the water.

This process is efficient because it allows the plant to capture nitrogen as it naturally moves within the soil solution, enhancing nutrient availability. During times of adequate moisture, mass flow becomes the dominant pathway for nitrogen uptake, facilitating better growth and development of the corn plants.

While diffusion and active uptake are also important processes for nutrient absorption, they play different roles. Diffusion is a passive movement of nutrients from areas of high concentration to low concentration, which can be slower and not as effective for larger nutrient quantities. Active uptake requires energy to transport nutrients against their concentration gradient, which is necessary for certain nutrients, but not the dominant pathway for the bulk uptake of nitrogen in corn. Leaching, on the other hand, refers to the loss of nutrients from the soil profile due to water movement, which is not a mechanism for nutrient entry into the roots but rather a process that can lead to reduced nitrogen availability