Surface application of fertilizer is relatively inexpensive and primarily affects which part of the soil?

The surface application of fertilizer primarily affects the upper few inches of soil due to how these nutrients interact with the soil and plant systems. When fertilizer is spread on the surface, it dissolves and becomes available to plants primarily in the top layer of soil where most of the root systems are located. This is especially important in ensuring that the nutrients can be readily absorbed by the active root zone within the topsoil, which is rich in organic matter and microbial activity that aid in nutrient uptake.

Unlike deeper soil layers, where the concentration of nutrients would be significantly lower and the physical movement of nutrients would be limited by soil structure and water movement, the upper layer is where plants can effectively utilize the nutrients provided by surface applications. This method is particularly beneficial for rapid nutrient availability and is often used in practice for maintaining healthy plant growth, especially in turf and landscape applications.