What impact does excessive tillage have on soil structure?

Excessive tillage can deteriorate soil structure due to the breakdown of soil aggregates and the disruption of the natural arrangement of soil particles. This disruption leads to a reduction in pore space, which is critical for water infiltration, root growth, and the movement of air and nutrients. When soil is frequently tilled, it can also lead to soil compaction beneath the surface layer, which further impedes water movement and root penetration.

Moreover, the biological activity in the soil, which contributes to the formation and stability of aggregates, can be negatively impacted by excessive mechanical disturbance. This disturbance can reduce the organic matter content, diminish microbial populations, and hinder the development of beneficial soil organisms.

It's essential to maintain a balanced approach to tillage, as well-managed tillage practices can enhance soil structure to a certain extent. However, over-tilling tends to cause more harm than good, leading to long-term degradation of soil health and fertility. Thus, the correct option highlights the adverse effects of excessive tillage on soil structure.