How do tillage practices affect soil structure and fertility?

Tillage practices can disrupt soil structure, leading to erosion, and can also deplete soil fertility over time.

Tillage is the agricultural practice of preparing the soil for planting by mechanical agitation, such as digging, stirring, and overturning. While it can initially improve soil conditions for plant growth, repeated tillage can have negative impacts on soil structure and fertility.

Soil structure refers to the arrangement of soil particles into small clumps, known as aggregates. Good soil structure is crucial for plant growth as it allows for proper water infiltration and retention, root penetration, and gas exchange between the soil and the atmosphere. However, tillage can break down these aggregates, leading to a more compacted and less porous soil. This can result in increased runoff and soil erosion, as water is less able to infiltrate the soil. Over time, this can lead to a loss of topsoil, which is the most fertile part of the soil due to its high organic matter content.

In terms of soil fertility, tillage can also have detrimental effects. The process of tillage exposes soil organic matter to the air, which accelerates its decomposition by soil microorganisms. This can lead to a rapid release of nutrients, which may not coincide with plant uptake, resulting in nutrient losses through leaching or runoff. Furthermore, the loss of organic matter can reduce the soil's ability to hold onto nutrients and water, further decreasing its fertility.

Moreover, tillage can disrupt the habitat of soil organisms, such as earthworms and mycorrhizal fungi, which play a crucial role in maintaining soil health and fertility. These organisms help to break down organic matter, recycle nutrients, and improve soil structure, and their decline can therefore negatively impact soil fertility.

In conclusion, while tillage can initially improve soil conditions for plant growth, repeated tillage can degrade soil structure and fertility over time. This highlights the importance of sustainable soil management practices, such as reduced tillage or no-till farming, which aim to minimise soil disturbance and maintain soil health and fertility.