Desertification is primarily caused by several human and natural factors, with deforestation being one of the key contributors. When trees are removed, the soil can become less stable, leading to erosion and a decrease in soil fertility. Other factors that contribute to desertification include:
- Unsustainable agricultural practices: Overgrazing, crop production that depletes soil nutrients, and improper irrigation can degrade the land.
- Climate change: Variability in rainfall and temperature can exacerbate conditions that lead to desertification.
- Urbanization and land development: Expansion of cities and infrastructure can lead to land degradation.
- Drought: Prolonged periods of low precipitation can result in the drying out of previously fertile land.
While mining can also contribute to land degradation and loss of vegetation, it is not as direct a cause of desertification as deforestation and agricultural practices. Soil fertilization can help improve soil quality but, if used improperly, can also lead to problems such as nutrient runoff and soil degradation over time. Infectious disease is generally not considered a direct factor in desertification.
In summary, the most relevant cause from your list is deforestation.