Soil Degradation (DP IB Environmental Systems & Societies (ESS))

Soil Degradation

Human Activities Reducing Soil Fertility

Deforestation

• Clearing forests for agriculture, logging, or building developments leads to the removal of vegetation cover, exposing the soil to erosion

• Without the protection of trees and plants, the soil is more susceptible to wind and water erosion, leading to the loss of topsoil, which is rich in organic matter and nutrients

• Deforestation also disrupts the nutrient cycling process as tree roots, leaf litter, and decaying organic matter contribute to nutrient replenishment

Photo by Quaritsch Photography on Unsplash 

Overgrazing by livestock can lead to the degradation of soil fertility

Intensive Grazing

• Continuous grazing without proper management results in the removal of vegetation, exposing the soil to erosion and compaction

• Livestock trampling and excessive grazing pressure can damage the soil structure, reducing water infiltration and nutrient availability

• Nutrient cycling is also disrupted as grazing animals remove vegetation and disrupt the deposition of organic matter

Urbanisation

• Urban development involves the conversion of natural or agricultural land into impervious surfaces such as buildings, roads, and concrete

• Urbanisation reduces the amount of vegetative cover, leading to increased runoff and soil erosion

• Soil in urban areas often becomes compacted due to construction activities, limiting root penetration and nutrient uptake by plants

• Urban areas also tend to have higher pollution levels, such as heavy metals and chemicals, which can negatively impact soil fertility and microbial communities

Agricultural Processes

• Irrigation:

  • Improper irrigation practices, such as excessive or poorly managed irrigation, can lead to soil salinisation

  • The accumulation of salts in the soil reduces its fertility and inhibits plant growth

• Monoculture:

  • Planting the same crop repeatedly in a field without crop rotation or diversification depletes specific nutrients from the soil

  • It can lead to imbalances in nutrient availability and increased vulnerability to pests and diseases

• Excessive fertiliser use:

  • Overapplication of synthetic fertilisers can lead to nutrient imbalances and water pollution due to leaching

  • It can also disrupt the natural nutrient cycling processes in the soil

• Soil erosion:

  • Unsustainable agricultural practices, such as excessive ploughing and inadequate soil conservation measures, can accelerate soil erosion

  • Eroded soil loses its fertility as the topsoil, which contains organic matter and nutrients, is washed or blown away

• Commercial industrialised food production systems generally tend to reduce soil fertility more than small-scale subsistence farming methods

Compaction, caused by various human activities such as livestock grazing or building construction works, has various negative impacts on soil health and fertility

Impacts of Reduced Soil Fertility

Soil Erosion

• Reduced soil fertility can lead to soil erosion through the loss of essential nutrients and organic matter, which provide stability to the soil structure and promote plant growth

  • Without these nutrients, the soil becomes more susceptible to erosion by wind and water

• When soil fertility is low, plants struggle to grow and establish strong root systems

  • This weakens the vegetation cover, making the soil more vulnerable to erosion by wind and water

Toxification of Soil

• This can occur when certain chemicals or pollutants, such as heavy metals, pesticides, or industrial waste, accumulate in the soil

  • These contaminants can harm soil organisms and disrupt nutrient cycling

Salinisation

• This happens when there is an excessive accumulation of salts in the soil

  • This can occur in arid or semi-arid regions where water evaporation exceeds precipitation

  • The salts can inhibit plant growth and degrade soil fertility, making it difficult for crops to thrive

Desertification

• This is a process where previously fertile land turns into arid desert-like conditions

  • It can be caused by a combination of factors, including soil degradation, climate change, overgrazing, and deforestation

  • As the soil fertility declines, vegetation cover decreases, exposing the soil to wind and water erosion, ultimately leading to desertification

• Sustainable land management practices, such as agroforestry, rotational grazing, and soil conservation techniques, are essential to mitigate the negative impacts of human activities on soil fertility and maintain productive soils for future generations