Land Degradation, soil erosion and Desertification

Summary

Dr. Covino’s lecture explains land degradation, soil erosion, and desertification as connected processes that reduce soil quality, harm ecosystems, and limit the land’s usefulness for farming and other human needs.

Soil and Soil Pollution

Soil is the upper layer of Earth’s crust. It contains mineral particles, organic matter, water, and air, and supports plants, animals, microorganisms, and people.

Soil pollution occurs when contaminants alter the soil’s natural composition. The lecture identifies several sources:

• Agricultural runoff, including fertilizers, pesticides, and herbicides.
• Domestic and urban waste, especially non-biodegradable materials.
• Industrial and sewage discharges.
• Mining and metallurgical activity.
• Radioactive waste and other accidental or incidental contamination.

These pollutants can impair the soil’s physical, biological, and chemical properties, reduce fertility, and contribute to land degradation.

Land Degradation

The lecture describes land degradation as a reduction or loss of the land’s biological or economic productivity, caused by land use or by processes that may include human activities.

Degradation may be temporary or permanent. As soil quality and fertility decline, the land becomes less useful for agriculture, grazing, and other purposes.

Causes discussed include:

• Droughts, floods, extreme weather, and acid rain.
• Overgrazing, which removes vegetation faster than it can regrow.
• Intensive farming and excessive use of agricultural chemicals.
• Deforestation, mining, oil extraction, and waste dumping.

Consequences include:

• Lower food production, food insecurity, and potentially higher food prices.
• Loss of freshwater resources and reduced water quality.
• Loss of biodiversity, vegetation, timber, and other natural resources.
• Damage to livelihoods and ecosystems, along with wider environmental and climate-related effects.
• Health risks such as malnutrition, water- and food-borne illness, and respiratory problems linked to dust and pollutants.
• Migration as people leave land that can no longer support them. The lecture notes that migration may also help spread infectious diseases between regions.

Soil Erosion

Soil erosion is the removal and movement of topsoil by natural forces—especially water and wind—or by human activities that leave soil exposed. It is a form of soil degradation and generally involves three stages:

1. Detachment of soil particles.
2. Movement of the particles.
3. Deposition elsewhere.

Erosion can happen slowly and go unnoticed, or occur rapidly. Factors that make soil more vulnerable include loose or compacted soil, loss of organic matter, and poor drainage. The lecture also mentions salinity and soil acidity as factors that affect soil condition.

Human activities that can accelerate erosion include deforestation, overgrazing, farming practices that disturb or expose soil, agrochemical use, road building, urbanization, and activities associated with climate change.

Forms of water erosion described:

• Splash erosion: Raindrops dislodge soil particles.
• Sheet erosion: Runoff removes a thin, relatively even layer of soil.
• Rill erosion: Runoff forms small channels in the soil.
• Gully erosion: Channels become wider and deeper as erosion progresses.
• Riverbank erosion: Rising or moving water removes sections of a river or stream bank.

Wind erosion can remove exposed topsoil during strong winds, storms, or hurricanes.

Desertification

Following the UN Convention to Combat Desertification (UNCCD), the lecture presents desertification as land degradation occurring in drylands—arid, semi-arid, or dry sub-humid areas.

It is associated with loss of fertility and vegetation, eventually leaving land barren or unsuitable for productive use.

Contributing factors include overcultivation, overgrazing, deforestation, increasing livestock production, urbanization, droughts and floods, and rising soil salinity. The lecture also notes that coastal incursions and waterlogging can damage land and vegetation.

Shifting cultivation can contribute when one area is cleared and cultivated before its vegetation and soil have recovered, prompting cultivation to move elsewhere.

India, Land Management, and Restoration

The lecture reports that India’s National Remote Sensing Centre estimated 29.3% of the country’s land had undergone land degradation or desertification in 2011–13.

It also cites a 2017 State of India’s Environment report estimating that about 30% of Indian land was degraded, with some areas experiencing desertification. The list of affected states in the subtitles is unclear.

The lecture says India had set a goal of restoring degraded or desertified land by 2030, using land reclamation and improved management.

Sustainable land management (SLM) is described as using land resources to meet changing human needs while maintaining their long-term productivity and environmental functions. In practice, the lecture emphasizes:

• Using land resources judiciously.
• Avoiding pollution and contamination.
• Preserving the soil’s physical, chemical, and biological properties.
• Applying sustainable land-use policies and better watershed management.

Speakers and Sources Mentioned

• Speaker: Dr. Covino, Department of Biotechnology, The Oxford College of Science.
• Organizations and references cited:
  • United Nations Convention to Combat Desertification (UNCCD).
  • World Health Organization (mentioned in connection with causes of land degradation).
  • World Overview of Conservation Approaches and Technologies (WOCAT), cited for the definition of sustainable land management.
  • India’s National Remote Sensing Centre (described in the subtitles as a space application centre).
  • State of India’s Environment (2017).