Issue of Land Degradation
What Is Land Degradation?
Land is a vital resource enabling the production of food, the preservation of biodiversity, facilitating the natural management of water systems and acting as a carbon store. Land resources are under pressure in the face of growing demand from an exploding population and the impacts of climate change. The ecosystem's services that the land provides are at breaking point. Increase in demand for goods and resources has led to land degradation.
Land degradation is deﬁned as the long-term loss of ecosystem function and productivity caused by disturbances from which the land cannot recover unaided. It may refer to the destruction or deterioration of the health of terrestrial ecosystems, thus affecting the associated biodiversity, natural ecological processes and ecosystem resilience. It also considers the reduction or loss of biological/economic productivity and complexity of croplands, pasture, woodland, forest, etc.
Under the UNCCD "land degradation" means reduction or loss, in arid, semi-arid and dry sub-humid areas, of the biological or economic productivity and complexity of rainfed cropland, irrigated cropland, or range, pasture, forest and woodlands resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns, such as:
(i) soil erosion caused by wind and/or water;
(ii) deterioration of the physical, chemical and biological or economic properties of soil; and
(iii) long-term loss of natural vegetation;
This is considered to be an important topic of the 21st century due to the implications land degradation has upon agronomic productivity, the environment, and its effects on food security. It is estimated that up to 40% of the world’s agricultural land is seriously degraded.
It is estimated that during the last 40 years nearly one-third of the world’s arable land has been lost to erosion and continues to be lost at a rate of more than 10 million hectares per year.
Causes of Land Degradation
This degradation may be the result of numerous factors or a combination thereof, including anthropogenic (human-related) activities such as unsustainable land management practices and climatic variations. Underlying causative factors of land degradation, and environmental mismanagement in general, are poverty and undervaluing of natural resources. In both cases, people focus on immediate economic gain irrespective of damage to the same resources they are dependent on. The latter in particular promotes the inefficient use and wastage of resources.
The natural causes include earthquakes, tsunamis, droughts, avalanche, landslides and mudflow, volcanic eruptions, flood, tornado, and wildfire.
Human induced causes include deforestation, overgrazing by livestock, wrong irrigation practices, urban sprawl and commercial development, pollution from industries, quarrying and mining activities.
Some specific causes are:
- Soil erosion: It is wearing away of the land surface by physical forces such as rainfall, flowing water, wind, ice, temperature change, gravity or other natural or anthropogenic agents.
- Soil contamination: It includes contamination by heavy metals, acidification, nutrient surplus (eutrophication), etc.
- Soil salinization: The salts which accumulate include chlorides, sulfates, carbonates and bicarbonates of sodium, potassium, magnesium and calcium.
- Soil sealing: The covering of the soil surface with impervious materials as a result of urban development and infrastructure construction.
- Overgrazing: Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods.
- Acidification of Soil: Acid soils are toxic to plants because they can release toxic levels of aluminium and other mineral elements.
- Mining and quarrying activities: This damages the soil and the underlying structure of the land. Chemicals used or mined themselves pollute soil and water courses.
- Improper crop rotations: It decreases fertility of the soil.
- Deforestation: The removal of trees and other vegetation for firewood, commercial logging or to clear land for farming and settlements.
- Poor land management: This can be inappropriate farming methods for the type of land/soil; farming that is too intensive (forcing the land to produce food crops year after year without letting it ‘rest’ to build up the nutrients again; using chemical or no fertilizers rather than natural fertilizers such as animal dung or organic matter).
- Fires: This includes bush and veld fires, caused by people, which strip the soil of the plant material that prevents soil erosion.
- Pollution: This is caused by dumping scrap metal, plastics, packaging and building rubble.
- Neglect: Failing to look after local plants, trees and biodiversity. Neglect means that the soil will not be naturally fertilized and protected, so it cannot in turn nurture other life.
• Land degradation over the next 25 years may reduce global food production by up to 12%, resulting in a possible 30% increase in world food prices.
Impact of Land Degradation
- Crop varieties and agricultural practices are not suitable to tackle the impact of climate change, which might further affect agricultural yields.
- Decrease in pastures for cattle leading to their diminishing health and lower quality of animal products like milk, meat etc.
- Reduction in crop and pasture productivity and fuel-wood and non-timber forest products, which are closely linked to poverty and food insecurity.
- Loss of fodder and forage production and a decline in production of timber.
- When the land is lost due to wind erosion or water erosion, apart from- physical, chemical and biological degradation, there is a loss of employment opportunities. This leads to migration towards cities and towns, causing social problems related to unplanned urbanization.
- Agricultural land is severely diminished in quality because of erosion and the use of chemical fertilizers, which prevent the land from regenerating. The decline in soil quality as a result of using fertilizers further leads to water and land pollution thereby lowering the land’s worth.
- It creates a significant loss of arable land. Most of the crop production practices result in the loss of topsoil and damage of soil’s natural composition that make agriculture possible.
Over the last ten years, approximately 5.2 million hectares of forest has been destroyed each year.
- An estimated 50 million people may be forced to seek new homes and livelihoods within 10 years due to land degradation, a study has estimated.
- Stress on Non-Timber Forest Products like honey, fruits etc. may cause food insecurity among forest dwellers and tribals.
- Decreased productivity is compelling farmers to bring more area under agriculture causing higher expenditures and lowering incomes to be spent on food.
- Land degradation is leading to lower productivity in the agriculture. Farmers requiring extra money for agriculture and for their sustenance are getting trapped in the vicious cycle of indebtedness. Due to this stress, farmers are committing suicides.
- Lack of any other source of income leading to social evils like alcoholism, dowry, psychological disorders, criminal activities and so on.
- The researchers found that land cover changes since the year 2000 are responsible for half to 75 percent of the lost ecosystem services value.
- Drought and aridity are problems highly influenced and amplified by soil degradation. The contributing factors to soil quality decline such as overgrazing, poor tillage methods and deforestation are also the leading causes of desertification characterized by droughts and arid conditions. In the same context, soil degradation may also bring about the loss of biodiversity.
- The land is commonly altered from its natural landscape and loses its physical composition due to soil degradation. For this reason, the transformed land is unable to soak up water, making flooding more frequent. In other words, soil degradation takes away the soil’s natural capability of holding water thus contributing to more and more cases of flooding.
- Most of the soil eroded from the land together with the chemical fertilizers and pesticides utilized in agricultural fields are discharged into waterways and streams. With time, the sedimentation process can clog waterways, resulting in water scarcity.
- The agricultural fertilizers and pesticides also damage marine and freshwater ecosystems and limit the domestic uses of the water for the population that depends on them for survival.
- Salinity is also an important land degradation problem.
'It is urgent to arrest land degradations and launch conservation and rehabilitation programmes in the most critically affected and vulnerable areas.'— Agenda 21 Chapter 14, paragraph 44 The Earth Summit Rio de Janeiro, June 1992
What can be Done?
There is a need to achieve Zero Net Land Degradation which means the achievement of a state of land degradation neutrality. Achieving it involves a combination of reducing the rate of further degradation of land and offsetting newly occurring degradation by restoring the productivity and other ecosystem services of currently degraded lands.The ZNLD is best achieved by the introduction and promotion of Sustainable Land Management(SLM) practices on a global basis.
- Sustainable Land Management-SLM practices include the integrated management of crops (trees), livestock, soil, water, nutrients, biodiversity, disease and pests to optimize the delivery of a range of ecosystem services. The overall objective is to maximize provisioning services (e.g. food, water, energy) while enhancing the resilience of land resources and the communities that depend on them. Adopting simple and affordable techniques that can stop land degradation and replicating them at the global level can have a major impact. Practices such as agroforestry and conservation agriculture, can boost yields and prevent future land degradation. For example- In Zimbabwe, water harvesting combined with conservation agriculture increased farmers’ gross margins 4-to-7-fold and increased returns on labour 2-to-3-fold compared to standard practices. These practices have had the greatest success in zones with lower rainfall. Also, in China, the adoption of no-till systems for wheat production raised yields and reduced production costs, resulting in an average increase of 30% net economic returns over 4 years.
- Avoiding degradation of non-degraded lands-Rather than bringing new land under managed ecosystems, productivity must be enhanced from land already devoted to agricultural production. While enhancing productivity from land already under production through land restoration, laws and policies and educational programs must also be in place to protect/preserve natural ecosystems against unauthorized cutting of firewood, grazing, etc. Protection and enhancement of vegetation cover are essential to erosion control. Afforestation of denuded lands with adaptable species is essential to conserving soil and water and strengthening nutrient cycling. In addition to trees, some grasses are also highly adapted to dryland conditions.
- Community-based and traditional approaches-In many regions there is an increasing realization that local communities have an important role to play in environmental management. The use of customary SLM practices, both in forested areas and in agricultural and pastoral regions, officially supported by government programmes and by local community participation, as well as regulatory frameworks, have the potential to reduce the causes and effects of Land degradation processes, and therefore contribute to ZNLD.
Some of the measures to prevent degradation and restore degraded lands are mentioned below-
- Improved early warning system and water resource management;
- Introduction of new species with a capacity to tolerate salinity and/or aridity; Windbreaks and shelterbelts of live plants;
- Afforestation and reforestation;
- Sustainable pasture and forest & livestock management; and
- Narrow strip planting.
- Management practices like water development, placement of salt and supplements, fertilizer application, fencing, burning can control the overgrazing.
- The irrigation system can be controlled like drip irrigation to reduce soil erosion.
- By proper management of mining process, using advanced technologies rather than conventional methods.
People and the natural resources on which they depend, directly or indirectly, are inextricably linked. Rather than treating each in isolation, all ecosystem elements should be considered together, in order to obtain multiple ecological and socio-economic benefits.
Sustainable land management can increase water productivity by up to 100%. Water use efficiency in multiple cropping systems is often 18%-99% higher than in single crop systems.— UNCCD Report
Worldwide Sustainable Land Management Practices-
Malaysia: leguminous shrubs for erosion control
In most areas of Malaysia, it is common to use a mixture of leguminous creepers as cover crops on land that is planted with rubber and oil palms. Erect shrubs can also be useful in erosion control, particularly where creepers might otherwise cause management problems, for instance in the establishment from cuttings of Gliricida as a shade tree for cocoa.
Research with Indifogera hirsuta in Malaysia has shown that once established, the shrub can provide 70 percent surface cover and can control erosion as effectively as a mixture of grass species. The shrub grows to about 1-metre tall, provides useful mulch material and can re-seed itself.
Research has also shown Desmodium ovalifolium, Stylosanthes gracilis and Clitoria ternatea to provide useful ground cover, though establishment from seed can be slow. Once established, though, the shrubs spread horizontally quite quickly.
Source: Ghulam M. Hashim, Leguminous Shrubs for Erosion Control, in Contour, volume 22. 1990.
Sri Lanka: the Kandyan home garden system
Kandyan home gardens are an excellent land-use system practiced on the steeply-sloping land of the wet hill country zone of Sri Lanka. These manmade forest gardens are similar to tropical rain forests. The system provides a healthy ecosystem for humans. flora and fauna. Fruits. spice trees, cocoa, coffee, coconut, timber trees, banana, root crops and fodder are grown on the same piece of land in a way that makes effective use of sunlight and rainfall and increases soil fertility. A dense living and dead vegetative cover protect the soil from erosion while enriching fertility, promoting water infiltration and creating a healthy environment for soil organisms. Both soil loss and runoff arc minimal. Research has shown that the maximum runoff during the peak of the northeast monsoon in 1980 was only 8 percent and that soil loss was only 0.05 tonnes/ha/year.
The system has been used for centuries and has evolved as an ideal system of land use for steeply-sloping homesteads. The gardens also provide a reasonably high income from spice crops, timber trees and food crops. The system is now being promoted for new settlements in the hill country.
Papua New Guinea: sustainable sweet potato production
Large compost mounds are used for growing sweet potatoes in the West and Southern Highlands of Papua New Guinea, on volcanic soils on slopes up to 10°. Weeds and excess sweet potato vines are placed in a pit and allowed to decompose for up to 10 weeks before they are covered over with soil and new sweet potato vines are planted. This system is considered highly sustainable, with some plots having been used in this way for 50 or more years. The benefits are enhanced soil fertility, retention of soil moisture but with good drainage, and efficient temperature regulation (especially beneficial at higher and cooler altitudes). Trials with mineral fertilizers have shown 110 effects on yields. Trials have also shown that yields are higher from mounds than from ridges which in turn are better than planting on the level.
Sand Dams in India
The traditional use of “sand dams” and underground storage techniques in India and East Africa help capture rainfall and run-off during the monsoon for use during the dry season. A typical dam road crossing can yield 50,000 liters per day and is often a catalyst for wider development through irrigated small holdings, tree nurseries, ﬁsh ponds and livestock watering. These local-scale water harvesting techniques offer a sustainable option for improving food and water security in areas where costly water infrastructure is not feasible.