Land degradation is the process of deterioration of soil or loss of fertility of soil. The causes of land degradation can be divided into natural hazards, direct causes, and underlying causes. Natural hazards are the conditions of the physical environment which lead to the existence of a high degradation hazard, for example steep slopes as a hazard for water erosion.
Direct causes are unsuitable land use and inappropriate land management practices, for example the cultivation of steep slopes without measures for soil conservation. Underlying causes are the reasons why these inappropriate types of land use and management are practised; for example,-the slopes may be cultivated because the landless poor need food, and conservation measures not adopted because these farmers lack security of tenure.
There is a distinction, although with overlap, between unsuitable land use and inappropriate land management practices. Unsuitable land use is the use of land for purposes for which it is environmentally unsuited for sustainable use. For example- forest clearance and arable use of steeply sloping upper watershed areas which would have more value to the community as water sources, managed under a protective forest cover.
Inappropriate land management practices refer to the use of land in ways which could be sustainable if properly managed, but where the necessary practices are not adopted. For example- the failure to adopt soil conservation measures where these are needed. It can also refer to land use which is ecologically sustainable under low intensity of use but in which the management becomes inappropriate at higher intensifies (shifting cultivation and the grazing of semi-arid rangelands).
Causes of land degradation
• Population: The indirect activities included pressure on agricultural intensification and population growth. About 220 million hectares of tropical forest have been degraded 1975 and 1990 mainly for food production.
With the increase in population, more land is needed for producing food, fibre, and fuel wood leading to increasing pressure on the limited land resources. Therefore the land gets degraded due to over exploitation.
• Human Activities: Human induced causes many human activities are leads to land degradation directly or indirectly include deforestation, overgrazing by livestock, wrong irrigation practices, urban sprawl and commercial development, pollution from industries, quarrying, and mining activities, Problems arising from planning and management of canal irrigation etc.
• Urbanization: Increased urbanization due to population growth reduces the agricultural land. To compensate for loss of agricultural land, new lands comprising of natural ecosystems such as forests are cleared. Therefore, urbanization leads to deforestation which in-turn affects millions of plant and animal species.
• Fertilizers and Pesticides: Increased application of fertilizers and pesticides are needed to increase farm output in new lands thereby leading to pollution of land, water and soil degradation.
• Damage to top soil: Increase in food production generally leads to damage of top soil through nutrient depletion.
Some specific causes are:
a) 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.
b) Soil contamination:
• It includes contamination by heavy metals, acidification, nutrient surplus (eutrophication), etc.
c) Soil salinisation:
• The salts which accumulate include chlorides, sulphates, carbonates and bicarbonates of sodium, potassium, magnesium and calcium.
d) Soil sealing:
• The covering of the soil surface with impervious materials as a result of urban development and infrastructure construction.
• Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods.
f) Acidification of Soil:
• Acid soils are toxic to plants because they can release toxic levels of aluminium and other mineral elements.
g) Mining and quarrying activities:
• Due to this excavation process alter the structure of the land, stacking of top soil, loss of soil due to dumping of the mine wastes.
h) Improper crop rotations:
• It decreases fertility of soil.
Impact of land degradation
• Loss of soil organic matter and nutrients.
• Loss of soil structure.
• Loss of soil biodiversity.
• Loss of water holding capacity and water infiltration.
• Soil pollution.
• Reduced yields of crops.
• Reduced land value and resilience to future events.
• Impact on food security.
• Reduces ability to adapt to climate change.
Sustainable Land Management
Thus Sustainable Land Management (SLM) is crucial to minimizing land degradation, rehabilitating degraded areas and ensuring the optimal use of land resources for the benefit of present and future generations.
SLM is based on four common principles:
• land-user-driven and participatory approaches;
• Integrated use of natural resources at ecosystem and farming systems levels
• Multilevel and multi-stakeholder involvement; and
• Targeted policy and institutional support, including development of incentive mechanisms for SLM adoption and income generation at the local level.
Some of the methods for sustainable management of land are:
• Management on overgrazing: Management practices like water development, placement of salt and supplements, fertilizer application, fencing, burning can control the overgrazing.
• Managing irrigation: Irrigation system can be controlled like drip irrigation to reduce soil erosion. Using high and low salt water was most effective in maintaining the productive capacity of the clay soil.
• Managing urban sprawl: The urban planning is the most important factor, to control the urban sprawl. Fertile field near by the urbane area need to be protected by the local government rules. There should be a proper waste management system dumping of these waste generated as part of urban sprawling will degrade the land, can cause soil salinity, acidity and loss of it vegetative properties.
• Managing mining and quarrying: The impact can be reduced by proper management of mining process, using advanced technologies rather than conventional methods. After mining by proper back filling, spreading the soil back over the top, the land can be reclaimed.
• Managing agricultural intensification: Agricultural intensification need to be managed properly to reduce the environmental effect. This can be done through education of the farmers.
‘Soil erosion’ has been defined as the gradual removal of the top soil by running water, wind, glacier, sea-waves, anthropogenic agents and animals.
– Soil erosion is a universal phenomenon.
– According to one estimate about 75, 000 million tonnes of soil is removed by these agents annually.
Types of soil erosion
• Normal erosion: This is caused by the gradual removal of topsoil by natural processes. The rate of erosion is slow.
• Accelerated erosion: This is caused by manmade activities. In this case, the rate of erosion is much faster than the rate of formation of soil.
Causes of soil Erosion
• Running water:
a) Uniform removal of soil
b) Rill erosion
c) Gully erosion (e.g. northern Punjab, Haryana, Rajasthan, M.P. U.P)
• Wind Erosion: Mainly in the arid and semi -arid regions.
• Anthropogenic factors: Farmland can be degraded in several other ways besides erosion. Physical degradation from mechanical tilling can lead to compaction and crusting. Repeated cropping without sufficient fallow periods or replacement of nutrients with cover crops, manure or fertilizer can deplete soil nutrients. In addition over application of chemical fertilizers, insecticides and pesticides can kill beneficial soil organism.
– Poor water management on irrigated crop land is a leading cause of degraded farmland.
– Inadequate drainage can lead to water logging of the soil or to Salinization, in which salt levels built up in the soil to toxic levels. About 15 to 20 percent of the irrigated land is suffering from some degree of waterlogging and salinization.
• Biotic agents: Overgrazing, mining and deforestation are the major biotic agents causing soil erosion. These processes disturb the top soil thereby exposing the soil to various physical forces inducing erosion.
• Landslides cause soil erosion: Construction of dams, buildings and roads removes the protective vegetal cover leading to soil erosion.
Harmful Effects of Soil Erosion
• Loss of fertile top soil leading to gradual loss of soil fertility and agricultural productivity.
• Loss of mineral nutrients from soil through leaching and flooding.
• Loss of soil ability to hold water and sediment
• Sediment runoff can pollute water courses and kill aquatic life
• Lowering of the underground water table and decrease in the percentage of soil moisture.
• Drying of vegetation and extension of arid lands.
• Increase in frequency of droughts and floods.
• Silting of river and canal belts.
• Recurrence of landslides.
• Adverse effect on economic prosperity and cultural development.
Unchecked soil erosion leads to poverty and reduces the strength of a nation. Some of the important steps for soil conservation areas under:
• Conservational till farming or no-till farming: Traditionally, land is ploughed to make a planting surface. This disturbs the soil and makes it susceptible to erosion. The no-till farming method makes minimum disturbance to the top soil by making slits in the unploughed soil. Seeds, fertilizers and water are injected in these slits.
• Contour farming: In this method, crops are planted in rows along contours of gently sloped land. Each row acts as a small dam to hold soil thereby slowing water runoff.
• Terracing: In this method, steep slopes are converted into a series of broad terraces that run across the contour. This retains water for crops and reduces soil erosion by controlling runoff.
• Alley cropping or Agro forestry: This method involves planting crops in strips or alleys between rows of trees or shrubs that provide fruits and fuel wood. Hence, when the crop is harvested, the soil will not be eroded as the trees and shrubs remain on ground holding the soil particles.
• Wind breaks or shelter belts: In this technique, trees are planted in long rows along the boundary of cultivated land which block the wind and reduce soil erosion. Wind breaks help in retaining soil moisture, supply wood for fuel and provide habitat for birds.
Soil health card scheme
• SHC is a printed report that a farmer will be handed over for each of his holdings.
• It will contain the status of his soil with respect to 12 parameters, namely N,P,K (Macro-nutrients) ; S (Secondary- nutrient); Zn, Fe, Cu, Mn, Bo (Micro – nutrients); and pH, EC, OC (Physical parameters).
• Based on this, the SHC will also indicate fertilizer recommendations and soil amendment required for the farm.
• Further, it will advise the farmer on the fertilizers and their quantities he should apply, and also the soil amendments that he should undertake, so as to realize optimal yields.
• It will be made available once in a cycle of 3 years, which will indicate the status of soil health of a farmer’s holding for that particular period.
• Soil samples will be drawn in a grid of 2.5 ha in irrigated area and 10 ha in rain- fed area with the help of GPS tools and revenue maps.
• This initiative will help in improving the soil fertility as the fertilizers and other parameters will be placed according to the need.
‘Deforestation’ is the conversion of forest to another land use or the long-term reduction of tree canopy cover below the 10% threshold. Deforestation defined broadly can include not only conversion to non-forest, but also degradation that reduces forest quality – the density and structure of the trees, the ecological services supplied, the biomass of plants and animals, the species diversity and the genetic diversity.
Deforestation includes cutting and felling of trees, removal of forest litter.
Browsing and trampling by livestock, forest fires, also leads to cause deforestation etc.
Deforestation leads to erosion. Deforestation further leads to land degradation, nutrient and the disruption of the delicate soil plant relationship.
Causes of Deforestation
• Expansion of farming land.
• Shifting cultivation.
• Demand for firewood.
• Demand of wood for industry and commercial purposes.
• Urbanization and developmental projects.
• Increase of wildlife tourism.
• Overpopulation and poverty.
• Construction of dam reservoirs.
Consequences of Deforestation
• Soil degradation and erosion.
• Changes in climatic conditions.
• Destruction of natural habitats.
• Destruction of a valuable sink for environmental pollutants.
• Intensive development schemes for afforestation should be adopted. High yielding varieties should be planted in suitable areas.
• Latest techniques of seasoning and preservation are necessary to avoid wastage.
• Proper arrangement to save forests from fires and plant diseases can go a long way to solve several problems.
• A thorough inventory of forest resources is necessary to make an accurate assessment of our forest resources and make plans for their proper use.
• Shifting cultivation should be discouraged and tribals depending on this type of cultivation should be provided with alternate sources of livelihood.
• People associated with forest protection should be properly trained.
a) Survey and inventorisation of floral and faunal resources are carried out by Botanical Survey of India (BSI) and Zoological Survey of India (ZSI). The Forest Survey of India assesses the forest cover to develop an accurate database for planning and monitoring purposes.
b) Biological Diversity Act 2002 has been enacted and Biological Diversity Rules 2004 have been notified, which aim at conservation of biological resources of the country and regulation of access to these resources to ensure equitable sharing of benefits arising out of their use.
c) Industries to obtain “Consent for Establishment” as well as “Consent to Operate” under the provisions of the Water (Prevention and Control of Pollution) Act, 1974 and the Air (Prevention and Control of Pollution) Act, 1981 from the concerned State Pollution Control Boards (SPCBs) prior to carrying out operations.
d) Environmental Impact Assessment of developmental projects and preparation of Environmental Management Plan as per the provisions of the Environmental Impact Assessment notification of September, 2006.
e) Adoption of cleaner technologies and use of improved fuel quality.
f) Regular monitoring of industrial units for environmental compliance.
g) In acknowledging this factor, the Ministry of Environment and Forests, Government of India issued policy guidelines for the involvement of village communities and voluntary agencies in the regeneration of degraded forest lands on June 1, 1990 under the JFM (joint forest management) programme. Joint Forest Management is a process in which protection and management of forests is jointly undertaken by Forest Department and the local communities.
h) Sacred groves comprise of patches of forests or natural vegetation – from a few trees to forests of several acres – that are usually dedicated to local folk deities or tree spirits (Vanadevatais). These spaces are protected by local communities because of their religious beliefs and traditional rituals that run through several generations.
i) The National Mission for a Green India for enhancing quality of forest cover and improving ecosystem services from 4.9 million hectares (mha) of predominantly forest lands, including 1.5 mha of moderately dense forest cover, 3 mha of open forest cover, 0.4 mha of degraded grass lands.
j) Eco-restoration/afforestation to increase forest cover and eco system services from 1.8 m ha forest/non forest lands, including scrub lands, shifting cultivation areas, abandoned mining areas, ravine lands, mangroves and sea-buckthorn areas.
k) Enhancing tree cover in 0.2 mha Urban and Peri-Urban areas (including institutional lands)
Other terms related to it
a) Social Forestry
• Social forestry has been defined differently by the different social scientists. In the opinion of some of the experts, the trees planted by the community, individuals, government or the individuals outside the conventional forest areas is known as social forestry.
• Social Forestry has also been defined as the forest by the people; of the people; and for the people.
• The main objectives of social forestry are as under:
1. To meet the fuelwood and timber requirements of the fast growing rural population.
2. To provide fodder to livestock and cattle.
3. To provide raw materials for the cottage and household industries, e.g. basket making, bidi- making, manufacturing of cane goods, sports goods, etc.
4. To obtain forest products like, gum, lac, wax, honey, resins, etc.
5. To generate rural employment for the landless workers and marginal farmers.
6. To work as a wind break.
7. To check soil erosion and flood control.
8. To keep the environment in a healthy condition and to improve the resilience characteristics of the ecosystem.
9. To provide the places of recreation for the rural people.
b) Agro Forestry
• Agro forestry is a system of land use in which perennial trees are used as annual agricultural crops to obtain more income.
• Apart from money, agro-forestry provides wood, timber and fodder to the cultivator.
• Agro forestry, however, lowers the underground water table and depletes the natural fertility of the soil Agro-forestry has become quite popular in the Sutlej-Ganga Plain.
Various Forms of Agroforestry
• Agri-silviculture system: Concurrent production of agricultural corps & forest trees.
• Silvipastoral System: Forest based livestock production system where production of wood and rearing of domestic animals are done simultaneously.
• Agro-silvipastoral system: Land is utilized simultaneously for the production of agricultural crops, forest trees and rearing of domestic animals.
• Multipurpose forest tree production system: In this system trees are grown not only for wood but also for leaves, fruits, fodder and other useful by-products, including soil cover crops and intercropping with high value spices in man-made plantations