LAND DEGRADATION AND SOIL CONSERVATION

CONTENTS

• Land Degradation

• Deforestation

• Soil Salinity and Soil Alkalinity

• Desertification

• Soil Erosion

• Soil Conservation

• Recent issues

• Soil degradation is the decline in soil quality caused by its improper use, usually for agricultural, pastoral, industrial or urban purposes.
• Soil degradation is a serious global environmental problem and may be exacerbated by climate change.
• It encompasses physical (soil erosion), chemical (salinity and alkalinity, pollution) and biological deterioration (pollution and deterioration of vegetal cover).

• Indiscriminate felling of trees as a result of urbanization, industrialization, mining operations, and use of wood for domestic and other purposes, have caused heavy depletion of forests.

A) Causes

Shifting cultivation

• In this practice a patch of land is cleared, vegetation is burned and the ash is mixed with the soil thus adding nutrients to the soil.
• This patch of land is used for raising crops for two to three years, and the yield is modest.
• Then this area is abandoned and is left to recover its fertility, and the same practice is repeated elsewhere on a fresh piece of land.

Development project

• Development projects like the hydroelectric projects, large dams and reservoirs, laying down of railway lines and roads are not only extremely beneficial, but they are also linked with several environmental problems.
• Many of these projects require immense deforestation.

Fuel Requirements

• The increasing demand for firewood with ever growing population increases greater pressure on the forests, which results in increased intensity of deforestation.

 Raw Material Requirements

• Wood is used as a raw material by various industries for making paper, plywood, furniture, match sticks, boxes, crates, packing cases, etc.

 Other Causes

• • Deforestation also results from overgrazing, agriculture, mining, urbanization, flood, fire, pest, diseases, defence and communication activites.

B) Effects of Deforestation

• Closed forests (based on canopy level) have diminished due to deforestation leading to an increase in degraded forests.
• Forests recycle moisture (natural motors) from soil into their immediate atmosphere by transpiration where it again precipitates as rain.
• Deforestation results in an immediate lowering of groundwater level (low percolation due to the quick surface runoff on barren lands) and in long-term reduction of precipitation.
• Due to deforestation, this natural reuse cycle is broken, and water is lost through rapid runoff.
• Deforestation affects the biota and neighbouring ecosystems, soil erosion, land degradation, alteration of groundwater channels, pollution and scarce.

Overgrazing

• During the rainy season, there is plenty of vegetation and animals get enough fodder.
• But during the dry period, there is a shortage of fodder, and the grass is grazed to the ground and torn out by the roots by animals.
• This leads to lose structure of the soil and the soil is easily washed away by rains.
• Moreover, the soil is pulverised (reduce to fine particles) by the hoofs of animals and thus proves detrimental to topsoil when heavy showers fall on it.
• Soil erosion due to overgrazing is a common site in the hilly areas.

Faulty Methods of Agriculture

• Much of the soil erosion in India is caused by faulty methods of agriculture.
• Wrong ploughing, lack of crop rotation and practice of shifting cultivation are the most adversely affecting methods of agriculture.
• If the fields are ploughed along the slope, there is no obstruction to the flow of water and the water washes away the topsoil easily.
• In some parts of the country, the same crop is grown year after year which spoils the chemical balance of the soil. This soil is exhausted and is easily eroded by wind or water.
• The removal of the forest cover shifting cultivation leads to the exposure of the soil to rains and sun which results in heavy loss of topsoil, especially on the hill slopes.

• In Saline and Alkaline Soils, the topsoil is impregnated(soak or saturate with a substance) with saline and alkaline efflorescences (become covered with salt particles).
• Undecomposed rock fragments, on weathering, give rise to sodium, magnesium and calcium salts and sulphurous acid.
• Some of the salts are transported in solution by the rivers.
• In regions with low water table (due to over irrigation in canal irrigated areas), the salts percolate into the subsoil, and in regions with good drainage, the salts are wasted away by flowing water.
• But in places where the drainage system is poor, the water with high salt concentration becomes stagnant and deposits all the salts in the topsoil once the water evaporates.
• In regions with the high sub-soil water table, injurious salts are transferred from below by the capillary action as a result of evaporation in the dry season.
• In canal irrigated areas plenty of the water is available, and the farmers indulge in over irrigation of their fields.
• Under such conditions, the groundwater level rises and saline and alkaline efflorescences consisting of salts of sodium, calcium and magnesium appear on the surface as a layer of white salt through capillary action.
• Vast tracts of canal irrigated areas in Uttar Pradesh. Punjab and Haryana; arid regions of Rajasthan, semi-arid areas of Maharashtra, Gujarat, Andhra Pradesh, Telangana and Karnataka etc. are facing this problem.
• Although Indira Gandhi canal in Rajasthan has turned the sandy desert into a granary, it has given birth to serious problems of salinity and alkalinity.

A) Effects of salinity and alkalinity

• Soil fertility gets reduced.
• Cultivation is not possible on saline soils unless they are flushed out with large quantities of irrigation water to leach out the salts.
• Choice of crops is limited to salinity-tolerant crops like cotton, barley etc.
• Quality of fodder and food produced is of poor quality.
• Salinity and alkalinity create difficulties in building and road construction.
• These cause floods due to reduced percolation of water.

B) Steps to treat salinity and alkalinity

• Crop rotation.
• Making judicious use of irrigation facilities.
• Providing outlets for lands to drain out excess water and lower water table.
• Seal leakages from canals, tanks and other water bodies by lining them.
• Improve vegetal cover to avoid further degradation by planting salt-tolerant vegetation.
• Liberal application of gypsum to convert the alkalis into soluble compounds.
• Alkali can be removed by adding sulphuric acid or acid forming substances like sulphur and pyrite.
• Organic residues such as rice husks and rice straw can be added to promote the formation of mild acid as a result of their decomposition.

• Desertification is the destruction of biological potential of the land which can ultimately lead to desert like conditions.
• In arid and semiarid regions, the restoration of the fragile ecosystem is very slow, and issues like deforestation, mining enhances the desertification.
• The process of desertification is attributed to uncontrolled grazing, reckless felling of trees, growing population, development activities, climate change etc.

A) Ecological implications of desertification

• Increase in frequency and intensity of droughts.
• Drifting of sand and its accumulation on fertile agricultural land.
• Excessive soil erosion by wind and to some extent by water.
• Deposition of sand in rivers, lakes decrease their water containing capacity.
• Lowering of water table leading to acute water shortage.
• Increase in area under wastelands.
• Decrease in agricultural production.

B) Control measures

• Afforestation
• Integrating land and water management to protect soils from erosion, salinization and other forms of degradation.
• Alternative sources of fuel can reduce the demand for fuelwood.
• Sandy and wastelands should be put to proper use by judicious planning.
• Mulching shifting sand dunes in deserts with different plant species. Mulches serve as an effective physical barrier to the moving sand.
• Grazing should be controlled.

C) Waterlogging

• The flat surfaces and depressions result in waterlogging.
• Waterlogged soils are soaked with water accumulated during the rainy season or due to leakage from various water sources.
• The extent of waterlogged soils is about 12 million hectares in India – half of which lies along the coast and the other half in the inland area.
• Waterlogging is believed to be one of the chief causes of salinity.
• Proper layout of drainage schemes is the only way to overcome the menace of waterlogging.
• The basic methods of removing excess water from waterlogged soils are (a) surface drainage and (b) vertical drainage.
  1. Surface Drainage. Surface drainage involves the disposal of excess water over ground surface through an open drainage system with an adequate outlet.
  2. Vertical Drainage. Any bore or well from which the underlying water is extracted is defined as vertical drainage. It works well in Indo-Gangetic plain where the pumped water is used for irrigating the neighbouringregions.

• Soil erosion is the displacement of the upper layer of soil, it is one form of soil degradation.
• This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, animals, and humans.
• In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind (aeolean) erosion, zoogenic erosion and anthropogenic erosion.
• Soil erosion in nature may be
  • A slow process (or geological erosion) or
  • A fast process promoted by deforestation,floods,tornadoes or other human activities.

A) Water Erosion

• Running water is one of the main agents, which carries away soil particles.
• Soil erosion by water occurs by means of raindrops, waves or ice.
• Soil erosion by water is termed differently according to the intensity and nature of erosion.
• Raindrop erosion (ii) Sheet erosion (iii) Rill erosion (iv) Steam banks erosion (v) Coastal erosion (vi) Erosion due to landslides

Consequences of water erosion

• Water erosion removes the most fertile part of the soil.
• The fine particles of the topsoil which contain the bulk of nutrients and organic matter needed by the plants are lost from soil erosion.
• Sedimentation of water bodies deteriorate water quality and damage aquatic habitats and organisms.
• Coastal erosion causes the adjourning land to become covered by sand.
• Erosion may result in removal of seeds or seedlings so that the soil becomes bare. Bare soil is more vulnerable to erosion both by wind and water.
• Removal of seeds and seedlings reduces the ability of soil to store water.Sheet, rill, gully and stream bank erosion also cause siltation of rivers, streams and fields.
• Deposition of silt results in damage of crops and pastures, and sedimentation of water bodies like streams, dams, reservoirs etc.

B) Raindrop erosion

• Raindrops behave like tiny bombs when falling on exposed soil, displace soil particles and destroy soil structure.
• Average size of a raindrop is approximately 5 mm in diameter falling through the air hits the soil at a velocity of 32 km/hr.
• Presence of vegetation on land prevents raindrops from falling directly on the soil thus erosion of soil in areas covered by vegetation is prevented.

C) Sheet erosion

• The detachment and transportation of soil particles by flowing rainwater is called sheet or wash off erosion.
• This is a very slow process and often remain unnoticed.

D) Rill erosion

• In rill erosion finger like rills appear on the cultivated land after it has undergone sheet erosion.
• These rills are usually smoothened out every year while forming.
• Each year the rills slowly increase in number become wider and deeper.
• When rills increase in size, they are called gullies. Ravines are deep gullies.

E) Stream bank erosion

• The erosion of soil from the banks (shores) of the streams or rivers due to the flowing water is called bank erosion.

F) Coastal erosion

• Coastal erosion of soil occurs along seashores. It is caused by the wave action of the sea and the inward movement of the sea into the land.

G) Landslide

• A sudden mass movement of soil is called a landslide. Landslides occur due to instability or loss of balance of land mass with respect to gravity.

H) Wind erosion

• Wind erosion is a natural process that moves soil from one location to another by wind power. It can cause significant economic and environmental damage.
• Wind erosion can be caused by a light wind that rolls soil particles along the surface through to a strong wind that lifts a large volume of soil particles into the air to create dust storms.
• While wind erosion is most common in deserts and coastal sand dunes and beaches, certain land conditions will cause wind erosion in agricultural areas.
• So, it is wind that drives the erosion, but it’s mainly the landscape and condition of the land which leads to the most damaging wind erosion.

Consequences of wind erosion

• Wind erosion removes the finer soil material including organic matter, clay and slit, in a suspension (colloidal) form and leaving behind coarser, less fertile material.
• The productive capacity of the soil is lost as most of the plant nutrients which remain attached smaller colloidal soil fraction are lost.
• Wind erosion also damages roads and fertile agricultural fields by depositing large quantities of air blown soil particles.

• Soil conservation is the prevention of soil from erosion or reduced fertility caused by overuse, acidification, salinisation or other chemical soil contamination.
• Soil erosion is the greatest single evil to Indian agriculture and animal husbandry.
• Notable Quotable from Khullar’s Indian Geography: “With soil conservation people rise and with its destruction, they fall. Neglect of soil is like killing the hen that lays the golden egg.”

A) Afforestation

• It includes the prevention of forest destruction along with growing new forests or increase area under forests.
• A minimum area 20 to 25 per cent of forest land was considered healthy for soil and water conservation for the whole country.
• It was raised to 33 per cent in the second five-year plan – 20 per cent for the plains and 60 per cent for hilly and mountainous regions.

B) Crop Rotation

• Adopting sustainable agricultural practices is the most important measure to conserve soil.
• In many parts of India, a particular crop is sown in the same field year after year. This practice leads to exhaustion of certain nutrients in the soil making it infertile.
• Crop rotation is a practice in which a different crop is cultivated on a piece of land each year.
• This helps to conserve soil fertility as different crops require different nutrients from the soil. Crop rotation will provide enough time to restore lost nutrients.
• For example, potatoes require much potash, but wheat requires nitrate. Thus, it is best to alternate crops in the field.
• Legumes such as peas, beans, and many other plants, add nitrates to the soil by converting free nitrogen in the air into nitrogenous nodules on their roots.
• Thus, if they are included in the crop rotation nitrogenous fertilisers can be dispensed with.

C) Strip Cropping

• Crops may be cultivated in alternate strips, parallel to one another. Some strips may be allowed to lie fallow while in other different crops may be sown.
• Various crops are harvested at different intervals. This ensures that at no time of the year the entire area is left bare or exposed.
• The tall growing crops act as windbreaks and the strips which are often parallel to the contours help in increasing water absorption by the soil by slowing down runoff.

D) Use of Early Maturing Varieties

• Early maturing varieties of crops take less time to mature and thus put lesser pressure on the soil. In this way, it can help in reducing the soil erosion.

E) Contour Ploughing

• If ploughing is done at right angles to the hill slope, the ridges and furrows break the flow of water down the hill.
• This prevents excessive soil loss as gullies are less likely to develop and also reduce run-off so that plants receive more water.

F) Checking Shifting Cultivation

• Checking and reducing shifting cultivation by persuading the tribal people to switch over to settled agriculture is a very effective method of soil conservation.
• This can be done by planning for their resettlement which involves the provision of residential accommodation, agricultural implements, seeds, manures, cattle and reclaimed land.

G) Ploughing the Land in Right Direction

• Ploughing the land in a direction perpendicular to wind direction also reduces wind velocity and protects the topsoil from erosion.

H) Mulching

• The bare ground (topsoil) between plants is covered with a protective layer of organic matterlike grass clippings, straw, etc.

Benefits

• Protects the soil from erosion.
• It helps to retain soil moisture.
• Reduces compaction from the impact of heavy rains.
• Conserves moisture, reducing the need for frequent watering.
• Maintains a more even soil temperature.
• Prevents weed growth.
• Organic mulches also improve the condition of the soil. As these mulches slowly decompose, they provide organic matter which helps keep the soil loose.

I) Contour barriers

• Stones, grass, soil are used to build barriers along contours. Trenches are made in front of the barriers to collect water.
• They intercept downslope flowing water and soil particles. These barriers slow down the water movement and reduce its erosive force. They also filter out and trap many of the suspended soil particles, keeping them from being washed out of the field.
• A long term advantage of barriers is that soil tends to build up behind them, creating a terrace effect. Barriers can be classified as live (strips of living plants), dead (rocks, crop residues), or mixed (a combination of the previous two).

J) Rock Dam

• Rocks are piled up across a channel to slow down the flow of water. This prevents gullies and further soil loss.

K) Terrace farming

• In terracing, a number of terraces are cut along the hill slope.
• These are made on the steep slopes so that flat surfaces are available to grow crops. They can reduce surface run-off and soil erosion.

L) Contour Bunding

• Contour bunding involves the construction of banks along the contours.
• Terracing and contour bundingwhich divide the hill slope into numerous small slopes, check the flow of water, promote absorption of water by soil and save soil from erosion.
• Retaining walls of terraces control the flow of water and help in reducing soil erosion.

M) Intercropping

• Different crops are grown in alternate rows and are sown at different times to protect the soil from rain wash.

N) Contour ploughing

• Ploughing parallel to the contours of a hill slope to form a natural barrier for water to flow down the slope.

O) Shelterbelts or Windbreaks

• In the coastal and dry regions, rows of trees are planted to check the wind movement to protect soil cover.

P) Sand fences

• Sand fences are barriers made of small, evenly spaced wooden slats or fabric. They are erected to reduce wind velocity and to trap blowing sand. Sand fences can be used as perimeter controls around open construction sites to keep sediments from being blown offsite by the wind.

Q) Dams

• Much of the soil erosion by river floods can be avoided by constructing dams across the rivers in proper places. This checks the speed of water and saves soil from erosion.
• But indiscriminate dam construction can worsen the condition by creating floods and landslides like it happens in the Himalayan region.

R) Checking Overgrazing

• Overgrazing accentuates erosion. During the dry period, there is a shortage of fodder, and the grass is grazed to the ground and torn out to the roots by animals. The soil is pulverised (reduce to fine particles) by the hoofs of animals. All this leads to the weak top layer.
• So overgrazing needs to be checked to prevent soil erosion.

This can be done by creating separate grazing grounds and producing larger quantities of fodder.

A) Why in news?

• The Compensatory Afforestation Fund bill, 2015 was passed by both Houses of the Parliament early this year.
• The Bill establishes the National Compensatory Afforestation Fund under the Public Account of India, and a State Compensatory Afforestation Fund under the Public Account of each state.

B) Background

• Currently Reserved Forest or a Protected Area (PA) land may be diverted under the Forest (Conservation) Act, 1980 for non-forest developmental activities like an industrial or infrastructure project with approval of central and state government.
• To compensate for diversion of forestland, afforestation must be done on a separate piece of land called as compensatory afforestation. In addition compensation must be paid for loss of forest ecosystem and biodiversity. Valuation of this forest ecosystem is called net present value.
• Cost for both is borne by agency responsible for diversion of forestland and money is collected by the state government for afforestation and forest development.
• In 2002, Supreme Court observed that these fund were not being utilized, and for this purpose an adhoc authority called compensatory afforestation fund management and planning authority (CAMPA) was set up. In the absence of permanent institutional mechanism more than Rs. 40,000 crores have accumulated which are being kept in Nationalized Banks and managed by CAMPA.

C) What bill does?

• Provides an institutional mechanism for safety and transparency in expeditious utilization of unspent amounts with ad hoc CAMPA to mitigate impact of diversion of such forest land.
• The National CAF and State CAFs will receive payments for: (i) compensatory afforestation (ii) net present value of forest (NPV), and (iii) other project specific payments.
• The National Fund will receive 10% and the State Funds will receive the remaining 90%.
• Establishes the National and State Compensatory Afforestation Fund Management and Planning Authorities to manage the National and State Funds.
• These Funds will be primarily spent on afforestation to compensate for loss of forest cover, regeneration of forest ecosystem, wildlife protection and infrastructure development.

D) Issues

Several factors that affect compensatory afforestation and forest conservation are:

• A 2013 CAG report noted that state forest departments lack the planning and implementation capacity for afforestation.
• Procuring land for compensatory afforestation is difficult as land is a limited resource, and is required for multiple purposes, such as agriculture, industry, etc. This is compounded by unclear land titles, and difficulties in complying with procedures for land use.
• The compensatory forests are low in quality and lacks in richness of biodiversity of a natural forest. A High Level Committee on Environment Laws observed that quality of forest cover has declined between 1951 and 2014; one reason is poor compensatory afforestation plantations.
• The Bill delegates the determination of NPV (value of loss of forest ecosystem) to an expert committee, its computation methodology would be important.
• Fragmentation i.e. breaking up of large forest blocks into smaller patches creating new edges that expose forests to degradation.

E) Way forward

• Planned implementation of said act at State and local level is very urgent to mitigate impact of loss of forests land and biodiversity. Since large amount is being devolved at state level, therefore, timely monitoring is very important.
• It will help in achieving our target of 33% forest cover and 2.5 billion tonne of carbon sink as indicated in our INDCs.
• The Department related Parliamentary Standing Committee had recently in 2016 had made certain suggestions:
• Provisions to be made for providing incentives to persons who are displaced or relocated elsewhere from eco sensitive zone.
• Compensatory Afforestation Fund Management and Planning Authority (CAMPA) funds should be permitted to be used for acquiring lands in eco sensitive areas in order to overcome loss of forests and native species plants should be selected so that ecology of the area is maintained.
• Need for people’s participation at various stages.

However, these suggestions have not been incorporated into the final Bill.

A) What are sacred groves?

• Forest Fragments of various sizes, which are community protected and usually have a significant religious connotation for that community.

B) Significance of sacred groves

• Traditional uses
• Medicinal use as it is a repository for plants with Ayurvedic properties.
• Source of replenishable resources like fruits and honey
• The groves are often associated with ponds and streams. They help in meeting the water requirement of communities and also in recharging aquifers.
• Hunting and felling trees is a taboo. This vegetation cover helps in preventing soil erosion.
• Modern uses
• In modern times, they have become biodiversity hotspots due to progressive habitat destruction in neighbouring areas.
• They act as a rich gene pool including rare, threatened and endangered species.
• Sacred groves in urban landscapes act as ‘lungs’ to the city as well

C) Threats

• Urbanization and encroachment
• Over-exploitation of resources like overgrazing and excessive firewood collection
• Religious practices; clearing them for construction of shrines and temples
• Invasion by invasive species

D) Protection measures

• The Wildlife (Protection) Amendment Act, 2002 had introduced a new protected area category called ‘community reserve’. Sacred Groves have been put under this.
• Under this significant power is given to the local communities with respect to administration of these areas.
• Many NGOs also work with local people for their protection.