Land Degradation and their Management: Key for Food Security and Agricultural Sustainability in India

India has about 17.4% of global population and 15% of livestock population with having 2% of global geographical area and 1.5% of global lands under forest (ICAR, 2012). The increasing human and animal population has reduced the availability of land over the decades. The per capita availability of land has declined from 0.89 hectare in 1951 to 0.28 hectare in 2013 and is projected to slide down to 0.20 hectare in 2035. As far as agricultural land is concerned the per capita availability of land has declined from 0.48 hectare in 1951 to 0.14 hectare in 2013 and is likely to decline further to 0.08 hectare in 2035. (World Bank 2014). Due to burgeoning population there is decline in per capita land availability in the country. Of 305 million hectare reported area out of total 329 million hectare in India, about 142 million hectares is net cultivated area. And of net cultivated area about 57 million hectare (40%) is irrigated and 85 million ha. (60%) is under rain fed. The area under cultivation is highly affected by anthropogenic as well as natural degradation. So, in order to meet the food demands of burgeoning population under threat of urbanization, we have to manage the land degradation specially under cultivation and also effective measures should be adopted for reclamation of wastelands and make them fit for agriculture. In addition with this, in changing climate scenario, the risk prone areas exhibit a wide variation and instability in yields.

Pic courtesy : unccd.int

The information on the extent of soil degradation in the country has been assessed by various agencies. The estimates of these agencies vary widely i.e. 63.9 m.ha. to 187.0 m.ha., due to different approaches in defining degraded soils and adopting various criteria for delineation. The main agencies that have estimated soil degradation are; National Commission on Agriculture (NCA, 1976), Society for Promotion of Wasteland Developments (SPWD, 1984), National Remote Sensing Agency (NRSA, 1985), Ministry of Agriculture (1985), and National Bureau of Soil Survey and Land Use Planning (NBSSLUP, 1984 & 2005).

The problems of land degradation are prevalent in many forms throughout the country. In most cases, a combination of such problem exists. In absence of comprehensive and periodic scientific surveys, estimates have been made on the basis of localized surveys and studies

LAND DEGRADATION AND AGRICULTURE:

Land degradation is a global problem, largely related to agricultural use. The major causes collectively include:

• Land clearance, such as clear-cutting and deforestation
• Agricultural depletion of soil nutrients through poor farming practices
• Livestock including overgrazing and over drafting
• Inappropriate irrigation and over drafting
• Urban sprawl and commercial development
• Soil contamination
• Overgrazing by livestock can lead to land degradation
• Vehicle off-roading
• Quarrying of stone, sand, ore and minerals
• Increase in field size due to economies of scale, reducing shelter for wildlife, as hedgerows and copses disappear
• Exposure of naked soil after harvesting by heavy equipment
• Monoculture, destabilizing the local ecosystem
• Dumping of non-biodegradable trash, such as plastic          

Pic courtesy : giz.de

Land degradation assessment by different organizations

Preliminary area statistics of degraded and wastelands of India

Pic courtesy : fao.org

CULTIVABLE PROBLEM SOILS:

• Waterlogged soils
• Salt-affected  soils
• Saline soils
• Sodic soils       

• Acidic  soils
• Physically degraded soils.

Salt-affected Soils

These soils contain excessive amount of either soluble salts or exchangeable sodium or both affecting crop yields and crop production. Depending upon the physiochemical properties and the nature of the salts, the soils are classified into saline, sodic and saline-sodic. Information on the salt-affected soils provided by the CSSRI, Karnal, was used for the harmonization of the degraded wasteland datasets of India. Gujarat has highest area under saline soil and Uttar Pradesh has highest area under Sodic soils. (www.nbsslup.in)

Management:

• Leaching with water
• Selection of salt tolerant crops and their varieties
• Use of green manure like Dhaincha

Waterlogged Soils: West Bengal has highest area under waterlogged soils. (www.nbsslup.in)

• Causes:
• Climatological : Rainfall and Flood water
• Irrigation : Uncontrolled, Unwanted
• Drainage : Poor drainage
• Topography : Depressed land
• Land shape : Saucer shaped land  become waterlogged
• Height of ground water table

MANAGEMENT:

§  Leveling of land

§  Mechanical drainage

§  Controlled irrigation

§  Flood control measures

§  Plantation of trees having high transpiration rate

§  Check the seepage in the canals and irrigation channels

§  Selection of crops and their  proper varieties 

§  Sowing on bunds or ridges

§  Nutrient management

Acidic Soil: 

These soils develop in humid and per-humid areas due to excessive leaching of cations with high rainfall, resulting in lowering of pH and loss of soil fertility, and can be reclaimed by addition of chemical amendments like lime. For assessing area under acid soils, soil maps of different states on 1: 250,000 scale were digitized in the GIS format. The non-spatial (attribute) data on pH values were linked to master soil layer to generate soil reaction (pH) map of India, which was reclassified to produce a soil acidity map of India. The acidity map of India, thus produced, facilitates understanding of spatial distribution and pH status of soils in different parts of India. Based on the range of pH values, the map has been reclassified as strongly acidic (pH < 4.5); moderately acidic (pH 4.5–5.5); slightly acidic (pH 5.5–6.5) and non-acidic (pH > 6.5). However, for the estimation of the degraded lands of India, only strongly acidic - pH < 4.5 and moderately acidic – pH 4.5–5.5 soils have been considered. West Bengal has highest area under acidic soils (www.nbsslup.in)

CAUSES:

¡  Management  and  land use

§  Fertilizers(acidic like ammonium sulphate), organic matter, and other amendments (like calcium sulphate)

§  Submergence and subsequent uplift of land exposing reduced sediments to oxidation processes

¡  Pollution

§  Acid rain

§  Mining

¡  Climate

§  Weathering and leaching

§  Rainfall leaching

    §  Metal hydrolysis: during hydrolysis of metal several acids are released which leads to acidity of soils

MANAGEMENT:

¡  Crop selection (acid tolerant varieties)

¡  Judicious use of acidic fertilizers

¡  Amelioration (with lime)

¡  Combination of above practices

Other Problem Soils:

Mainly consists of eroded soils and compacted soil.

¡  Others are

             a) Fluffy paddy soils

             b) Sandy soils 

             c) Hard Pan

             d) Surface crust soil

             e) Waste lands

Compacted Soils:

When stress applied to a soil causes increase in density as air is displaced from the pores between the soil grains.

§  BD >1.6-1.8 g/cm³

§ Compaction led soil degradation worldwide area of 68,000 km². Oldeman et al. (1991)

§ About 32% of subsoils in Europe are highly vulnerable and 18% are moderately vulnerable. (Fraters, 2011)

Management:

§  Periodic  deep ploughing

§  Controlled  traffic of heavy farm implement

§  Conservational tillage and building organic matter

§  Crop rotation with deep tap root system( like pigeon pea)

§  Avoid field operations when soils near field capacity

Management of Eroded Land:

Several measures depending upon slope and resource availability like

1)   Agronomic (<2%):-

     Contour cultivation, various mulching, strip cropping and other crop rotation and systems of Agroforestry.

    2) Mechanical (>2%):-

      Sub-soiling, Bunding, terracing, basin listing, levelling and other improved techniques like BBF.

CONCLUSION

The pressure on land has been mounting up at an alarming rate due to burgeoning population. Among Asian countries, India has severe problem in soil due to erosion and chemical degradation. Waterlogged soil can be managed through controlled irrigation, proper drainage and nutrient management. Chemically affected soils can be managed through hydro technical and chemical amendments with suitable crops and varieties. Physically degraded soils can be managed through proper engineering of machines used and proper conservation measures for soil management. There is a need of spatial distribution of problem soil through innovative techniques like remote sensing and GIS, which can act as a platform for policy makers in due course of management of problem soils. Here the problem is the lack of time series data disaggregated by local specific micro-data, which could be analyzed for assessment of situation change over time at specific problem areas.

Future Outlook

§ Suitable and economic conservation measures have to establish with response to changing climate and land use pattern

§ To reclaim soil  to a minimum level with incorporation of crop residues and replenish the nutrients removed by the crops judiciously along with chemical treatments

§ People consciousness and public-private co-operation need to be emphasized to combat  problem with robust and future oriented policy support by government

REFERENCES

Eswaran, H.; R. Lal and P.F. Reich. (2001). "Land degradation: an overview". New Delhi, India:  Oxford Press. Retrieved 2012-02-05.

Abrol, I.P. (1990). Problem soils in India, pp. 153-65. In: Problem Soils of Asia and the Pacific FAO/RAPA, Bangkok.

Das, D.C. (1985). Problem of soil erosion and land degradation in India. Proceedings of the National Seminar on the Soil Conservation and Watershed Management held on 17–18 September New Delhi.

Gautam, N.C. and Narayan, L.R.A. (1988). Wastelands in India, pp. 96. Pink Publishing House, Mathura, India

•  http://en.wikipedia.org/wiki/Land_degradation
•  http://www.agricoop.nic.in/nrm/statnrm.pdf
• http://www.preservearticles.com/201101082861/adverse-effects-of-land-     degradation.html
• http://slusi.dacnet.nic.in/ldm.htm

How climate change and land degradation are interrelated?

How we can have control on land degradation efficiently?

(Written by Prakash Jha, National Secretary at All India Agricultural Students Association (AIASA) and Research Fellow at IARI (Indian Agricultural Research Institute), New Delhi)

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