Feb , 2022, Volume : 3 Article : 6

Land Degradation Causes, Consequences and Potential Solutions

Author : Dinesh Chand Meena

ABSTRACT

Land degradation is a global issue, threatening agricultural growth and food security. Water erosion is the major leading factor for land degradation problems followed by wind erosion and chemical. Appropriate approaches and actions for sustainable land management practices are significant factors for the rehabilitation of land degradation. Adopting and scaling up suitable land management practices particularly, soil and water conservation technologies are considered key factors for ensuring sustainable food and livelihood security through eradicating poverty, achieving land degradation neutrality, and building climate-resilient agriculture.

Keywords: Land degradation neutrality, SWC measures, watershed, water erosion, India

Land degradation refers to a loss of the biological and/or economic resilience and adaptive capacity of the land system. About one-third (120.7 Mha) of the total geographical area of India suffers from various forms of land degradation with water erosion being the chief contributor- affecting 83 Mha (68.4%) (NAAS, 2010). Annually, about 15 ton fertile soil is lost permanently per hectare due to water erosion, leading to loss of 5.37-8.4 Mt of nutrients, reduction in reservoirs’ capacity (1 to 2%) (CSWCRTI vision, 2030), significant loss of biodiversity and ecosystem services- food security, water purification, the provision of energy and other contributions of nature essential to people (Fig.1). Both natural events and human activities are the drivers of land degradation. Natural events include earthquakes, floods, tornadoes, tsunamis, landslides, droughts, and wildfires whereas, human activities include land clearing and deforestation, unsustainable agricultural practices, over-grazing, surface mining, inappropriate management of industrial effluents and wastes, poor management of forests, urbanization, and industrial development. This article provided valuable information for different stakeholders to make better-informed decisions for avoiding, reducing, mitigating as well as restoring the degraded lands.

Status of land use and land degradation

The land is the most precious resource on the earth planet which supports life and it cannot be expanded to meet the needs of an increasing population. Land use is mainly influenced by the nature of economic activities carried out in the region or country. Fig.2 revealed that about 12% of total geographical area of India is under barren, permanent pastures & other grazing lands, and culturable wasteland that can be put under sustainable use through adoption of appropriate technologies for restoration of ecology and to increasing bio-mass availability especially that of fuelwood, fodder, fruits, fiber & small timber.

Water erosion is the major contributor to the land degradation problem in India, resulting in topsoil loss and terrain deformation, followed by wind erosion and chemical degradation in the form of soil acidity (Fig. 3). Intensive agricultural practices with unabated use of groundwater, chemical fertilizers, and pesticides have triggered water logging and salinity in many parts of the country. The enlargement of the irrigation system without appropriate treatment of the catchment areas has exacerbated this. In some command areas of Gujarat, Maharashtra and Uttar Pradesh, due to progressive salt accumulation in the soils, crop choice has changed from rotation of paddy and sugarcane to paddy only and ultimately to a barren-like desert with no cropping.

The area under different soil erosion classes is presented in Fig.4. The country has a substantial percentage of the total geographical area under each category of soil erosion. The maximum area (24.96%) is in the moderate erosion category while the minimum area (9.54%) is in the severe erosion category. About one-fourth area of TGA falls under the severe and very severe erosion classes. The lack of appropriate approach and action for adoption of Sustainable Land Management Practices (SLMP) are important factors for such excessive erosion in the country.

Soil and Water Conservation (SWC) measures are considered key to addressing the problems of low agricultural productivity and soil degradation and, achieving land degradation neutrality (Fig. 5). These measures have been implemented in the country through many schemes and programs in watershed mode (Meena et al., 2020). Details of SWC measures are as follows:

 

A.      Structural SWC measures

Mechanical SWC measures (such as terraces, trench, bunds, check dams, etc.) are adopted permanently or for a long duration to change the slop profile for controlling soil erosion, retaining maximum rainfall within the slope, and for safe disposal of excess runoff from the top to the foot.  The details of structural SWC measures are given below:

1. Leveling and bunding (graded and counter bunds): Leveling and bunding is adopted on undulating land with slopes ranging from 1–6% to collect surface run-off, increase water infiltration and prevent soil erosion. A study conducted at Doon valley in the northwestern hills region indicted that contour bunds decreased runoff by 25–30% compared to field bunds [CSWCR&TI Vision, 2030].

2. Bench terrace and half-moon terrace: Bench terraces and half-moon terraces are adopted where soil depth is >1.0 m, and are used for planting and maintaining saplings of fruit and fodder trees in horticulture/agroforestry land uses. Bench terraces are flatbeds constructed across the hillslope; spaces between two contours are leveled by the cut and fill method.

3. Water harvesting structures (WHS): WHS (such as percolation ponds, farm ponds, tanks, check dams, etc.) are constructed to reduce soil erosion and flood hazards and recharge groundwater by reducing the flow of water and collecting rainwater. The harvested water can be used for agriculture, bathing, fish farming, and groundwater recharge.

4. Drainage line treatments (DLTs): DLTs are implemented to reduce erosion and prevent gullies formation. It increases the duration of flow which allows groundwater recharge and sediment to settle out.

 

B.      Biological SWC measures

Biological SWC measures (such as mixed cropping, contour cultivation, mulching, vegetative barriers, etc.) are usually adopted for a short duration or repeated routinely for soil and water conservation and improving soil health. These measures are not permanent or for a long duration. Graded broad bed and furrow system: This practice improves surface drainage and allows better water infiltration in the black soil of central India. Broad bed furrow decreased soil loss to a greater extent (31 to 55%) than its effect on runoff volume (24 to 32%) compared with that of flat on grade system.

1. Vegetative barriers: Vegetative barriers (such as grass strips, hedge barriers, windbreaks, etc.) could be applied to all types of land-use systems. It is used to prevent sheet and rill erosion through reduction/retardation of surface runoff by promoting infiltration, trapping sediment, and stabilizing the soil.

2. Reforestation and grassland development: Reforestation and natural grass development in wastelands have great potential to decrease land degradation. Vegetative barriers of Guinea grass, Khuskhus, and Bhabar were effective (after 3–4 years) in reducing soil loss by 6–8 ton/ha/year and runoff by 33–38% [CSWCRTI Vision, 2030].

3. Agroforestry systems- Agroforestry is an appropriate management tool for degraded land, because perennial woody vegetation recycles nutrients, maintains soil organic matter, and protects soil from surface erosion and runoff.

 

C.      Bioengineering treatments

High soil erosion rates such as landslides and mine spoil could be checked and brought within permissible limits by using appropriate bioengineering treatments with some suitable vegetation. These measures were effective to reduce the sediment load from 320 to 6 ton/ha/year, whereas vegetative cover increased from 5 to more than 95% on landslide and mine spoil in Nalota Nala watershed in the Shiwalik region (CSWCRTI Vision, 2030).

 

D.      Participatory watershed approach

Integrated watershed management (IWM) is a package of practices involving SWC measures, agronomy, forestry, soil management, and livelihood generation activities. IWM is one of the excellent strategies to stop the vicious cycle of land degradation. IWM provided a visible strategy to overcome several negative externalities that arise from water erosion. The meta-analysis, including 636 micro-watersheds (100 to 1000 ha area), was performed by Joshi et al., 2008. They evaluated the impacts of watershed programs in terms of rural employment generation (151 person-days ha-1), increased cropping intensity (36%), decreased runoff (45%), and soil loss (1.1 ton/ha/year).

Chemical land degradation mitigation measures

Many Researchers have facilitated the development of several cost-effective technologies to augment and sustain agricultural production in chemically degraded land. Recommended package of practices includes:  a) Field bunding, land shaping, construction of field channels, etc. b) Green manuring & residue mulching into the soil along with the use of F.Y.M; c) Growing of suitable crops/horticultural/agroforestry species including food, fuel & fodder plantations based soil and slope conditions; d) Capacity building for the adoption of recommended package of practices to prevent recurrence of acidity/salinity in the soil.

Acid Soils: These can be reclaimed through applying lime at the rate of 2 to 4 q/ha in furrows, depending on the extent of acidity, along with growing crops suited to such soils to enhance productivity. Pigeon pea, groundnut, soybean, gram, pea, lentil, cotton, sorghum, maize, wheat, mustard, and linseed crops are recommended for acid-affected soil.

Alkali and Saline Soils: These soils can be reclaimed through applying Gypsum/Pyrite at the average rate of 5 tons/ha, which mixes with soil when the temperature is around 40 °C. Construction of surface/sub-surface drainage is recommended for flashing out salt accumulated upper soil layer crop root zone. The high-yielding salt-tolerant varieties of rice, wheat, sunflower, mustard, and castor crops are recommended for these soils. Tree species such as Prosopis juliflora, Tamarix articulate, Acacia nilotica, Casuarina equisetifolia, and Leptochloa fusca grass are promising species for sodic soil reclamation. Similarly, to reclaimed salt-affected soil, Populus deltoides, Eucalyptus tereticornis, and Tectona grandis based agroforestry systems are recommended.  A Prosopis juliflora-Leptochloa fusca silvi-pastoral model is suggested for sustained fuelwood and forage production in high pH soils.

Wind erosion control measures

Wind erosion is a severe problem in arid regions of the country. It can be reduced effectively through the adoption of proper land use and adequate moisture conservation, crop residues management, timely tillage practices, vegetative barriers, windbreaks and barriers, and shelterbelts. 

Conclusion

Land degradation often has serious repercussions on key ecosystem functions such as food, fodder & fiber production, water retention, climate regulation, and carbon sequestration. The desertification or abandonment of land can be the worst consequences of land degradation. Therefore, there is an urgent need for avoiding, reducing, and reversing land degradation through the land degradation neutrality approach. Appropriate attention to transfer and adoption of land degradation mitigation technologies through effective information sharing amongst the stakeholders may play a significant role in achieving the objectives of the land degradation neutrality mission.

 References

 

CSWCRTI Vision, 2030. ICAR-Indian Institute of Soil and Water Conservation, Dehradun. June 2011.

Joshi PK, Jha AK, Wani SP, Sreedevi TK and Shaheen FA. (2008). Impact of Watershed Program and Conditions for Success: A Meta-Analysis Approach. Global Theme on Agroecosystems (Report 46), ICRISAT, Hyderabad, and NCAP, New Delhi, India.

Mandal D, Giri N and Srivastava P. (2020). The magnitude of erosion-induced carbon (C) flux and C-sequestration potential of eroded lands in India. European Journal of Soil Science 71: 151–168.

Meena DC, RamaRao CA, Dhyani BL, Dogra P, Samuel J, Dupdal R, Dubey SK and Mishra PK. 2020. Socio-economic and environment benefits of soil and water conservation technologies in India: A critical review. International Journal of Current Microbiology and Applied Sciences, 9(4), 2867-2881.

NAAS. 2010. Degraded and Wastelands of India -Status of spatial distribution. National Academy of Agricultural Sciences, New Delhi.

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