UESCO states that according to the World Atlas of Desertification, 75% of soils are already degraded, directly affecting 3.2 billion people. The current trend may increase the impact to 90% by 2050.
Soil degradation is defined as a change in soil health status resulting in a diminished capacity of the ecosystem to provide goods and services for its beneficiaries. It involves biological, chemical, and physical decline in soil quality.
This degradation can manifest through loss of organic matter, decline in soil fertility, structural damage, erosion, and adverse changes in salinity, acidity, or alkalinity. It also includes contamination by toxic chemicals, pollutants, or excessive flooding.
Estimates of soil degradation in world :
About 33% of the world's soils are moderately to highly degraded.
with 40% of degraded soils located in Africa.
Approximately 12 million hectares of agricultural soils are lost globally each year due to degradation.
30% of the soil in India is degraded according to the national bureau of soil survey and land use planning.
Causes and types of soil degradation :
Factors and process that accelerating soil degradation: human and natural factors along with climate change, unsustainable land use and pollution
1) mechanical tillage expanded the amount of land exposed to soil degradation
2) degradation of soil organic matter : loss of organic carbon from soil.
3) water and wind erosion
4) physical properties of soil degraded
5) chemical degradation: nutrient depletion, acidification, salinisation
6) contamination of soil by heavy metals, toxic chemicals
7) deforestation, overgrazing, intensive farming, mining, construction
8) climate change accelerated the rate of loss of soil moisture, expansion of dryland and desertification due to heat waves, changes in rainfall patterns
9) unsustainable land uses leads to removal of vegetation cover, exposed arable land more to agents of erosion and pollution.
10) faulty agricultural practices such as shifting cultivation, intensive farming practices, use of chemical fertilisers and pesticides, excessive tillage and irrigation, HYV seeds.
11) physical processes leading to the loss of fertile soil such as floods, surface runoff, landslides, wind and storms, intensive tillage, heavy machinery use. Long term physical degradation harms soil fertility, composition and structure.
12) ecological degradation of soil by exposing it to erosion and causing disruptions in ecosystems. Decreased land productivity due to climate changes, deforestation, loss of ground cover.
13) chemical changes in soil affects its mineral nutrients, pH values, humus content, etc due to excessive use of chemical fertilizers, pesticides, release of industrial and municipal effluents, salinity, acidity,etc
14) Biological productivity of soil is reduced due to reduced soil organic carbon, decreased microbial activity, and destructive biochemical reaction .
Adverse impacts of soil degradation:
1) reduced agricultural production and productivity due to nutrient loss like nitrogen, phosphorus, potassium and soil organic carbon, loss of arable land to desertification reducing yields.
2) food security in the world especially affecting poor nations and poor people as food shortages due to poor soil quantity and quality, rising food inflation unaffordable food prices leads to depletion of economic of poor people, increased poverty and famines already in Africa more than 20 million affected with famines.
3) ecological and environmental degradation accelerated by soil degradation as water cycle disrupted , more release of stored carbon dioxide from soil into atmosphere contributing to global warming and climate changes, destroying habfor species, reducing bio capacity of the region, leading to loss of biodiversity.
4) socio-economic adverse consequences of soil degradation and desertification arise due to continues crop failures, loss of livelihood, drought and famines triggered by forced migration to urban areas or other regions increased social and economic tension further grows into political crisis, humanitarian crisis, etc., example in sub Saharan African countries, Horn of Africa,
5) health impacts: in soil degraded areas health deteriorates due to increased malnutrition, under nutrition, contaminated water
6) sedimentation of water bodies due to erosion , leads to reduced water storage capacity and increased the rate of drought and floods.
7) soil degradation leads to loss of ecosystem services like nutrient recycling, water conservation,etc.
MEASURES :
1. Organic Matter Addition
2. Planting Cover Crops
3. Green manure, farm yard manure
4. Reforestation and Afforestation
5. agroforestry practices
6. sustainable farming prctices like vermicompsting, soil organic cabon, natural farming, organic farming, conservation tillage, avoid use of chemical fertilizers and pesticides.
7. No-Till or Reduced Tillage
8. Mulching, contouring, terracing and bunding to conserve soil and mositure
9. rain water harvesting structures like check dams, percloation tanks,etc
10. addition of lime and gypsum to maintain pH values of soil
Some of the important measures for controlling desertification in India are as follows:
(i) Intensive tree plantation programmes should be initiated.
(ii) Shifting sand dunes in Bikaner, Barmer, Churu, Jaisalmer and Jhunjhunun districts of Rajasthan cover an approximate area of 74 thousand sq km. Central Arid Zone Research Institute, Jodhpur has suggested mulching them with different plant species. Mulches are put in small squares and serve as an effective physical barrier to the moving sand.
(iii) Grazing should be controlled and new pastures should be developed.
(iv) Indiscriminate felling of trees should be banned.
(v) Alternative sources of fuel can reduce the demand for fuel wood and save the trees from destruction hence checking the onward march of the desert.
(vi) Sandy and wastelands should be put to proper use by judicious planning.
(Vii) green walls is a narrow Strip of forest around the desert to prevent wind erosion and its consequences in surrounding areas. For example in India , Green wall is planned along NH-8.
(Viii) water erosion is controlled by adopting integrated watershed management practices such as check dams, percolation tanks, recharging pits/well/tube wells.
(ix) plugging gullies ,alignment of rivers / streams,
(X) soil moisture conservation measures such as mulching, bunding, contouring, agricultural waste cover , increase vegetative cover , etc.,
(xi) adoption of agro-economic practices which reduces the water use, more efficient methods are : micro-irrigation facilities such as sprinklers, drip or subsurface irrigation system; dry farming practices, avoiding the use of HVY seeds, chemical fertilisers, zero budget natural farming, organic farmings, drought resistant crops or other sustainable farming technologies.
(Xii) supporting the livelihood of local communities,poverty alleviation programme, increase theirs off-farm incomes, as reduction in poverty reduce the pressure on local resources exploitation.
(Xiii) international effort under UNCCD-1994 commitments need to be achieved
International efforts to conserve and restore degraded soils are critical to addressing global challenges like food security, climate change, and environmental sustainability. Here are some key international initiatives and collaborations focused on soil conservation:
1. United Nations Convention to Combat Desertification (UNCCD)--1994
2. Land Degradation Neutrality (LDN)
3. Global Soil Partnership (GSP)--2011
4. The Bonn Challenge is a global effort to restore 350 million hectares of deforested and degraded land by 2030. established in 2011.
5. Launched at the 2015 UN Climate Change Conference (COP21) in Paris, the "4 per 1000" initiative aims to increase global soil organic carbon stocks by 0.4% annually.
6. Several SDGs, particularly Goal 15 ("Life on Land"), emphasize the importance of land and soil conservation. Goal 15 targets the restoration of degraded land and soil, including land affected by desertification, drought, and floods, and the goal of achieving a land degradation-neutral world by 2030.
7. TerrAfrica Initiative in sub saharan africa launched in 2005
8. Great Green Wall Initiative in sahel region by African union.
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