Soil & weathering

Weathering
• gradual and ongoing process of breaking down of rocks, soil and minerals through their contact with the Earth’s atmosphere, biota or waters.
• in‐situ phenomenon, resulting from the forces of weather such as changes in temperature, frost action, and rain action.
• involves various physical, biological, and chemical processes.
• conditioned by many complex geological, climatic, topographic and vegetative factors. Climate in particular has significant impact on the weathering
process and depth of weathering mantle.

Ecological Significance of Weathering
• initial stage in the formation of soil. breaks down the initial rock mass into smaller fragments thus preparing the rock material for the formation of soil.
• Trees are able to 'mine' essential nutrients such as calcium through their association with symbiotic mycorrhizae through small pores in the mineral soil, which is possible only due to weathering.
• Erosion, with the aid of weathering, helps in mass wasting and reduction of relief. This leads to modifications in various landforms.
• Depth of weathering mantles determines the type of forests. These forests then result in various biomes or biodiversity.

Economic Significance of Weathering
• formation of various natural resources such as clay used in making bricks.
• Formation of soil ‐ agricultural economy
• weakens the rocks, thus facilitating the mining and quarrying activities. Ex. aluminium is extracted from bauxite ore which is produced by weathering of related minerals.
• augmentation and concentrations ores of manganese, aluminium, iron, and copper, etc. Thus, though weathering is a disintegrating process yet it plays an integral role in sustaining life on earth.

Soil Health:
Healthy soils are crucial for achieving sustainable global food security, fighting climate change, and protecting biodiversity. With rising population, limited availability of agricultural land, small land holdings, industrialization, urbanization and declining soil fertility, India is under serious threat of losing its food surplus status in the near future.
The most prevalent land degradation in India is soil erosion, followed by soil degradation due to salinity, water logging and
shifting cultivation among others. Regional variations are as follows:
• Central India ‐ prominently affected by water induced soil erosion. North‐Eastern and Southern regions are also affected.
• Western India particularly Rajasthan and adjoining areas of Punjab, Haryana, Gujarat and Western Uttar Pradesh, is affected by wind erosion.
• Canal‐irrigated areas in Indo‐Gangetic Plains, Haryana, Rajasthan, Maharashtra, and Karnataka are affected by salinization and/or alkalisation due to inadequate drainage, inefficient water management and subsidized energy pricing. Intensive farming practices, particularly with wheat and rice, initiated during the Green Revolution in 1970s, have also adversely affected soil.
• Coastal areas suffer from coastal erosion with highest percentage of the shoreline under erosion in Nicobar Islands. Coastal land salinization and salt water ingress are also major hazards encountered along the Indian coast.
• Areas with heavy dependence on fertiliser due to low phosphorus content in Indian soil also leads to soil deterioration.
• Excessive deforestation coupled with shifting cultivation practices have resulted in tremendous soil loss in North East region.

Government initiatives to improve soil health:
Being a signatory to the United Nations Convention to Combat Desertification, India has taken a holistic approach in dealing with soil degradation by implementing programmes like
• Integrated Watershed Management Programme
(IWMP), MGNREGA and Swach Bharat Mission.
• Soil Health Card Scheme, o carry crop‐wise recommendations of nutrients and fertilisers required
o to improve productivity through judicious use of inputs.
• Encouragement of Social Forestry, promotion pf organic farming through initiatives like Paramparagat Krishi Vikas Yojana, National Mission on Sustainable Agriculture etc.
• Vigyan Kendras and schemes like Mera Gaon Mera Gaurav to connect farmers with agricultural scientists for accessing information, knowledge and advisories.
• National Mission on climate Resilient Agriculture have been started to inculcate the ideology of clean and good agricultural practices to improve soil
health.

The above initiatives are in line with international developments such as the Rio+20 outcome document‘s land‐degradation‐neutral world, Target 15.3 of the SDGs to achieve Land Degradation Neutrality (LDN) worldwide by 2030 and the formation of Global Soil Forum (GSF) which envisions a world in which soil is sustainably managed and responsibly governed.

Soil Degradation:
• change in the soil health status resulting in a diminished capacity of the ecosystem to provide goods and services for its beneficiaries.
• It includes loss of organic matter, decline in soil fertility/structural condition, erosion, adverse changes in salinity, acidity or alkalinity, and the effects of toxic chemicals, pollutants, excessive flooding/overgrazing/mining.

Soils are a fundamental natural resource, and are the basis for all terrestrial life. Soils provide a range of functions upon which humans depend, such as food production, water regulation, a
physical basis for construction etc.

Socio‐economic consequences of soil degradation include:
• Loss of Productivity and arable land:
• It leads to reduced income for the farmers which have implication for the economy as a whole,
• threat to food security, higher production costs; it also
• hampers poverty reduction especially when agriculture is the dominant occupation.
• Infrastructure damage: Degraded pastures may lead to floods and landslides
• Rise in natural disasters: such as mud flows, floods, droughts and aridity.
• Increased land reclamation costs: cost of afforestation, de‐salinization etc.
• Rise in inequalities: Reduced income in the absence of other alternatives to livelihood aggravate inequalities for families completely dependent on soil.
Ecological consequences:
• Soil provides various ecological services like nutrient cycling, carbon storage and habitat for living organisms.
• Soil degradation threatens these services and has other undesirable consequences like:
• Sedimentation and eutrophication of waterways and reservoirs: leading to water pollution.
• Soil compaction and surface sealing: It will affect the percolation capacity of soil, thus, affecting recharge of groundwater
• Soil contamination (including effects of toxic chemicals and pollutants) – This affects nutrients in food crops.
• Loss of biodiversity: soil degradation may involve perturbation of microbial communities, disappearance of the climax vegetation and decrease
in animal habitat.
Measures
• Afforestation: it restores the carbon cycle, binds the soil and prevents soil erosion while facilitating soil formation.
• Tackling salinization: by improving irrigation efficiency, using gypsum to reduce salinization.
• Improved Agricultural practices: Conservation tillage (makes minimal changes to the soil‘s natural condition), strip farming, crop rotation, contour farming, rational use of fertilizers and pesticides, moving towards organic farming; preventing slash and burn agriculture, promoting soil testing to ascertain the nutrient requirement of the farm , agroecological farming etc.
• Improved data management and coordination between various stakeholders.
• Land use planning for agriculture, settlement and industry.
• Soil degradation threatens world food security and various ecological services especially in the face of growing population and global climate change and needs to be tackled in earnest.