Why is salinity a problem

India would require around million tons of food grains cereals and pulses during to feed around 1. To achieve food security in the country, the attempts need to focus on both area expansion under agriculture as well as rise in crop productivity. Massive urbanization is putting pressure on agricultural lands, resulting in shrinking of land holdings. The possibility of area expansion under agriculture, therefore, exists in restoring the degraded lands.

Government of India has fixed a target of restoring 26 million ha of degraded lands, including salt-affected soils, by the year to ensure food security for the people.

Around 6. Several innovative technologies have been developed and on-farm tested. Gypsum-based sodic soil reclamation, sub-surface drainage of water-logged saline lands, salt tolerant crop varieties and improved agroforestry techniques are some of the well-adapted technologies in the country. Reclamation of 2. Other technologies of management of salt-affected soils, viz. The ongoing consistent research efforts for the management and reclamation of such soils would hopefully continue ensuring food security in the country.

The Government needs to make policies favorable for implementation of reclamation technologies in the country. Since independence, India has made significant achievement in agriculture sector. Food grain production increased by about 5. According to Tiwari , with a record production of rice and wheat at While the increase in food grain production during —65 was mostly due to area expansion under cultivation Narain, ; Vaidyanathan, , after mid-sixties, the adoption of a package of high yielding inputs, including use of high yielding varieties, assured irrigation, use of plant protection measures and credit support was responsible for increased production Dantwala, It ushered green revolution in India.

In spite of the technological innovations in agriculture, which dramatically increased food production in the past few decades Godfray et al. Sustainability of rice-wheat cropping system in the Indo-Gangetic plains of India has been challenged, as evidenced by the stagnating rice-wheat yields and declining factor productivity during the last about three decades, by the fast receding water table, climate variability, deteriorating soil health, environmental pollution, and secondary salinization Aggarwal et al.

Population growth in India has also kept pace with food production. According to the revision of the World Population Prospects, India's population stands around 1. Even at this growth rate, India is projected to be the world's most populous country by The massive population increase despite the slowing down of the growth rate and substantial income growth demand an extra about 2. The changing lifestyle and food habits of the people, due to the sustained economic growth, literacy and awareness, are other challenges associated with food security in India.

People in general are shifting from staple food grains toward high-value horticultural and animal products Kumar et al. Although it may lower per capita food grain requirement, yet overall demand for food grains would increase for increasing population and increasing food needs of livestock and poultry. The grain requirement for rearing cattle and poultry etc.

Table 1 provides global average feed conversion efficiencies for different animal categories and production systems. India would require around million tons of food grains including pulses during , and the requirement would further increase to million tons by Kumar et al.

At the current growth rate in agricultural production, food security in India appears to be a big challenge. Table 1. Global average feed conversion efficiency per animal category and production system. The projections of higher food requirements due to demographic, economic, and trade liberalization are exerting heavy pressures on India's limited land and water resources. It is estimated that nearly Land degradation in some regions of India, especially in arid and semi-arid tracts desertification , is touching irreversible limits.

Land degradation has become a big challenge to policy makers who need to balance the multiple goals of poverty eradication, food security, and sustainable land management. Soil salinization alone has rendered significant chunks of land unproductive or less productive.

Soil salinization is a global and dynamic problem and is projected to increase in future under climate change scenarios, viz. Precise statistics on the recent estimates of global extent of salt-affected soils are not available and different data sources provide variable information Shahid et al.

The global figure of However, figures such as According to Mandal et al. Around 52 million ha lands are salt-affected in South Asia Mandal et al. Soil salinization, in addition to reducing net cultivable area, has serious implications for agricultural productivity and quality, the choice of cultivable crops, biodiversity, water quality, supply of water for critical human needs and industry, the longevity of infrastructure and the livelihood security of the people.

Growing trend in the salt-affected soils in India is becoming a threat to national food security and economic development. A paradigm shift is, therefore, needed in the policy and methodology of food production in the country. Food security attempts need to focus on both area expansions under agriculture as well as rise in crop productivity.

Restoration of degraded lands, including salt-affected soils, offers a potential opportunity of sustaining food security in the country. With this thing in mind, the Government of India has fixed a target of restoring 26 million ha of degraded lands by the year Soil salinity is an index of the concentration of salts in soil and is usually expressed as electrical conductivity EC. Soil salinization is a process by which there is build-up of salt concentration in soil to such a level that impacts on the agricultural production, environmental health, and economics and quality of life.

Soil salinization involves a combination of processes like evaporation, salt precipitation and dissolution, salt transport, and ion exchange etc. The salt-affected soils contain excessive concentrations of either soluble salts or exchangeable sodium or both due to inadequate leaching of base forming cations. Hyper-saline soil water may also contain boron B , selenium Se , strontium Sr , lithium Li , silica Si , rubidium Rb , fluorine F , molybdenum Mo , manganese Mn , barium Ba , and aluminum Al , some of which can be toxic to plants and animals Tanji, Soil salinization may occur through both natural and anthropogenic reasons.

Out of Arid and semi-arid regions, where evaporation rates are high and fresh waters are scanty to flush out the excess salts from soil, favor the formation of such soils. Gupta and Abrol have extensively reviewed processes of soil salinization. Natural processes of soil salinization i. They are transported away from their source of origin through surface or groundwater streams.

In arid regions, the concentration of salts gradually increases until they start precipitating in soil due to limited natural precipitation and leaching, high evaporation and transpiration rates. Low-lying areas with high groundwater table and locked topography favor salinization. Fossil salts can be dissolved under water storage or water transmission structures causing salinization Bresler et al. The salt-laden winds and rains sea sprays along sea coasts carry oceanic salts along with them in quantities sufficient to cause salinization in coastal areas.

The sea sprays may contain salt content as high as The coastal regions are also exposed to the risk of progressive salinization of land due to processes like storms, cyclones, tidal surges, flooding etc. Anthropogenic reasons of soil salinization i. Change of land use from natural forest vegetation to annual food crops decreases evapotranspiration and increases leaching. Even irrigation with good quality water over a period of time in the absence of proper soil-water-crop management practices may cause salinization.

Fall of civilizations like Mesopotamia, Nile Valley, Mohanzoadaro, and Indus Valley are glaring examples of imminent occurrence of salinity following irrigation Dagar, Irrigation with sea water causes salinization in coastal areas.

Of particular concern is the entry of heavy metals into soils. At several occasions the socio-economic and political considerations become extremely important in accelerating soil salinization processes. Many times, such factors are beyond the control of individual farmers.

Some of such examples, especially in developing countries, may be the ill-conceived or poorly implemented irrigation schemes, intensive vs. It is, therefore, the responsibility of respective governments to take appropriate policy decisions and corrective measures in order to keep a check on soil salinization. The salt-affected soils are classified into three groups depending on the nature and concentration of salts present in them:. The remaining arable lands are not cultivated.

Around 2. The salt-affected soils in India broadly fall in two categories: sodic soils and saline soils. At certain places, with mean annual rainfall around mm, saline-sodic soils are also found in the form of narrow band separating saline and sodic soils Arora and Sharma, , but because their chemical properties and management are almost the same as the sodic soils, they are grouped with sodic soils category Qadir et al.

Majority of the sodic soils occur in Indo-Gangetic region of India. They originate primarily due to weathering of rocks and minerals containing high sodium minerals, irrigation with groundwater containing excessive quantities of carbonates and bicarbonates, rise in groundwater table due to introduction of canal irrigation and salt laden run-off from the adjoining areas and un-drained basins.

The saline soils are widespread in the canal irrigated arid and semi-arid regions. Table 2 shows the distribution of salt-affected soils in India.

Mandal et al. Sodic soils are confined in the Indo-Gangetic plains, arid and semi-arid region of western and central India, and Peninsular region in the southern India.

Largest area under saline soils Largest area under sodic soils Introduction of the canal irrigation projects without proper provision of drainage has led to wide spread salinity in the country. Substantial salt-affected area occurs in different canal commands viz. Continuous seepage from the canals has resulted into rise in water tables and subsequent upward flux of salts to the surface, water-logging, formation of marshy lands, increased soil salinity, and decreased biodiversity.

Two glaring examples include: i salinization of around 0. Good quality irrigation water is scarce in the country. Increasing pressure of producing more food per unit available arable land forces for extensive use of brackish groundwater for irrigation. Many more areas with good quality aquifers are endangered with contamination as a consequence of excessive withdrawals of groundwater.

The salinized areas in India continue to increase each year due to introduction of irrigation in new areas Patel et al.

According to Sharma et al. Delineation and digitization process of salt-affected soils in India is on. Fifteen salt- affected states have been mapped on , scale and digitization on , scale is in progress. The planning and execution of soil reclamation programmes by the policymakers and stakeholders are based on the state-wise data and maps of saline and sodic soils Mandal et al.

The first approximation of water quality map of India has been published Sharma et al. The soil salinization has tremendous environmental, ecological, agricultural, and social impacts in terms of shrinkage of agricultural lands, low agricultural productivity, uncertain and unstable livelihood security, low economic returns, and poor quality of life. Excess salts in soil affect the metabolism of soil flora and fauna, leading ultimately to the destruction of all soil life, transforming fertile and productive lands into barren and desert lands.

Soils are rendered useless agriculturally as well as for several other purposes e. The salt accumulation damages existing infrastructure, farm machinery, waterways, roads etc. History records that soil salinization was partly responsible for the collapse of ancient civilizations like Mesopotamia, Nile Valley, Mohanzoadaro, and Indus Valley Dagar, Salinity affects almost all aspects of plant development including germination, vegetative growth, and reproductive development due to drought and high soil salinity, and harsh environmental conditions Machado and Serralheiro, Plants in salt-affected environments experience two types of stress, the osmotic stress and nutrient stress.

The osmotic stress is due to low osmotic potential of water in saline soils which adversely affects water absorption by plants. It also results in nutritional imbalances.

Soil salinity significantly reduces phosphorus uptake by plants because phosphate ions precipitate with Ca ions Bano and Fatima, Reduced leaf area, chlorophyll content and stomatal conductance in salt-affected soils also affect photosynthesis Netondo et al. Apart from high ESP and nutrient deficiencies and toxicities, other constraints for plant growth in sodic soils include poor soil physical conditions, viz.

They affect plant root penetration, seedling emergence, and tillage operations Murtaza et al. Although salinization has strong implications on socio-economic aspects, yet very few publications are available in literature Shahid et al. Social consequences of soil salinization include decline in agricultural harvest, low income, change of livelihood options and related social constraints.

The estimates based on —14 moving average data suggest that due to soil salinization India loses annually It has strong implications on the national economy. The state of Uttar Pradesh topped the list with 7. In terms of monetary loss, Gujarat topped the list with Rs. All these states deserve policy attention for management of salt-affected areas to reduce the crop production and monetary loss.

Peoples' living standard, daily life activities and socio-economic conditions are adversely affected. Farmers in response to salinity problem are forced to shift their livelihood strategies Ziaul Haider and Zaber Hossain, Farmers in salt-affected areas are generally resource constrained and require financial and technical assistance to sustain their livelihood efforts Oo et al.

Such degraded ecosystems, nevertheless, offer immense opportunities to harness the productivity potential through appropriate technological interventions. Even marginal to modest gains in crop yields in such soils would mean dramatic improvements in the lives of thousands of poor farmers in salinity affected regions in a country facing many challenges in agriculture.

After decades of experiments globally including ICAR-CSSRI, Karnal and several SAUs in India, understanding the problems of salt-affected soils, poor-quality irrigation waters, water dynamics, causes of salt accumulation and behavior of plants under salt stresses, recommendations have emerged as technologies for reclamation and management of salt-affected soils, viz. There may be two approaches to tackle problem of soil salinity. One, to reclaim salt-affected soils; two, to manage salt-affected soils as they exist, i.

The choice depends on the feasibility of reclamation and the cost effectiveness. Salinity may also indirectly affect people by reducing the quality of the natural environment for example, where the numbers and variety of wildlife decrease in salinised natural wetlands.

Salinity increases repair and maintenance costs for a range of services provided for public use as there is a need to replace infrastructure earlier than normal. Road and bridge damage caused by shallow, saline groundwater is a major cost and many towns also experience damage to footpaths, parks, sewage pipes, housing and industry.

These relate to the additional costs incurred by the community to minimise salinity and rising watertable problems. Examples of this include the costs associated with preventive measures like:. Home Environment, land and water Land, housing and property Land and vegetation management Soil management Salinity Impacts of salinity.

Print Impacts of salinity As a result of rising water tables in irrigated and non-irrigated areas or the use of saline water supplies—salinity can have significant impacts on the following aspects. Agricultural production Water moves into plant roots by a process known as osmosis , which is controlled by the level of salts in the soil water and in the water contained in the plant.

Water quality The most significant off-site impact of dryland salinity is the salinisation of previously fresh rivers. Ecological health of streams Salt interacts with in-stream biota animals and plants , changing the ecological health of streams and estuaries.

Terrestrial biodiversity Much of the natural vegetation of salt-affected areas has been destroyed or damaged. Soil erosion Dryland salinity is closely linked to other soil degradation issues, including soil erosion. Flood risk Shallow water tables can increase the risk of flooding. Infrastructure and fixtures Impacts include large decreases in the lifespan of road pavements when groundwater levels rise to within 2 metres of the pavement surface. Salt also corrodes and destroys the properties of bitumen, concrete and brick structures.

It deteriorates drinking and irrigation water and adds to further salinization of drylands. The Colorado River basin is one of the most affected areas in the world. The impact is multifold :. While non-saline soils do not affect crops, strongly saline ones are suitable only for salt-tolerant species and halophytes.

Thus, salinization reduces ecosystem varieties and threatens their normal conditions to exist. A reduction of flora diversity inevitably causes a reduction of fauna as well by shortening food chains and areas of habitats. Salinization reduces biodiversity in rivers or fresh-water lakes, shortening aquatic populations solely to salt-tolerant species. Soil salinization effects refer to crop diversity and, correspondingly, food variety as farmers are forced to produce plants that can survive in salty earths.

Soil salinization is a serious problem itself, but it rarely comes alone. Salinity causes continuous wetness of land surface and a lack of cover due to poor plant growing conditions. These make lands highly prone to erosion. With heavy rainfalls or river flooding, soils cannot cope with high amounts of water flows. Thus, insufficient absorption results in runoffs and floods.

Strong water currents ruin constructions, damage farmlands, increase sedimentation, and contaminate aquatic bodies. The best way to deal with soil salinization is not to let it happen. In case it did, it is important to eradicate the problem — the sooner, the better, before the consequences get too severe. So, soil salinization solutions deal with prevention and management. Soil salinization prevention bases on avoiding excessive salt penetration.

Even though plants require a certain amount of salts to develop, their needs are small compared to the content in salt-affected soils.

Here are some typical methods to prevent soil salinization :. As a preventative measure, Crop Monitoring allows tracking the vegetation state in the field and identifying areas with sparse vegetation or bare ground surface. Timely scouting of such zones enables farmers to understand and eradicate the root cause, tackling the issue before it gets too severe.

Crop Monitoring may assist the process of reducing soil salinity. Shallow-rooted plants may not reach subsoil moisture, and extra subsoil moisture may induce salinity. Crop Monitoring provides reports on surface soil moisture and root-zone moisture, facilitating the choice of crops for planting in the exact areas.

Practices leadership seminar, pp. B arbour , M. CrossRef Google Scholar. B oumans , J. B oyko , H. Salinity and aridity: New approaches to old problems. The Hague: Junk B radley , W. Southwest Nat. C airns , R. Talajtan 18 , —37 Soil Sci. C hapman , V. Salt Marsh Symp. AIBS meeting In: Ecology of Halophytes: Ed. R eimold M and Q ueen M, Acad. Press Lehre: Cramer Verlag C usick , A. Rhodora 72 , —86 D ahlbeck , N. P, C oupland , R.