He points out that it was responsible for the decline of ancient Mesopotamian civilization 4, years ago. Salt problems exacerbated by human activity are altering habitat and farmland in the Colorado River basin.
The river and its tributaries supply water to more than 38 million people and irrigate more than 7, square miles 18, square kilometers of farmland. The salinity of the river has doubled in 60 years , mostly due to the building of dams, irrigation and evaporation in reservoirs, says researcher Gabriel LaHue, a graduate student in the Soils and Biochemistry Graduate Group at the University of California, Davis.
Salinity costs farmers and states dearly. Chen says salinity caused by rising sea levels is likely to force about , farmers a year to migrate from Bangladeshi coasts. Sign up now to receive our newsletter. In the coastal region of the U. Soil salinity can be reversed, but it takes time and is expensive. Solutions include improving the efficiency of irrigation channels, capturing and treating salty drainage water, setting up desalting plants, and increasing the amount of water that gets into aquifers.
Mulches to save water can also be applied to crops. The more high-tech solution is to develop genetically engineered and other salt-tolerant crops. But the science is not straightforward and is controversial, and the result is that not many varieties are available in large quantities. In coastal areas of many developing countries, like Bangladesh, Vietnam and Thailand, where brackish or salty water is most common, many thousands of small farmers have switched from rice to shrimp farming.
This is lucrative, but can be financially and ecologically risky, leading to more salinization and deforestation. The rush to shrimp farming has also led to conflict, with rice paddy fields being deliberately flooded in order to force farmers off their lands. In the brackish waters of the Mekong Delta, some rice farmers have taken up raising shrimp instead of, or in addition to, rice.
One option is a per-acre cover crop mix of 25 pounds of barley, 5 pounds of sunflowers, and 2 pounds of sugar beets. Reclamation of saline areas can take five to 10 years, with periodic monitoring and management modifications needed to minimize salts in the soil. Skip to main content. Content ID Site-specific management can reduce salt in your soil. By Raylene Nickel. Read more about Cover Crops. 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. Not all salt-affected soils can be reclaimed practically and economically.
While it is feasible to reclaim alkali and sodic soils by specific amendments and manage thereafter, the coastal salt-affected soils and black soils cannot be fully reclaimed. They require continuous soil and water management practices for their productive uses. In addition, several State Agricultural Universities, especially those located in salt-affected regions, are also engaged in soil salinity research.
Their efforts have resulted in the development of several technological interventions for the reclamation and management of salt-affected soils and use of poor quality water for irrigation in different agro-ecological zones of the country Sharma et al. The popularity of gypsum-based sodic soil reclamation, sub-surface drainage of water-logged saline lands, salt tolerant crop varieties and improved agroforestry techniques are a few laudable testimonies to the research credentials of these research Institutes.
Salt leaching with ponded fresh water, sub-surface drainage, mulching between two irrigations and during fallow period, irrigation management are some of the effective and well-known technological intervention to tackle the problems of water-logging and soil salinity Smedema and Ochs, ; Gupta, ; Arora and Sharma, The sub-surface drainage technology has been successfully adopted in Haryana, Rajasthan, Gujarat, Punjab, Andhra Pradesh, Maharashtra, Madhya Pradesh, and Karnataka, restoring around , ha waterlogged saline soils Sharma et al.
The adoption of sub-surface drainage technology in saline soils resulted in 3-fold increase in farmers' income. Besides, it significantly increased cropping intensity and socio-economic benefits in terms of on-farm employment generation Singh, The sub-surface drainage technology was able to generate around man-days additional employment per ha per annum Sharma et al. The cost of installation of sub-surface drainage system per hectare was estimated Rs.
The reclaimed area contributed about 0. The technology is useful but constrained by bottlenecks like higher initial costs, operational difficulties, lack of community participation and the problems of safe disposal of drainage effluents, for the rapid adoption of this technology Singh, Successful implementation of sub-surface drainage projects demands a collective approach and responsibility duly supported by appropriate institutional arrangements Ritzema et al.
In this section Salinity Type of salinity and their prevention. Salinity locations and mapping. Topics Land and soil Soil degradation Salinity Type of salinity and their prevention Type of salinity and their prevention There are different types of salinity, each with different causes and varying treatment. Treatment expand. This can be done by: maintaining adequate vegetation cover maximising water use by choosing an appropriate mix of pasture species minimising long fallows, using crop rotations and conservation farming methods in cropping areas maintaining soil health fertility, pH and structure to maximise plant growth.
Modelling expand. Modelling dryland salinity allows us to: assess and compare different actions to manage salinity fill gaps where data is limited forecast additional data based on our current data in space and time predict future trends.
Models help us to understand salinity processes in a landscape. We need to know: where is the salt and how much is there how salt and water moves how geology and landscapes influence movement what affects how fast salt and water are moving how changing something in one location affects the rest of the catchment or basin. Several models have been used in NSW to help answer these questions: PERFECT Used at a property scale, this well-established tool estimates surface runoff, lateral flow, recharge and the impacts of vegetation changes on the water cycle.
In , this model was used to forecast the impacts of climate change on surface runoff and recharge. The model predicts the impacts of various land use scenarios on catchment water yield and salinities to stream. It can be used for modelling water balance, solute balance, vegetation growth, recharge-discharge dynamics, lateral flow and streamflow.
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