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 majority of the salinity affected regions, however, the community participation appears lacking as evidenced by the non-existent or non-functional water-user organizations for irrigation as well as drainage projects. It slows down the up-scaling of reclamation technologies in salt-affected areas. The technology package based on chemical amendments consists of the components such as land leveling, bunding, flushing, drainage for removal of excess water, good quality irrigation water, application of amendments, selection of crops and efficient nutrient management.
Different chemical amendments used for the reclamation of sodic soils may be grouped into two categories: soluble calcium sources e. Farmyard manure and pressmud are also used as amendments for reclaiming sodic soils. Chemical amendments require moisture rainfall or irrigation to activate the chemical processes that can reduce sodium levels or leach salts from the root zone.
The organic amendments, on the other hand, are capable of alleviating problems associated with excessive salts or sodium without supplemental irrigation. The amount and type of chemical amendments required for reclamation of sodic soils depend primarily on soil pH, EC, and ESP. Soluble calcium sources are recommended for use in non-calcareous soils while for calcareous soils acids or acid-formers are recommended.
Gypsum followed by pyrites has emerged as the most preferred and acceptable chemical amendment for sodic soils in India due to their easy availability and low cost Abrol et al. Pyrite was much less effective than gypsum Tyagi, Gypsum requirement for restoring an alkali soil depends on the initial exchangeable sodium percentage ESP , texture and mineralogy of soil, depth of soil to be reclaimed and tolerance of crops to sodicity.
A good correlation exists between soil pH and gypsum requirement Abrol et al. The addition of organic materials in conjunction with gypsum hastens the reclamation process and also reduces the gypsum requirement Chorum and Rengasamy, ; Vance et al. Addition of organic material increases soil microbial biomass while gypsum lowers soil pH Wong et al.
Industrial byproducts such as phosphogypsum, pressmud, molasses, acid wash, and effluents from milk plants help in the reclamation of sodic soils by providing Ca directly or indirectly by dissolving soil lime Arora and Sharma, However, care should be taken that toxic elements like F, which is present in large quantities in products like phosphogypsum, are not added to soil Chhabra et al.
The equivalent amounts of other amendments relative to gypsum are given in Table 4. Table 4. Equivalent quantities of some common amendments for sodic soil reclamation. The gypsum-based alkali land reclamation technology has found large scale on-farm adoption in the country.
Nearly 2. Besides, it also provides an employment opportunity to about 2. Sharma et al. The reclamation cost was estimated to be around Rs. A number of technologies have been standardized and perfected to restore coastal saline soils and sustain crop production in them. Rabi cropping in mono-cropped coastal saline soils, salt tolerant rice cultivars, rainwater harvesting in dugout farm ponds, integrated rice-fish culture and efficient nutrient management have been successfully practiced Sharma and Chaudhari, Multi-storeyed integrated agroforestry systems involving fish or shrimp culture, poultry, plantation crops, cattle, and diversified arable crops etc.
Khan et al. Initial cost on land excavation for constructing farm ponds, paddy-cum-fish culture and raised-sunken beds in coastal salt-affected areas was around Rs. Similar encouraging results were obtained through land modification technology pond based and raised and sunken bed under sodic soils in Uttar Pradesh Verma et al.
Phytoremediation of salt-affected soils refers to the processes of removing excess salts from soil by growing different type of plants. Growing of salt tolerant trees, shrubs, and grasses is a cost-effective and environmental-friendly way of restoring salt-affected soils Mishra et al.
Different species of salt tolerant trees, shrubs, and grasses have been identified and put to use Table 5. Excellent reviews are available in literature on phytoremediation, e. Table 5. Soil ECe and SAR reduction through phytoremediation and chemical amendments using different plants i initial, f final.
Plants remove excess salts from soil through root absorption and accumulate them in their biomass, a process called phyto-accumulation or phyto-extraction. It decreases exchangeable sodium and soluble salt concentrations in soil. They also augment soil organic carbon and nutrient content thereby gradually improving physical bulk density, porosity, infiltration, water holding capacity etc.
Tree plantation, besides making degraded lands productive, provides fuel wood, and forage and helps in moderating climate change impacts through carbon sequestration Dagar, ; Sharma et al. Reclamation of sodic and saline waterlogged soils through afforestation and agroforestry practices is well established and documented Dagar, ; Dagar et al.
Some of the promising species for sodic soil reclamation include Prosopis juliflora, Acacia nilotica, Casuarina equisetifolia, Tamarix articulate, Eucalyptus tereticornis , and Leptochloa fusca Singh et al. Plant species like Eucalyptus tereticornis, Populus deltoids , and Tectona grandis are effective for reclaiming sodic soils Singh et al. Dagar et al. These trees were grown on raised beds to avoid damage due to water stagnation.
In highly sodic soils of semiarid regions, having kankar pan in upper 2-m soil layer, Dagar et al. Many grass species suited for sodic soils have been identified but all of them could not find field application due to the reason that they absorb and accumulate sodium and other toxic elements in their foliage and, thus, are unfit as fodder.
Efforts are on to identify and popularize those grass species which can retain high proportion of sodium in their root system, rendering the shoots palatable for cattle.
However, Biswas and Biswas have advocated that most of the field crops are less tolerant than grasses to alkali environment. Para grass Brachiaria mutica , rhodes grass Chloris gayana , matricaria Matricaria recutila , Karnal grass Leptochloa fusca have been found the most promising grass spp. Aeluropus lagopoides, Chloris barbata, Echinocloa colonum, Dicanthium annulatum, Sporobolus helvolus, Phragmites spp.
Large tracts of salt-affected community and government lands lying barren have been restored and put to best productive use through adoption of agroforestry techniques and agronomic practices. Promising agro-forestry models, fruit-based agro-forestry models, silvi-pastoral models etc. Under saline irrigation conditions medicinal and aromatic plants such as isabgol Plantago ovata , aloe Aloe barbadensis , kalmeg Andrographis paniculata , Matricaria chamomilla, Vetiveria zizanioides, Cymbopogon martini , and Cymbopogon flexuosus have been found to produce high biomass Tomar et al.
Salt-affected Vertisols i. The high clay content of these soils makes them vulnerable even at low salt and exchangeable sodium concentrations. Major chunk about 1. Such soils also occur in appreciable extent in Karnataka, Maharashtra, and Rajasthan.
Commercial cultivation of salt tolerant plants like Salvadora persica a halophyte, non-edible oil tree , dill Anethum graveolens a spice crop, industrial species like Euphorbia and Mulethi Glycyrrhiza glabra , castor and sunflower has been found useful in reclaiming these soils and have largely been practiced by the farmers Rao et al.
Large stretches of canal irrigated lands in many arid and semi-arid regions have become unproductive due to water-logging and the subsequent secondary salinization. Water seepage from canals and faulty on-farm water management practices together create shallow water table conditions. Higher capillary salinization in such areas has caused significant increase in root zone salinity Chhabra and Thakur, The conventional approaches to reclaim such lands are expensive, difficult to operate and pose problems in the safe disposal of saline drainage effluents and so have necessitated interest in other viable alternatives such as bio-drainage Chhabra and Thakur, ; Ram et al.
Analogous to energy-operated water pumps, bio-drainage is a proven technology to arrest salinity build-up in canal commands with growing of suitable tree species e. Efforts are on in exploring combined applications of bio-drainage and suitable land modifications to effectively utilize the water-logged salt-affected soils Sharma et al. The bio-remediation approach, which involves plant-microbial interaction, has received increased attention worldwide for enhancing productivity of salt-affected soils Arora et al.
The microorganisms have the capability of rapid adjustment toward environmental changes and deterioration, and thus can play an important role in the maintenance and sustainability of any ecosystem. Microorganisms possess some unique properties such as salt stress tolerance, genetic diversity, synthesis of compatible solutes, production of plant growth promoting hormones, bio-control potential, and their interaction with crop plants.
If these traits are suitably exploited, microorganisms can play a significant role in alleviating salt effects on crop plants Shrivasata and Kumar, Microorganisms present in the rhizosphere could promote plant growth and yield in salt stress environment in different ways, directly and indirectly Dimkpa et al.
For example, some plant growth-promoting rhizobacteria may directly stimulate plant growth and development by providing plants with fixed nitrogen, phytohormones, iron sequestered by bacterial siderophores , and soluble phosphate Hayat et al. Halophilic bacteria have the potential to remove sodium ions from soil and increase metabolic and enzymatic activities in plants. Arora et al. In a field experiment, bio-inoculation of wheat seeds with halophilic bacteria increased grain and straw yield of wheat in a sodic soil by The bacterial inoculation improved soil properties by decreasing soil pH from 9.
Cultivation of salt tolerant crops and crop varieties is another way to address the problem of soil salinization. This technique is viable and cost effective and suits well to the small and marginal farmers who without financial support are unable to bear the high costs of chemical amendment-based reclamation technologies.
Use of salt tolerant varieties of field crops is another practical option to manage salt-affected soils with the poor farmers, especially small and marginal, for whom chemical amendment technologies are not feasible without Government subsidies Arora and Sharma, Several varieties of important field crops like rice, wheat and mustard, having potential to yield reasonable economic returns in saline and sodic soils, have been developed Singh and Sharma, Cultivation of salt tolerant multipurpose trees, bushes, and grasses, fruit plants, medicinal and aromatic plants etc.
Tissue culture techniques find usefulness in developing suitable salt-tolerant trees and crops of high economic value. It may be noted, however, that crop production on salt-affected soils is generally costlier and crop yields are usually low, net returns are low and the risk of crop failures continues even after suitable amendments are provided Minhas and Sharma, Inland saline aquaculture land-based aquaculture using saline groundwater is being commercially practiced in many saline tracts of Australia, Israel, and USA Allan et al.
This knowledge was used in India also to make the saline water-flooded soils profitable. The experience in many parts of south-western Haryana and Punjab have shown that the degraded soil and water resources could be put to profitable use by shrimp and fish farming Purushothaman et al.
In coastal areas of Andhra Pradesh, many farmers have converted their rice fields into brackish water fish farms for reason of high remuneration from aquaculture. They store brackish water, drawn from the sea through creeks and drains, in big tanks for raising high value prawns.
Estimates suggest that nearly 0. Integrated multi-enterprise models comprising different components, viz. The models have been standardized for specific conditions such as saline soils of Haryana, water-logged sodic soils of Uttar Pradesh, highly saline black soils of Gujarat and coastal saline soils of West Bengal Singh, ; Sharma and Chaudhari, The aim is to sustain resource use efficiency, high and regular income and employment generation to the farmers.
The models drastically reduce the production costs by synergistic recycling of resources among different components. The model on daily basis generates a gross income of Rs. Biogas produced 2 m 3 per day in the Model adequately meets the energy requirements of farmer's family. It is estimated that due to soil salinization India loses around Rs.
The Indian Government, therefore, has attached highest priority to the policy planning for the reclamation of degraded lands, including salt-affected soils in the country.
The Indian Government is keen to restore 26 million ha of degraded lands by the year in order to ensure food security in the country. Significant research efforts have been made during the last 4 decades with encouraging results. The response of the farming community in salt-affected regions is overwhelming. Sharma and Chaudhari reported reclamation of 1. It provided additional income of around Rs.
According to a recent publication of Mandal et al. The reclamation has been achieved through gypsum technology in saline soils and sub-surface drainage technology in sodic soils. It has contributed an estimated The technological interventions on other aspects of salt-affected soils such as alternate land-use systems, saline aquaculture, cultivation of salt tolerant crop varieties, agroforestry, phytoremediation, bioremediation etc.
Soil salinization is a serious problem challenging food security in India. It is a dynamic process caused by several natural and human-induced processes, and quite often, the socio-economic and political considerations become extremely important in accelerating the processes of soil salinization. Many times, such factors are beyond the control of individual farmers and call for the attention of the policy makers.
It becomes the responsibility of respective governments to take appropriate policy decisions and corrective measures in order to keep a check on soil salinization and also to restore the soils already affected by salts. Several on-farm tested technologies are available for the reclamation and management of salt-affected soils.
The efforts put-in by Government agencies and farmers for the reclamation and rehabilitation of salt-affected soils in the country so far have been encouraging. Nevertheless, in order to achieve the target of reclamation of 26 million ha of salt-affected soils, concerted efforts are needed by all the stakeholders.
The site-specific restoration programmes be conceived and implemented in mission mode with the genuine participation of the local farmers. The farmers need to be incentivized rather than subsidized to undertake corrective measures.
Under the scenario where the cultivable lands are shrinking due to increased urbanization, the restoration and management of salt-affected soils offer a potential hope of land expansion and production enhancement for future food security in the country. PK contributed in conception and first draft preparation. PKS reviewed, analyzed, and provided interpretation. All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Abrol, I. Crop responses to differential gypsum applications in highly sodic soil and the tolerance of several crops to exchangeable sodium under field conditions. Soil Sci. How does agriculture affect the environment? What are the different branches of agriculture and their definitions? What is the definition of unsustainable agriculture and some examples?
What does the Committee on Agriculture in congress do? Why is agriculture important? What are some pros and cons of sustainable agriculture? Some laboratories use different units for salinity. The extent of plant yield loss when irrigated with saline water depends on a number of factors including:. The key to irrigating successfully with saline water is to leach or move salts downwards away from the root zone. In well drained sandy soils, irrigation water can readily flush salts out of the root zone but this is less successful on poorly drained, heavy soils.
The amount of leaching to maintain acceptable growth depends on:. The amount of additional water required to leach salt from the root zone is called the leaching fraction. Salt concentration in the root zone continually changes following irrigation.
As the soil dries, the salt concentration in the soil solution increases and this reduces the moisture available to the plant. Frequent, light irrigations increase salt concentrations in the topsoil and should be avoided. Watering during hot dry conditions will increase evaporation and therefore increase the concentration of salt. Replace muriate of potash potassium chloride with sulphate of potash and use nitrogen, phosphorus and potassium NPK fertilisers which contain sulphate of potash.
Plants are generally more susceptible to salinity damage during germination and at the seedling stage than when established. Rootstock and variety differences are important factors affecting salt tolerances of tree and vine crops, especially with avocado, citrus, grapes and stone fruit see Table 2.
Drip irrigation allows water with higher salt content to be used than other delivery methods, as evaporation losses are minimal. Drip irrigation can alsoreduce the effects of salinity by maintaining continuously moist soil around plant roots and providing steady leaching of salt to the edge of the wetted zone.
Sprinkler irrigated crops are potentially subject to additional damage caused by salt uptake into the leaves and burn from spray contact with the leaves. If using saline water for sprinkler irrigation, irrigate when temperatures are coolest. Watering in the heat of the day concentrates the salts due to high evaporation. Watering during high winds also concentrates salts. Do not use sprinklers which produce fine droplets and misting.
Avoid knocker sprinklers if possible, especially slow revolution sprinklers which allow drying periods, causing salt to build up on the leaves. Tables 5 to 8 show the tolerance of plants to irrigation with saline water. These values should only be used as a guide because the extent of salinity damage depends on the factors described previously.
If the salinity of the water is near the upper recommended limit, conduct preliminary trials under the specific conditions present to determine if crop damage will occur. The yield loss data depends on several assumptions.
These figures are applicable to sprinkler irrigation systems in which there is an extended drying period between irrigations.
Crops can usually tolerate higher salinity under higher frequency irrigation. These guidelines are likely to be too restrictive for sprinkler irrigation on very permeable sands of the Swan Coastal Plain. Sprinkler irrigation of crops with water high in chlorine or sodium may result in damage via absorption through the leaves, even though the salinity concentration is below the critical level listed in Tables 5 to 8.
The guidelines apply mainly to sprinkler irrigation. Trickle irrigation is applied frequently which reduces salinity concentrations in the root zone and increases in salinity due to evaporation are minimal. For crops where yield loss data is not available, a maximum recommended concentration or range of concentrations is given.
Groundwater below horticultural properties on the Swan Coastal Plain may become more saline over time. The longer an area is irrigated, the higher the risk. Large amounts of water are pumped from the shallow aquifer in some areas. As excess irrigation water infiltrates back to the aquifer, the salt level increases because of evaporation and addition of fertiliser salts. Good irrigation management should, in most cases, overcome these problems. Excessive pumping from an aquifer can also result in the intrusion of salty water.
If several sources of differing quality water are available, blend the poorer quality with better quality to reduce or prevent salinity damage. A number of laboratories in Western Australia will analyse water for electrical conductivity.
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