Sanjay Arora

Diagnostic Properties and Constraints of Salt-Affected Soils

Salt-affected soils include saline or sodic soil that covers over 400 million hectares, i.e. over 6 % of the world land area. In India, about 6.73 million hectares (Mha) of land is affected by salinity and sodicity problems. Coastal soils in a number of situations are constrained by various technological factors limiting the agricultural productivity and, therefore, merit attention. The numerous constraints need proper diagnosis of the problem and its appropriate remediation. The chapter highlights the soil resources of India and the distribution of problematic soils with their specific constraints for agricultural production. This gives complete background information on the properties, issues and problems associated with inland and coastal saline and sodic and waterlogged soils.

Arbuscular Mycorrhizal Fungi (AMF) for Sustainable Soil and Plant Health in Salt-Affected Soils

Continuous utilization of quality land in civilization and industrialization has gained interest in the utilization of salt-affected soils for crop production. However, crop growth and productivity is severely affected in saline soil. Many strategies were proposed to overcome the salt detrimental effects like development of salt-tolerant cultivars through breeding and/or genetic engineering, removal of excessive salt accumulation in soil, desalinization of irrigation water etc. Though these strategies are efficient but costly. Hence, a cost-effective new alternative attempt has taken up to mitigate soil salinity which involves inoculation of salt-tolerant arbuscular mycorrhizal fungi (AMF) in agricultural crop. Mechanisms of amelioration of salt stress in AMF-plant symbiosis involve enhancing the uptake of less mobile phosphorus, increasing nutrient acquisition, maintaining osmotic balance, enhancing antioxidants and polyamines, altering hormonal status, reducing ion toxicity and enhancing photosynthetic efficiency. AMF colonization induces an increase in root hydraulic conductivity of the host plants under osmotic stress conditions. Furthermore, AMF symbiosis also alters expression of cation channels and transporters, late embryogenesis abundant protein and aquaporins. AMF symbiosis not only changes plant physiology but also changes nutritional and physical properties of the rhizosphere. In the mycorrhizosphere, AMF interact with natural and introduced microorganisms and affect soil properties and quality. The quality of soil largely depends on its physical and chemical properties as well as diversity and activity of soil biota. Thus, AMF have been considered as bio-ameliorators of saline soils.

Microbial Approach for Bioremediation of Saline and Sodic Soils

The salt-affected soils are dominated by many types of halophilic and halotolerant microorganisms, spread over a large number of phylogenetic groups. The biotic approach ‘plant-microbe interaction’ to overcome salinity problems has recently received a considerable attention throughout the world. The halophilic microbes have potential for bioremediation of salt-dominant soils. Halophilic bacteria having plant growth promotion potential were isolated that could tolerate up to 15 % NaCl in liquid media. Soil inoculation showed their sustenance and activity up to electrical conductivity (EC) of 8 dS/m. Also, plant growth-promoting endophytic halophiles from leaves of halophyte plants have potential to remediate salt-affected soils. The efficient plant growth-promoting isolates were inoculated in seeds of maize and wheat to mitigate salt stress. There was 10–12 % increase in yield attributes and yield of wheat at 6 % NaCl irrigations in soil as compared to 2 % NaCl irrigations in experiments.

Bio-amelioration of Salt-Affected Soils Through Halophyte Plant Species

Agriculture is the principal lever of economic and social development. A significant amount of arable land is becoming lost to urban sprawl, forcing agricultural production into marginal areas. Salinity-related land degradation is becoming a serious challenge to food and nutritional security in developing countries. Many crops cannot be grown on salt-affected lands, but nature has provided us with a unique group of plants, that is, halophytes. Halophytes, plants that survive to reproduce in environments where the salt concentration is around 200 mM NaCl or more, constitute about 1 % of the world’s flora. Some halophytes show optimal growth in saline conditions; others grow optimally in the absence of salt. However, the tolerance of all halophytes to salinity relies on controlled uptake and compartmentalization of Na+, K+, and Cl− and the synthesis of organic “compatible” solutes, even where salt glands are operative. The cultivation of economically useful halophytes has the potential to remediate saline wastelands and to meet the demands for fodder, fuel, etc., from saline lands, thereby helping the farming community to improve their livelihood.

Bioremediation of Salt-Affected Soils: Challenges and Opportunities

A lot of work has been done on improving practices for remediation of coastal and inland salt-affected soils. This has resulted in improving crop yields in these degraded lands and thereby improving the socioeconomic status of the resource-poor farmers. Keeping in view the limited availability of good quality waters for flushing out salts and scarce mineral gypsum availability for reclaiming sodic soils, vegetative and microbial bioremediation of salt-affected soils has emerged as a promising technique. Cultivation of economically useful halophytes, salt-tolerant plants, and crop varieties capable of growing under salt-stress environments has enabled conversion of saline and sodic wastelands. The high potential for bioremediation of salt-affected soils using applications of halophilic bacteria has been reported by some researchers. The applications of halophilic bacteria include recovery of saline soil by directly supporting the growth and stress tolerance of vegetation, thus indirectly increasing crop yields in saline soil. The biotic approach “plant-microbe interaction” to overcome salinity problems has received considerable attention from many workers throughout the world recently. Plant-microbe interactions are beneficial associations between plants and microorganisms and also a more efficient method for reclamation of salt-affected soils. However, there are many challenges to overcome for widespread adoption of these techniques and opportunities for the future to reclaim salt-affected soils through bioremediation approach.

Soil and Water Conservation in Ravinous Watersheds: Case Studies from Uttar Pradesh in India

Ravines and gullies occur all over India especially in states of Madhya Pradesh and Uttar Pradesh. The state of Uttar Pradesh has taken the lead role in reclamation of ravine lands starting from 1884 to till recently, but most of the project activities gradually approached toward the requirement of reclamation based on integrated farming system approach on watershed basis. Some projects have resulted in cumulative gain in terms of area reclaimed, people benefited, and knowledge gained which can be fruitfully utilized for future ravine reclamation planning. However, the reason of the not much benefit from the earlier projects was due to failure of stable use of reclaimed land for productive purposes. Still about 75% of the ravine land needs to be effectively reclaimed for productive use. In this chapter, an attempt has been made to identify the gaps and suggest approaches and components for effective reclamation of ravine lands on watershed basis. The reclamation should aim for improvement of socio-economic conditions of ravine areas indicating the scope of providing sustainable livelihood to the people of the area. The region has potential for diversified crops including highly remunerative medicinal and aromatic crops. Introduction of these crops calls for an integrated bio-industrial approach for locally processing the produce that would provide additional income to farmers and generate employment.

Land Resource Inventory (LRI) for development of sustainable agricultural land use plans using geospatial techniques: A case study of Pata Meghpar village, Jamnagar district, Gujarat

The soil and land resource inventory at village, as basic unit, are providing baseline data on soils, their constraints and potentials for crop production. Considering this fact, Pata Meghpar village (22013’14’’ to 22016’09’’ N latitude and 70029’16’’ to 70032’59’’ E) in Jamnagar district of Gujarat with an area of 1683 hectares was selected for land resource inventory on 1:10000 scale for land use planning activity. The soils developed on Deccan trap geological formations with distinct basaltic landforms appear at an elevation of 100 meters above mean sea level near Und river. The landform analysis of study area was carried out with the visual interpretation of Indian Remote Sensing Satellite P6 LISS-IV data of April 2012 in conjunction with cadastral map. The four basic landforms identified are isolated upland (119.3 ha & 7.1%), ravinous land (409.6 ha & 24.3%), very gently to gently sloping plains (543.9 ha & 32.3%) and nearly level plains (610 ha & 36.2%). The detailed soil survey was carried out and identified seven soil series with 10 phases. The soil series Pata Meghpar-1(Loamy, Lithic Ustorthents) and Patameghpar-2 (loamy-skeletal, Lithic Ustorthents) occurring on isolated upland are very shallow, excessively drained, brown loam (7.5YR 4/4) to dark yellowish brown (10YR 3/4), gravely loam and slightly alkaline (pH 7.27.8). The Pata Meghpar-3 (fine-loamy, Typic Ustorthents) on ravinous lands are moderately shallow, excessively drained, strongly calcareous, dark yellowish brown (10YR 3/4), weak fine sub-angular blocky structure, slightly alkaline to moderately alkaline (pH 7.7 to 8.6). The Pata Meghpar 4 (fine, Typic Haplustepts) and Pata Meghpar-5 (fine, Vertic Haplustepts) occurring on very gently to gently sloping plain are moderately deep (50-75cm), moderately well drained, slight to moderately calcareous, very dark grayish brown (10YR 3/2), moderate, medium, sub angular blocky structures and moderate to strongly alkaline (pH 8.1 to 8.8). The Pata Meghpar 6 (fine, Leptic Haplusterts) and Pata Meghpar – 7 (fine, Typic Haplusterts) occurring on nearly level plains are deep, clayey, moderately well drained, very dark grayish brown (10YR 3/2) to very dark gray (10YR 3/1), weak fine angular blocky to moderate medium angular blocky structure, moderately calcareous and moderately alkaline (pH 8.0-8.5). The baseline resource data are useful for deriving soil-landscape relationships in basaltic terrain at village and forms the basis for upgrading management packages for sustainable crop production at farm level.

Resource Conservation Technologies (RCTs) for Climate-Resilient Agriculture in the Foothill of Northwest Himalayas

Potential threats to agriculture in the foothills of northwest Himalayas are the climate change. Further, erratic rains, undulating slopes and traditional management practices further strengthen the problem which might be responsible for soil erosion, low NUE, lower grains and finally to the lower livelihoods of the farmers. Climate change phenomenon influences the agriculture over the globe. India especially the northwest Himalayan region is one of the most vulnerable areas. Climate change is projected to reduce timely sown irrigated wheat production by ~6 % by 2020. In the case of late-sown wheat, the projected levels are alarmingly high, to the extent of 18 %. Similarly, a 4 % fall in the yield of irrigated rice crop and a 6 % fall in rain-fed rice are foreseen by 2020 due to climate changes. The warming trend in India over the past 100 years is estimated at 0.60 °C. The projected impacts are likely to further aggravate yield fluctuations of many crops with impact on food security. Thus there is a need for the serious attention on adaptation and mitigation strategies to overcome the problems of climate change more particularly in the northwest Himalayan region. Sustainable food security is further affected by persistent land degradation, land fragmentation, labour problem, overexploitation of natural resources, etc. We need to focus on sustainable production systems by strengthening the ecological foundations and mitigating the adverse effect of the global warming. This requires an integrated approach by considering technological, biophysical, socio-economic, political and environmental factors in one basket. Food security and environmental sustainability can be attained by improved land and water management, adopting eco-friendly technologies and initiating good agricultural practices in different agroecosystems. Further, strategic research and technology in agriculture and adoption of sustainable practices are necessary to meet current and future threats to food security.

Salt affected soils in Jammu and Kashmir: Their management for enhancing productivity

Saline soils in valley of Kashmir and Kandi belt of Jammu have been reported, having soluble salts in the range of 0.15 to 0.45% with Cl, NO3, SO4 and HCO3 anions. Saline soils have been reported in many soils of Jammu district derived from alluvium parent material in the plains as well as in soils of Parmandal and Uttar bani areas which are their origin to Siwalik group of rocks. Presence of soluble salts greater than 0.2% was found harmful to plants. In the canal command area, located in the Kathua and Jammu districts it was found that an area of 25, 670 ha become unproductive due to salinization alkalization as well as waterlogging. The soils are very strongly alkaline having pH range from 8.6 to 10.5 (average pH 9.9), with dominance of exchangeable Na (ESP 25.3) and sodium adsorption ratio (SAR) of 78.41. The highest ESP was recorded in Tarore soil with ustic and aquic moisture regimes associated with hard surface crust, calcic and natric sub-surface horizons. Gypsum requirement (GR) to amend sodic soil was calculated and applied at the rate of 100% GR. This application has increased rice and wheat yields 43.3 and 86.9%, respectively, over control. Improvement in soil properties was noticed, soil pH decreased from 9.7 to 8.8, bulk density decreased from 1.52 to 1.48 Mg m−3 and infiltration rate was improved.

Bio-remediation of saline and sodic soils through halophilic bacteria to enhance agricultural production

Bio-remediation is one of the cheap and eco-friendly approaches for remediation of salt affected lands as the traditional physical and chemical techniques are becoming costly. The possibility of application of halophilic bacteria in saline/sodic soil recovery and the importance of microbial diversity in soil is important in order to realistically access their future application in the rehabilitation of degraded lands. The plant growth promoting halophilic bacteria helps in bio-remediation of salt affected soils and thereby improves the agricultural crop yields. Bio-inoculation of seeds of wheat with plant growth promoting halophilic bacteria resulted in increase of 18.1 and 24.2 per cent in grain and straw yield, respectively under sodic conditions. Also, soil pH of sodic soil reduced from 9.4 to 8.6 when consorita of halophilic bacteria was applied. Soil bio-chemical properties improved and there was increase of microbial biomass C upto 137 zg/g as compared to 82 zg/g in control.