eChapters

Agriculture is world’s single largest employer and probably the most weather dependent of all human activities.  Climate and its variability have been and continue to be, the principal source of fluctuations in global food production. Throughout history, extreames of heat and cold, droughts and floods, and various form of violent weather have wretched havoc on the global agricultural production. With the unprecedented increase in population over past few decades, clearly the mankind faces undertaking task to ensure food and nutritional security for all, considering reduced per capita land, reduced availability of water, depleting biodiversity and need to preserve ecology and environment. In India, of the total geographical area of 328 m ha, about 175 m ha (53 % of total) are categorized as degraded land, of which 150 m ha are subjected to serious water and wind erosion (Singh et al. 1981). Crops are sown in about 180 m ha annually. Since it seems very much impossible to bring more area under cultivation we need to achieve greater efficiency in the natural resources use while conserving the environment by placing greater emphasis on understanding and exploiting climatic resources for the benefits of agriculture.

The Gujarat state is located on the north-west of India between 20^o6' N and 24^o42' N latitude and 60^o24' E to 74^o24' longitude. The climate of Gujarat is semi-arid tropical . the summers are very hot, the winter season is uncertain and irregular. The Arabian sea and Gulf of cambay have a moderating effect on the climate of the coastal areas of the state.

The state has a coastline of 1600 km (27% of the country) out of which Saurashtra and Kutch has about 1125 km long coastal line. The total coastal cropped area of the state is 8.75 lakh ha (9.11% of total cultivated area) spread over three agro-climatic regions of the state, out of which 91% comes under arid and semiarid climate type (Table 1). The important crops of the region are groundnut, bajara, sorghum, cotton, and wheat. The ground water availability is also scare. In the state recently the soil degradation through salinity has caught hold over 1.2 m ha of land, of which, about 0.3 m ha occurs in the coastal area. About 1125 km long coastal line is in Saurashtra and Kutch which comprises about 0.1079 m ha of saline land which needs to be treated for salinity reduction.
 

Importance

Drought is a climatic anomaly characterized by deficient supply of moisture, which may result from sub-normal, untimely and unevenly distributed rainfall. Among the various hazards of nature, drought is one of the major disasters because it brings innumerable miseries to the mankind. Almost every year some part or the other of the country suffers from such calamities. Drought is a recurring phenomena and its occurrence cannot be avoided. However, its impact can be minimized through application of science and technology by developing drought management plans.

For better yield irrigation water must be free from soluble salts and from concentration of specific chemical substances that may hazard to soil with respect to salinity, sodicity, alkalinity and toxicity. Water analytical data which helpful to predict the magnitude of the effect of irrigation water on soil and plant growth under specific environmental circumstances so irrigation water must be analyzed for EC, pH, Na+, Ca⁺⁺, Mg⁺⁺, Cl^-, CO₃–, HCO₃-  and SO₄.^– 

Agricultural land drainage is adopted for removal of excess surface and subsurface water, either from irrigation or rainfall in order to improve the profitability of land use.  Drainage also plays a role in removal of salts from the root zone. Therefore, land drainage is closely linked to irrigation in arid and semi arid regions. India has a long history of practicing irrigation and drainage in its semi arid irrigated regions. During the ancient times in the Indus Valley dams and drainage system were built for cultivation of different crops. The earlier experience of drainage was more concerned with surface drainage because from time immemorial India has been experiencing floods of varying magnitudes.

India is an agricultural country. The geographical area of India is about 328 mha out of which 147 mha of land under cultivation and 84-mha land is under irrigation. The population is increasing at an alarming rate that requires producing more food for the growing population. This problem can be solved either by increasing the land under irrigation or using different soil water conservation techniques. It is well known fact that during rainfall a considerable amount of water goes to sea due to high rate of runoff. It is highly needed to trap as much as water falling in the form of rainfall and recharge the groundwater so that it is made available for irrigation purposes.

Mulching

The technique of covering the soil with plastic films or natural crop left over (residues) for soil and water conservations is called mulching.

This technique was practiced by farmers using dry leaves straw, trash, stones etc to conserve water. Presently plastic film have come into use for the purpose of mulching due to inherent advantages.

Introduction

Salinity in India is a major issue affecting the sustainability of irrigated as well as non-irrigated areas particularly in the states of Rajasthan, Gujarat, Haryana, Uttar Pradesh, West Bengal and Orissa. Salt affected soils are unproductive unless excess salts are reduced or removed. These soils occur most extensively in arid and semi-arid climates, but these soils are also found in coastal sea areas where soils are unundated by ocean or sea water. Soils are said to be saline if they contain an excess of soluble salts and sodic or alkali if they contain an excess of sodium salts. Again soils are said to be saline-sodic or saline-alkali if they contain appreciable amounts of both soluble salts and sodium. The impact of salinity manifests itself in several ways. As the salinity increases, not only does the productivity decline but sensitive crops also go out of cultivation and are replaced by salt-tolerant, low value crops and other plant species.

Soil Erosion As a Process
 
Soil erosion is a three stage process, namely (1) detachment, (2) transport, and (3) deposition of soil. Different energy source agents determine different types of erosion. There are four principal sources of energy: physical, such as wind and water, gravity, chemical reactions and anthropogenic, such as tillage. Soil erosion begins with detachment, which is caused by break down of aggregates by raindrop impact, sheering or drag force of water and wind. Detached particles are transported by flowing water (over-land flow and inter-flow) and wind, and deposited when the velocity of water or wind decreases by the effect of slope or ground cover. Processes like dispersion, compaction and crusting, accelerate the natural rate of soil erosion. These processes decrease structural stability, reduce soil strength, exacerbate erodibility and accentuate susceptibility to transport by overland flow, interflow, wind or gravity. These processes are accentuated by soil disturbance (by tillage, vehicular traffic), lack of ground cover (bare fallow, residue removal or burning) and harsh climate (high rainfall intensity and wind velocity).

Aquaculture is the cultivation of fish, molluscs, crustaceans (shell fish) and aquatic plants in controlled conditions, provides an increasingly significant proportion of food production globally. The sector has represented the greatest growth of all food production systems in the last two decades and an estimated 10% yearly increase in output is likely to bring productivity to a predicted 47 million tonnes in the year 2010 (Pedini and Shehadeh, 1997). Significantly, the greatest contribution to total production and the greatest rate of uptake of aquaculture activity is in the developing world. More than 82% of the total global yield in 1999 was produced by developing countries (GESAMP, 2000) and growth rates between 1984 and 1995 were six times higher than that from developed countries (Rana, 1997; Tacon, 1996).

Groundwater is a precious renewable resource which gets replenishment from the precipitation. Total water resources of the world are estimated at 1.37 x 10⁸ million ha-m. Of these, about 97.2% is salt water, mainly in oceans, and only 2.8% is available as fresh water. And, out of this 2.8%, about 2.2% is available as surface water (2.1% is fresh water in glaciers and icecaps, 0.1% is available in lakes and reservoirs, 0.0001% in streams) and 0.6% is available as groundwater. Only 50% of groundwater resource is economically extracted with available technology. Presently, 1.3 x 10⁴ million ha-m fresh water in reservoirs and 41.1x10⁴ million ha-m groundwater is theoretically available to provide usable water for drinking, domestic use, irrigation, etc., to mankind. Groundwater is the largest source of fresh water excluding the polar icecaps and glaciers. The amount of groundwater within 800 m from the ground surface is over 30 times the amount in all fresh water lakes and reservoirs, and about 3000 times the amount in stream channels, at any one time.

Experiment

An experiment is a planned inquiry to obtain new facts or confirm or deny the result of previous experiment. Such inquiry can aid in an administrative decision, such as recommending a variety, a feed, a cultural practices, a fertilizer, a pesticide or a fungicide etc.

Type of Experiments

    1.     Preliminary experiments : Here investigator tries out large number of treatments in order to obtain leads for future work. Here replications are not taken for such treatments tried e.g. number of pesticides for control of diseases - take single observation for each treatment and take decision that some of them worth trying for use.

The coastal agro ecosystem is very important among the different agro ecosystems of our country both economically and environmentally. It spans over a length of 8129 sq. km. covering 9 states and 2 Island ecosystems. Agriculture and allied activities constitute the single largest component of India’s economy, contributing nearly 27 per cent of the total Gross Domestic Product (GDP) in the year 1999-2000 (TERI, 2002). Agriculture exports accounts for 13 to 18 per cent of total annual exports of the country (MoF, 2002). However, given that 62 per cent of the cropped area is still dependent on rainfall (MoEF, 2002). Coastal agricultural region comprises of hinterland, which has a varied geometric and topographical features of mountains valley, coastal plains, riverine systems, climatic conditions, different soils and water bodies, vegetation ranging from rich tropical rain forests to coastal mangroves and a wide range of crops that are cultivated in this region (Table 1). The agro climatic conditions of the coastal zones are congenial for growing various field and horticultural crops.

Introduction

Indian agriculture was contributing 70% to total GDP of the country at pre-independent time, but it decreased drastically year by year and contributed 66.8% in 1960, 55.6% in 1994, 27.1% in 1997 and now a days, it reached only to 25% in 2001. With the advancement of civilization our population is increased, whereas, the cultivable lands is decreased side by side, thus, on an average income of agriculture is decreased.

Gujarat is the leading state to concern with the productivity, production and the area of the some crops like Groundnut, Castor, Cotton, etc. in India. The major part of the state is surrounded by sea coast border, which is 1600 km. Gujarat is popular for production of oilseed crops like groundnut, cotton ; horticultural crops like mango, chiku, coconut, banana, papaya, citrus; spices crops like chili, cumin, funnel etc.

Introduction

The globally growing demand for water has ushered the need for its efficient and judicial utilizations in all fields, and agriculture in particular being a single largest consumer of water. The majority of irrigation projects in India perform at a very low efficiency, which calls for application of efficient water management technologies for meeting the increasing water demands. Estimation of soil moisture or crop evapotranspiration from climatic parameters provides objective criteria for irrigation management. Methods to estimate evapotranspiration require huge climatic data, which are seldom available and not applied by common crop growers. Determining crop water requirement through soil moisture measurement at several locations is time consuming, destructive exercise, and may not give proper assessment of crop water need. The plant based indicator approach considers the plant water status for scheduling irrigation. This might be considered as the ideal criterion because the plant water is a good integrator of the soil, water and climatic parameters.

Introduction

Water is a precious natural resource vital, for sustaining all life on the earth. It is in a continuous circulatory movement - hydrologic cycle. It is not uniformly distributed in time and space. Due to its multiple benefits and the problems created by its excesses, shortages and quality deterioration, water as a resource requires special attention. On a global scale, total quantity of water available is about 1600 million cubic km. The hydrological cycle moves enormous quantities of water about the globe. However, much of the world’s water has little potential for human use because 97.5% of all water on earth is saline water. Out of remaining 2.5% fresh water, most of which lies deep and frozen in Antarctica and Greenland, only about 0.26% flows in rivers, lakes and in the soils and shallow aquifers which can be readily used. Sustainable water management in India is fast becoming a necessity, with the looming crisis over water resources in the country threatening the security and livelihood of the population and the environment over the coming decades. Managing water resources, river catchments, and coastal zones are outstanding challenges of today and tomorrow’s. Global changes ask for a comprehensive scientific approach, an international multi-disciplinary orientation and require a new mind-set towards water and coastal management problems.

Abstract

Microbiological synthesis of nanoparticles has emerged as rapidly developing research area in nanotechnology across the globe with various biological entities being employed in production of nanoparticles constantly forming an impute alternative for conventional methods. Simple prokaryotes to complex eukaryotic organisms including higher plants are used for the fabrication of nanoparticles. In the present article, the synthesis of important plant nutrients like Mg, Zn, Ag, Au, Ti, P and Fe nanoparticles from different fungal species, their characterization and application potential of nanonutrients in agriculture is elaborately discussed.

Abstract

Microorganisms inhabiting in the rhizosphere play a vital role in ecosystem functioning. Rhizosphere is an area around the root surface where pathogenic and beneficial microorganisms repose and influence the plant growth and health. These microbial groups of bioagents found in the rhizosphere include bacteria, fungi, nematodes, protozoa, algae and micro-arthropods. Because of their rich diversity, complexity of interactions and numerous metabolic pathways, microbes are an amazing resource for biological activity. These microorganisms require organic matter for their growth and activity in soil and provide valuable nutrients to the plants and hence maintaining the plant health. The most promising fields for the use of bioinoculants are agriculture, horticulture and forestry. There are many reports on the inoculation of bioagents in agriculture and horticulture crops but only a few reports are available in forestry. This article is an overview on various bioinoculants which are used during inoculation and a compilation of scattered reports of bioinoculants in forestry only.

Abstract

Amongst various oilseed crops grown across the world, soybean (Glycine max L. Merrill) is globally important as a high source of protein and oil for human consumption and is also being used as potential feed for animals. Soybean is grown under rain-fed conditions in the tropics and subtropics in the marginal lands with less amount of external application of chemical fertilizers. The frequent climate variations have created a number of biotic and abiotic stresses, drought being a major abiotic stress which adversely affects the soybean productivity. Thus, to enhance the productivity of soybean, besides managing the nutrients, stress management is of utmost importance. There is a great opportunity of application of microbes especially arbuscular mycorrhizal fungi (AMF) where its application alone or in combination with plant growth promoting rhizobacteria (PGPR) can help in nutrient mobilization and remediation of plant stresses.

Abstract

Soil salinization is an important factor limiting crop production, mainly in the arid and semiarid regions of the world. Nevertheless, plants naturally have evolved several physiological, biochemical and molecular mechanisms to establish and thrive in salt stressed soils. In addition to breeding crops for salt tolerance, recent emphasis is on exploring the possible role of plant-microbe interactions in amelioration of salt stress in plants. It is now well established that arbuscular mycorrhizal (AM) symbiosis alleviates the effect of salt stress in plants. Further, available evidence does suggest that AM symbiosis regulates many of the plant’s salt stress alleviation mechanisms. However, the molecular basis for many of these mechanisms is yet to be ascertained. In this chapter, we summarize the current knowledge on the role of AM symbiosis in alleviation of salt stress in crop plants, which now appears to be a promising strategy to improve crop yield in salt stressed soils.

Abstract

Abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. The arbuscular mycorrhizal fungi (AMF)-symbiosis can confer a greater degree of tolerance against drought stress in many cash crops. The significance of heat shock proteins (Hsps) and chaperones in abiotic stress responses in plants, and co-operation among their different classes and their interactions with other stress-induced components is well known. Soil salinity is a major abiotic stress adversely affecting plant growth and crop production worldwide. Phyto-mycoremediation utilizing AMF as plant inoculants is regarded as a promising strategy to heavy metal pollution remediation. Plants have stress specific adaptive responses as well as responses which protect the plants from more than one environmental stress. The potential of phytoremediation of contaminated soil can be enhanced by inoculating hyper-accumulator plants with mycorrhizal fungi most appropriate for the contaminated site.

Abstract

Drought and salinity are two major abiotic stresses that affect various aspects of human lives of one third world population including human health and agricultural productivity. Abiotic stresses such as salinity, drought, nutrient deficiency or toxicity, and flooding limit crop productivity world-wide. A living organism is considered resistant if it tolerates a given physicochemical stress. The presence of microorganisms within the soil, specially a main group known as arbuscular mycorrhizal fungi (AMF), is a key factor in the adaptation of plants to the different ecosystems. The AMF colonizing within the plant roots can determine the success of plants in salt- and/or drought-affected areas. The symbiosis with AMF has been proposed as one of the mechanisms of salinity and water stress avoidance. Studies have shown greater drought and salinity tolerance in AMF-colonized plants by a number of mechanisms. These mechanisms include enhanced water and nutrient uptake directly by extraradical hyphae, higher leaf stomatal conductance and/or better root system architecture, higher capacity of osmotic adjustment and antioxidant defense systems, better soil structure due to higher glomalin and over expression of genes encoding antioxidant enzymes.

Abstract

A majority of the plants studied in natural ecosystems are symbiotic with microorganisms that either reside entirely (endophytes) or partially within plants. These microorganisms express different associations ranging from mutualism to parasitism. These symbiotic relationships appear to impart tolerance to various types of abiotic stresses such as heat, drought, salinity, heavy metals, etc. and sometimes may be responsible for the survival of both plant hosts and microbial symbionts in high stress habitats. The amelioration of the abiotic stresses by the endophytes assumes increasing significance in the light of rapidly changing global climate, which is likely to face frequent incidences of extreme weather conditions like high temperature, droughts, etc.

Abstract

Variously defined endophytes are highly diverse in plants in natural ecosystems, and most of them are symbiotic with of them are Asymptomatic presence of endophytic fungi in internal tissues on healthy host plants are able to play vital roles in physiology and biochemical processes. As a result of this interaction endophyte produces chemical substances having various applications. This chapter provides a brief review of certain grass and non-grass endophytes capable to extend beneficial impacts on host plants to sustain the unfavourable conditions of abiotic stresses. However, biotic stresses are also a matter of great concern, where endophytes can play important roles in combating the unfavourable situation. Endophytic fungi used in bio-control and other agriculture related sectors are also  highlighted in this review. Endophytic fungi producing volatile organic compounds reported from all over the world and their various applications find place in this article which has opened new frontiers of bioprospecting of endophytic fungi.

Abstract

Microbes are endowed with a high and exploitable potential of being useful associates with their surrounding environment and host in case of symbiotic relationship. Most of the microbes live alone but many of them require association of other living system for its survival. Hence, the beneficial role of microbes is always correlated with growth promotion and survivability of other associated living system. Now it is established that microbes play an important and key role in plant growth and development, even its survivability in case of symbiotic mycorrhizal association with orchids. They are nothing but potential tool protecting plants from different adverse conditions like diseased state, environmental stress like cold temperature, drought, metal contamination, salt and acidic or alkaline stress.

Abstract

In its natural environment, a plant faces various types of stressors. In fact, stress in moderation is a welcome event in plants. Only when it is in excess, would it compromise the productivity of plants. Beyond a threshold, stress (biotic and abiotic) has a detrimental effect on plant growth causing extensive yield losses in crop plants worldwide. Plants being sessile, have evolved a complex set of mechanisms to perceive the changes in the environment. Plants respond to minimize the potential damage due to stress while simultaneously preserving resources vital for their growth and development. The chapter presents an overview of various types of biotic and abiotic factors that act as plant stressors and the mechanisms by which plants respond to these stresses. The chapter concludes with a perspective on how the plant’s innate stress response machinery can be exploited for achieving higher tolerance to stress in crop plants.

Abstract

Impact of climate change and related stresses on plant productivity are being witnessed worldwide with developing countries being more vulnerable due to more dependency on agriculture. Microorganisms can play important role as economic and farmer’s friendly strategy to combat abiotic stress in agriculture. A wide range of microorganisms associate with plants, and many of them confer beneficial effects to their hosts through different mechanisms like production of growth promoting substances, nutrient acquisition, protection against plant pathogens etc. In the last few decades, role of microorganisms in imparting tolerance to plants against different abiotic stress has been reported in many crop plants. Under stresses conditions, plant-microbe interactions become more common towards coping with the stress. Selection and application of efficient abiotic stress tolerant microorganisms can be a fruitful strategy to alleviate negative effects of abiotic stresses in plants.

Abstract

With increasing population and subsequent human requirements; the generation of municipal solid waste (MSW) has increased all over the world. In India, the safe disposal of the municipal solid waste still remaines a problem for the authorities concerned. Depending upon the nature and type of the MSW, there are physical and chemical methods for the disposal of the waste, but these methods have their own limitations. Those limitations may be overcome by biological methods. Higher number of microorganisms are present in MSW which may either be pathogenic or nonpathogenic. These microorganisms may play a vital role in bioconversion of MSW into compost. The compost thus produced is useful in increasing soil fertility and reducing the concentration of the waste.

Abstract

The rhizomicrobiome plays a vital role in maintaining plant health and is highly influenced by the root exudates of the host plant. Plants select a subset of microbes at different stages of their development, and determine the microbiome community composition in its immediate vicinity presumably for specific functions. The rhizomicrobiome is composed of diversified microbial community with specific functions and is highly influenced by the plant type, soil type and environmental conditions. The rhizomicrobiome communities apart from promoting plant growth also elicit induced systemic tolerance to salinity and drought in stressed plants. Bacterial communities producing 1-aminocyclopropane-1-carboxylate (ACC) deaminase modulate stress ethylene in plants and alleviate the effects of abiotic stress and increases plant adaptability to stressed environment.

Abstract

Ever growing population and associated food scarcity are the major issues of concern globally. Microorganisms are the ultimate solution for addressing this severe problem in association with recent advances made in genomics and molecular biology. Many bacterial and fungal species which are in association with plant rhizosphere soil can immensely contribute in better growth and developments, ultimately leading to better yield. Exploring these novel organisms happens to be the need of an hour. Metagenomics and next generation sequencing technologies can contribute in identifying those microbes which are otherwise impossible to cultivate traditionally.

Abstract

Geochemical processes occurring within the groundwater and reactions with aquifer minerals have a profound effect on water quality. Hydrogeochemical composition of groundwater can also be indicative of its origin and history of passage through underground materials which water has been in contact. Assessing groundwater quality and developing strategies to protect aquifers from contamination are necessary aspects for proper planning and designing water resources. Anthropogenic activities like explosion of population, industrial growth, inputs of fertilizer, pesticides, and irrigation has been a crucial factor for determining the quality of groundwater. In this scenario, 43 groundwater samples were collected from the Dindigul district of Tamilnadu, a Hard rock terrain. The samples wereanalyzed for major cations and anions along with heavy metals to derive the different quality parameters and to obtain the pollution indices of different samples. This study focuses to find out the spatial relationship between the analyzed fluoride concentration in groundwater and pollution indices derived from the heavy metal concentration in the groundwater of the study area and their variation with respect to season.

Abstract

Amongst all types of major land-use change, extending irrigated agriculture using a surface-water source has the greatest influence on groundwater – both significantly increasing recharge and changing water quality as excess irrigation water infiltrates into shallow aquifers. Hence, in order to understand the impact of the landuse on the groundwater system the study has been aimed to understand the process by adopting geophysical, geochemical and microbial analysis of groundwater samples. The study has been conducted in Chidambaram taluk, with a total area of 92.51Sq.km. A total of 39 groundwater samples were collected for the analysis of major cation and anion along with the microbial analysis, like Total Coliform, Total Viable Counts, Fecal coliforms, Vibrio cholera and Total Streptococci. The geochemical studies reveal that there is no correlation between these parameters and the microbial population. The migration of the water from the elevated regions (urban region) is witnessed and the concentration of the microbial population is higher in these regions except in the southern region which has impermeable clay and this arrest the movement of water.

Abstract

Groundwater is most favored as a source of drinking water in all over world. It is often thought to be cleaner and easier to treat when compared with surface water and as a result, many wells have been sunk. Uranium and other radionuclides in water can lead to health problems if present in higher concentrations. In order to study the behavior and to understand the influence of lithology in groundwater of Madurai district, a study was conducted by collecting a total of 216 samples of different seasons (Premonsoon, South west monsoon, Northeast monsoon and Post monsoon) with respect to lithology and the number of samples was depending upon their spatial coverage in the study area. The groundwater samples were analysed for U, Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃^-, Cl^-, SO₄^2-, PO₄^3-, NO₃^-, F^-, H₄SiO₄, pH, EC, TDS. It was identified that the higher concentration of Uranium (156 ppb) were noted in the northern part of the study area. They are chiefly restricted to the Granitic terrain and nearby Charnockitic regions. The weathering process induces the release of higher U ions from the granitic terrain and the evaporated recharge water from the tank /reservoir  also induces the release of U ions from the rock matrix, it may also be due to fertilizer enriched agricultural return flows. The key source for all these processes and hydrogeochemical processes is identified to be lithology which inturn controls all the other processes in the study area.

Abstract

Dissolved Organic Carbon (DOC) consisting of water soluble organic molecules and by products of organic decomposition and chemical degradation processes, constitutes a critical link in carbon and nutrient cycles. The quality, or chemical and physical character, of DOC affects the degree to which it is transformed by biological and chemical processes. The significance of DOC was studied in layered coastal aquifers of the Pondicherry region during four different seasons. Pondicherry region has varied geological set up ranging from Cretaceous to Recent formations. A total of 52 groundwater samples were collected from various aquifers like Alluvium, Tertiary(Upper Cuddalore, Lower Cuddalore) and Cretaceous for two different seasons of pre- monsoon(PRM), and post-monsoon (POM). The samples were analyzed for major ions and DOC. The range of DOC in the study area is 0-14 mg/l. Very high DOC concentrations were measured during PRM in the samples from Alluvium and Lower Cuddalore Formation. The samples of these formations were compared with pH, Ionic strength, log pCO₂ and carbonate minerals concentration. The alluvial aquifer shows that pH governed dissolution along the coastal tracts and in Upper Cuddalore formation it’s based on interaction between aquifer matrix and groundwater.

Abstract

The development and management of fresh groundwater resources in coastal aquifers are seriously constrained by the impact of seawater intrusion. The coastal aquifers are fragile and this situation becomes more intense like that of the coastal Cuddalore region. The geochemical signature of groundwater of Cuddalore coast was studied for Pre Monsoon, Southwest, North east and Post Monsoon seasons by collecting total of 64 groundwater samples in each season. The collected samples from were analysed for physical parameters, such as electrical conductivity (EC), pH and major ion concentrations, such as Ca, Mg, Na, K, Cl, HCO₃, PO₄ and SO₄. Interpretation of analytical data shows the predominance of  Na–Cl type   in PRM and Ca- Mg-Cl type  is the dominant facies during POM. The Chaddas evaluation diagram shows that the hydrogeochemical evaluation plot for PRM samples fall in  Na-Cl type. The ratios of Na/Cl and Cl/HCO₃ is also enumerated the fact that the most of the samples from PRM and few samples from other seasons also indicates dominance of salt water intrusion.

Abstract

In Gadilam river basin, groundwater is found in both hard rock and sedimentary terrain and is the most important source of rural/urban drinking water supply. Gadilam river basin has gained its importance due to the presence of Neyveli Lignite open cast mine (NLC), group of industrial estate (SIPCOT), extensive depressurization of Cuddalore aquifer and boreholes of New Veeranam Scheme (NVS) in the downstream of the basin. A total of 178 water samples were collected in four different seasons at various lithologies. The collected samples were analyzed for various physico-chemical parameters using standard procedures. Geochemical indicators of groundwater were used to identify the chemical processes that control hydrogeochemsitry. Interpretation of hydrogeochemical data suggests that leaching of ions followed by weathering and anthropogenic impact controls the chemistry of the groundwater. Isotopic study reveals that recharge from meteoric source in sedimentary terrain and rock water interaction with significant evaporation prevails in hard rock region. This thorough understanding helps us to make judicial usage and to maintain the quality of this commodity.

Abstract

A study on colloids in groundwater and its relationship with the geochemical parameters is reasonably essential because of its facilitating nature to transport radionuclides in groundwater. Colloid sampling has been carried out in the coastal aquifers of southeast coast of India. Two different bore wells were selected based on the distance from the coast to collect groundwater samples. On the basis of the result achieved from this study, a reliable representation is emerging. The values of pH and EC are governed by the different size fraction of colloids. In this study, the relation between different size fractions of groundwater colloids and its pH, TDS and EC were carried out. These parameters were analyzed in the lab and its influence with four fractions of colloid like 1.2, 0.8, 0.45 and 0.22 µm have been discovered by smooth scatter plot. The accumulation of particles weighting by normal weighing instrument. There is an higher accumulation of particles found in Kalpakkam than Anupuram in all the size fractions. For separation of particles high frequency pressure was used by ultrasonic cleaner had been carried out. This method is very simple and more reasonable than any other methods.

Abstract

A study on the Subsurface groundwater discharge (SGD) in the coastal Cuddalore region of south east India has been carried out. Measurement of surface water Radon, Water level, Electrical Conductivity (EC) and pH for a total of twenty four hours, by hourly interval the measurement has been calculated and promote correlated with tidal values calculated by WX Tide 32 software. The SGD measurements were made by using a modified seepage meter. The study reveals a match with water level variation and tide with minor variation due to influx of surface water. Saline discharges, fresh groundwater discharges and surface water mixing processes were identified along the coast. Lower SGD (37.24 – 79.16 cm/day) were observed during fresh groundwater discharge.

Abstract

Aquifers are usually composed of permeable layers that can ways a considerable amount of groundwater. Usually, aquifer units are correlated through the concept of lithostratigraphy. For low-permeable aquifers, it is difficult to define the spatial distribution of hydrogeological units, and this study attempts to use geochemical methods to identify the groundwater flow paths in an area of Southeast coast of Tamil Nadu, India. Multiple geochemical analyses, including groundwater chemistry; stable isotopic compositions of d¹⁸O and 8D contents were performed.  Spatial distribution of d¹⁸O, dD, Cl-/HCO-₃ show that northeastern part of the study area seriously affected by seawater intrusion. The highly permeable aquifers at the east coastal region are characterized by high hydraulic conductivity as compared with other regions of the study area. Hydrogeochemical characteristics based on bivariate diagrams of major and minor ions show that changes in the chemical composition of groundwater are mainly controlled by the salinization process followed by cation-exchange reactions.

Abstract

Coastal aquifers are the sources of freshwater which are being over extracted due to increase in population, agriculture and industrial activities. This over exploitation has resulted in decline in groundwater level and intrusion of sea water into the coastal aquifers making it unfit for human utilities. An attempt has been made in the coastal tracts of Pondicherry region using Electrical resistivity imaging. The survey has been attempted in six locations spread thought the study area and the interpretation has been attempted by RES2DINV software. The profile length attempted was between 150 to 300 m with electrode spacings between 5 to 10 m. The apparent resistivity ranges between 0.1 to 1183 & ohm. Sea water intrusion was prominent along the northern parts of the study area and lower resistivity isolated in kirumambakkam has been interpreted as salinity due to the presence of clay minerals. In nallavadu saline intrusion has been identified at shallow depth.

Abstract

Deduction of overindulgence fluoride (F)  from the water has been endeavor by numerous investigators by using different materials both natural and artificial. The objective of this paper was to attempt the fluoride removal by using the locally available natural materials such as red soil, untreated charcoal, local powdered brick, fly-ash from Neyveli (thermal power plant) and mineral serpentine were used, adopting column method. Maximum defluoridation occurs immediately after the experiment has started. The morality of fluoride removed per gram is more in red soil when compared to the other materials. Variation of fluoride removal with time was studied after the erection of the column /unit, the defluoridation setup was then connected to the public water supply from the overhead tank of 50,000L capacity. Higher F removal was noted when flow rate was lesser. An attempt on the regeneration of the fluoride adsorbed soil was also made.

Abstract

A total of 30 groundwater samples were collected in four different seasons (Pre Monsoon, South West Monsoon, North East Monsoon and Post Monsoon) from the coastal aquifers of Kalpakkam region of Tamilnadu. The samples were collected covering the seasonal and lithological variations to infer the influence of natural geochemical processes and anthropogenic sources on the groundwater chemistry. The collected samples were analysed for the parameters like EC, pH and Major ions. The saturation index of silicates and carbonates shows that state of saturation to over saturation, but the sulphate minerals is dominantly under saturated. In the inverse modeling three models are obtained using PHREEQC and the error percentage is noted as 7.45%.

Abstract

The geochemical signature and vulnerability of groundwater of the East Coastal aquifers of  India from Pondicherry to Nagapattinam were determined. The coastal aquifers are fragile and this situation becomes more intense in aquifer systems like that of the Pondicherry to Nagapattinam region. A total of 136 water samples were collected during pre and post monsoon of 2008 and 2009 respectively. Out of which 45 samples for each pre and post monsoon from shallow groundwater and 23 samples for each pre and post monsoon from deeper groundwater.. The samples collected were analysed for major, minor cations and anions. Selected samples were also analysed for stable isotopes (d¹⁸O and dD). The analysed samples were studied for; their utility for different purpose, the nature of the geochemical classification, their variations in ion ratios, extent of sea water intrusion and the percentage of mixing, The study reveals that chief mechanism controlling shallow groundwater is the salts precipitated in the pore spaces during the Pre monsoon were leached and dissolved during the subsequent monsoon apart from sea water intrusion. Southern part of the study area  is more vulnerable than the Northern part of the study area.

Abstract

In semiarid climates, a significant component of recharge to basin aquifers occurs along the mountain front. In this scenario Mountain Front Recharge study has been carried along the foothills of Courtallam ,Tamil Nadu. A total of 53 groundwater samples were collected along the foothills and measured for major cations and anions using standard procedure. Saturation index (SI) of carbonate minerals like Aragonite,Magnesite, Calcite and Dolomite,LogpCO₂ and Ionic strength obtained from WATEQ4F output. pH plays a significant role in the saturation index of the minerals. Most of the Carbonate minerals shows undersaturation  with the pH range 7.5. Positive relationship between SI and HCO₃ is noticed. A sharp increase of pCO₂ values towards the foothills region suggests that the groundwater has been recharged by, acquiring longer flow path during its infiltration into deeper level near foot hill region. The SI of these carbonate minerals was spatially distributed to identify the areas of higher SI and also it is compared with the water level fluctuation to understand the recharge process along the foothill region as well as riparian zone.

Abstract

Quality of water is affected by natural and man induced contamination to groundwater system. Area chosen for study has gained its own importance due to the location of two lignite mines and a Thermal power plant in operation. Extensive large scale pumping of water is done for lignite mining. The mine drainage and drainage from thermal power plant along with agricultural return flow from lignite charged waters increases the severity of problem. In order to achieve a panacea for the above-mentioned situation, the study has incorporated and integrated in all related factors to get a meaningful interpretation for groundwater quality and quantity management in and around Neyveli area. The frequent failure of monsoon has added to the existing problem of over exploitation. To attain a panacea for water chemistry groundwater samples were collected for four different seasons. Higher EC and TDS values are observed in Southeast and Southwest part of the study area. In Southwest monsoon and Summer seasons HCO₃Cl dominates the anions, with few representations for SO₄. In Northeast monsoon and Post monsoon season Na + K – Ca + Mg is the dominant. Thermodynamic, studies reveal that groundwater of the region are stable with Kaolinite stability field in all the silicate systems. Bicarbonates derived from silicate mineral weathering are noted in the NW, Northern and in the mining region. These regions are located in the NW and NE part of the study area. Comparison of water quality to standards shows that the water can be used for drinking and for irrigation purposes except in few locations.

Abstract

Radon being the radioactive daughter product of Uranium; the interrelationship between U and Rn has been established in the present study. It is found that Radon coexist with Uranium in the region. A total of 61 samples were collected spatially from hand pumps and bore wells of the study area. Major ions such as Ca²⁺, Mg²⁺, Na⁺, K⁺, F^-, Cl^-, HCO^3-, NO^3-, H₄SiO₄,PO₄- and SO₄^2- and U, Rn were analysed. The lithological influence of U and Radon occurrence is also highlighted. Hard rocks especially Granites are the source for both U and Rn in the study area whereas the lack of correlation exist between U and Rn in sedimentary terrain can be attributed to difference in flow conditions and chemical properties of these elements. 

Key words: Radon, Uranium, Granite, Ground water, Source.
 

11.1 Introduction

The laws governing the flow of water in wells are referred to as the hydraulics of wells. Just like surface water flows from a higher elevation to a lower elevation by gravity, groundwater also flows from a region of higher water table to a region of lower water table. This difference of water table measured by any two piezometers divided by the longitudinal distance between them is called as hydraulic gradient. Hydraulic gradient plays a dominant role in deciding the flow of groundwater. This hydraulic gradient together with the hydraulic conductivity of the aquifer material forms the main law of well hydraulics called as Darcy’s law. An understanding of Darcy’s law together with some other laws as discussed subsequently in this chapter is essential in order to know the discharge of a well in a particular formation. Darcy’s law is valid for studying groundwater flow in alluvial formations. However, it is not valid for aquifers having hard rock areas.

10.1 Introduction

During rain or heavy irrigation, a part of the rainfall or irrigated water moves below the effective root zone of the crop which moves further below and adds to the water table lying above the impermeable bed or hard rock which is called as  ground  water  reservoir. At  times  the  accumulated  surface  water  is  also recharged to the soil reservoir both naturally as well as artificially that add to the underlying ground water reservoir. This groundwater is an important source of water for irrigation as well as domestic uses. It is the most abundant fresh water resource of the earth. Underground water reservoirs contain large stock of fresh water resources. Total quantity of groundwater within 800 m distance below  the  ground  surface  is  more than  30  times  the  total  water  in  all fresh water lakes, more than 60 times the total water in soil and other unsaturated rock materials, more than 300 times the water vapour in the atmosphere and 3000 times the average volume of all rivers and rivulets in the world (Lenka, 2001). But the distribution of groundwater is not uniform.

Bhuva is a small village in north-west Gujarat – India.  My mother was born there. The loving people of Bhuva called me ‘Bhano’ (Sister’s Son / Nephew) and it was my favourite place to go as a child. I have my fondest memories of Bhuva, but could not visit for several decades, until when I was once at the Junagadh Campus of Gujarat Agricultural University, to inaugurate the International Conference on New Developments in Agriculture. Bhuva was not too far and I decided to go there. Soon as I reached, a familiar face, now aged with time, recognized me from a distance and with tears rolling from his old eyes (and mine) he hugged me, calling out “MaroBhano, MaroBhano” (My sister’s son, my sister’s son)! Now in his eighties, it was overwhelming to meet Nanji Ata, who I always remembered being wise, educated and cheerful. He was a relatively progressive farmer with about 6 to 7 acres of land, a few cows and a buffalo. Though water was scarce and saline, he managed to make a good living and was considered a well to do man.

It is well recognized that sustainable management and sustainable livelihoods are inseparable. If neglected and if the present trends are not corrected in time, everyone’s future is threated. On the other hand, there is increasing recognition of living examples and demonstrated evidences of how the eco agricultural practices can help provide a solution to some of the major problems of today and tomorrow. Also, the main stream international agencies are emphasizing that agro-ecological approaches are the way forward. What the policy makers, farmers and people would like to know is How !it has been our experience that in most countries of the developing world the answer to ‘How’ of eco-agricultural is being demanded!