eChapters

Introduction

Solar energy could be converted to electricity both through thermal route and photovoltaic cells but the latter is more advantageous as it has no moving part, it doesn’t require water, a rare commodity specifically in arid regions. Moreover, the maintenance of PV systems is easy, it can be installed right at the place of utility, the system is modular and these are reliable having life more than twenty years and of course eco-friendly.

In photovoltaic cells, generally known as solar cells, charge carriers are generated by the incoming irradiance (energy greater than band gap) and these are separated and swept away by an internal electric field, which is created by either making metal semiconductors contact (Schottky barrier) or p-n junction or MIS (Metal Insulator Semiconductor) or SIS (Semiconductor Insulator Semiconductor) devices. The height of potential barrier at the junction determines the voltage and the flowing charge carriers contribute to the current when connected externally. The choice of material depends on its band gap, absorption coefficient, diffusion length, mobility of charge carriers, ease in contact formation, type of junction with thermal and electronic compatibility, availability of material, toxicity and several other fabricational opto-electronic and practical aspects. PV cells based on single crystal and polycrystalline silicon, amorphous silicon, CdS, CdTe, CuInGaSe, InP, GaAs etc. have been much studied. PV modules of efficiency above 16% on silicon and 10% on CdTe, CuInGaSe and 8-9 % on amorphous silicon are commercially available. Dye sensitized TiO₂ devices have also been receiving more attention with coloured panels for windows. Organic semiconductors are explored and more recently perovskite solar cell has been studied. Flexible solar cell panels based on thin film devices are in use. The applications have gone from solar lighting to operation of pumps, small and medium size equipment, stand alone and grid connected solar power plants, roof top and building integrated PV and now even energizing cars and aero planes. With technological advancement and enhanced production (233 GW in 2015) the cost of commercially available PV modules, which used to be high at one time has been brought down from 30 $/Wp in seventies to about $0.5/Wp at present.

Introduction

As the most of the conventional resources are depleting and can last only for about a few 30 to 50 years. Scientists worldwide are looking for alternative energy resources and they have come to an agreement that solar energy can provide much of our energy needs in the future. The major challenge before them is to store this energy. The radiation falling on the earth surface can be tapped and stored in no of ways. However, the most efficient way is done through the latent heat storage through PCM. The PCM has many added advantages i.e. high energy density, isothermal behavior, non-polluting and low cost. Nowadays, it gaining popularity worldwide and now seen as the most efficient way of thermal energy storage. There is a large number of PCM at use i.e. organic, inorganic, eutectic and salt hydrates. Their utilization depends on the user’s requirement technological constraints. They also serve the purpose of energy availability at night beside the uninterrupted supply during the day. They are seen as the materials for ensuring the environmental sustainability

Introduction

The thermal performance of a building refers to the process of modeling the energy transfer between a building and its surroundings. For a conditioned building, it estimates the heating and cooling load and hence, the sizing and selection of HVAC equipment can be correctly made. For a non-conditioned building, it calculates temperature variation inside the building over a specified time and helps one to estimate the duration of uncomfortable periods. These quantifications enable one to determine the effectiveness of the design of a building and help in evolving improved designs for realizing energy efficient buildings with comfortable indoor conditions. The lack of proper quantification is one of the reasons why passive solar architecture is not popular among architects. Clients would like to know how much energy might be saved, or the temperature reduced to justify any additional expense or design change. Architects too need to know the relative performance of buildings to choose a suitable alternative. Thus, knowledge of the methods of estimating the performance of buildings is essential to the design of passive solar buildings.

Introduction

Considering the accountable post-harvest losses which is approximately 30-35 percent, food processing becomes an extremely important sector for preventing the losses and feeding the growing population. The Indian food industry is poised for huge growth, as currently valued at US$ 1.3 billion with compound annual growth rate of 20 per cent per year, increasing its contribution to world food trade every year. In India, the food sector has emerged as a high-growth and high-profit sector due to its immense potential for value addition, particularly within the food processing industry. Increasing population of the country and high cost of fuels have also created a demand for new alternate sources of energies for post-harvest processing of foods. Solar food processing technologies may become a viable option that provides good quality foods at low or no additional fuel costs. The energy policy of the developing countries now focuses on the clean renewable energy to create a further reduction of the petroleum import and to alter the utilization of petroleum energy toward the utilization of solar energy. It is an interesting fact that most of the developing countries fall in the climatic zone where the insolation is considerably higher than the world average of 3.82 kWh m-2 (Majumdar 2015). The daily horizontal insolation of India is approximately 5.80 kWh m-2 (Visavale 2009, Visavale et al. 2011). Solar dyers are an alternative to traditional drying technique and a contribution towards the solution of the problems of the open sun drying from perspective of renewable and clean energy. The International Energy Agency (IEA) declared in its 2011 solar energy perspectives executive summary (SEP 2011): “Solar energy offers a clean, climate-friendly, very abundant and inexhaustible energy resource to mankind, relatively wellspread over the globe. Its availability is greater in warm and sunny countries that will experience most of the world’s population and economic growth over the next decades.

Analytical chemistry is a branch of chemistry dealing with the determination of constituents of a substance or mixture of substances.

1.1 Qualitative Analysis

Qualitative analysis deals with the identification of the constituents of a substance, mixture of substances, or solutions and the way in which component element or a group of elements are constituted.

1.2 Quantitative Analysis

Quantitative analysis is concerned with the determination of quantitative contents of individual element or group of elements or compound present in the substances. This branch of analytical chemistry is of enormous scope and importance in science, industry and agriculture. The quantitative analysis can be divided into several categories based on the different methods employed for their quantitative measurements such as:

2.1 Beakers

Beakers are the one of most important vessels used in laboratory which is made up of heat resistant glass.

They are available in various capacities ranging from 10 to 3000 mL.

For convenience of pouring solution, spout is provided in the beaker.

They are used to perform titrations & for boiling solutions, etc.,

Beakers are constructed in tall and low forms.

Instrumental methods of chemical analysis are the quantitative methods of analysis that use, as principal measuring devices, instruments other than those employed in conventional gravimetric and volumetric determinations.

The main basis for this method of analysis is the physical property of any particular element or compound being analyzed. These properties include:

Practice to calculate the weight / volume of reagents required to prepare the following standard solutions.

Preparation of Standard Solution - (1 M, 0.1 M, 1 N, 0.1 N, 0.5 N, 5%, 10%, 20%, 10 ppm, 20 ppm, 100 ppm)

5.1 Volumetric Techniques or Titrimetric Analysis

Acid Base Neutralization Reactions-Acidimetry & Alkalimetry

Oxidation –Reduction Reactions-Oxidometry (Permanganometry) & Dichrometry

Principle

Standard solutions are the solutions of accurately known concentrations. There are two types of standard solutions viz., primary and secondary.

A known quantity of the substances is dissolved in a volumetric flask and the volume is made upto the mark. Standard solutions prepared in this way are known as primary standard. This method can be used for preparation of standard solutions of substances which satisfy the following conditions.

More often, if the reagent is not a primary standard, a secondary standard solution must be prepared. The chemical is dissolved and made up or diluted to the desired concentration and then it is standardized against a primary standard or against another reliably known secondary standard solution. Such solutions are called as secondary standard solutions.

Principle

Equal volumes of all acids / bases containing their gram equivalent weights per litre of the solution react completely with each other.

Soil is analyzed to know the nature of soil, to classify and advocate to farmers about the peculiarities of the soils and how much of fertilizers should be applied for better crop production.

A composite soil, of course, can not be moved to into a laboratory. The value of the laboratory work depends upon care in sampling. Each soil sample needs to be a fair representative of the specific area or horizon worth sampling.

If the sample is to be a representative of an area, it is necessary to take large number of samples spread over the area, pool them and sub-sample it so as to get a sample of desired size. For soil survey work, samples are collected from a profile which is typical of the soil of the surrounding area.

Principle

Soil moisture content is determined by drying a known quantity of soil sample in an electric oven at 105° C to 110° C and finding out the loss in weight.

Bulk density is the mass per unit volume of soil including pore space. The normal range of bulk density in most soils is ranging from 1.02 to 1.80 g / cm³. The bulk density of coarse textured soils will be on the higher side while organic soils will have lower bulk density.

Particle density is the mass of soil per unit volume excluding pore space. Pore space is that fraction of soil volume not occupied by solid particles.

Principle

The bulk density and percent pore space are determined from the apparent and true volumes of the soil measures by adding a known quantity of water to a measuring cylinder contain a weighed quantity of soil.

(International/Robinson’s Pipette Method)

Principle

This method is based on Stoke’s law. According to this law, the rate of fall of a particle in liquid is directly proportional to the square of its radius.

Principle

When water is ponded inside the concentric metallic rings driven into the soil, the rate of recession (fall) of the water level, or the rate of water withdrawn from a supply source used to maintain a constant head of water on the soil surface, gives the infiltration rate of the soil.

During infiltration of water into the soil, appreciable lateral movement of water may also occur. To avoid the error due to this lateral movement, two concentric rings are used. Equal heights of water are to be maintained in both the rings. The infiltration is measured in the inner ring only. The rate of water intake per unit area varies markedly with the size of the rings and the depth of the soil to which they are driven into. Infiltration rate studies are preceded by the profile, initial soil moisture and any other problems of the region in which the soil is located.

(Keen-Rackzowski/Hilgard Apparatus Method)

Principle

With the capillary rise of water, the soil immediately above a water table gets saturated. The height upto which the soil is saturated depends on the texture, structure and packing of the soil mass. The experimental technique discussed herein permits approximation of maximum water holding capacity while determining the amount of water held in the soil at the point of saturation.

The pH is defined as negative logarithm of hydrogen ion concentration or the log of the reciprocal of the hydrogen ion concentration (Sorenson, 1906).

Principle

A glass electrode in contact with hydrogen ions of the solution acquires an electric potential which depends on the concentration of hydrogen ions. This is measured potentiometrically against some reference electrode which is usually a calomel electrode. The potential difference between glass electrode and calomel electrode is expressed in pH units.

Two electrodes are used in the determination of pH. One is reference electrode which provides a standard voltage and is usually a saturated calomel electrode which has two layers of saturated solution of KCl and mixture of solid HgCl₂ and Hg. The outer tube is usually 5-15 cm long, 0.5-1 cm in diameter. The mixture of solid HgCl₂ + Hg paste is contained in an inner tube that is connected to the saturated KCl solution in the outer tube by means of small opening. The resistance developed by this type of electrode is 2000-3000 Ohms.

The outer electrode is glass electrode that consists of a tube enclosing a lead wire made up of Ag coated with AgCl. This wire is again enclosed in a wax insulation. To the tube at the bottom is attached a glass bulb made up of a special kind of glass which is sensitive to hydrogen ions. The thickness of the glass membrane varies from 0.03 to 0.1 mm and has a resistance of 50 to 500 mega Ohms.

When these electrodes are dipped in solution, the saturated solution of KCl comes out of reference through small holes and forms an invisible ionic bridge between electrodes through which current passes. The hydrogen ions are absorbed by glass electrode and depending upon the amount of hydrogen ions present in the solution, an electric potential develops between electrodes. This potential difference is measured in terms of pH units by suitable Galvanometer.

The Electrical Conductivity (EC) of the soil is a measure of soluble salts present in the soil and is expressed as millimhos/cm or dSm^-1.

Principle

As the amount of the soluble salts in a solution increases, the electrical conductivity also increases. This electrical conductivity is measured in terms of resistance offered to the flow of current using a conductivity bridge.

It is known that solutions offer some resistance to the passage of current through them, depending upon the concentration of the soluble salts present. Hence, EC is measured in terms of electrical Resistance between parallel electrodes immersed in the soil water suspension.

In such a system, the solution between the electrodes becomes the electrical conductor to which the physical laws relating to resistance are applicable. The electrical resistance ‘R’ is directly proportional to the distance ‘L’ between the electrodes and inversely proportional to the cross sectional area ‘A’ of the conductor.

[Titrimetric/ Walkley and Black (1934) Method]

Introduction

The role of soil organic matter, in relation to soil fertility and physical conditions, are widely recognized. The organic matter is the source of plant nutrients which are released inassimilable forms during microbial degradation. A major proportion of N (95 – 99 % of the total), P (33 – 67 % of the total) and S (75 % of the total) in soils occur in organic combinations, which mineralize to release the nutrients in inorganic forms to be used by plants. Nevertheless, it serves as a reservoir of plant nutrients, in promoting water storage, and in regulating microbial activity.

The organic matter content of a soil varies from 0.344 % in very sandy arid soils to more than 86 % in Peats and Mucks. Soil organic matter contains 5 % N, and 0.5 % each of P and S, thereby, having a N:P:S ratio of 10:1:1. The organic matter content of a soil is estimated by the amount of organic carbon (C) present, as this element represents, on an average, 52 – 58 % of the organic matter, and the C:N ratio is 10 – 15. In the sub-soil, the average organic carbon amount is 36 – 44 % (40 %), and the C:N ratio is < 8. In order to find out the amount of humified organic material, the organic carbon content is multiplied by 1.724, which represents the ratio between the humus and the organic carbon (100/58) and is known as the ‘von Bemmlen factor ’.

The organic matter content of soils is estimated from the organic carbon, determined by using the ‘Titrimetric method / Walkley and Black method. The Titrimetric determination, also known as the ‘wet-digestion method’ involves a rapid titration procedure for the estimation of organic carbon content of soils.

[Alkaline Permanganate / Subbiah and Asija (1956) Method]

Introduction

Nitrogen (N) is found in the arable horizon of the soil, mostly in organic material. In the soil solution, organic N is gradually transformed into ammoniacal (NH₄ ⁺), nitrite (NO₂ ^–) and nitrate (NO₃ ^–) nitrogen by microbial processes. Organic-N is, in itself, of very little use to plants, as it can not be absorbed as such. It is, therefore, necessary to estimate the different forms of mineralized or available N. The NO₃ ^–_N and NO₂ ^–-N together, hardly, exceed 1 % of the total N in normal soil.

The available N in soil refers to a fraction of the total N which is converted into forms accessible to the plants. This constitutes, on an average, only 0.5-2.5 % (rarely 5 %) of the total N in a soil at any given time. Nitrogen is, generally, absorbed by plants as NO₃ ^–, under oxidized environment (upland condition), and as NH₄ ⁺, under reduced condition. NO₂ ^– is sometimes, detectable, but the amount is, generally, very small vis-a-vis NH₄ ⁺ or NO₃ ^– and, hence does not warrant its determination. The sum total of NH₄ ⁺ and NO₃ ^–- N is smaller than the total N, which becomes available to plants and the difference being attributed to the mineralization of the organic N, during the crop growth cycle.

[Bray’s Method (Bray and Kurtz, 1945) – Acid Soils]

Introduction

The term available phosphorus (P) refers to the inorganic form, occurring in the soil solution, which is almost exclusively ‘orthophosphate’. This orthophosphate occurs in several forms and combinations, and only a small fraction of the total amount present may be available to plants, which is of direct relevance in assessing the P fertility level.

The phosphate concentration in solution is governed by heterogeneous equilibria in which it takes part. This situation can be represented as follows:

P adsorbed in solid phase ↔ P in the soil solution ↔ P precipitated

The phosphorus absorbed by plants from soil solution comes from the soil solution in which it exists as inorganic orthophosphate ions viz., H₂PO₄ ^–, HPO₄ ^2– and PO₄ ^3–. The most accessible ion is H₂PO₄ ^–, with the greatest activity coefficient, followed by HPO₄ ^2–. The quantity of P accessible to the plants is influenced by a series of soil properties. The relative abundance of these ions is, however, relatively dependent on the soil pH. For soils having a pH between 4.5 and 7.5, ions of H₂PO₄ ^– as well as HPO₄ ^2– exist in soil solution. At a pH of 7.2, H₂PO₄ ^–and HPO₄ ^2– ions have an equal activity, and, when the pH is strongly alkaline (>8.3), ions of HPO₄ ^2– predominate in solution. Above pH of 9.0, the trivalent ion (PO₄ ^3–) becomes more important than H₂PO₄ ^–, but even at a pH of 12, the HPO₄ ^2– concentration is still greater than that of PO₄ ^3–. Soluble phosphorus may be adsorptively retained at the surface of colloidal particles. This retention is more marked when the higher amounts of clay and sesquioxides are present. Relatively, the available inorganic P tends to accumulate in its most stable state under prevailing conditions, thus, in calcareous soils, the available inorganic P would be acid-soluble, whereas, in acid soils the adsorbed P would be more available. In flooded soils, with low oxidation potential, certain forms of P, normally considered as unavailable, for example, iron and phosphate, can be regarded as available. In most soils, the main source of orthophosphate is organic matter unless, of course, direct fertilization, with soluble phosphate, has been made.

(Neutral Normal Ammonium Acetate Method)

Introduction

The total potassium (K) content of a soil varies from 0.05 to 2.5 %. The total K is distributed in mineral form (lattice – K, 90-98 %), fixed non-exchangeable or temporarily retrograded K (1-10 %) and exchangeable plus water soluble K (1-2 %). Exchangeable K represents an average of 2 – 15 % of the sum of exchangeable bases and 1 – 3 % of the total capacity for cation exchange. The K concentration in the soil solution is on an average 0.08 – 3 meq/litre. Both water soluble and exchangeable K are most accessible to the plant. Available K can, thus be separated into that, immediately available, which is water soluble and exchangeable, and that, potentially available or fixed. The neutral normal ammonium acetate extract contains both water soluble and exchangeable K. K extraction by this extractant is considered as a suitable index of K availability in most soils, based on crop response correlation study. Thus, the K extracted by this method is equated as the available K.

[Williams and Steinbergs (1959) Method]

Introduction

Sulphur (S) occurs in numerous forms in soil, viz., sulphites, sulphates, sulphides and in organic compounds. It is considered that the most accessible form is ‘sulphate’ (SO₄ ^2–). The organic forms of S compounds become assimilable, especially following, microbiological transformation into SO₄ ^2–. The mineralization of organic S in a soil depends primarily upon the N:S ratio, and any SO₄ ^2– formed may be fixed against extraction, particularly if much Fe or Ba is present or if the soil is very acid. Despite the fact that the plants absorb S almost exclusively as SO₄ ^2–, mobility of SO₄ ^2– in soil may not always yield satisfactory results in accordance with the time of sampling, while assessing SO₄ ^2– availability.

[Shoemaker, Mc Lean and Pratt (SMP) Method, 1961]

Introduction

For proper plant growth, the soil should have a pH between 6.5 and 7.5, though there are certain plants which can grow satisfactorily at low pH, for example, tea, and at high pH, for example, sugar beet. In India, acid soils are located mostly in Eastern, Southern and South Central parts though some soils, at higher elevations, in North India are acidic.

In order to achieve maximum yield and sustained productivity through efficient soil management practices, it is essential to lime an acid soil, as it has considerable influence on soil environment, besides correcting soil acidity.

Several methods have been proposed to determine the lime requirement of acidic soils, to raise the pH around 6.5. The soil pH value alone, however, is not a good criterion for lime recommendation, because of variations in the exchange acidity of soil, and the nature of crops which may not require as high as this pH to produce maximum yield. Of these various methods proposed, the Shoemaker / SMP method was found satisfactory.

The recent trend of liming is to use it as a fertilizer rather than as amendment so as not to disturb heavily the natural environment while ensuring sustained productivity.

[Schoonover (1952) Method]

Introduction

Sodic (Alkali) and Saline-Sodic soils are characterized by the presence of large amounts of sodium, as high as 15% or more, on their exchange complex. As a result of this, the pH of soils increases beyond 8.0, causing nutritional imbalances, elimination of soil organic matter, deterioration of soil physical condition, etc., besides affecting the soil biotic community. Gypsum (CaSO₄. 2H₂O) is commonly used for the management of such soils, when applied in right amounts and size.

Principle

A given weight of soil is equilibrated with a known amount of Ca solution, and the amount of Ca, left in the solution is determined by EDTA titration. The difference between the amount of Ca added and the Ca left in the solution, gives the amount of Ca exchanged. In practice, gypsum of about 1/3 of the value, obtained by this method, is satisfactory in most cases.

Climate Change has emerged as one of the most serious environmental concerns of recent times. The most imminent climatic change is increase in atmospheric temperature due to increased levels of greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O) and hydrochlorofluoro carbons (HCFCs). Because of increasing concentrations of the greenhouse gases in atmosphere, there is much concern about future changes in the climate system viz., Atmosphere, Lithosphere, Biosphere, Hydrosphere and Cryosphere. Direct or indirect effects on the society linked sectors like water, forestry, agriculture, animal agriculture, fisheries, land and marine biodiversity and health due to climate change/variability are many-fold and economic impact of climate change is enormous. The recurrent drought and desertification threaten seriously the livelihood of over 1.2 billion people who depend on land for most of their needs.

Natural disasters are of meteorological or hydrometeorological origin. Disasters such as earthquakes and tsunamis are occasional, but rainfall-related hazards, flood or drought, are very frequent and thus call for proper monitoring of large-scale rainfall variation, and better manage- ment and planning to combat the problem(s). Variation in rainfall is very large spatially and temporally compared to any other atmospheric parameter, such as pressure or temperature. The large temporal variability in the Indian rainfall has produced frequent flood/drought and periods of above/below normal rainfall for several centuries past. Areas of high rainfall and runoff are flooded in the summer monsoon season whereas others face water stress and drought conditions. The influence of global warming on rainfall variations over India is reported in numerous observational (Singh et al., 1991, 1992) and modelling studies (Lal, 1994). 

Food security is one of the most important issues during this century under the projected climate change scenario. The world is facing severe food crisis due to weather vagaries as a part of global warming and climate change. Many countries are under severe food crisis during the crisis of weather abnormalities since 75 per cent of world’s population is dependent on agricultural activities for their livelihood. Therefore, there is an urgent need to produce more and more foodgrains at the global as well as national levels to meet the food requirement of growing population under the projected climate change scenario. There has been a major decline in world rice production since late 2007 due to various reasons including global warming and climate change in top rice producing countries. 

The Intergovernmental Panel on Climate Change (IPCC) in its fifth assessment report (AR5) stated that warming of the climate system is unequivocal and is more pronounced since the 1950s. The atmosphere and oceans warmed, the amounts of snow and ice have diminished, and rise in sea level is noticed. Each of the last three decades has been successively warmer at the earth’s surface than any preceding decade since 1850 and the globally averaged combined land and ocean surface temperature data show a warming of 0.85°C over the period 1880 to 2012. The recent years viz., 2015, 2016 and 2017 were the hottest years on record. The warming trend in India since 1961 has indicated an increase of 0.9°C, which is likely to impact many crops, negatively impacting food production. There are already evidences of negative impacts on yields of wheat and paddy in northern India due to increased temperature, water stress, and reduction in number of rainy days. Coastal agriculture has the onus of providing livelihood to nearly 20 % of Indian population. The water logging and coastal salinity are the major factors affecting the agricultural output from the regions.

Climate risk management in the semi-arid tropics (SAT) is one of the major challenges to achieving food security and development in India and large parts of sub-Saharan Africa and also in the case of Australia. Climate-induced production risk associated with the current season-to-season variability of rainfall is a major barrier in making rainfed agriculture sustainable and viable farm business. Since season outcomes are uncertain, even with the best climate information, farmers have limited flexibility in applying management with confidence. In fact in risky environments, farmers most often respond by adapting a risk averse strategy and are reluctant to invest in even risk reducing measures (Leathers and Quiggin 1991). In the SAT agro-ecologies, there are a limited range of enterprise or crop options to consider which may be further restricted by cultural traditions, food preferences or market opportunities.While there are fundamental differences between large scale commercial farms in Australia compared to the predominantly smallholder resource poor farms found in India, when it comes to climate risk management in the SAT, there are many commonalities. The purpose of this paper is therefore to (i) establish a framework for managing climate variability and transforming farming systems to be more resilient and sustainable for future climates; and (ii) provide some case study examples from climate risk management in low rainfall cropping system in Australia and consider how they may be applied in smallholder systems of the SAT.

The State of Kerala has witnessed an unprecedented and unusual flood which devastated the entire State during August 2018 after the notorious 1924 flood, popularly known as the flood of 1099. Heavy rainfall from 14 to18 August 2018 led to flash floods across the State. This was aggravated by the dam opening and subsequent water level in the downstream of the rivers. 33 dams were opened across the State. This has caused the river water to flow into the inland areas. Rivers overflowed and inundated the river side villages and towns. It was reported that the water levels at many places were of the order of 20 feet. Landslides were the major threat that claimed many human lives. A chain of mud slip/land slide events took place during the heavy rainfall period at the time of flood across the mid and high lands of the State, which are ecologically sensitive areas. Even before the heavy rainfall events started on 14th August, 2018 there were major rainfall events on August 8thand 9th. On 9thAugust 2018, Nilambur (Malappuram District) recorded extremely heavy rainfall of 400 mm which is a record rainfall in 24 hours as far as the State is concerned.

Tamil Nadu has unique physiography with western and eastern Ghats on the west and northwest, Bay of Bengal in the east and Indian Ocean to the south. Tamil Nadu has high dependence on natural resources and hence faces the threat of climate change and its impacts. Available evidence shows that there is high probability of increase in the frequency and intensity of climate related natural hazards (Stephen, 2012). Out of 13 million hectares of geographical area, about 7 million hectares of land is under cultivation. Of this 55 per cent is irrigated and rest is under rain fed / dry lands. In Tamil Nadu, ground water has been harnessed fully and dry land productivity is found oscillating with ruling variability in seasonal monsoon rain and hence agricultural productivity is always under stake.

The State of Karnataka is located between 11.50° to 18.50° N latitudes and 74.25° to 78.50° E longitudes and covers an area of 19.1 m ha which accounts for 5.8 percent of the total geographical area (TGA) of the country. Out of the total 19.1 m Ha in Karnataka the net cultivated area (2010-11) was 10.5 M Ha, net irrigated area 3.49 m Ha and net rainfed cultivated area 7.01 m ha. Karnataka has the largest area under rain-fed agriculture (Fig. 8.1). Nearly 55% of total food grain production and 74% of oilseeds production come from rainfed agriculture in Karnataka. Therefore rain-fed agriculture plays an important role in total food grain production in the state. Further the rain-fed agriculture has substantial untapped potential, which can be brought to use by increasing the crop yields in the dry land areas through the adoption of proper dry-land production technologies. The climate of the state is determined mainly by the geographical location with respect to the Sea, monsoon winds and physiography.

The extreme weather events of the present day and the expected future climate scenarios at global and regional scales have been attributed to the changes in the atmospheric chemical composition and the massive amounts of greenhouse gases (GHGs) emitted by humans since the industrial revolution, bringing about the global warming and resulting in Climate Change. Further, the natural disasters like flash floods are attributed to the highly conspicuous human interventions with nature – the earth and its atmosphere. The parody of the situation is that, while the GHGs sourcing countries are mainly the developed ones, the sink of the result are the agrarian-dominated and eco-sensitive economies of the tropics. Invariably, tropical regions are to be affected the most, because, on the one hand the general circulation of the atmosphere directly and naturally causes divergence of the polluted air from extra tropical regions towards tropics, while on the other, the industrialization within the tropical regions too would affect the local atmosphere. Karnataka State, being located well within the tropics, can be truly impacted by the climate change caused by anthropogenic sources and it is demarcated into 10 agroclimatic zones (Fig. 9.1) based on crops, soils and climate. Climate experts have warned that Karnataka is likely to be more vulnerable to climate change than other states in India.

The State of Andhra Pradesh in the present form came into being on June 2, 2014 as a result of the Andhra Pradesh Reorganization Act. The state has 13 districts out of which nine are along the coast of Bay of Bengal and four are land locked in the southern part. A part of Khammam district, which is now in the Telangana state, was also added to the East and West Godavari districts of the State of Andhra Pradesh. The existing data for these two districts do not include this part and this fact is to be borne in mind. The state has a geographical area of 1.602 lakh km2 with a population of 49.83 million. The state in the current form is more agrarian compared to the undivided state as about 62 per cent of population depends on agriculture as a source of livelihood. Yet, the contribution of agriculture to the state’s gross domestic product is only 17 per cent. Though the state is known as ‘rice bowl of India’, not all is well with agriculture in the state. Some parts, especially the coastal districts, are prone to incidence of cyclones and floods while some other districts, Rayalaseema districts, are chronically drought-prone. 

Evidence is fast accumulating that the problem of climate change is of a scale not previously encountered by human societies. The scale and scope of climate change challenges to food and water security are unprecedented. World food supply is already facing significant pressures. Even without climate change, ensuring sufficient food for all in the 21st century would be difficult enough. Climate influences food security through many channels. Climate change will increase the severity and frequency of cyclones, flooding and drought. It will intensify rainfall variability, increasing water stress, weeds, pests, and erosion and reducing soil fertility. Above certain temperature ranges, crops develop more rapidly, resulting in lower overall grain production, even moderate increases in temperature can decrease yields in major food crops. Population growth, urbanisation, higher per capita calorie intake, and increasing consumption of meat combine to put more pressure on exiting water recourses.

Importance of rice in Konkan area is characterized by heavy rains of 100 mm per week or so over an extended period and contributes 42.9 % of total rice production in the Maharashtra State. Rice is the only suitable crop that can be grown under puddled soil conditions, i.e. with standing water over bunded fields. Tansplanting method of rice is commonly followed by most of the farmers in this region. Puddled rice is said to be of assistance in mitigating the effects of floods. The problem of weeds is minimal in puddled rice culture. Thus, rice serves as a livelihood crop for millions of small, and marginal farmers in Konkan who can afford only low-cost technologies. Even though the crop is robust and versatile, it has faced drawbacks in terms of low yield and reduction in acreage. In Konkan region of Maharshtra, there are two agro climatic zones viz., North Konkan coastal zone comprising three districts viz., Thane, Raigad and Greater Mumbai and South Konkan Coastal Zone comprising two districts viz., Ratnagiri and Sindhudurg. Ratnagiri district receives the highest rainfall of > 3500 mm while Thane district receives the lowest rainfall (2000-2500 mm) in this region. Sindhudurg and Raigad districts receives 3000-3500 and 2500-3000 mm rainfall, respectively.

In order to achieve maximum and sustainable crop production from available farm resources, it is essential to have proper knowledge of the agro-climatic resources of the location/region. Therefore, a thorough understanding of the climatic conditions would help in determining the suitable agricultural management practices for taking advantage of the favorable weather conditions and avoiding or minimizing risks due to adverse weather conditions. better planning of cropping pattern, developing irrigation and drainage plans for an area (Chaudhary et al. 2015). Hence, trends of temperature and rainfall are studied in this section with possible impact studies on rice production for Chhattisgarh state. Challenges of rainfed rice production can be understood through trend studies of key weather variables. Analysis of rainfall in the context of rainfed rice production in Chhattisgarh state has been carried out. Analysis has been done at Department of Agrometeorology under All India Co-ordinated Research Project (Raipur) to characterize the key weather parameters statistics.

The Inter-governmental Panel on Climate Change  has confirmed that change in climate system is gradually leaving a strong impact. Observations undoubtedly show that there is increasein global temperatures, wide spread melting of snow and ice, and rising global mean sea level. Global climate has shown warming of 0.89 [0.69 to 1.08] °C over the period 1901–2012 which is mainly attributed to anthropogenic activities. Scientific findings indicate that warming is more pronounced than expected and the impact would be particularly severe in the tropical areas, which mainly consist of developing countries, including India (Shukla, 2016). Thus, climate change is a great challenge which is continuously being faced by the sustainable economic growth of the India. Climate sensitive sectors like agriculture, forestry, hydrology oriented sectors faces major threat due to projected changes in climate. India Meteorological Department (IMD) in 2012 reportedincreasing temperature trends during last 112 years and increase in heavy rainfall events and decrease in low and medium rainfall events over India.

India, as a developing country has reasons to be concerned about the adverse impact of climate change on its economy. A large part of its population depends on climate sensitive sectors for livelihoods which makes it highly vulnerable to climate change. Climate change can have serious impact on its crops, forests, coastal regions, etc. which can in turn affect the achievement of its important national development goals. The issue of climate change cannot however be taken up without linking it to developmental needs such as poverty, health, energy access and education. Traditionally climate change experts have focused on mitigation measures, adaptation measures have also been acknowledged of late as effective and equitable means to deal with climate change impacts. Most of the mitigation measures are high in terms of technology and capital. Therefore, while developed economies choose to mitigate climate change by making heavy investments, developing economies choose to adapt (Monika and Hooda, 2018). There is increasing recognition that the world’s current progress on reducing greenhouse gas emissions is not occurring rapidly enough to avoid impacts from climate change in the coming century. Because of this, the world is “committed” to a certain level of global warming and therefore,

Climate change is one of the most important global environmental challenges facing humanity and as per the instrumental records, the earth’s climate system has demonstrably changed on both global and regional scales since the preindustrial era. Further evidence shows that most of the warming (of 0.1°C per decade) observed over the last 50 years, is attributable to human activities. The levels of greenhouse gases namely carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) have increased markedly as a result of human activities. The CO₂ concentration in atmosphere is now more than 400 ppm and the decadal increase is from 0.86 ppm per year to 1.99 ppm per year (Table 16.1) which is the highest ever. The Intergovernmental Panel on Climate Change (IPCC, 2007) projects that the global mean temperature may increase between 1.4 and 5.8 oC by 2100. This warming of the earth-atmosphere system is expected to have severe impacts on the global hydrological system, ecosystems, sea level, crop production and related processes. Agriculture sector is the most vulnerable entity in light of the global warming and its impacts.

The Jammu and Kashmir State lies in the extreme North of the Himalayas and constitutes about 67.5 per cent of the North West Himalayan region. The State is predominantly a mountainous state with all the major Himalayan ranges and trans-Himalayas adequately represented. The State of Jammu and Kashmir located in the north Western corner of India, extends between 32o-17' and of 37o-50' North parallels of latitude and 73o-26' and 80o-30' East of meridians of longitudes and 81o East of Greenwich. The State on the basis of physiography may be divided into three main regions (i) outer Himalayas which comprise of Jammu province (ii) lesser Himalayas which comprises of Kashmir Valley and (iii) inner Himalayas which comprise of Ladakh province. Jammu, Kashmir and Ladakh regions have distinct agro climatic characteristics. Jammu region has two different climatic zones depending primarily on altitude. Lower hills & plains bear subtropical climate with hot dry summer lasting from April to July. The summer monsoon commences around first fortnight of July and fading away in early September.

Agriculture is very intensely influenced by weather and climate. While farmers are often compliant in managing weather and annual variability, there is however a high degree of adaptation to the local climate. This may be in the form of conventional infrastructure, native agricultural practices or personal experience. Climate change an in this way be relied upon to affect the agriculture, possibly threatening established characteristics of farming systems and provide chances for improvements. The role of climate change in influencing human activities and the natural environment is all around acknowledged. This may go from an extreme event enduring just a couple of hours (i.e. hurricane, thunderstorm and showers) through to the multi-year dry spells (Maracchi et al., 2005). Increase in concentration of greenhouse gases in the atmosphere further contribute to climate change. This results in a strong impact on human activities and natural environments. Essential areas, for example agriculture and forestry, will be more susceptible than auxiliary and tertiary segments, for example manufacturing and retailing (Parry et al., 1998).

The State of Himachal Pradesh encompasses a geographical area of 55.7 lakh ha and is situated between 31°22’40" and 33°12’40"N latitude and 75°45’55" and 77°10’20"E longitude. The state is bordered by Jammu and Kashmir on the north, Punjab on the west, and Haryana on the south-west (Fig. 19.1). About 12 per cent of the state area is under agriculture which is mostly (80 per cent) rain fed. Wheat, maize, rice, and barley are the principal crops. In state, there are 12 districts, viz., Bilaspur, Chamba, Hamirpur, Kangra, Kinnaur, Kullu, Lahaul & Spiti, Mandi, Shimla, Solan, Sirmaur and Una. About 20 per cent of the area is under forest cover. It is rich in biodiversity of flora and fauna. Nearly 27 per cent of the area of the state is covered under permanent pastures. The state is endowed with a wide range of physiography/landform, climate, vegetation and geology which have influence on genesis of soils. The soils are mostly shallow, medium deep to deep, well/excessively drained, sandy, sandy-skeletal, loamy-skeletal, coarse-loamy and fine-loamy, calcareous as well as non-calcareous with low available water capacity. The State is the biggest montane ecosystem in India situated in northern part of the country. It is seventeenth largest state in terms of area and twentieth in population of which 65 per cent people are dependent on agriculture and 60 per cent of GDP comes from agriculture sector. Increasing temperature and reducing rainfall affecting the crop growth and crop production is a major issue everywhere in the world nowadays and this state has also not remained untouched by these prime issues of climate change. For sustainable development of agriculture in state, there was/is a need to identify and quantify climatic change where agriculture has a significant influence on both the economy and livelihood.

Bihar’s economy is highly dominated by agriculture and allied sectors. Around 85 to 90 percent of the population still lives in rural areas, where agriculture along with animal husbandry, is the main source of their livelihood. In Bihar, the gross and net sown area is estimated at 8.26 and 5.64 million hectares, respectively. Nearly 60 per cent area under cultivation in the state is rainfed (Anon, 2008). The region comes under sub-humid subtropical monsoon climate. Most of the annual rainfall (almost 85 per cent) received from south-west monsoon, occurs during June to September (Sattar, 2010). There are three crop growing seasons in the state commonly known as kharif, rabi and zaid. The important kharif season crops, which are planted in May-June and harvested in September–October, are rice, maize, sesame, sorghum and bajra. Pigeon pea is an important long duration pulse crop sown during kharif season as sole crop or intercropped with maize. The important rabi crops which are sown in October–November and harvested in February–March are wheat, rabi maize, potato, chickpea, lentil, rapeseed, mustard, barley.

Climate change and its variability imposed a great threat to agriculture production and ultimately on food security. Understanding of anomalies in climatic variables is essential to make agriculture sector resilient. Jharkhand state, geographically located at 220 28’ N – 250 30’ N latitude and 830 22’ – 870 40’ E longitude with an altitude up to 1142 m above msl and having humid to sub-humid tropical monsoon type of climate, has a number of agro-climatic/physiographic constraints. The state has 3 agroclimatic sub-zones viz; Central and North Eastern Plateau sub zone (zone IV), Western Plateau sub-zone (zone V) and South Eastern Plateau sub-zone (zone VI) falling under agroecological regions XI, XII and XIII. Zone IV is having 15 districts; Zone V has 6 and Zone VI have 3 districts. Agriculture in Jharkhand is very tedious due to topographical, physiographic and climatic constraints. Vagaries of climate put greatest limitation before the agricultural production system in the State.