eChapters

Introduction

Origin of Water Bodies and Hot Arid Regions (Thar Desert) 

The origin of the hot arid regions (Thar Desert) is a controversial subject. Some consider it to be 4000 to 10,000 years old, whereas others state that aridity started in this region much earlier. Another theory states that area turned to hot arid zones (desert) relatively recently: perhaps around 2000 - 1500 BC. Around this time the Ghaggar-Hakra ceased to be a major river. It now terminates in the desert but at one time was a water source for the Indus Valley Civilization centre of Mohenjodaro. It has been observed through remote sensing techniques that Late Quaternary climatic changes and neotectonics have played a significant role in modifying the drainage courses in this part and a large number of palaeochannels exist.

14.1. Water Source Identification

• In places where Ficus religiosa tree is found, underground water will be more.
• Underground water will be more in places where the neem tree with more knots is found.
• In places where termite hills are found, underground water will be more.
• Farmers are practicing traditional method of using neem stick, metals etc. for finding the water resource in underground for digging wells. While they are walking with this stick on hand it will be rottate automatically at the place where underground water is surplus.
• Some farmers are using the magnetic stones for identifying water sources. Magnet is tied with a thread and held like a pendulum while walking over the fields. The magnet will rotate automatically at the place where underground water is more and this is taken as the indication for digging wells.

A water budget quantitatively accounts for water entering, leaving and remaining within a defined agricultural or hydrological system. Comparable to a financial budget, it considers precipitation, irrigation, runoff, evapotranspiration, percolation and changes in storage. This chapter explains the climatic and soil-water budget, potential and actual evapotranspiration, water surplus, water deficit and moisture adequacy. It discusses how water-balance analysis supports irrigation scheduling, crop planning, drought assessment, rainwater harvesting and watershed management. Understanding the timing and magnitude of water availability helps farmers and planners select crops and management practices suited to local conditions. Water budgeting therefore provides a fundamental tool for climate-resilient and resource-efficient agriculture.

Water budgeting and its importance, methods of soil moisture estimation, evapo-transpiration and crop water requirement and effective rainfall Water budgeting and its importance, irrigation scheduling approaches
Water budgeting
Allocation of the water receipt including anticipated within the crop period and its detailed account of expenditure for efficient and profitable farm management is called as water budgeting.
Water budgeting may be for an irrigation system planned by irrigation engineers; may be for a canal or for an area (block) or may be for a farm according to the need and plan by responsible persons who plan the irrigation efficiency.
Importance of water budgeting
Efficient utilization of available recourse (water) for bringing more area under irrigation:
1. To increase the productivity of a region / farm.
2. To increase cropping intensity of a region / farm
3. To tide over some dry-spells
4. To reduce excess irrigation and losses caused thereby
5. To avoid run off losses
Irrigation scheduling
Irrigation scheduling is defined as frequency with which water is to be applied based on needs of the crop and nature of the soil.
Irrigation scheduling is nothing but number of irrigations & their frequency required to meet the crop water requirement.

Why Water Budget?

The reliability of water supply in desert regions is at risk due to a multitude of issues including low rainfall, low snow runoff, court-ordered water transfer restrictions and hence higher price of wholesale water. Agencies in desert regions understand the importance of improving water supply reliability, facilitating better water storage, adapting to changing climate patterns and reduced precipitation, improving Environment and Water Quality.

The Desert regions have always fought back the perpetual water scarcity with infrastructure designed around saving water and utilizing alternative water resources. Off late, not only new construction but also new policies and programs have added to their water conservation activities.

One such program attends to the fair distribution of water by tending to consumers who are price sensitive and hence use water without wasting it and by extra-charging those who do not know where to put a stop to their wasteful water use.

Allocation of the water receipt including anticipated within the crop period and its detailed account of expenditure for efficient and profitable farm management is called as water budgeting.

Water budgeting may be for an irrigation system planned by irrigation engineers; may be for a canal or for an area (block) or may be for a farm according to the need and plan by responsible persons who plan the irrigation efficiency.

Water conservation and efficient irrigation are key components of natural farming in India, especially in light of challenges like erratic rainfall, declining groundwater, and unsustainable water practices. Natural farming minimizes the use of external inputs, including water, and promotes ecological balance. Traditional knowledge, combined with sustainable farming principles, helps farmers use water wisely while preserving soil moisture and improving its waterholding capacity.
A primary focus in natural farming is maintaining soil health, which directly influences its ability to retain water. Organic matter from cow-based inputs such as Jeevamrutha and compost enhances soil texture and porosity, enabling better
water absorption. This results in less frequent irrigation needs, allowing crops to grow even with limited water. Mulching is widely used in this approach. Covering the soil with organic materials like straw or crop residue helps reduce evaporation, moderate soil temperature, prevent weeds, and preserve moisture. This is particularly effective in dry areas or seasons with low rainfall.
Rainwater harvesting is another vital aspect. Farmers are encouraged to build farm ponds, bunds, and trenches to capture and store rainwater. These methods help recharge groundwater and provide a backup during dry periods, reducing drought vulnerability. Natural farming discourages water-intensive methods like flood irrigation. Instead, it promotes efficient techniques like drip irrigation, which targets water delivery to plant roots, and pitcher irrigation, where buried clay pots gradually release water—both minimizing waste.

Introduction

Water is a prominent element in the daily life of human beings as well as in agriculture. In better crop production, the quantity of water, but the quality of water is also important. With respect to the current scenario of water harvesting or water conservation there are some techniques adopted in Indian agricultural practices, such as the use of drip irrigation to minimise water surplus, rain fed agricultural practices, storing rain water in different storage components, using mulching (either natural or plastic), proper tillage practices, selecting crops which need less amount of water, using laser leveller for better water uses to encounter surplus water flow to the lower elevated portion of the field etc. Water conservation techniques and measures are directly related to the type of meteorological factors of specific watershed. For the arid and semi arid regions proper method of tillage practice improves water use while in conventional practices of farming consumes more than required water quantity. Some crops are water-intensive where the quantity of the available water is crucial. Sources of water can be ground water, rain water and irrigation water. In sustainable crop production, the right amount of water is necessary for the optimal physiological growth of specific crops. Although the availability of water depends upon the geographical location, for example in the Gangetic plains of India there is less need for water conservation agricultural purposes. On the other, in the region of Deccan Plateau of India, availability of water is comparatively lower than in the Gangetic plains. It is also important that water conservation techniques can be adopted irrespective of the geographical locations. Water is conserved in nature itself but the availability of water depends on the hydrological cycle. Therefore, conservation has become a trending topic. Water conservation can be improved through sustainable agricultural practices such as proper scheduling of irrigation, selection of crops based on sustainability, monitoring soil moisture content, maintaining records of crop growth and physio-chemical data, implementing effective drainage systems, intercropping operations and utilising recycled water for other purposes.

5.1 Introduction

A farm pond that collects and harvests in-situ rainfall as well as runoff from the catchment area can be used for many purposes: the most important of which is the supply of water to crops as supplemental irrigation. It is no doubt a viable source for integrated farming system. In addition, the water of the pond can be used for domestic and to some extent for the industrial uses. It is also a good source for recreational use. Total water demand of the pond including irrigation to different crops in different seasons, domestic and other non agricultural uses are to be assessed. While estimating the crop water requirement and irrigation requirement, various crops to be grown in the service area of the pond, their water requirements, crop duration, extent of coverage and water management practices followed are to be taken into consideration. Multiplying the irrigation requirement with crop coverage area, volumetric irrigation water requirement of crop can be found out. Summation of irrigation requirement of all crops grown in service area of the pond, gives total irrigation demand of the pond.

Farm ponds are normally used for irrigation to crops as well as to meet the live stock water demand. Normally the large live stocks like horse, cattle require 20 thousand litres of water per head per year whereas the small live stocks like sheep, goat, pigs require 2 thousand litres of water per head per year. Adding the irrigation demand to the livestock demand, total water requirement of the pond is calculated. In addition to this, if the pond water is used for industrial, domestic and other sectoral purposes, then water used in all such sectors are to be added to irrigation and livestock demand to estimate the total water demand of the pond.

Introduction

Water resource is imperative for the survival of all life-forms on planet earth and defines the limits of sustainable development, without any substitute. Only 2.5% of all water on the earth is freshwater, and of that, around 0.5% is accessible through ground or surface water supplies. The increasing world population, industrialization and climate change is putting additional pressure on water resources. This is also true for livestock sector. As per prediction equations, the requirement of water for livestock will rise from 2.3 billion m³ in 2000 to 2.8 billion m³in 2025 and 3.2 billion m³ in 2050 (Hedge, 2012).

The balance between humanity's demands and the quantity available is already precarious (Karin et al, 2002). Additionally, climate change poses a serious threat to water resources as the climate system and the hydrological cycles are intimately linked, and any variability in climate affects the hydrological cycle. The World Bank report on the water and climate change inter-linkages also reiterated that climate change could profoundly alter future patterns of both water availability and use, thereby increasing levels of water stress and insecurity, both at the global scale and in sectors that depend on water (Alavian et al., 2009).

I. General information

1. Lotus stem is referred as naval cord of Lord Vishnu
2. Lotus flower is described as the throne of Brahma
3. Vishnu, Brahma and Laxshmi are associated with lotus
4. Poet Asvaghosa reported that Lord Buddha saw lotuses and flowering trees in Nandavana
5. Surface flowering plants of water garden are

Introduction

Normally, water is a liquid substance made of molecules containing one atom of oxygen and two atoms of hydrogen (H₂O). Pure water has no colour, no taste, no smell, turns to a solid at 0°C and a vapour at 100°C. Its density is 1 gram per cubic centimetre (1 g/cm₃), and it is an extremely good solvent.

An extraordinary property of water is its ability to dissolve other substances. There is hardly a substance known which has not been identified in solution in the earth's waters. Were it not for the solvent property of water, life could not exist because water transfers nutrients vital to life in animals and plants.

A drop of rain water falling through the air dissolves atmospheric gases. When rain reaches the earth, it affects the quality of the land, lakes and rivers.

10.1. Introduction

Irrigation facilities are created by the Government at huge cost for supplying water to the farmers for raising crops to increase agricultural production. The major and medium irrigation projects are planned, constructed, managed, operated and maintained by the Irrigation Departments, wherein certain procedures and rules are evolved and followed to the delivery schedule of canals, frequency of supply and distribution of water to the farmers, and closing of canals. The creation of such facilities resulted in ushering the green revolution in the sixties and seventies in the production of food grains and also employment generation in the country, thereby improving the socio-economic condition of Indian farmers. However, optimized management of irrigation water is the key to the sustainable development of agriculture and livestock. Since management of water for irrigation is highly location-specific, depending upon agro-ecological and socio-economic conditions, type of irrigation project and land use pattern, it differs from project to project and region to region in the country.

Natural resources conservation and their management hold key to sustainable agriculture and livestock production. It is all the more crucial for countries with predominant agrarian economies where development of sustainable agriculture is essential for overall growth, redressal of poverty and security. Conservation of both soil and rain water as very crucial and basic resources have been practiced since ancient times in India. However, there has been renewed emphasis on conservation and efficient utilization of these resources in the recent past. The fact that 70% of the arable area of India is rainfed with precarious supply of water and that rainfed agriculture supports 44% of India’s human population and contributes 90 per cent of coarse cereals and pulses, 80 per cent of oilseeds and 65 per cent of cotton and growing realization that further gains in productivity of crops and livestock will emanate from rainfed regions, leave no room for complacency in this regard.

Year after year, the fate of a vast majority of Indian farmers hangs in balance, as success with rainfed agriculture continues to be a gamble. It is evident that crop yields in semi-arid areas depended more on rainfall distribution than on total rainfall and lack of serious efforts to create the water supply for crops through scientific management of rainwater is a factor favoring this avoidable uncertainty. In rainfed agriculture no other input can perhaps enhance the yield without effectively tackling of the rainfall aberration related sub-optimal moisture availability. Therefore a prerequisite for substantial improvement in the agriculture production in the semi-arid region is to manage runoff water and to use it either at the time of moisture stress even during the monsoon or in next season. It has been reported that only one supplementary irrigation at proper stage can double of rabi crops. But supplemental water is a developed resource and is more expensive than the natural resources. Hence, it is all the more necessary to use this water judiciously and efficiently. Standardization of techniques by which as much of precipitation as possible can be conserved for crop use, either directly in the soil profile through infiltration or through runoff collection and recycling is an area of priority in research.

Land, water and weather are natural resources that are critical for survival. Modern agriculture requires precise information on various agro-climatic parameters like soil, crop, climate and water resources for formulating efficient agricultural planning. Out of these, water is considered most scarce input in agriculture because its availability is reducing drastically for agriculture as well as drinking purposes. Besides, declining water tables and deteriorating quality of water resources caused pollution and sewage and effluents have further multiplied the problems.

In the present scenario of rapidly increasing population and decreasing cultivable land, there is urgent need to increase the agricultural productivity. According to Indian Council of Agricultural Research (ICAR), 280 million tones food grain would be required to match the country’s demand by 2020. It will be a difficult task to meet this food requirement in near future from the present productivity levels. It is necessary to increase agricultural productivity, because about 60% of Indian agriculture is rainfed. Proper use of even a single drop of rain water is necessary to ensure the success of rainfed agriculture. In hills, agriculture is main source of livelihood of rural people. However, small and scattered land holding, difficult topography, womendependent agriculture, totally rainfed, typical socio-economic factors and migration of youth towards urban/plain areas are major constraints of hill horticulture.

In the high altitude areas, the river flow in deep valley at the toe of slopes rarely serve any purpose as far as domestic water supply and irrigation are concerned and hence, agriculture in these areas is mostly rainfed. However, these areas received high magnitude of rainfall but this rainwater is not possible to convert into soil moisture due to steep terrain of hills which provided minimum opportunity time for infiltration of rainwater. It has been estimated that only less than 15 per cent of the rainwater is able to percolate down through slopes and recharge the soil moisture. The rainfall pattern hill is erratic i.e. most of rain (approximately 70% of annual rain) received only during the two months of monsoon. Furthermore, the climate of high altitudes comprises several climatic anomalies such as wide variability in temperature (-3 ^oC to 35 ^oC), frequent snowfall, hail, sleet and erratic pattern of rainfall. Under such abrupt conditions crops grown in open conditions could not be sustained.

Natural resources conservation and their management hold key to sustainable agriculture and livestock production. It is all the more crucial for countries with predominant agrarian economies where development of sustainable agriculture is essential for overall growth, redressal of poverty and security. Conservation of both soil and rain water as very crucial and basic resources have been practiced since ancient times in India. However, there has been renewed emphasis on conservation and efficient utilization of these resources in the recent past. The fact that 70% of the arable area of India is rainfed with precarious supply of water and that rainfed agriculture supports 44% of India’ s human population and contributes 90 per cent of coarse cereals and pulses, 80 per cent of oilseeds and 65 per cent of cotton and growing realization that further gains i n productivity of crops and livestock will emanate from rainfed regions, leave no room for complacency in this regard.

Year after year, the fate of a vast ‘majority of Indian farmers hangs in balance, as success with rainfed agriculture continues to be a gamble. It is evident that crop yields in semi-arid areas depended more on rainfall distribution than on total rainfall and lack of serious efforts to create d water supply for crops through scientific management of rainwater is a factor favouring this avoidable uncertainty. In rainfed agriculture no other input can perhaps enhance the yield without effectively tackling of the rainfall aberration related sub-optimal moisture availability. Therefore a prerequisite for substantial improvement in the agriculture production in the semi-arid region is to manage runoff water and to use it either at the time of moisture stress even during the monsoon or in next season. It has been reported that only one supplementary irrigation at proper stage can double of Rabi crops. But supplemental water is a developed resource and is more expensive than the natural resources. Hence, it is all the more necessary to use this water judiciously and efficiently. Standardization of techniques by which as much of precipitation as possible can be conserved for crop use, either directly in the soil profile through infiltration or through runoff collection and recycling is an area of priority in research.

Introduction

Water is not only a vital environmental factor to all forms of life, but it has also a great role to play in socio-economic development of human population. Since antiquity humans have valued the importance of clean water and have used various techniques to improve its quality. In modern times, the safe drinking water became first a public health issue and then a human rights issue. The access to safe drinkin gwater now considered as a basic human right which is an essential component of effective policy for health protection. Improving access to safe drinking-water can result in tangible as well as intangible benefits to health. It has been shown that investments in water supply and sanitation can yield a net economic benefit, because the reductions in adverse health effects and healthcare costs outweigh the costs of undertaking the interventions (WHO, 2017). Past experiences have also proved that interventions in improving access to safe water favour the poor in particular, whether in rural or urban areas, and can be an effective part of poverty alleviation strategies. The disparity in water availability, reliability, and quality between the developed world and developing countries is enormous. Unfortunately, in many developing countries people lack access to safe water and therefore waterborne diseases are still a major cause of death, especially among children under age of 5. According to a joint report by World Health Organization (WHO) and United Nations International Children’s Emergency Fund (UNICEF) (WHO/UNICEF report 2017), around 2.1 billion people worldwide lack access to safe and readily available water at home, and around 4.5 billion, lack safely managed sanitation facilities. Moreover, many of these countries that have set drinking water standards often lack the resources to implement or enforce them.

Principle: To determine water in soluble solids, a known quantity of sample is boiled in water and the insoluble material is collected on a weighed filter paper. The insoluble mass is then washed with hot water and dried in oven.

10.1 Introduction

Irrigation is an age old practice. It has been practiced for thousands of years. It is chiefly used to irrigate rice in wetter areas; especially in Asian countries and dry land crops including vegetables and fruits in dry land areas having low rainfall in all most all countries. Devices for irrigation water lifting range from age old indigenous water lifts to highly efficient pump. Unlike canal irrigation where water is fed to the fields through gravity system, water from the surface and sub-surface sources is lifted either mechanically by pump or manually by any indigenous lifting devices. Irrigation by lifting water from a lower level to a higher level is called as lift irrigation. Several types of indigenous water lifting devices are in vogue in India since ancient times. These are animal or/and manually operated ones, the animal operated ones being more efficient than the manually operated ones. The earliest water lifts were simple man-powered devices, many of which are still being used with modifications in different forms. With gradual improvement, principles of simple machines, like the liver, pulley, screw etc. were employed in smooth lifting of water from surface and sub-surface sources. The selection of a suitable water lifting device for a particular situation depends on the following factors:

(i) Characteristics of source of water and the lifting device

(ii) Amount of water to be lifted

(iii) Depth of water table

(iv) Type and amount of power available and

(v) Economic status of the farmers.

Q. 1 A submersible pump may be
(A) Single stage pump       (B) Multi stage pump
(C) Centrifugal pump         (D) Both (A) and (B)

26.1. What?

These devices are used to lift water to a height that allows access to water. Lifting devices can be used to lift groundwater, rainwater stored in an underground reservoir and river water. For agricultural use, water is lifted either from a borewell or open well to irrigate the crops. According to power sources, lifting of water can be accomplished either manually or by animal or electricity sources of power.

26.2. Human-powered devices

Man has a limited physical power output, which may be in the range of 0.08 to 0.1 hp. This power can be used to lift water from shallow depths for irrigation. These include swing basket, counterpoise lift, don, Archimedean screw and paddle wheel. However, nowadays these are not commonly used.

26.3. Animal-powered devices

Animal power is abundantly available in India. They are used to lift water, besides being put to use for other field operations and processing works. A pair of bullocks may develop approximately 0.80 horsepower. They can lift water from a depth of 30m or more. Of course, the rate of discharge will go down with increase in the lift. These include rope and bucket lift, self emptying bucket, two bucket lift, Persian wheel and chain pump.

Abstract: Water lily, bulbous ornamental, constitute element of aquatic gardens. A variety of flower colour, flower forms, modes of reproduction and leaf sizes exist in Nymphaea. This species is a complex hybrid group. A wide range of polyploidy (including aneuploidy, trisomy, polysomaty), polymorphism and heterozygosity exists within the cultivars of water lily. Genetic information and trait heritability is almost unknown for this crop. Breeders have created synthetic water lily hybrids. Low fecundity, limited fertility, reproductive barriers, low seed set, relatively low elemental (founding) species among elite germplasm often pose significant challenges to flower breeders. Breeding objectives with high priority include tolerance to drought, year round flowering and lower seed tannins. Future breeding and genetic studies are needed to further transform this crop.

Keywords: Nymphaea, correlation, sterility, interspecific hybridization polyploidy.

Water lily is an important aquatic ornamental flower crop valued for its attractive flowers, cultural significance and use in water gardens, ponds and decorative landscapes. Different flower colours and forms provide considerable ornamental diversity, while flowers also have importance in religious and ceremonial activities. The chapter introduces water lily through its botanical characteristics, origin, distribution, genetics and important varieties. It discusses the environmental conditions required for successful cultivation, including suitable water bodies, soil and temperature conditions. Propagation, planting, nutrient management, irrigation and routine cultural operations are described. The chapter also covers pest and disease management, flower harvesting, postharvest handling, yield and commercial possibilities associated with water-lily production.

Submerged soils/Flooded soil

Submerged soils are the type of soils that are saturated with water for a sufficiently long time in a year. This gives the soil the following distinctive gley horizons resulting from oxidation-reduction processes:

The soil is intermittently saturated with water, oxidation of organic matter is slow and it accumulated within the “A” horizon. Fe and Mn are deposited as rusty mottles or streaks if the diffusion of O2 into the soil is slow in the second horizon, whereas if the diffusion is rapid, they are deposited as concretions.

Types of submerged soils

1. Waterlogged soils- Waterlogged soils are saturated with water for a sufficiently long time annually to give the soil the distinctive gley horizons resulting from oxidation-reduction processes. Saturation with water may be due to impermeability of the soil material, or the presence of an impervious layer, or a high water table.

2. Marsh Soils- These types of soils are more or less permanently saturated or submerged. Freshwater marshes can be classified according to their origin into upland, lowland, and transitional. Upland marshes are poor in bases and have pH 3.5-4.5 because they receive mainly rainwater. Lowland marshes are saturated or submerged with water-carrying bases and have pH 5.0-6.0.

16.1 Water logging

For optimum growth and yield of field crops, proper balance between soil air and soil moisture is quite essential. Except rice many of the cultivated plants cannot withstand excess water in the soil. The ideal condition is that moisture and air occupy the pore spaces in equal proportions. When the soil contains excess water than that can be accommodated in the pore spaces it is said the field is water logged.

Causes of water logging

1. Excessive use of water when the water is available in abundance or cheaply due to the belief that more water contributes better yield.

2. Improper selection of irrigation methods

3. Percolation and seepage from lands canals and reservoir located at nearby elevated places

4. Improper lay out and lack of outlets

5. Presence of impervious layer with profile impeding percolation

6. Upward rise of water from shallow ground water table or aquifer.

Water Scarcity Issues
The world is running out of clean water. The subsurface water table decreases and surface runoff rises as a result of deforestation. The amount of water stored underground is decreasing as wells are being dug deeper and deeper. As a result of desertification and deforestation, perennial rivers are turning seasonal. There is not enough potable drinking water because of abuse and overuse.
Conserving Water
• In certain situations, manipulating plants, harvesting water, and other techniques might increase the availability of water supplies.
• Water use reduction achieved by the application of water efficiency or conservation techniques; alternatively,
• Better techniques for managing water can either decrease or increase the useful use of water.
• Any activity, behavioral modification, tool, technology, or better design or procedure used to lower water loss, waste, or use is referred to as a water conservation method.
• One method of conserving water is water efficiency.
Among the Objectives of Water Conservation Initiatives
• The goal of sustainability is to guarantee that water extracted from an ecosystem will not be lost faster than it naturally replaces itself for future generations.
• The pumping, delivering, and treating of water results in energy conservation.
• Habitat conservation includes limiting the amount of water used by humans, which lessens the need to construct new dams and other water diversion infrastructure while also preserving freshwater habitats for nearby species and migratory waterflow.

Soil, climate and water decide the nature of crop to be grown in a particular region. While soil and climate can be manipulated to certain extent, there is no substitute of water. Water is governed by the hydrological cycle. The major source of water is rainfall which has been reduced over the years due to climate change. The per capita water availability in India was 4944 m3 in 1955 which has been reduced to 1750 m³ now and is expected to come down to 1500 m³ by 2025.

Introduction

The climatic elements such as solar radiation, temperature, precipitation, humidity, evaporation, evapotranspiration and wind velocity affect growth and development of saplings. These climatic factors are not favourable for successful propagation of various horticultural crops in arid region. The main climatic features of Indian hot arid agro-ecosystem is high wind speed, sand storm and high temperature during summers up to 48-50oC  and during winter season temperature falls to the 2-3^°C, low atmospheric humidity i.e. 20-30% during maximum period of the year. Moreover the relative humidity goes down to below 10 per cent during summer months.

Abstract

In the emerging era of wide spread use of IT tools, up-to-date information on water resources is the key to support economic development, conserve the nature as well as to improve the quality of life. Due to rapid rise in population  and food demand, growing economy and improving living standards; the pressure on our water resources is increasing and it will become scarce in the coming decades if not managed at this stage in a integrated way. Water resources management requires a multi-disciplinary approach that combines a collection of technical tools and expertise along with stakeholders of diverse interests and priorities in planning and management and an operational water resources information system at national level is the first requirement.

When rocks and minerals under go weathering process large quantities of soluble salts are formed. In humid regions these salts are washed down to the ground water and to the sea. But in arid and semi arid regions they accumulate in the soil. Excessive irrigation and poor water management are the two chief causes of water logging and salt accumulation. An accumulation of salts in soil leads to unfavourable soil water-air relationship and effect the crop production.

The following are the main causes which leads to development of salty soils (salinity or alkalinity)

Water is a critical input for agricultural production and plays an important role in sustainable agriculture and food security. Agriculture is the principal user of water, accounting for around 70% of total withdrawals. Producing each calorie of food requires approximately one litre of water.

Increasing population, declining natural resources, changing climate and political stability are the major threat to our food, nutritional as well as environmental security. It is expected that India’s population will boom to 1.5 billion by 2030 and to feed them we need approximately 341mt food grain including 315 mt cereals and 26mt pulses) (Kumar et al., 2016).

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.

Relationship Between Plant and Water

Water is the most vital component of the living cells and the basis of plant feeding. Water is also characterized with extraordinary physical properties: it has high specific heat, biggest latent heat of vaporization, very high thermal conductivity and greatest surface tension. Large amounts of heat are tied up with water because of very high specific heat, which contribute to both climatic stability and to heat budgets of the plants and other organisms. Water molecules are integral part of living systems being the solvent for metabolites and structural component of proteins and nucleic acids. In fact, biological macro-molecules cannot exist in their complicated secondary folding or spiralled helixes without the support of hydrogen bonding within their water matrix. The water matrix is also critical for metabolic activity because its properties of hydration permit ready reactivity between molecules in solution as well as between enzymes and their substrates, and the biochemical processes are sensitive to tissue hydration. A reduction of only 20-25 per cent below maximum hydration is sufficient to cause metabolic malfunctioning of many enzymes. It is the substrate for photosynthesis and a product of respiration. Water also helps to buffer plant tissue against fluctuations in the external environment. Plant growth including leaf expansion, organ enlargement, reproductive development and stomata function are all clearly associated with moisture status. Hormonal changes (abscisic acid and cytokinins) in plant body occur with brief reduction in water potential. Water is the also major force in shaping the climatic patterns.

Water management in agriculture is a critical component of ensuring sustainable food production and environmental conservation. This article explores various strategies for conserving water in agricultural practices, examining both traditional methods and modern technological innovations. It addresses the challenges posed by climate change, population growth, and resource scarcity, highlighting the importance of efficient water use. Key strategies discussed include irrigation optimization, soil moisture management, rainwater harvesting, and the adoption of drought-resistant crops. The article also considers policy measures and community-based approaches that support water conservation. By implementing these strategies, the agricultural sector can contribute to sustainable water management and enhance food security.

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.

1.0 Introduction

Population in dry lands of the world is increasing; more fresh water is required in order to meet the growing demands. To meet this challenging situation developing new technologies for identification of potential sites for rainwater harvesting (RWH) is an important step towards maximizing water availability in semi-arid areas.

Water is a critical input for crop production. Its optimum availability is important in augmenting and sustaining crop productivity. Lack of adequate supply of water can limit crop yields ranging from 10 to 90% or even be subjected to mortality if moisture go below permanent wilting point. It is also observed that the moisture shortage during some critical crop growth stages would cause severe detrimental effect. This necessitates us to provide irrigation to crops at right quantity and frequency. In other words, irrigation schedule plays key role in optimizing or maximizing crop yield. Moreover, judicious use of irrigation water has potential to enhance the agricultural productivity which in turn would lead to food security. As water resources are getting diminished day by day, the application of water saving techniques would be needed for addressing the food security objectives of the nation.

Irrigation is one facet of the inputs which need to be carefully managed so that profits are maximized. Irrigation plays a major role in any agriculture crop production. One should be aware of different types of irrigation adapted in orchards or crop cultivation to become a successful grower. Irrigation is very important component of crop cultivation as sufficient moisture must be maintained in the soil for obtaining the optimum growth and good quality yield. The aim of irrigating a plant should be to wet the entire root zone without allowing any wastage of water beyond the root zone.

Irrigation is one facet of the inputs which need to be carefully managed so that profits are maximized. Irrigation plays a major role in any agriculture crop production. One should be aware of different types of irrigation adapted in orchards or crop cultivation to become a successful grower. Irrigation is very important component of crop cultivation as sufficient moisture must be maintained in the soil for obtaining the optimum growth and good quality yield. The aim of irrigating a plant should be to wet the entire root zone without allowing any wastage of water beyond the root zone. The irrigation systems have to be properly devised so that the water requirements of the trees are met at the minimum expenditure without any wastage of water. Irrigation practices can be improved if a range of important factors like crop type, crop water requirements, climatic conditions, soil type, water quality, method of irrigation are taken into account.

Crop type

The type of horticultural crops grown influences irrigation practices. Annual vegetable and melon crops have high water requirement, hence irrigation management is extremely critical to their productivity during their relatively short life span (10-20 weeks). Perennial fruit crops tend to require less water and management, although critical, is not generally as critical as for annual crops.

Pulses can be grouped into kharif and rabi pulses according to their temperature requirements. In India chick pea, pea, lentil and beans require relatively less temperature and are grown in rabi season, whereas others are confined to kharif season. However, kharif pulses can also be grown in pre-rabi on stored soil moisture or as irrigated crops in rabi and summer seasons.

Pulse crops have long tap root system which extracts soil moisture from deeper layers. Water uptake across the depth of rooting zone is not uniform. In general 40 per cent of the total water uptake occurs from first one fourth of the rooting zone, 30 per cent from the second, 20 per cent from the third and remaining 10 per cent from the last one-fourth region of total rooting depth (Nageshwararao and Writ, 1994). Plants often maintain higher root length densities than required in the surface layers to facilitate rapid uptake of recent rain/irrigation before it evaporates.

India is a major exporter of vegetables with 10th position in the world. In the past, the Dexport of Indian vegetables was restricted to potatoes and fresh onions, however, now, the Government of India finds great opportunities for expanding exports of several vegetables including lettuce, fresh peppers, tomatoes, squashes, gherkins, etc. Under World Trade Organization (WTO) regime, the development of stronger seed industry and improved production technology will give India a competitive edge in global market. New opportunities and challenges are emerging every day in the dynamic and global vegetable-based industries. However, such opportunities can be harnessed only if assured quality, in terms of organic farming and reduced pesticide residues, is maintained (Shanmugasundaram, 2004).

Introduction
Surface irrigation is the distribution of water using open canals in which water flows by gravity. This type of irrigation, which includes flood irrigation, requires relatively flat fields and deep soils.
A good irrigation will ensure a uniform and homogenous distribution of water in small and regular doses. The status of moisture in the soil also aims at maintaining the relative humidity in a plot at a stable level, to limit the development of weeds and pathogens. Irrigation is also used to avoid the transmission of phyto-sanitary problems or the leaching of pesticides.
The volumes of water to apply depend on the climatic conditions, the frequencies of the applications, the soil type and the irrigation method. The choice must take into account the efficiency of each method, the water availability, the installation and running costs, the maintenance needs, the spatial requirements and whether it’s possible to work while the field is irrigated.
Water Management Practices of Different Crops Rice
Total water requirement is 1100-1250
The daily consumptive use of rice varies from 6-10 mm and total water is ranges from 1100 to 1250 mm depending upon the agro climatic situation. Of

17.1 Rice

Rice culture at present dominates irrigated agriculture. About 64% of the irrigation water resources in Andhra Pradesh are used for cultivation of rice. An adequate water supply is one of the most important factors in rice production. In many parts of India including Andhra Pradesh rice plants suffer from either too much or too little water because of irregular rainfall and land topography.

Percolation losses in rice fields

Percolation losses are a function of the local soil and topographic conditions. Therefore, at any time the amount of rainfall or irrigation water entering the soil becomes greater than its water holding capacity, losses by downward movement of free water (vertical percolation) will occur. Percolation is often defined as the movement of water through saturated soils due to gravity, hydrostatic pressure or both.

Thus where the soil is heavy and the water table is close to the soil surface, percolation losses are low, about 1 – 2 mm/day. On the other hand, where the soil is light and the water table is deep, percolation losses may be high, about 8 – 15 mm/day, or more. About 50 to 60% of applied water to rice is lost by deep percolation. The percolation losses can be reduced by adopting following agronomic practices:

4.1. Introduction

Globally, rice is cultivated on about 165 million ha of land, which provides around 787 million tons of paddy annually (FAO, 2023). In Asia, 708 million tons of paddy is produced from nearly 143 million rice-cultivated areas. Rice crop is grown in a wide range of climates, varied soil types, and hydrological situations. Rice is the lone cereal crop that grows well in floods.

The rice habitat can be divided into four groups based on the hydrology of the rice field: irrigated lowland rice (79~80 million ha), rainfed lowland rice (54~55 million ha), upland rice (14~15 million ha), and flood-prone rice (11~12 million ha) (Table 4.1) (Bouman et al., 2006).

5.1. Introduction

Rice-fallows are a rainfed rice mono-crop production system, where only a single crop (rice) is grown and these lands remain without any crop for the rest of the period of the year (fallow). An estimate shows that rice-fallow areas extended over 22.3 M ha in South Asia, maximum in India ( 88.3%) followed by Bangladesh (8.7%), Nepal (1.4%), Sri Lanka (1.1%), Pakistan (0.5%), and Bhutan (0.02%) (Gumma et al., 2016). The eastern part of India accounts for ~ 84% (9.7 million ha) of the country’s total rice-fallow area (i.e. 11.7 million ha) (Ali et al., 2014; Singh et al., 2017), despite high rainfall during rainy / monsoon season. The reasons are that after the rainy season, irrigation facilities are lacking, very fast depletion of the soil residual moisture due to temperature rise, the poor economic condition of the farmers, and a lack of awareness or knowledge of available technologies. Additionally, delayed harvesting of long-duration rice (150-160 days) results in late sowing of winter crops, which, in turn, exacerbates the temperature and moisture stresses in winter crops (Kumar et al., 2018a; 2018b). Overall, the challenges of growing another crop in rice-fallow areas are the lack of irrigation facilities including declining groundwater levels, the dominance of the long-duration rice varieties cultivation, higher evaporative loss of the residual soil moisture, degradation of soil quality, and poor financial conditions of the farming community with diminishing profit. Recently, climate change with erratic rainfall and delayed monsoon arrival added more challenges for these areas in several places. Deficit soil moisture imposes stress on the crops and negatively affects the winter crops productivity in the rice-fallow system, and several times it results in complete crop failure (Singh et al., 2012; Ghosh et al., 2016).

Agricultural water consumes about 85% of the available water. The future hopes to solve world’s food problem lies in irrigation development. Considering the need of efficient management of water, which is crucial at this point understanding of different efficiencies of the irrigation related experiments or projects, is necessary. Irrigation efficiency is used to evaluate how effectively the available water is used in crop production. Water is conveyed through canal system, watercourses and channels to crop fields. Irrigation is applied to store water in the effective root zone of soil for use of crops. A considerable loss occurs after its diversion from sources to its actual use by crops. The extent of water loss in the process decides the irrigation efficiency. Irrigation efficiency declines as the water loss increases. A high efficiency of an irrigation project is always desirable. The efficiency may be estimated for various operations beginning from diversion of water to its actual use by crops, uniformity in its distribution in the root zone, its use for crop productivity, economics and so on.

Introduction

Crop production system includes the components like soil, climate and plant (genetic) material. Within a particular genetic make up of the crop, productivity of the system is limited either by climatic factors, that is, radiation, temperature and rainfall (water), or by inherent edaphic environment that govern the root development and consequent uptake of water and nutrients. Where soils are cultivated over long periods, the edaphic conditions reach at its low levels. When water, nutrients and CO2 are plentiful, yield is determined by radiation and temperature regimes during the growing season. However, under actual field situations, the yields are limited by factors other than climate, which is water and nutrients. These are not only limited in amounts but also are becoming costlier every year. It is, therefore, important that available fertilizers be used efficiently.