eChapters

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.

Introduction
Water management is a critical aspect of agricultural science and environmental sustainability, influencing not only the efficiency of food production but also the health of ecosystems and the balance of global water resources. This chapter delves into the principles, techniques, and modern advancements in water management, emphasizing its significance in ensuring food security, conserving vital resources, and combating global warming. The chapter begins by exploring the foundational principles of irrigation, a key component of water management in agriculture. Various irrigation techniques, such as surface, sprinkler, and drip irrigation, are discussed in detail, along with the factors that influence irrigation efficiency, such as soil type, crop needs, and climatic conditions. The importance of optimizing irrigation practices to enhance water use efficiency and minimize waste is underscored. Water use efficiency and conservation strategies form the next major focus of the chapter. As global water resources face increasing pressure from population growth, industrialization, and climate change, the need for efficient water use in agriculture becomes ever more critical. The chapter discusses various methods to improve water use efficiency, including advanced irrigation technologies, crop selection, and soil management practices. Conservation strategies, such as rainwater harvesting, groundwater recharge, and the use of drought-resistant crops, are also explored. Effective drainage systems and waterlogging control are essential for maintaining soil health and agricultural productivity. The chapter provides an overview of drainage system principles, techniques for assessing soil drainage, and strategies for controlling waterlogging, a condition that can severely impact crop yields. The benefits of well-managed drainage systems, including improved soil structure, reduced salinity, and enhanced crop performance, are highlighted. Water quality and salinity management are crucial for sustaining agricultural productivity and preventing soil degradation. The chapter discusses methods for assessing water quality, the impact of salinity on soils and crops, and techniques for managing salinity, such as the use of salt-tolerant crops and soil amendments. Effective water quality management ensures that crops receive the nutrients they need while preventing harmful buildup of salts and other contaminants

Water

Water is one of the most important inputs essential for the production of crops. Plants need it continuously during their life and in huge quantities. It profoundly influences photosynthesis, respiration, absorption, translocation and utilization of mineral nutrients etc. Both its shortage and excess affects the growth and development of a plant directly and consequently its yield and quality.

Soil needs the application of water to:

Remove stress condition.

Release nutrients in the soil solution for absorption by plants.

Leach or wash out injurious salts from the soil.

Preparation of land for raising crops.

To maintain the temperature and humidity of the soil micro-climate and the activity of soil microbes at optimum level.

For the normal aeration and functioning of roots and shoots of the plants.

Excess water needs to be removed for the normal aeration and functioning of roots and shoots of the plants

Excess water creates unworkable soil condition.

Water

• Water constitutes about 35–95% of the different portion of the plants. The leaves of the plant contain 35–95% water, Roots 60–90% and Fleshy fruit contain 70–90% water.
• Water is one of the most important inputs essential for the production of crops.
• Plants need it continuously during their life and in huge quantities.
• It profoundly influences photosynthesis, respiration, absorption, translocation and utilization of mineral nutrients etc.
• Soil needs the application of water to:
• Remove stress condition.
• Release nutrients in the soil solution for absorption by plants.
• Preparation of land for raising crops.
• To maintain the temperature and humidity of the soil micro–climate and the activity of soil microbes at optimum level.

Irrigation/ Drip/ Fertigation

Pomegranate is considered to be drought hardy fruit crop. Supplemental irrigation, however, is necessary for realizing higher fruit yield and better quality. Irrigation is also used to regulate cropping in pomegranate and the total water applied therefore depends on the desired bahar. In Gujarat and Maharashtra, where Ambe bahar is taken, regular irrigation is required during March to July and irrigation is stopped after the fruit harvest until January. For Mrig bahar crop irrigation is not required from July to September. However, in case of prolonged break in monsoon one or two supplementary irrigation at an interval of 10-15 days during October to December are required. In hasta bahar (September flowering) prolonged rainy season helps in reducing requirement for irrigation 3-4 irrigation at monthly interval after cessation of rainfall are must to obtain good fruit size and higher yield.

12.1 INTRODUCTION

Water is a factor of prime importance in agriculture industry. Water management is one of the largest and most important inputs into an orchard. An efficient water management refers to artificial application of water, i.e., irrigation in crop root zones in case of soil moisture deficit and removal of water, i.e., drainage from the root zone in case of excess so as to provide the crops a most optimum soil moisture regime for best production. It means how best we are in irrigating and dewatering our fields so that plants are protected from stress as well as water logging (Goswami, 2015). Water resources are continuously overburdened with excessive drafts and water sources are shrinking at faster rate. Groundwater levels are falling at the rates faster than ever. Under this type of circumstances, judicious use of water should be given due attention for water conservation and also in increasing water productivity. Area under horticultural plantations is increasing at exponential rate. The unproductive uplands and low productive midlands and lowlands are brought under fruit based horticultural plantations. For a profitable orchard enterprise, a well-planned irrigation system and efficient water management practice are of utmost importance. Horticultural sector, which includes vegetables, f lowers and fruits, has enormous potential for development owing to varying agro-climatic conditions in India. There is tremendous scope for increase in productivity and quality of horticultural crops, which is necessary to compete in this modern competitive world market. There are many production technologies available to increase the per unit vegetable production and also to increase its quality. One of the widely acceptable, reliable and cost- effective technologies is pressurized irrigation.

Water: Water is one of the most important inputs essential for the production of crops. Plants need it continuously during their life and in huge quantities. It profoundly influences photosynthesis, respiration, absorption, translocation and utilization of mineral nutrients etc. Both its shortage and excess affects the growth and development of a plant directly and consequently its yield and quality.

Soil needs the application of water to:

•    Remove stress condition.

•    Release nutrients in the soil solution for absorption by plants.

•    Leach or wash out injurious salts from the soil.

•    Preparation of land for raising crops.

•    To maintain the temperature and humidity of the soil micro-climate and the activity of soil microbes at optimum level.

Summary
 
This chapter explores different approaches to manage water in rain-fed and irrigated agricultural systems. The first methods support the retention of water and reduce soil erosion. These methods include mulching – the application of a surface coating over the soil – which is usually organic mater. This reduces the damage to soil caused by rain and wind and reduces water loss to evaporation and helps with infiltration. The other methods explored are bunding and terracing.  These approaches are about stopping the flow of water across land to increase the amount of water infiltration into the soil and to reduce or prevent soil run off.  These approaches are labour intensive. A less labour -intensive approach is contour ploughing. This approach is about encouraging farmers and tractor drivers to plough across sloping fields not up and down them. The second group of technologies refers to the introduction of water through irrigation methods.

As water consists of two positively charged hydrogen ions and a single negatively charged oxygen ion, water is arranged as a polar molecule having positive and negative sides. This molecular polarity leads to water’s high dielectric constant (ability to withstand or balance an electric field). Water is able to dissolve many substances because the polar water molecules align to shield each ion, resisting the recombination of the ions.

Water melon is tender to frost and most of cultivars require relatively long growing season. Plant growth and fruit development are fallowed by higher temperature and abundant sunlight. Atmospheric humidity greatly regulates fruit and foliage diseases.

Taxonomy and Origin: Ealier it was classified as Citrullus Vulgaris Schrod. But in 1963 Thieret called attention to the correct name, C. lanatus (Thumb) Mansf. Africa is centre of origin of the genus. In 1857 David Living Stone, the famous missionary explorer found both bitter and sweet melons grown together in Africa and native people used them as source of water. Cultivation is prehistoric as there are pictures made in ancient Egypt. Early cultivation occurred in Mediterranean area and as far as India also and It was brought to USA by European colonist as early as 1629.

6.1 INTRODUCTION

Water in soils is essential to plant growth, being the medium through which inorganic nutrients are translocated to the root surface and carried through the plant. Most of the water in soils at or near field saturation can be considered as equivalent to bulk water, and only bulk properties need be considered in discussing its movement through soil interstices and its retention in soil capillaries; this is the field with which soil physics deals. But, in the first molecular layer in contact with soil particles, and perhaps for several molecular layers beyond, the behaviour of water molecules is very different from that in the bulk. Strong adsorptive forces can reduce the volatility of these molecules and restrict their mobility. Such an adsorbed layer of water competes with other polar molecules for adsorption sites, and so has an important role in determining the release and retention of fertilizers and pesticides. Such strongly adsorbed layers confer wettability on soils, but hydrophobic surfaces can also be present and these lead to non-wettable soils with serious consequences in run off and inefficient use of precipitation. This region of distinctive molecular interactions between water and soil particles falls within the field of soil chemistry.

Abstract

A transect was performed along the Chubut River (Patagonia) from the Atlantic towards the Andes measuring major water parameters of this drainage area. Samples were taken at different locations of the Chubut River, and also brooks several Andes lakes in the Chubut and Río Negro Provinces as well as from several Andes rivers and mountain creeks. For comparison, the Laguna Cacique Chiquichano in Trelew (Chubut) was investigated. Several physico-chemical parameters were determined (pH, oxygen, nitrogen compounds, conductivity, redox potential, water hardness and spectral transmission), as well as photosynthesis by means of PAM fluorimetry. Water toxicity was assessed with a bioassay based on toxicity-induced changes of the movement behavior of a flagellate.

ABSTRACT

Remote Sensing and Geographical Information System play major role in the water planning of river basins. Varahanadhi is one of the 17 major river basins of Tamilnadu, bounded in North by Palar basin, East by Bay of Bengal and West & South by Ponnaiyar basin. It drains through Thiruvannamalai and Villupuram districts. There are three sub basins viz., Ongur, Nallavur and Varahanadhi sub basins. From Survey of India top sheets, Basin boundary, sub basin boundary maps were generated. Administrative map with district, block boundaries was prepared. GIS software - Arc view, was utilized for this purpose. By using ERDAS IMAGINE, Digital Image processing software, satellite image mosaic of Varahanadhi Basin, Geomorphology, Land use, Wasteland, Structural-Lineament maps were generated. IRS P 6 RESOURCESAT, LISS III and PAN data were used for the thematic map preparation. From the collateral data collected, the thematic maps on Geology, Soil, and annual north east, south west. summer, winter rainfall, irrigation system, pre monsoon and post monsoon groundwater levels, ground water quality were prepared using ARC GIS Software. Relief and Drainage map were also generated in GIS environment. The surface water potential was assessed by rainfall run off method for which geomorphology map interpreted by remote sensing and GIS was utilized. Based on geomorphology and land use maps, draft for irrigation was estimated. Geology, geomorphology, depth to bedrock, rainfall pattern, water level maps were used

to asses groundwater potential and draft. Sectoral demand on power, industry and domestic were made based on collected collateral data. Environmental Impact Assessment was assessed using land use maps and ground water quality maps interpreted from remote sensing data for years 1998 and 2004 were prepared and compared. Wasteland map was prepared to know the extent of wastelands and their types as per National Waste Land Board norms. Remedial measures to convert waste lands into productive lands were also suggested. By superimposing geomorphology and lineament maps upon the wastelands, sites suitable for groundwater development in the waste lands were identified. In the same way by using GIS overlay analysis developmental and action plan maps were also prepared with technical recommendations. By applying remote sensing and GIS techniques the basin water resources assessment, draft to meet out sectoral demands and balance of water available for future use can be decided. Varaganadhi basin is a surplus basin as per the study.

Introduction
Water is chemical substance which important for all living organism to survive on this planet. Water is necessary for all cell of the living organism’s body to performance any normal work. Water covers 71% of the Earth’s surface, most like in oceans and other more water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapors, clouds and precipitation. Some observation have estimated that by 2025 more than half of the world population will be facing water-based vulnerability, a situation which has been called a ‘water crisis’ by the United Nations. A recent report suggests that by 2030, in some developing regions of the world, water desire will be exceed supply by 50%. The total volume of water 1,385 million Km3 on the planet earth, 96.5% is salt water (oceans and seas), the fresh water is mostly ice (24 million Km3). The fresh water available as annual stream flow is 46,768 Km3, that is 0.00034% of the total global water. If there is no intake of water into the body, death can ensue in 7-10 days. Water is also essential to man for maintaining personal hygienic and freedom from disease. Today there are many cities worldwide facing actual shortage of water and nearly 40 percent of the world’s food supply is grown under irrigation and a wide variety of industrial processes depends on water. Water is the most vital element among the natural resources, and is critical for the survival of all living any organisms including human, food production, and economic development. The environment, economic growth and developments are highly affected by water is regional and seasonal availability and the quality of surface and groundwater. The quality of water is affected by any human activities and is declining due to the rise of urbanization, population growth, industrial production, climate change and other factors. The resulting water pollution is a serious surrounding to the well-being of both the Earth and its population. The pressures is increasing population, growth of industries, urbanization, energy intensive life style, loss of forest cover, lack of environmental awareness, lack of implements of environmental rule, regulations and environment improvement plans, untreated effluent discharge from industries and municipalities, use of non