eChapters

Aquaculture is practiced in the majority of countries worldwide, however the significance of water quality standards remains largely unknown to farmers and new aqua entrepreneurs. They may achieve maximum fish production with minimal input costs if they are trained and stay up to date on water quality management in the aquatic ecosystem. The water quality categorised into three main of metrics as physical, chemical, and biological parameters. Dissolved oxygen (DO), biochemical oxygen demand (BOD), free carbon dioxide (CO2), pH, temperature, total dissolved solids (TDS), turbidity, ammonia, nitrite, nitrate, alkalinity, bacterial density primary productivity (chl a), plankton population, etc. play a significant role for fish production. However, even small variations in certain physical and chemical parameters—particularly pH, temperature, and dissolved oxygen (DO)—can cause stress in the animals, which may manifest as physiological changes, reduced reproductive capability, and altered behavior. Water parameters such as alkalinity and hardness are relatively stable, whereas others like pH, dissolved oxygen (DO), and temperature fluctuate regularly. Proper maintenance and monitoring of these water quality parameters in aquatic environments support fish health and enhance fish production. On the other hand, variability in dissolved ammonia, nitrites, and nutrients like nitrate significantly affects aquaculture production. It has also been observed that high feeding rates in aquafarms create eutrophic conditions in water bodies, leading to substantial algal blooms. These blooms are responsible for die-offs, and as a result, ammonia levels in the ponds rise rapidly. The environmental factors responsible for generating high ammoniacal concentrations may also lead to increased nitrite concentration in aquafarm. Both ammonia and nitrite are directly toxic or sublethal cultured aqua animals, leading to reduced resistance to diseases. In aquaculture system, ammonia is produced through the ammonification process, which occurs when organic matter is broken down by the microbial community. However, this decomposition also reduces dissolved oxygen levels in the system. Low dissolved oxygen surges the toxicity of ammonia to cultured animals. Ionized ammonia (NH4 +) and hydroxide ions occurs in equilibrium with unionized aqueous ammonia solution. The unionized form of ammonia (NH3) is toxic

The term hydrogeomorphology can be divided into three terms hydro- means water including both surface and groundwater; geo- means the earth and morphology- is the surface expression of the features in the form of landforms. This means that the hydrogeomorphology is dealing with the aspects of water, rocks and earth’s morphological features (land). Of these water and land are most important natural resources for human beings.

Water is synonymous with life. This is a natural resource and an absolute necessity for the survival of the living beings. Human beings have an organic relationship with water. For living and livelihood, human beings solely depend upon the availability of water. They have an inalienable right on water. This is a community resource and cannot be made a tradable commodity, violating normative law of nature. Water is among the most precious gifts of nature to mankind. Most of the ancient towns of the world grew on the banks of the river, and some of the ancient civilizations are known by the names of rivers. Rivers have always been important sources of drinking water and the means of sustaining human, animal and plant life. Whenever one is dealing with water resources development and utilization, it has to be kept in mind that not only quantity of water but also quality of water is very important. The well being and development of our society is dependent on the availability of water.

1.1 Importance of Water for Agriculture

All animals and plants require water for their survival. Animals cannot prepare their own food. They depend on plants for their food. Plants need water for preparation food by the process of photosynthesis. Majority of this water requirement of the crops is met from different forms of precipitation. However, when the water requirement is not fully met from precipitation, then growth of the crops is affected. Water requirement of crops depend on many factors. It depends on the type of crops, irrigation schedules practiced, soil texture, position of groundwater table below effective root zone of the crop and management practice followed in crop cultivation. The dry land crops need less water compared to rice which is a water loving crop. The perennial crops like sugarcane, banana etc. need more water than other crops like cereals, pulses, oilseeds etc. Water requirement of crops is partly met by the upward flux of groundwater. The capillary rise of shallow water table in the form of upward flux helps in meeting the water requirement of crops to some extent. The upward flux depends on the type of the soil, effective root zone depth of the crop, depth of water table below effective root zone depth of the crop and potential gradient of soil moisture suction. If the soil is heavy like clay, effective root zone depth of the crop is more (deep rooted crop) and position of ground water table is near to ground level (shallow water table), then the upward flux is more.

Due to rainfall or application of irrigation water, some amount of water is recharged to soil reservoir. This recharged water is stored in the soil as soil moisture content. The stored moisture or called as water in the soil reservoir helps in supporting water requirement of crops also. The heavy soil like clay has more moisture retention capacity than the light soils like sandy soil. The residual soil moisture held in clay soil is released slowly and supports more soil moisture to the crops for a longer period than the sandy soil which has less soil moisture retention capacity. After meeting the water requirement of crops from all sources including different forms of precipitation, ground water contribution by capillary rise and residual soil moisture, if there is any shortage of water, then this shortage should be met from other sources which are called as irrigation. It is to be noted that irrigation is not the natural phenomenon of supply of water; rather it is the artificial means of supply of water to the crops. Irrigation may, therefore, be defined as the science of artificial application of water to the crop in accordance with the crop requirement for better nourishment of the crops.

The role of plant nutrients in crop production is well established. Estimation of nutrients contents and forms in materials, which are involved in nutrient supply and dynamics is a crucial step in scientific nutrient management and crop production. There are 16 essential plant nutrients. These are carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), sulphur (S), zinc (Zn), manganese (Mn), copper (Cu), boron (B), molybdenum (Mo) and chlorine (Cl). These nutrients have to be available to the crops in quantities as required for a yield target. Any limiting or deficient nutrient (s) will limit crop growth.

Around the world, nearly one billion people live along the 3,12,000 Km long coastline. The Indian coastline runs around 8,129 Km distributed along nine coastal states, two groups of islands and two union territories. The coastal ecosystem of India forms a very valuable resource community, supporting the livelihood security of several million rural poor and also contributing the national economy in a large measure. The latest estimates by National Bureau of Soil Survey and Land Use Planning (NBSS & LUP), Nagpur, India, using Global Assessment of Soil Degradation (GLASOD) guidelines indicate that the coastal area in the country is spread over an area of 11.8 million hectares (Mishra, 2005). Yadav et al. (1983) have reported about 3.1 M ha and 2.1 lakh ha of coastal salinity in India and Tamilnadu respectively.

Plant absorbs large number of elements from the soil and other sources during their growth and development. But all these elements are not essential for plant growth. Seventeen mineral elements are known to be essential for the growth and development of all plants. A list of essential nutrients, their source and forms by which they are absorbed by plants are presented in Table 1.1.

Except carbon (C), hydrogen (H) and oxygen (O), all the other nutrients are obtained by plants largely from soils, fertilizers or manures. It has been seen that the number of nutrients obtained from soil is about 5 times the number of nutrients obtained from air and water. However, most of the plant tissue, in general, from 74 to 99.5% is made up of C, H and O i.e. nutrients obtained from air and water and only 0.5 to 26% of the plant tissue is synthesized from soil constituents. In ordinary (normal) conditions of agriculture, except drought, C, O and H are not limited for plant growth. It is the remaining 14 elements from soil that are usually limiting plant development and hence considerable emphasis is placed on the improvement of soil in respect of greater availability of these 14 nutrients. It may be borne in mind that all nutrients are essential for all crops even though their requirements differ from crop to crop and even among varieties of a given crop. Secondly, all nutrients are equally essential regardless of amounts required. For example, to produce one tonne of grain, wheat may absorb 25, 9, 33, 3.7, 5.3 and 4.7 kg of nitrogen (N), phosphorus (P), potassium (K), sulphur (S), calcium (Ca) and magnesium (Mg), respectively and 56, 624, 70, 24, 48 and 2 g of zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), boron (B) and molybdenum (Mo), respectively. If the crop (any crop) does not get the smallest amounts of micronutrients needed, it cannot make the best use of abundant NPK.

According to Liebig’s Law of minimum which he enunciated in 1855, the growth of a plant is limited by that nutrient which is in shortest supply. This law in fact lays the ground rules for balanced crop nutrition.

1.1 Background

The aftermath of Green Revolution has contributed to both coercions and pollution, albeit, it saved human civilization from hunger, malnutrition and impoverishment. The beginning of GR era, with the prevailing objective and condition, has got less but few choices to go for intensive cultivation that invited chemical fertilizer, assured irrigation and farm mechanizations to make the 'magic gene' revolutionizing the production, productivity and livelihood security in agriculture as well.

The welcome of exotic genes into Indian agriculture has also triggered the silent oftraditional cultivars. Nevertheless, the quantum jump of an agriculture with a production of 55 million tons to 120 million tons during 70s, has contributed to make India self-reliant in food and we have been able to earn a new esteem in the global geo-political scenario by throwing away the 'begging bowl' called PL480.

India is an agriculture based country which is one of the few developing countries in the world. It successfully achieved Green Revolution during the late 1960s (1967-68). At present, agriculture is a principal means of livelihood for over 58.4 per cent of Indiaís population directly or indirectly (Anonymous, 2011). It is worthwhile to mention that although agriculture continued to be the mainstay of the Indian economy previously (Anonymous, 2010b) yet now its share in the Indian economy is declining year after year (Anonymous 2013d). After Independence, agricultureís sector contribution to GDP swings between 50-60 per cent. Even in 1950-51, it was 55.1 per cent, but fell to mere 17-18 per cent in 2008-09 (Mahajan and Gupta, 2009).

1.0 Overview

Natural resources sustain life and are critical for economic development of nations. In developing countries like India where more than half the population is rural, economic development is inextricably linked with agricultural development. In these countries, the food and livelihoods security of the poor are critically associated with access to the services provided by the natural resources - land, soil, water, biodiversity and climate resources. The natural resources are finite, and with increasing population, economic growth, urbanization, and demands for food and other agricultural commodities, these are being increasingly strained. As a result, the productive capacity of the natural resource base is shrinking and deteriorating. Sustaining the productive capacity of natural resources for future generations, while meeting the food and other demands of the growing populations, is the major development challenge of the twenty first century.

In India, during the last forty years the net sown area under agriculture has remained nearly constant at 141 million ha. In the same period, the population has more than doubled (from 541 million in 1970 to 1186 million in 2010) and per capita income grew by more than 3.5 times (from Rs 14824 in 1970 to Rs 53331 in 2010). As available land resources for agriculture are finite, increases in agricultural production to meet the growing demands of the population have to come from intensification of agriculture on the same lands. As a result, the quality of soils on these lands is gradually deteriorating both at the farm and ecosystem levels. The major threats to soil quality come from loss of organic carbon, erosion, nutrient imbalance, compaction, salinization, water-logging, decline in soil bio-diversity, urbanization, and contamination with heavy metals. More than 100 million ha of the total cultivated land of 141 million ha is stated to be under some form of soil degradation.

Similarly, utilizable fresh water resources of India are finite at about 1123 billion cubic meters (BSM), of which about 690 BCM are from surface water resources and 433 BCM are from groundwater. This supply is shared among multiple uses: human and animal consumption, agriculture, urban uses, industry and for provision of environmental services. The total water demand in 2010 is estimated at 710 BCM and is projected to increase to 1180 BCM by 2050. Several parts of India are already facing severe water shortages as a result of the growing demand for water. The quality of water resources is also impacted by agricultural intensification and development, and is increasingly a matter of concern. By the year 2050, when population is expected to stabilize, the shortages will only intensify. The country as whole can be on the verge of becoming a water scarce country, with nearly all the presently estimated utilizable water resources being put to use.

Biodiversity natural resources refer to the abundance of different species and ecosystems in nature. These resources are the primary sources of present and future productive agriculture and human well being, as they provide the basic resources for use in breeding crops and livestock, soil formation and structure, soil fertility, nutrient cycling and the provision of water services. India is among the 12 mega diversity regions of the world. It is known to have more than 18,000 species of higher plants including, 160 major and minor crop species and 325 of their wild relatives. Increasing pressure from human population growth, agricultural intensification, urbanization, pollution and degradation of land, soil and water resources are having a negative impact on the plant, animal and microbial biodiversity resources of the country and their productivity.

Soil acidity is a major constraint for crop production. The production of acid in soils is a natural process, especially in the high rainfall areas. The removal of basic cations especially Ca and Mg, by leaching and erosion results in their replacement by acidic cations, H, Al and Fe on cation exchange sites and in the soil solution, which are in dynamic equilibrium with each other. Soils, that develop from weathered granite are likely to be more acidic than those developed from shale or limestone. Organic matter decay produces H+ in soils, which also contribute to soil acidity. Intensive cropping and use of hybrid & high yielding crop varieties remove large quantities of basic elements essential for their growth i.e. Ca, Mg and K & deplete the soils. Rate of acidification is also accelerated by  faulty fertilizer (especially Nitrogen) management practices.

Throughout history, humanity has been locked in a perpetual struggle with the forces of nature, and one of the most insidious and destructive of these forces is drought. A creeping disaster that seeps into the very fabric of communities, drought leaves behind a trail of devastation and despair, testing the resilience of societies and pushing the boundaries of human endurance. From the ancient civilizations of Mesopotamia to modern-day cities, droughts have ravaged the landscape, claiming lives, destroying livelihoods, and reshaping the course of human history. • The impact of drought is far-reaching and multifaceted, affecting not just the environment, but also the economy, health, and overall wellbeing of individuals and communities. Crops wither and die, livestock perish, and entire ecosystems are disrupted, leading to food and water shortages that can have catastrophic consequences. The economic toll of drought can be equally devastating, as agriculture, industry, and tourism is severely impacted, leading to widespread unemployment and poverty. • What makes droughts particularly pernicious is their ability to unfold slowly, their effects accumulating over time,

13.1 Exchange Capacity

Soil colloidal particles carry both negative and positive charges on their surface which attract and hold equivalent amount of oppositely charged ions to their surface. The total number of negative charges present on a given mass of soil or capacity of a given mass of soil to exchange cations or total number of cation held by a given mass of soil is termed as cation exchange capacity (CEC). Similarly, the capacity of a soil to retain anions is known as anion exchange capacity (AEC). The ion exchange capacity of a soil depends upon the type and amount of colloidal particle (clay and organic matter) present in the soil. Ion exchange capacity (CEC / AEC) is expressed as milliequivalent ion (cation / anion, respectively) per 100 g of soil (meq / 100g). It is also expressed as centimoles of charge (positive / negative) per kg of soil [cmol (±) / kg]. Meq / 100g = cmol (±) / kg of soil.

Cation Exchange of Clay Minerals in Soil

The term “clay mineral” refers to phyllosilicate minerals and to minerals which impart plasticity to clay and which harden upon drying or firing. Clay minerals are layer silicates that are formed usually as products of chemical weathering of other silicate minerals at the earth’s surface. Clay minerals in soil play a significant role in exchanging cations, which are positively charged ions, and in regulating soil fertility and nutrient availability. Cation exchange capacity (CEC) is a measure of a soil’s ability to exchange cations and is influenced by the type, abundance, and charge properties of clay minerals in the soil. Clay minerals have a high CEC due to the presence of charged surfaces (silanol and alumoxane groups) that can exchange cations with the soil solution. The most common cations exchanged by clay minerals are hydrogen (H+), calcium (Ca2+), magnesium (Mg2+), potassium (K+), and sodium (Na+). When a soil solution comes into contact with clay minerals, cations in the soil solution are adsorbed or attracted to the charged surfaces of the clay particles.

8.1. What is an ion exchange reaction and its application in soil system

Ion exchange is a reversible chemical reaction between two substances, either between two electrolytes or between an electrolyte solution and a solid complex as well as between two solid phases (if in close contact with each other), where ions of equal charge may be interchanged in equivalent proportion.

Organic colloids and inorganic micelles (clays) are sites of ion exchange. Soil contains silicate clay minerals which exhibit charges due to isomorphous substitution as well as due to the pH dependant charges for ionisation of hydrogen and hydroxide functional groups. Organic matter present in soil also contributes to the pH dependent charges due to the presence of various active functional groups. Thus, the organic and inorganic colloids present in soil bear positive or negative charges. Electric charge on soil particles is neutralized by equivalent amount of oppositely charged exchangeable counter ions, held by coulomb forces and van der Waals forces. Ca⁺², Mg⁺², H⁺, K⁺, Na⁺, NH₄ ⁺, Al⁺³, Fe⁺³, Fe⁺², Mn⁺², etc. are the common cations present in soil where Ca⁺² serves as the dominant ion. However, Na⁺ and Al(OH)₂ ⁺ are the dominant cations found in the exchangeable phase in strong alkali and strong acid soils, respectively. SO₄ ^- 2, Cl^-, HCO₃ ^-1, NO₃ ^- etc. are the most common anions found in soil to neutralize positively charged soil colloids.

Artificial brainpower (Artificial Intelligence) is quite possibly of the quickest developing innovation in this cutting edge world. Artificial intelligence is presently broadly utilized in different enterprises going from the improvement of mechanical technology to the observing of natural issues. Computer based intelligence innovation has evident extensions in medical services gadgets, self driving vehicles, satellite imaging, scene planning, Climate change checking, also medical services frameworks. Artificial intelligence has heightened the improvement of mechanical technology across the globe that has made the life very simpler and added to a greatly improved existence of prosperity. Artificial intelligence interceded robot of a few areas including farming will create great quality items with more positive effects on Climate. Artificial intelligence utilizes various Smart sensors that cycle information progressively with higher precision. Consequently, Artificial intelligence has upgraded the presentation of any gadget to a few folds with more prominent reasonableness and Precision in their results. Computer based intelligence with Smart sensors has lead to the improvement of a cutting edge innovation called as Internet of Things (IoT). IoT is center of remote frameworks and Artificial intelligence manages information progressively and creates suitable results. This innovation has been taken on in pretty much every area of science and examination. IoT based advanced advancements can possibly create inventive models for improved creation of buyer items including agro-items.
Agriculture is fundamental piece of people local area. It is overhauled with time to increment rural production. Present day advancements has additionally been utilized in farming, agriculture, also ranger service for better observing of plant development, sicknesses, and bug populace. Artificial intelligence and IoT have various expanding extensions in farming to settle different issues such as soil conditions, Climate status, bother discovery, assurance of collecting time, etc. Likewise computer based intelligence and IoT offers fantastic extensions for continuous observation of temperature, dampness, contamination, soil quality, water content, radiation, and others. Brilliant

Iron Toxic Soils

Lowland rice is being cultivated on approximately 128 million hectares of either irrigated or rainfed land out of which 100 million hectares suffer due to nutrient deficiency or toxicities. Among the toxicities, iron toxicity is well recognized as a nutritional disorder in low land rice production. Iron toxicity is a syndrome of disorder associated with high concentration of Fe²⁺ in soil solution. A wide range of soil types show iron toxicity problem including acid sulphate soils, acid clay soils, peat soil and valley bottom soil. During monsoon rains in the wet season, soluble iron (Fe²⁺) migrate to the surface and its iron content increases to subtoxic or toxic levels.

In rolling topography and with heavy monsoon downpour there is considerable lateral flow of iron containing water from the adjacent uplands to mid – and low lands. This increases the iron content to toxic levels. Poorly drained sandy soils in valleys receiving interflow water from adjacent uplands with laterite horizon (Plinthudults) showed iron toxicity in Srilanka and Kerala and Odisha in India. These soil groups come under the taxonomic orders Alfisols, Ultisols and Oxisols occurring in association with Entisols and Inceptisols. The iron concentration (Fe²⁺) in soil solution that affect low land rice yield ranges from 10 to > 2000 mg L^-1 Iron toxicity induced yield reduction which is associated with poor nutrients . status (deficiency of P, K and Zn) and H₂S toxicities.

Water is one of the most critical resources in horticultural production, directly influencing plant growth, flowering, fruit development, and quality. This chapter introduces principles of irrigation scheduling, water requirements, soil–water relationships, and efficient water application. Surface, sprinkler, drip, micro-irrigation, fertigation, and other modern systems are discussed in relation to crop type and environmental conditions. The chapter emphasizes irrigation efficiency, root-zone moisture management, water quality, salinity, drainage, and conservation. Proper irrigation scheduling reduces water losses and prevents both drought stress and excessive wetness. Modern technologies such as sensors, automated irrigation, and precision fertigation are also considered important tools for sustainable horticultural water management.

1.1 Introduction

Like animals, plants are living beings and so require water and air for their survival. In addition, they need water for preparation of food by the process of photosynthesis. Majority of this water requirement of the crops is met from different forms of precipitation. However, when the water requirement is not fully met from precipitation, then growth of the crops is affected. This results in reduction of yield of the crops. The reduction in yield depends on the amount of scarcity of water requirement of the crops. It also depends on the stage of crop growth and also depends on the types of the crops. Generally all the crops are sensitive to water stress during reproductive stage. Water requirement of crops depend on many factors. It depends on the type of crops, irrigation schedules practiced, soil texture, position of groundwater table below effective root zone of the crop and management practice followed in crop cultivation. The pulses, oilseeds, vegetables etc. which are also otherwise termed as dry land crops need less water compared to rice which is a water loving crops and perennial crops like sugarcane, banana etc.

Water requirement of crops is partly met by the upward flux of groundwater. The capillary rise of shallow water table in the form of upward flux helps in meeting the water requirement of crops to some extent. The upward flux depends on the type of the soil, effective root zone depth of the crop, depth of water table below effective root zone depth of the crop and potential gradient of soil moisture suction. If the soil is heavy like clay, effective root zone depth of the crop is more (deep rooted crop) and position of ground water table is near to ground level (shallow water table), then the upward flux is more.

An efficient irrigation system implies effective transfer of water from the source to the filled with minimum possible loss. The objective of the efficiency concept is to identify the nature of water loss and to decide the type of improvements in the system.

Evaluation of performance in terms of efficiency is prerequisite for proper use of irrigation water.

3.1 Introduction
Irrigation efficiency evaluates how effectively the water has been distributed for the purpose of crop production. Water is conveyed to crop field through canal water courses and channels. During this process considerable amounts of water get lost through run off, deep percolation, evaporation, etc. The losses of water greatly depend on the skill of the irrigator, degree of land preparation, and design and planning of the system. The extent of water losses starting to diversion of water from its source to crop field though conveyance and ultimate application and distribution of water in crop field which can be estimated separately. The estimation of these efficiencies enables one to identify the step(s) where improvement is required. The method of measurement and evaluation for its efficiency is prerequisite for proper use of water. Irrigation efficiency in developing countries in general is poor particularly in gravity irrigation methods. However, water is become more and more scarce. Due to pressing need of it judicious and efficient management is one of the vital issues to be solved on priority basis.