eChapters

1. Introduction

1.1 Background

The historical backdrop of irrigation is rich and diverse, reflecting the ingenuity of civilizations in adapting to their environments to meet the basic human need for sustenance. Ancient cultures such as the Sumerians, Egyptians, and Chinese were pioneers in developing rudimentary irrigation systems, channeling water from rivers, and constructing canals to nourish their crops. These early practices laid the foundation for the evolution of irrigation, marking a significant transition from relying solely on rainfall to actively controlling water distribution.

8.1 Introduction

For maximization of yield of crops, it is essential to provide irrigation to crops. When either the natural sources like rainfall, dew, snowfall and other forms of precipitation or when the capillary rise of groundwater is not sufficient to meet the crop water demand, then there is need to supply irrigation. This irrigation water is a precious resource and need to be used cautiously. There are three important things need to be understood for optimum utilization of irrigation water with basic purpose to maximize the yield and returns. 

7.1 Introduction

For maximization of yield of crops, it is essential to provide irrigation to crops. When either the natural sources like rainfall, dew, snowfall and other forms of precipitation or when the capillary rise of groundwater is not sufficient to meet the crop water demand, then there is need to supply irrigation. This irrigation water is a precious resource and need to be used cautiously. There are three important things need to be understood for optimum utilization of irrigation water with basic purpose to maximize the yield and returns. These three things are:

(i) When to irrigate?

(ii) How much to irrigate? and

(iii) How to irrigate?

In fact these three things form the core concept of irrigation scheduling.

Efficient irrigation water management is essential for achieving high crop productivity while conserving limited water resources and minimizing environmental hazards. This chapter presents the principles and practices required to manage irrigation according to crop demand and soil-water conditions. It begins with how plants obtain water from soil and explains irrigation requirements, crop water requirement terminology, water-use efficiency, field water balance and the effective root zone. Crop response to water at different growth stages is considered for important crops including rice, wheat, maize, sugarcane and mustard. Different irrigation methods are described, including surface, corrugation, sub-irrigation, sprinkler and drip irrigation. The chapter provides several approaches to irrigation scheduling based on water-holding capacity, degree of water depletion, soil-water potential, evaporation pans, leaf-water potential, canopy temperature, crop water stress index and leaf reflectance. Methods for measuring irrigation water and flowing water, including water-measuring devices and current meters, are also discussed. Scheduling based on IW/CPE ratio and depletion of available soil moisture provides practical approaches for improving water-use efficiency.

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

Water Quality Parameters
Irrigation water contains impurities in varying concentration. The suitability of irrigation water mainly depends up on the amount and type of salts present in the water. The main soluble constituents are calcium, magnesium, sodium as cations and chloride, sulphate, bicarbonates as anions. The other ions present in minute quantities are boron, selenium, molybdenum and fluorine which are harmful to animals fed on plants grown with excess of these ions.
Quality of irrigation water is judged with three parameters
1. Total salt concentration
2. Sodium absorption
3. Bicarbonate and boron content.
Total Salt Concentration
Salt content of irrigation water is measured as electrical conductivity (EC). Conventionally, water containing total dissolved salts to the extent of more than 1.5m mhos /cm has been classified as saline. Saline waters are those which have sodium chloride as predominant salt. Brackish water is one that is contaminated with acid, bases, salts or organic matter, whereas saline water contains mainly dissolved salts, Based on EC irrigation water is classified as below.

Water required for irrigation of cropped land is being degraded in terms of quantity and quality due to fast increasing demand for its use. Furthermore, the soil quality and crop productivity is linked to the quality of the water available for irrigation. In general, evaluation of irrigation water quality should focus on salt content, sodium concentration, the occurrence of nutrients and trace elements, alkalinity, acidity, and hardness of the water.

Introduction

Irrigated agriculture is dependent on an adequate water supply of usable quality. The water quality used for irrigation is essential for the yield of crops, maintenance of soil productivity, and protection of the environment as well. The quality of irrigation water is defined with respect to its effect on plant growth, soil properties, soil biological equilibrium, and irrigation technology. Conceptually, water quality refers to the characteristics of a water supply that will influence its suitability for a specific use, i.e. how well the quality meets the needs of the user. Specific uses have different quality needs and one water supply is considered more acceptable (of better quality) if it produces better results or causes fewer problems than an alternative water supply. For example, good quality river water which can be used successfully for irrigation may be unacceptable for municipal use without treatment to remove its sediment load. Similarly, snowmelt water of excellent quality for municipal use may be too corrosive for industrial use without treatment to reduce its corrosion potential.

1.1 Introduction

Water scarcity is seen as a major constraint to intensify agriculture in a sustainable manner as an attempt to meet the food requirements of a rapidly growing human population. The ever-increasing human population, climate change due to increased emissions of greenhouse gases (GHGs), and intensification of agriculture, are putting severe pressure on the world’s two major non-renewable resources of soil and water, and thus pose a big challenge to produce sufficient food to meet the current food demand. The present world population of 7.3 billion people is predicted to grow to over 9 billion by 2050, with the majority of this population increase occurring in developing countries, most of which already face food shortages. A 70% increase in current agricultural productivity will be required to produce sufficient food if these human population growth predictions prove to be correct. In this context, concerted efforts are being made globally to improve the effectiveness of water which will be used for enhancing the production of irrigated crops. Additionally, efforts are also being made to improve water harvesting and water conservation in rain-fed agriculture.

The injudicious use of saline/brackish water is all too often associated with the development of soil salinity, sodicity, ion toxicity, and groundwater pollution. Because of these negative effects, it is important to have a better understanding of exactly how the quality of water influences the management of irrigated agriculture, especially in arid and semi-arid regions.

OBSERVATION

The examination of the IRS - 1A imagery under raw and the digitally enhanced modes vividly display heavy concentration of suspended sediments in certain sectors along the east coast of Tamil Nadu. Such pockets of suspended sediments are seen as long and linear bodies trending parallel to the coast to the strike length of 20 - 30 km and width of 5 - 10 km. Such Phenomenon of suspended sediments concentration are strikingly observed in two sectors. One in between Tuticorin harbour and Vaippar river mouth and the other just at the mouth of Ponnaiyar river along Cuddalore-Pondicherry coast. Both of them are observed along conspicuous (Fig.1& 2) concave coasts.

The capacity of soil to function as a vital living system, within ecosystem and land use boundaries, to sustain plant and animal production, maintain or 

enhance water and air quality, and promote plant and animal health (Doran and

Zeiss, 2000). A healthy soil may function is as follows:

• Sustain biological activity, diversity, and productivity

• Regulate, store of nutrients and cycle water and, decompose organic

matter

• Filtering and buffering, degrading, mineralizing, immobilizing, and

detoxifying organic and inorganic materials

• Inactivate toxic compounds, suppress pathogens, protect water quality,

and enhance catchment soil health.

In this chapter we will look at the Expert system which can guide and assist an individual once it is provided with the enough Knowledge to do so. Here we will discuss about expert system and its architecture with proper steps of making an expert system in any field by several tools which are available to do so. For expert systems the most important is Knowledge Engineering which is the collection of Knowledge from an expert and Engineering it in such a form that a machine could understand it.

Introduction

One of the pioneering fields of AI study is Expert Systems (ES). It is proposed by researchers in the computer science department of Stanford University. An expert system is a computer system which emulates a human expert’s decision-making skills. Expert systems are developed by reasoning through information structures, representing laws, rather than through traditional procedural code, in order to overcome complex problems.

Expert Programs use professional expertise systematically to address human expert problems. An expert is an individual with experience in a specific field. The expert has expertise or special credentials which most people do not learn or care about. An expert can solve or solve problems more effectively than people can solve. Expert System actually emulates all these qualities of expert and solve the problem in a better way and fast.

Today, Expert System (ES) is used in the fields of finance, research, engineering, technology, medicine and many others where there is a well-defined problem area. The fundamental principle is that an expert method should also define the steps to illustrate why a problem can be solved. Unless an individual can justify his reasoning for Expert System.

Introduction

In geographical location, the observations taken in proximity tend to be more alike than observations made at points that are far apart-that is, the values tend to be correlated. An area of study that takes this sort of spatial consideration into account is called geostatistics. A primary motivation for sampling is to make meaningful estimates of values at nearby positions in space and time. When values are assumed independent, the best estimate for an unmeasured point will be the mean. However, for correlated values nearby values are estimated by interpolation. The simplest interpolation scheme is a nearest neighbor estimate for which the unknown values are based on the closest measured location. Inverse distance is another sort of interpolation technique where weights are estimated based on the inverse distance squared. Kriging is a geostatistical interpolation technique that considers both the distance and the degree of variation between known data points when estimating values in unknown areas.

It makes the best use of existing knowledge by taking account of the way that a property varies in space through the variogram model. In its original formulation a kriged estimate at a place was simply a linear sum or weighted average of the data in its neighbourhood. Weights are based on the distance between the measured points, the prediction locations, and the overall spatial arrangement among the measured points. Since then kriging has been elaborated to tackle increasingly complex problems in mining, petroleum engineering, pollution control and abatement, and public health. The term is now generic, embracing several distinct kinds of kriging, both linear and non-linear.

Labile fractions of soil carbon (C) refer to the fraction of soil carbon that are easily altered by microbial activities. These fractions serve as sensitive indicators to changes in management induced soil quality and are grouped under active soil C pool. The method described by Weil et al. (2003)estimates changes in biologically active soil C using a dilute KMnO . This is an improvement over the method used by Blair et al (1995), where a very high concentration (0.333 M) of KMnO₄ was used.

Organic carbon present in soil can be very labile, labile or non-labile. This procedure measures the extent of lability of soil organic carbon through relative degree of oxidation by K₂Cr₂O₇.

2.1 Beakers

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

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

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

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

Beakers are constructed in tall and low forms.

For efficient nutrient use, most important factors are the timely supply/recycling of adequate amount of nutrients to the production system and its retention and release by soil for timely and ready availability in the root zone for its mobility to the plant in the presence of optimum moisture content in the soil. For keeping the applied nutrients retained in the root zone one has to reduce the soil erosion and leaching losses through technologies available in hand which include direct measures of soil and water conservation and maintain the soil aggregation and porosity through suitable tillage and organic residue recycling. For movement of nutrients into plant system we need to ensure optimum soil moisture content through water management.

Introduction

Land capability classification is one of the very important issues in terms of sustainable land use. Land is the most valuable natural resource which needs to be harnessed according to its potential. Land use planning and management is a known strategy for achieving sustainable development. A properly prepared land use plan based on sound scientific and technical procedures, and land utilization strategies can summarize rationally the future demands. This accompanied by a strong planning process, where communities and various stakeholders are involved, can strengthen the decision making process on allocation and utilization of land resources. Land capability is referred as suitability of the land based on inherent characteristics of the soil associated land features, and climatic conditions that limit their safe use under agriculture, forestry etc. Land capability classification is a system of grouping soils primarily on the basis of their capability to produce common cultivated crops and pasture plants without deteriorating over a long period of time. The capability classification is one of a number of interpretive groupings of soils made primarily for agricultural purposes, mainly based on the inherent soil characteristics, external land features and climatic factors that limit the use of land for agricultural purposes. The land capability is governed by the different land attributes such as the type of soil, its depth and texture, underlying geology, topography, hydrology, etc. It also includes soil irrigation classes and ground water table position to decide overall suitability of lands for sustained use under irrigation. The classification points out automatically the possibilities and limitations of the climate and soil for each crop and type of agriculture.

Abstract

Land degradation is defined as human induced or natural process that negatively affects the lands to function effectively. It is temporary or permanent lowering of the productive capacity of land (UNEP, 1992). Several definitions of land degradation have been suggested by different authorities to express the degree of deterioration in potential of land in terms of physical, chemical and biological aspects. It has both environmental and economic consequences. The information on land degradation is needed for a variety of purposes such as to improve productivity levels in degraded lands through reclamation programmes, rational land use planning and also to bring more areas under cultivation.

10.1 Application Efficiency and Irrigation Uniformity

All irrigation systems have some non-uniformity. This non-uniformity influences yields and irrigation efficiency especially application efficiency. If the net amount of water applied during irrigation is the same as that required to fill the soil water deficit, then because the distribution of water is never perfect, half of the field will receive too much water while the other half will receive too less water. In such a context, a farmer will try to apply more irrigation water to his field so that a larger fraction of the field has an adequate amount. This will tend to have higher percolation and runoff and thereby declining the application efficiency. An alternative to adding extra water is to improve the uniformity of water application. A major advantage when the uniformity is improved is that the amount of deficit in the area under irrigation is reduced and the potential for water logging and salinization is also reduced.