eChapters

Q. 1 If the forward speed of a tractor drawn seed drill is increased twice,
then the seed rate delivered will be
(A) Reduced to half            (B) Double
(C) Increased by four time (D) Remains the same

The plants draw water from the soil for growth and development. The soil acts a reservoir for soil moisture (Fig.5.1). The basic aim of a soil water balance model is to quantify the manner in which the water supplied to the soil either through precipitation and irrigation is disposed off. In the process, the soil water balance models were found to be extremely useful to determine the amount of water utilized by the crop for evapotranspiration.
The concept of water balance was originally developed by Thornthwaite, an American geographer and it formed the basis for development of more scientifi c advances due to its wide range of applicability including
• Choice of crops/ cropping systems based on water availability
• Irrigation scheduling
• Optimisation of limited water resources for higher productivity
• Characterization of droughts and agricultural droughts
• Assessment of crop yield and pre harvest forecasting of crop yields
• Designing irrigation projects
• Development of water storage structures
There are quite a large number of water balance models available in literature nowadays. Several of these models may be applicable for regions where there are developed. There were considerable efforts to develop water balance models can be used by the crop on daily basis in case of different crops as well. The choice of a water balance model to a large extent depends on the availability of data required for running the model. It may not be possible to cover all models available in

5.1 Kinds of Soil Water

The following re the three main classes of soil water:

(i)  Hygroscopic water. Water held tightly to the surface of soil particles by adsorption forces.

(ii) Capillary water. Water held by forces of surface tension and continuous films around soil particles and in the capillary spaces.

(iii) Gravitational water. Water that moves freely in response to gravity and drains out of the soil.

The movement of water through soil is fundamental to irrigation efficiency, drainage, nutrient transport and plant water availability. This chapter examines the principles governing water movement in both saturated and unsaturated soil conditions. It introduces the movement of water through the soil profile and discusses saturated hydraulic conductivity as an important parameter describing the ability of soil to transmit water. Water flow under unsaturated conditions is considered in greater detail, including the relationship between soil-water content and hydraulic conductivity. The chapter presents the equation for unsaturated flow and describes experimental approaches for studying water movement. Unsaturated hydraulic conductivity, represented as K(θ), provides an important basis for understanding the changing ability of soil to transmit water as soil moisture conditions vary. The chapter also considers prediction of soil-water flux, linking theoretical concepts with practical irrigation and soil-water management. Understanding water movement helps in determining irrigation requirements, reducing water losses, improving drainage and maintaining favourable soil-water conditions for crop growth.

5.1 Soil

Soil and water are the two most important natural resources required for crop production. Without soil, no crop can be produced even if there is availability of plenty of water. It is vital not only for agriculture but also very vital for sustenance of life. No building can stand on any place without soil. Soil gives foundation support for any building. The term ‘soil ’is defined in various ways depending on the general professional field in which it is used. However to an agriculturist, soil is the substance existing on the earth surface, which grows and develops plant life. It contains all vital elements including its inherent fertility contents that support the growth of plants. For an engineer, soil is the unaggregated deposits of mineral and organic particles covering major part on the earth crust. It includes widely different materials like boulders, sand, gravel, clays and silts. Soil is produced by the weathering of solid rocks. The formation of soil is due to geologic cycle continuously taking place on surface of the earth. The geologic cycle comprises weathering or denudation, transportation, deposition and upheaval, again followed by the above mentioned processes. Weathering may be natural or artificial. In natural weathering, physical processes like temperature changes, flow of water, ice, wind and rain play the role. In artificial weathering animals especially human beings interference causes soil erosion and formation. It is obvious that it takes hundreds of years to form one inch of soil.

The soil consists of many solid particles of different sizes and is capable of absorbing and retaining water in the soil within certain limits when water is received through either from precipitation or by irrigation. The water that is held in the soil is called soil water (Fig.4.1). It can exist also in the form of water vapour as well. The crop production depends upon the soil water. All the water that is present in the soil may not be available for plants.
The water availability to the plants from the soil depends upon some physical properties of the soil as well as on the physical processes that govern the existence of water in the soil. Therefore, it is necessary to understand about the relationships that govern the water availability in the soil as explained in the following text-
4.1. Energy Concept of Soil Water
Soil water energy concept is all about potential energy, gravitational potential, osmatic potential, pressure potential energies.
4.1.1. Soil Water Energy: The total energy state of soil water is defined by its
equivalent potential energy as determined by various forces acting on the water per unit quantity. Different energies are involved including kinetic and potential energy.

The soil is a heterogeneous, polyphasic viz., solid, liquid and gaseous, particulate, disperse and porous system (Fig. 3.1). The solid phase constitutes the soil matrix, the liquid phase consists of soil water, which always contains dissolved substances so that it should properly be called as soil solution and the gaseous phase is the soil atmosphere.

The soil–plant relationship is central to crop productivity because soil conditions directly influence root development, water uptake, nutrient availability and plant growth. This chapter focuses particularly on the problems associated with salt-affected soils, including saline, sodic and acid soils. It explains the formation, distribution and characteristics of saline soils and describes the production constraints created by salinity stress. The effects of salinity on plant growth, evaluation of saline soils, reclamation and leaching are discussed together with leaching requirements and crop salt tolerance. Water and nutrient management strategies for saline soils, including the use of biofertilizers, are considered. Sodic soils are examined through their formation, characteristics, exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR), followed by reclamation practices and amendment use, particularly gypsum. The chapter also addresses acid soils, their formation, chemical characteristics, nutrient availability, plant-growth constraints and amelioration through liming. Calcareous soils and their management are also included, providing a comprehensive treatment of problematic soils affecting soil–plant interactions

The soil–plant–water relationship integrates the major concepts of soil-water availability, root water uptake and plant transpiration into a unified system. Water movement through the soil and plant is governed by differences in water potential and by resistance within the water-conducting pathway. This chapter examines water uptake by roots and the process of transpiration, emphasizing the continuous movement of water from soil through the plant and ultimately to the atmosphere. Variations in water potential and water flux within the soil–plant system provide the basis for understanding how water is transported under different environmental and soil conditions. The resistance of the water-conducting system is considered as an important factor controlling water movement. The chapter separately discusses water movement through soil and within plants before connecting these processes with water movement from the leaf surface to the atmosphere. Control of transpiration is also examined, linking plant water relations with environmental conditions and crop water use. The chapter provides an integrated framework for understanding soil–plant–water interactions essential for efficient irrigation, crop productivity and sustainable management of water resources.

The plants collect water by its root system available in the soil medium. A soil rich in nutrients cannot ensure success of crops unless the presence of satisfactory state of water and air, mechanical attributes and thermal regime. The physical properties of soil and plants greatly influence the movement, retention and use of water. The soil should provide sufficient pore spaces and size distribution and decomposition of rocks and for the movement and retention of water for plant needs. Rainwater, irrigation, groundwater, seepage, etc., contribute in replenishing the water in dried up soils. In all the cases thorough understanding of behavior of water is required to ensure the need of water to plants and optimize the use of irrigation water.

6.1 Soils

Soil is initially formed by the disintegration and decomposition of rocks and minerals and accumulation of biological residues. Usually the outer layer of the land surface is referred

Different kinds of soil water and soil water movement; Water in relation to plant growth and crop production; Soil texture, structure, infiltration and permeability; Bulk density and particle density of the soil; Concept and theories of water retention in soils; Consumptive use and ET; Soil moisture characteristics curves; Different losses of water (seepage and run off) and Soil moisture measurement, stress and plant growth
Soil-Water-Plant Relationships and Irrigation Scheduling Concepts
A good understanding of soil-water-plant relationships is the foundation for understanding irrigation concepts.
Water reaches the soil through irrigation, precipitation, or from groundwater drawn up into the root zone through “capillary action”. To be available to plants, it must be held by the soil strongly enough so it is not lost to gravity before the plant gets it, but not so strongly that the plant cannot extract it from the soil. At the same time, the roots must have sufficient aeration to function properly.
Roots are responsible for obtaining almost all of the plant’s water and nutrients. These substances move through the soil during and after irrigation/fertigation and rainfall. In addition, root systems are continually growing and branching to seek out water and nutrients. Root hairs are very fine structures that extend at right angles to the roots. Water and nutrients predominantly enter the root system via specialized cells near the tips of root hairs.
The xylem is the cellular pathway through the plant that transports water from the roots to the leaves for use in photosynthesis and to cool the plant by evaporation. The process by which water vapour is released to the atmosphere by the leaves and other parts of a living plant, resulting in evaporative cooling, is called transpiration. The xylem also transports water and nutrients to other parts of the plant. In a living plant, the xylem is completely filled with water, just as the veins and arteries of the human circulatory system are filled with blood. The plant needs a continual replacement of water lost through transpiration to keep the xylem full of water, and of course, this has to be accomplished without an organ analogous to a human heart. Tomato plants

Soil and growing media provide the physical, chemical, and biological foundation for successful horticultural production. This chapter explains soil properties, soil fertility, soil health, growing media, nutrient availability, and principles of plant nutrition. Emphasis is placed on soil testing, pH, electrical conductivity, organic matter, nutrient balance, and crop-specific fertilizer management. The chapter also introduces soilless media used in nurseries and protected cultivation. Understanding root-zone conditions is essential because horticultural crops are highly sensitive to water, aeration, salinity, and nutrient imbalance. Sustainable approaches such as composting, mulching, biofertilizers, and integrated nutrient management are discussed to maintain productivity while improving soil health and resource-use efficiency.

Introduction Soil, often referred to as the “skin of the earth,” is a critical component of our planet’s ecosystem, serving as the foundation for all terrestrial life. This chapter explores the science of soil, delving into its formation, classification, and the complex properties that define its role in agriculture and environmental sustainability. Understanding soil is fundamental to addressing global challenges such as food security, climate change, and sustainable land management. The chapter begins with an examination of soil formation and classification, providing insights into the diverse types of soils that exist across different landscapes. It then discusses the physical and chemical properties of soil, including their impact on soil health and fertility. The role of soil microbiology is highlighted, emphasizing the importance of microorganisms in maintaining soil health and promoting plant growth. As we progress through the chapter, we explore modern concepts in soil science, including sustainable soil management practices and their significance in mitigating the effects of global warming. The chapter also addresses the crucial role of soil in food security, demonstrating how effective soil management can enhance agricultural productivity and resilience in the face of climate change. Finally, the chapter touches upon the threats to soil health and the importance of sustainable soil management in ensuring a prosperous future for all. Soil science is a vital discipline within agriculture that focuses on the study of soils and their properties. This chapter delves into various aspects of soil science, including soil formation and classification, soil physical and chemical properties, soil fertility and nutrient cycling, soil conservation and erosion control, and soil microbiology and soil health. Soil is the foundation of agriculture, providing the medium for plant growth and supporting the intricate web of life that sustains our ecosystems. Understanding the science of soil is essential for optimizing crop production, protecting natural resources, and ensuring sustainable land management practices. In this chapter, we will explore the fascinating world of soil science, delving into its various aspects to gain insights into soil formation, composition, fertility, and conservation. By understanding the principles and processes underlying soil science, we can make informed decisions to enhance soil health, maximize nutrient availability, mitigate erosion, and promote sustainable agricultural practices.

Water is one of the most important resources governing crop production in irrigated agriculture, and its behaviour within soil determines the availability of water to plants. This chapter presents the fundamental relationship between soil and water, beginning with the importance of soil water in crop production and the classification of soil water. Soil moisture constants and methods for measuring soil moisture content are discussed to explain the different forms and availability of water in the soil profile. The chapter introduces the potential concept of soil water and the components contributing to total soil water potential, including potential energy. Available water capacity is examined in relation to plant water supply, while capillarity and water retention explain how soil texture and pore characteristics influence water storage. The soil-water characteristic curve provides a basis for understanding changes in water content with soil-water potential. Soil-water hysteresis is also discussed to explain differences in wetting and drying behaviour. These concepts provide an essential foundation for efficient irrigation, crop water management and sustainable use of soil water resources

Soil is generally defined as the upper layer of earth in which plants grow. It is regarded as a source of nourishment to all animals, moving or static. From agriculture or crop production point of view, soil is loose earth surface that supports vegetation, its quality, type and density. It is generally treated as a dynamic living entity and its physic-biochemical properties are responsible for its nutritional index. Precision production technology with suitable management is the key factors for its longer sustainability.

1.1. Definition

Soil: Thin layer of earth’s crust made up of disintegrated and decomposed rocks, complex mineral compound, organic matter, water/air and living organism like bacteria, fungi, insects and worms and serves as the natural medium of growth of plants.

Provides nutrients, moisture, anchorage (support) and air to plants.

Parent materials are igneous rocks, sedimentary rocks and metamorphic rocks.

Soil Science: Science dealing with soil (Natural resource) on the surface of the earth, including pedology (Soil genesis, classification and mapping), physical, chemical, biological and fertility properties and their relation to management for crop production.

Introduction

Cooking accounts for a major share of energy consumption in developing countries. Fifty per cent of the total energy consumed in India is for cooking (Fritz 1981). Most of the cooking energy requirement is met by non-commercial fuels such as firewood (75%), agricultural waste and cow dung cake (25%) in rural areas. The fuel wood requirement is 0.4 tons per person per year in India. In rural areas firewood crisis is far graver than that caused by a rise in oil prices. Marginal villagers have to forage 8 to 10 hours a day in search of firewood as compared to 1 to 2 hours ten years ago. One third of India’s fertilizer consumption can be met if cow dung is not burnt for cooking and instead is used as manure. The cutting of firewood causes deforestation that leads to desertification. Fortunately, India is blessed with abundant solar radiation (IMD, 1985). The arid parts of India receive maximum radiation i.e. 7600-8000 MJ m^-2 per annum, followed by semi-arid parts, 7200-7600 MJm^-2, per annum and least on hilly areas where solar radiation is still appreciable i.e. 6000 MJm^-2 per annum. Therefore, solar cookers seem to be a good substitute for cooking with firewood.

Principle of cooking

The different methods of cooking of food are boiling, frying, roasting, and baking. For boiling of rice, lentils etc. the temperature of food being cooked is about 100° C while for other methods, high temperatures are required. Heat is supplied at the bottom of the vessel for frying and boiling purposes in conventional cooking. Roasting and baking is generally performed on open fire or in ovens, wherein food is surrounded by hot surfaces and heat is transferred to the food by radiation and convection.

Introduction

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

6.1. Introduction

Solar crop drying has been demonstrated to be cost effective and an effective alternative to traditional and mechanical drying systems, especially in location with god sunshine during the harvest season. Considerable energy savings can be made with open sun drying since the source of energy is free and sustainable. However, this method of drying is extremely weather dependent and has the problems of contamination, infestation, microbial attacks, etc., thus affecting the product quality. Additionally, the drying time required for a given commodity can be quite long and results in post-harvest losses. Solar drying of agricultural products in enclosed structures by natural convection is an attractive way of reducing post harvest losses and low quality of dried products associated with traditional sun-drying methods. The crop is vulnerable to damage due to hostile weather conditions. The crop is also susceptible to re-absorption of moisture, if it is kept on the ground during periods of no sun, which reduces its quality. This type of problem can be solved by solar dryer. Many dryers have been developed and used to dry agricultural product in order to improve shelf life .Most of these either use expensive sources of energy such as electricity or combination of solar energy and some other form of energy which is not cost effective and dependent on regular supply of fuel.

Principally, drying requires temperature for removing moisture from product, air flow rate to remove moisture from drying chamber and optimum relative humidity within the drying chamber to allow fast drying. These all three requirements for drying can easily be achieved from solar energy. Solar drying is one of the direct applications of solar heat, which involves removal of moisture from the products through the application of solar energy. The removal of moisture requires only low temperature heating, which can be met easily by absorbing solar energy by the surface. This increases the temperature of the air inside the dryer. The moisture produced from the drying product is usually carried out along with the exhaust air. The characteristic of solar energy is good for the drying at low temperature i.e. high flow rates with low temperature rise. The intermittent nature of solar radiation can not affect the drying performance at low temperature. Further, solar energy is available at the site of use and saves transportation cost.

Solar energy is the energy emitted by the sun in the form of electromagnetic radiation. It is the most abundant, renewable, and sustainable energy resource available on Earth. Every hour, the Earth receives more energy from the sun than the entire human population consumes in a year. This makes solar energy a key candidate for solving the world’s growing energy needs while addressing environmental concerns. The solar energy reaching Earth can be harnessed and converted into useful forms of energy
Solar Photovoltaic Fencing
Solar photovoltaic fencing utilizes solar energy to provide an effective security solution, using high-voltage electric pulses to deter intruders or animals. The system operates by converting solar energy into electricity, which is then stored in a battery for later use. The battery powers an energizer that sends high-voltage pulses along the fence, creating an electric shock when an intruder touches the live wire.
System Components and Working
1. Solar Module: Converts sunlight into direct current (DC) electricity, which charges the battery.
2. Battery: Stores the energy generated by the solar panel. The 12V/100AH battery allows the system to operate even at night or during cloudy days.
3. Energizer: The energizer is the heart of the system, generating high-voltage pulses. It works by sending electrical pulses at regular intervals (usually one pulse per second) through the fence. The energizer is powered by the battery.