Preface This book Agricultural Engineering: A Practical Approach that integrated post harvest engineering, protected cultivation, land surveying and soil-water conservation engineering. The main aim of this book is to organize the scattered information and provide better practical skill to the students. The book has been mainly designed to serve as a practical reference book for the undergraduate students of Agricultural Science, Horticulture and Agricultural Engineering. Specially, Agriculture Science students will find it very suitable as it includes different topics as per the undergraduate Agricultural Science curriculum. Moreover, the students of Agricultural Polytechnics, Trainees of professional training institutions including post harvest laboratories, KVK, Soil Conservations Training Centres, etc. can also make use of practical reference book. The book has several practical lessons including moisture content determination, equilibrium moisture content estimation, moisture estimation by moisture meters, determination physical, frictional, thermal and mechanical properties of agricultural materials, drying rate calculations, drying characteristics of grain, evolution of lab model thin layer and fluidized bed drier, performance evaluation of seed cleaner, grader, seed separators, rubber-roll paddy dehusker, maize sheller, groundnut decorticator, paddy parboiling unit, design of bag storage, shallow and deep bins, design of conveying equipment, study of different types of green houses, greenhouse construction, covering materials, design of greenhouse heating and cooling systems, chain survey, cross-staff survey, compass survey, plane table survey, leveling, profile leveling, contouring, irrigation water measurement, design of grassed water ways, design of contour and graded bund, design of bench terrace, estimation of soil loss using Universal Soil Loss Equation.

Determination of size of the food materials Size is an important physical attribute of foods used in screening solids to separate foreign materials, grading of fruits and vegetables, and evaluating the quality of food materials. Various types of cleaning, grading and separation equipment are designed on the basis of size. The size and shape of the grains are used to determine the size of screen openings, angle of inclination, vibration amplitude and frequency of screen in designing an air screen grain cleaner and conveying characteristics of the solid materials.

Theory Bulk density of the food material play an important role in many applications such as drying, storing, separation of undesirable material, determining the purity of seeds, grinding, maturity evaluations, design of storage structures, etc. It is an important parameter in packaging requirement and is often 2-20% of true density. Bulk density is the density of material when stacked or packed in bulk. Bulk density of powder can be determined under loose conditions. Loose packing is defined as the state obtained by pouring a powder sample into a vessel without any consolidation. Bulk density Bulk density of the food material can be defined as the ratio of weight of an untapped material to its volume including the contribution of the inter-particulate void volume. There are two kinds of voids, voids between particles and void within particles. Weight of the material can be determined by weighing balance. Volume can be determined by measured dimensions or using liquid or gas or solid displacement methods.

Aim To determine the tapped bulk density and flowability of the food powder. Materials required Raw material (powder) Measuring cylinder Electronic weighing balance Tapped bulk density of the powder Tapped bulk density is measured for powdery samples. The volume is measured after tapping the powdery material so that the product is adjusted to inter-granular spaces, but it cannot eliminate all the inter-granular spaces. The tapped density is an increased bulk density attained after mechanically tapping a container containing the powder sample.

Theory Porosity is a physical property characterizing the texture and the quality of dry and intermediate moisture foods. Porosity means inter-granular space. It is the measure of void space between the materials. Porosity may be defined as the percentage of volume of inter-grain space to the total volume of grain bulk. Porosity depends on size, shape, dimension, and roughness of grain surface. The porosity of an unconsolidated agricultural material can either be determined experimentally using the porosity tank method or theoretically from bulk and true densities of the material. Porosity can be determined from the difference between bulk volume of a porous material and its volume after destruction of all voids by compression. Porosity determination requires the knowledge of the total or apparent volume, and the void volume included in the material matrix; their difference is also known as the particle volume.

Theory The specific gravity is defined as the unit weight of the product mass divided by the unit weight of distilled water at 4°C. The unit density is obtained by measuring the volume and weight of a unit product. Sometimes it is required to compare the density of the product to the density of water. This comparison is in the form of ratio and is termed as the specific gravity. Specific gravity also known as relative density is the ratio of density of a substance to the density of a standard substance at the same temperature and pressure. For solids and liquids the standard substance is water while for gasses it is air. The specific gravity of food material play an important role in design of storage bins, conveying equipments, separation equipments, etc. The specific gravity is frequently used to solve the various phase relationships, including void ratio, porosity and degree of saturation together with the moisture content and unit weight. It is also used in calculations associated with the grain size analysis, consolidation and compaction. Pycnometer method, which is a standardized vessel for determining specific gravity. It involves a standard container of accurately defined volume used to determine the specific gravity of solids and liquids.

Theory The volume of food material play an important role in design of storage bins, conveying equipments, separation equipments, etc. Volume of larger products such as fruits and root crops can be determined using the platform scale or water displacement method.

Aim To determine the water solubility and absorption index of given food powder. Materials required Digital centrifuge machine Graduated measuring cylinder Beaker and distilled water

Aim To determine the angle of repose of the given biological materials. Materials required Angle of repose apparatus Grains Scale

Aim To determine the thermal conductivity of the agricultural materials probe method. Materials required Thermal conductivity probe Stainless-steel sample container Grain or powder sample Graph sheet Power source

Theory Specific heat is defined as the amount of heat needed to raise the temperature of one kg of the material by one degree at constant pressure without a change in state. With food materials, specific heat is a function of different components of a food, moisture content, temperature, and pressure. Specific heat is an important parameter in thermal analysis of food processing and equipment used in heating or cooling of foods. The numerical values of specific heat of the food materials are used in designing food processes and processing equipment. It can be used to calculate the heat load imposed on the refrigeration equipment by the freezing of foods. An apparent specific heat is used in freezing or thawing and in most food processing applications. The specific heat of a food increases as the product moisture content increases. In unfrozen foods, specific heat capacity is relatively constant with respect to temperature. However, for frozen foods, there is a large decrease in specific heat capacity as the temperature decreases. The specific heat of a material can be determined experimentally by static (adiabatic) calorimetry or differential scanning calorimetry. It can be also predicted quite accurately with the help of a number of empirical equations. The equations are empirical expressions, obtained by fitting experimental data into mathematical models. The mathematical models are based on one or more constituents of the food. Since water is a major component of many foods, a number of models are expressed as a function of water content.

Theory The energy available in food is expressed in unit is called joules or calories. One kilocalorie is equal to 4.184 kilojoules. The kilocalorie is defined as the amount of heat required to raise the temperature of 1 kg of water by 1°C. The calorific/ energy value of foods is usually determined using the instrument called bomb calorimeter. It is working based on the principles of calorimetry. Basically, this device burns a food sample and transfers the heat into a known mass of water. It measures the heat produced when the food sample is ignited by an electric spark in the presence of oxygen and platinum which acts as a catalyst. The quantity of food sample to be tested is placed inner part and known volume of water is taken in outer part of the bomb calorimeter. When the food sample is electrically ignited, the surrounding water absorbs the heat produced. The energy value of the food is calculated by measuring the rise in temperature of water.

Theory Texture testing is a well-established technique for evaluating the mechanical properties of raw materials, food structure, pre- and post- harvest quality control checks. The texture testing has many applications across wide range of foods including cereals, fruits, vegetables, meat, poultry, fish, baked foods, confectionaries, snacks, dairy, gelatins, pasta, etc. Food texture analysis of foods can highlight the quality improvement throughout the supply chain. At research and development stage, new or alternative ingredients can be compared with existing ingredients. Texture profile parameters The texture profile parameters including hardness, firmness, crispiness, rupture strength springiness, chewiness, cohesiveness, gumminess, gel strength, adhesiveness, consistency, crunchiness, elasticity, extensibility, fracturability, stiffness, stringiness, toughness, work to cut, penetrate and shear can be measured by the mechanical food texture analyzer.

Theory The amount of moisture in a product is given on the basis of the weight of water present in the product and is usually expressed in percent. Moisture content is designated by (i) wet basis (wb) and (ii) Dry basis (db). The moisture content on dry basis is more simple to use in calculation as the quantity of moisture present at any time is directly proportional to the moisture content on dry basis.

Theory Indirect methods are based on the measurement of electrical properties of the grain that depends upon moisture content. There are two indirect methods namely (i) electrical resistance and (ii) dielectric methods are used. The electrical conductivity or resistance of a product measures its moisture content at a given compaction and temperature. The electrical resistance is depends on its moisture content, degree of compaction, grain temperature and impurities present in the sample. The universal digital moisture meter measures the electrical resistance of the grain at a given compaction. Universal moisture meter gives fairly accurate readings of moisture content on wet basis. In dielectric method, grain moisture content can be measured with the help of dielectric properties of the grains.

Theory This type of moisture measurement is called brown-duvel fractional distillation method. The method is recognized as an official method for determination of moisture content. In this method, directly measures the volume of moisture in cubic centimeter. This apparatus consists of flask, burner, thermometer, condenser, graduated cylinder. This apparatus consists of flask in which grain sample is boiled with mineral oil.

Aim To study the numerical problems on grain moisture content and equilibrium moisture content. Problem 1 Five hundred kilograms of paddy at 22% moisture content (wb) is dried to 14% moisture content (wb) for milling. Calculate the amount of moisture removed in drying.

Aim To study the determination of drying rate of agricultural products Problem In a drying experiment on paddy at an air temperature of 60ºC, the following data were obtained. Prepare a drying rate curve for the experiment. Initial weight of the sample is 1250 gm and initial moisture content is 35% (d.b).

Aim To draw the drying characteristic curve for given grain by thin layer drying. To determine the drying constant, heat utilization factor and coefficient of performance.

Theory Fluidized bed drying is a method of drying by keeping the material in fluidized/ floating condition inside a chamber by hot air. In this drying process higher rate of moisture migration takes place.

Aim To study the working principle and cleaning efficiency of air-screen seed cleaner cum grader Apparatus required Lab model air-screen seed cleaner cum grader Seed sample Weighing balance

Aim To determine the effectiveness of inclined belt separator To determine the capacity of inclined belt separator Materials required Inclined belt separator Weighing balance Feed material Sample divider

Aim To evaluate the performance of the gravity separator. Materials required Specific gravity separator Weighing balance Sample divider Stopwatch Grains

Aim To determine the effectiveness of the spiral separator. Materials required Spiral separator Weighing balance Sample divider Stopwatch Grain mixture (round and others)

Aim To determine the efficiency of groundnut decorticator Apparatus required Manually operated groundnut decorticator Weighing balance Groundnut pods

Theory Removal of outer sheath is called husking and removal of kernel from maize from maize cob is called shelling. The performance of the sheller is expressed in terms of capacity, percentage of unshelled kernels (corn) and percentage of breakage. The above terms are defined as:

Theory Paddy parboiling is a hydrothermal process where the paddy is partially boiled to gelatinize the starch. During the gelatinization process the void of the rice kernel are filled and become hard on drying resulting minimum breakage and maximum head rice recovery. The nutrients are also absorbed into the inner mass and loss of nutrient is avoided. In general, the steps are involved in parboiling process are (i) Soaking (ii) Steaming (iii) Drying.

Rubber-roll Sheller consists of two rubber rolls rotating in opposite direction at different speeds. One of the roll is fixed while the other is adjustable to obtain desired clearance between them. The rolls are driven by mechanically. The adjustable roll normally runs about 25% slower than the fixed one. A feeder feeds paddy uniformly to the machine (Fig.27.1). Paddy is fed in thin layer through the clearance between two rubber rolls, rotating in opposite directions at different speed. Difference in speeds of the rolls develops a shearing force on grain surface results in the splitting, breaking and separating the husk from the grains. One part of the husk is subjected to shearing forces whereas the other part in contact with the slower roll is under compression and is thus subjected to breaking forces. Husking is done by the action of these forces. The clearance between them should be smaller than the mean thickness of paddy and may be adjusted subsequently by judging the shelling efficiency. If the gap between rolls is properly adjusted, it can shell up to 95% of paddy fed to it. At decreased gap excess pressure results more breakage of grain and can also cause coloring of shelled rice. During shelling the faster roll should have a peripheral speed of 10 -13 m/ s, while the slower roll 8-10 m/s.

Specifications These structures are generally used for the storing grain in the bags. The length of the structure is about twice the width or greater than that. Special care should be taken to make the side walls, floor and roof in constructing the structure. The walls are made of bricks or stones laid either in lime mortar (1:2) or cement mortar (1:6). The thickness is restricted to a minimum of 37.5 cm or maximum of 45 cm. The height of the walls on which the trusses are placed is kept about 5.5 m. Each of the structures is provided with two large size doors of 2.4 × 2.4 m and top ventilators.

Aim To design shallow and deep bins Theory The structure behaves as a deep or shallow bin depending upon its relative dimensions such as depth and diameter or width. It is decided from the concept of the plane of rupture. Plane of rupture: The plane of rupture is that surface down which a wedge of material bounded by one wall face, the free surface, and the plane of rupture would start sliding if bounding wall were to move.

Aim To design a screw conveyor Theory The screw conveyor consists of screw blade, screw shaft, coupling, tubular trough, cover, inlet and outlet gates, bearings and drive mechanism. A shaft with spiral screw revolves in the tubular trough. The screw shaft is supported by end and hanger bearings. The rotation of screw pushes the grain along the trough. The screw blade or flight is a continuous one-piece helix, shaped from a flat strip of steel welded on to the shaft. The screw shaft is usually a joint less tube with thick sides and a high tensile strength to reduce the weight.

Aim To design a bucket elevator Theory The bucket elevator’s capacity mainly depends on bucket size, conveying speed, bucket design and spacing, the way of loading and unloading, the bucket and the characteristic of bulk material. Bucket elevators with a belt carrier can be used at fairly speeds of 2.5 to 4 m/s. The speed of the belt depends on the head pulley. If the belt speed is too low, the discharge of the grains become more difficult, with too high speed the buckets are not fed well.

Aim To design a belt conveying system Theory The design of belt conveying system is based on available space, horizontal conveying length, conveying lift, characteristics of the materials to be conveyed and capacity requirement. On the basis of overall requirement and information, the belt width, belt speed, required horsepower, maximum belt tension and breaking strength of the belt, diameter of the pulleys and idlers and quantity of belt (thickness) are determined to design a belt conveyor (Fig.32.1).

Description Screw conveyor is one of the equipment used in material handling to convey the material horizontally. The screw conveyor consists of screw blade, screw shaft, coupling, tubular trough, cover, inlet and outlet gates, bearings and drive mechanism. A shaft with spiral screw revolves in the tubular trough. The screw shaft is supported by end and hanger bearings. The rotation of screw pushes the grain along the trough. The pitch of a stranded screw which is the distance from the center of one thread to the center of the next thread is equal to its diameter

Description Bucket elevator is one of the equipments used in the material handling to convey the material vertically. The lab model bucket elevator (Fig.34.1) consists of number of buckets/cups arranged to an endless flat belt. The belt with cups run vertically and cups are placed at a particular interval in the belt. The belt is wrapped over two pulleys, one at the top is called head pulley which receives power from an electrical motor 0.5 hp through suitable power concentration and rotates at required rpm. The belts, cups and pulleys are mounted on a steel frame. The grain from the hopper is reaches to the bottom pulley. The bucket is filled with grains during upward movement and is discharged at the top due to the centrifugal force. An outlet is provided at the top to collect the discharge grain. The capacity depends on the bucket size and seed of operation. For proper discharge of the material, the weight of the material in each cup should be equal to the centrifugal force created due to rotation.

Aim To determine cost of operation of processing machineries with available data. Total operation cost For calculation of cost of operation of processing machineries, two types of cost viz., fixed cost and variable cost to be estimated.

Greenhouse selection Selection of greenhouse to be constructed is important as each type has its own merits and demerits. There are two common types of commercial greenhouses namely; (i) Freestanding (single span) and (ii) Ridge and furrow (gutter connected or multi-span). Multi-span structure permits economy in construction, heating and cooling but the single span gives flexibility as far as microclimate inside the greenhouse in concerned. The freestanding Quonset type is usually accommodates many growing situations but there height restrictions near the side walls. Another freestanding type is single gable greenhouse and its many variations. The ridge and furrow or gutter connected greenhouse are joined at the eave by a common gutter.

Theory Heat required for heating greenhouses is based on the quantity of heat lost through different structural components of greenhouses per unit time. Shapes of greenhouse (A-frame and quonset) and structural components (roof, wall, gable, curtain wall, curved covering and end) are mainly influencing the calculation of heat requirement. The amount of heat lost from a greenhouse depends on glazing materials, exposed surface area of the house, inside desired temperature, outside existing temperature, wind speed, and condition of house (old, new, tight or loose). The outside temperature should be based on the lowest average expected temperature during the heating season.

Aim To design of greenhouse cooling system To determine the rate of air exchange in an active summer and winter cooling system. Theory Elevation factor (Felev) Elevation factor is directly proportional to the elevation. The values of elevation factors, used to correct the rate of air removal for a particular elevation. The rate of air removal from the greenhouse increase as the elevation of the greenhouse site increases.

Aim To study the different materials used for chain survey Theory Chain surveying is the method of land surveying in which only linear measurements are made. This method of surveying quit simple and it requires only a chain, a tape, few ranging rods and few arrows. It is used for securing data for exact description, marking the boundaries of land and preparing the maps of the area to show various details. The term details mean a natural or man-made feature at the ground surface.

Aim To measure horizontal distance on the level ground using chain Materials required Chain Ranging rods Chain pins Field note book

Aim To determine the area of given field by triangulation method of chain survey Materials required Metric chain Measuring tape Ranging rods Chain pins

Aim To find out the area of given field by cross-staff survey method Materials required Cross-staff Metric chain Measuring tape Ranging rods Chain pins

Theory Area computation is an important part of surveying. The term ‘Area’ is meant the projected area on a horizontal plane. The area is computed from the following methods: (i) Graphical method (ii) Instrumental method and (iii) Use of formulae. In graphical method, the area can be computed by dividing the whole area either into triangles or squares. The area of individual triangle is computed from base and the altitude and summation of individual area gives the total area. A tracing paper is divided into number of small squares is placed over the plan. The number of complete squares within the boundary is counted. The squares more than half are counted as full squares and those less than half are neglected. The total number of squares multiplied by the area of each square gives the total area of the field. In instrumental method, the planimeter is used to measure the area of a plotted plan. In use of formulae, computation of area by formulae depends on the shape of the field.

Aim To identify different parts of prismatic compass and to know their functions. To practice of taking the angular measurement. Compass survey principle Compass surveying is a branch of surveying in which directions of survey lines are determined with a compass and the lengths of the lines are measured with a chain or tape. In practice, the compass is generally used to run a traverse. In compass surveying, a traverse consists of a series of straight lines connected together to form an open or closed polygon as shown in Fig.44.1. The points A, B, C, D and E defining the ends of the traverse lines are called traverse station or traverse points. The lengths of the traverse lines are measured with a chain or tape. At each traverse station, where the traverse lines meet, the angle is measured with a compass.

Aim To determine the area of the given field by radiation method using a prismatic compass. Materials required Prismatic Compass Tripod Measuring tape Arrows Ranging Rods

Aim To determine the area of the field by intersection method using a prismatic compass. To determine the included angle of the closed polygon. Materials required Prismatic Compass Tripod Measuring tape Arrows Ranging Rods

Aim Studies on plane table survey instruments To determine the area of given open field by radiation method of plane table survey. Plane table survey Plane table surveying is a simple method of surveying for determination of area of field. The plane table survey is quite suitable for plotting small-scale and medium scale mappings directly in the field where great accuracy is not required. It is also used for plotting the topographical maps in the field. The plane table survey is generally more rapid and less costly than other types of survey. In this survey, a plane table is used for taking the measurements and for plotting the plan in the field. Plane table surveying is a method in which the field observations and plotting of the plan proceed simultaneously. The plotted map can be compared with the actual features in the field. Errors in measurements and plotting can be easily detected in the field by taking suitable check lines.

Aim To determine the area of given field by intersection method of plane table survey. Materials required Tripod Plane table Plumbing fork Level tube Magnetic compass Alidade Measuring tape Ranging rods Drawing sheet Pins, pencil and eraser

Aim To determine the area of given field by intersection method of plane table survey. Materials required Tripod Plane table Plumbing fork Level tube Magnetic compass Alidade Measuring tape Ranging rods Drawing sheet Pins, pencil and eraser

Aim To study the levelling instruments To practice the simple leveling Leveling Leveling is a method of surveying used for determination of the difference of elevations or levels of various points on the surface of the earth. The elevation of a point is its vertical distance above or below a reference level, called datum. Most commonly used datum is the mean sea level (M.S.L). Leveling is required to determine the undulations of the earth’s surface for topographic mapping. Leveling is needed for the design of highways, railways, canals, sewers, etc. Leveling is essential for the layout of construction projects, locating the excavation levels and for the control of various elevations in buildings, bridges, dams etc. The results of the leveling can be used to determine the catchment area, volume of the reservoir and the area submerged by a reservoir.

Aim To determine the reduced level of various points To find out difference of elevations of two points Materials required Dumpy level Levelling staff

Aim To determine the reduced levels on various points on the road To plot the profile of the road Materials required Dumpy level Levelling staff Theory Profile leveling is the process of leveling along a fixed line to determine the elevations of the ground surface along that line. The fixed line is generally the centre line of a highway, railway, canal, sewer, etc. The profile leveling is done to determine the undulations of the ground surface. Cross-sectioning is required to determine the levels across the line along which profile leveling is done. Profile leveling should be commenced from a bench mark and should end at a bench mark, as far as possible. When the ground surface does not have many undulations, the intermediate points are fixed at a uniform interval. If the ground surface is irregular and there are abrupt changes in the ground surface, the interval may be non-uniform.

Aim To prepare a contour map by direct method using dumpy level. Materials required Dumpy level Leveling staff Measuring tape Wooden pegs/chain pins Field book Theory For locating a point on the ground on a contour, its position and elevation in a horizontal plane should be known. In direct method, the contours to be plotted are located on the ground with a level by making various points on each contour, and these points are surveyed and plotted on plan. This method is more accurate but slow and tedious, and is suitable for contouring small areas where great accuracy is required. For locating the points of the same elevation, the instrument is set in such a commanding position from where maximum number of points can be covered. The bench mark is established near the site of survey. The height of the instrument (H.I) is determined after taking a back sight (B.S) on the established bench mark.

Aim To determine the contours by grid method using dumpy level. Materials required Dumpy level Leveling staff Measuring tape Wooden pegs/chain pins Field book

Aim To determine the contours by cross-section method using dumpy level. Materials required Dumpy level Leveling staff Measuring tape Wooden pegs/chain pins Field book

Aim To determine the contours by radial line method using dumpy level. Materials required Dumpy level Leveling staff Measuring tape Wooden pegs/chain pins Field book

Aim To measure irrigation water by volumetric method Apparatus required Siphon tube Stop watch Measuring bucket

Aim To measure irrigation water by area-velocity method by using (i) float and (ii) current meter Apparatus required Float Current meter Theory The rate of flow of water in open channel can be determined by multiplying the cross sectional area of the flow section at right angles to the direction of flow by the average velocity of water. In area-velocity method, the water can be measured at motion. The water is measured in motion by means of rate of flow or discharge and is expressed in litre per second (lps), litre per minute (lpm), cubic metre per second (m3/s), etc. Litre per second: A continuous flow amounting to 1 litre passing through a point each second. Cubic metre per second: A flow of water equivalent to a stream of 1 m long, 1 m wide and 1 m deep flowing at a velocity of 1 metre per second. In area-velocity method, the velocity of water is measured either by float or current-meter

Aim To measure the irrigation water by using weirs a) Weirs A weir is a notch or opening of some definite shape installed on a channel or a stream through which waterfalls (Fig.59.1). Materials like wood, concrete, mild steel, rigid PVC etc. can be used for construction of a weir. Mainly a cut on a sheet metal is used for fabrication of weirs, to be installed at various locations in a channel. Advantages of weirs are (i) capable of accurately measuring a wide range of flows (ii) easy to construct, portable and adjustable (iii) tends to provide more accurate discharge rating than flumes and orifices.

Aim To measure the irrigation water by using orifice Orifices An orifice is an opening in a bulk head with closed perimeter usually circular or rectangular cross-section through which water flows. For measurement of water, orifices are fabricated by making an accurate cut of proper size and shape in a mild steel sheet, aluminum plate etc. Proper machining is done to have a sharp edge through which water flows (Fig.60.1). Free discharge If the downstream water level is lower than the bottom of the orifice opening, the water jet discharges freely into the air and then it is said to be free discharge. The depth of water on the upstream side of the orifice that causes the flow is called the head. The orifice flow formulae can be applied only when the orifice flows fully.

Aim To measure the irrigation water by using parshall flume Construction of Parshall flume Parshall flume is a water measuring device that can be used to measure water flowing in an open channel and intended primarily for use in irrigation. The flume consists of a converging inlet section, a throat section with straight parallel sides, and a diverging outlet section (Fig.61.1). The floor of the converging section is level with walls which converge in the direction of flow, towards the throat. The throat section constitutes the middle portion of the Parshall flume. The floor of the throat section is dips downward in the direction of flow, but the walls are parallel. The throat width specifies the dimensions of the parshall flume. The diverging outlet section of the flume has a floor which rises in the direction of flow. The walls become further separated in the direction of flow (diverge).The parshall flume can be constructed by G.I. sheet, aluminum sheet, M.S. sheet, brick masonry, reinforced concrete or timber. Flumes made of G.I. or aluminum sheets are easily portable. Brick masonry and concrete flumes are permanently constructed in the channels. Stilling wells should be constructed at the side to take measurements.

Aim To measure the irrigation water flowing through a pipe by using Venturimeter Theory A venturimeter is a device used to measure the rate of flow of a fluid through a pipe and is often fixed permanently at different sections of the pipeline to know the discharge there. Venturimeter consists of three parts: (i) a short converging part (ii) a throat (iii) a diverging part (Fig.62.1). In the venturimeter, the fluid is accelerated through a converging cone of angle 15-20° and the pressure difference between the upstream side of the cone and the throat is measured, and provides the signal for the rate of flow. Due to the constriction there is an increase in the flow velocity and hence an increase in the kinetic energy. The fluid slows down in a cone with smaller angle (5-7°) where most of the kinetic energy is converted back to pressure energy. Because of the cone and the gradual reduction in the area there is no “vena contracta”. The flow area is at minimum at the throat.

Aim To design the grassed water ways or open channel Geometric characteristics of different waterways The shape of open channel is dependent upon the field conditions and types of the construction equipments used. The common shapes of open channels generally used are (i) Parabolic or semi circular (ii) Triangular (iii) Rectangular and (iv) Trapezoidal section. The parabolic shape approximates a natural channel. The reason is that in natural course of channel flow, the trapezoidal and triangular sections tend to become in parabolic shape due to deposition of sediments and bank erosion.

Aim To design the contour bunds Design parameters The design of contour bund includes determination of following parameters: Choice of bund Spacing of bunds Size of bund Alignment of bund 1. Choice of bund The choice of bund should be selected weather the contour bund or graded bund depends on the annual rainfall, soil condition and types of outlets used.

Aim To design a graded bunds The procedure in design of contour bund is followed while design a graded bund. A stability of 10-25%, should be given to contour bund. This is called graded bund. Example: Design a graded bund length of 500 m with an average land slope of 3.5% in a sandy loam soil. Vertical distance between consecutive bund is 2.5 m. Rainfall intensity for the time of concentration and for the recurrence interval is 18.5 cm/hr. The runoff coefficient is 0.3. For stability, the grade provided for first 100 m is 0.1%, for next 200 m is 0.15% and for last 200 m is 0.18%. For the sandy loam soil, side slope of the bund and slope of seepage line are 1.5:1 and 5:1 respectively is assumed.

Aim To design bench terrace 1. Components of bench terrace The bench terrace essentially consists of the four components namely: riser, outlet channel, platform and shoulder bund

Aim To estimate the soil loss using universal soil loss equation Universal soil loss equation Wischmeir and Smith (1962) has been developed a predictive equation for estimating the soil loss taking into account following factors: Climatic characteristics, soil characteristics, crop management and conservation practices. It is called Universal soil-loss equation (USLE).

Bibliography Amin, M.N., Ahammed, S., Roy K.C. and Hossain, M.A. (2005). Coefficient of friction of pulse grains on various surfaces at different moisture content. International Journal of Food Properties, 8(1), 61-67. Arora, K.R. (1993). Surveying Volume-1 (3rd ed.). Standard Book House, Delhi, India. Bansal, R.K. (2005). A Text Book of Fluid Mechanics and Hydraulic Machines. Laxmi Publications, New Delhi, India. Bohanon, H.R., Rahilly, C.E and Stout, J. (1993). The Greenhouse Climate Control Handbook. Acme Eng. and Manufacturing Corp, Form C7S, Muskogee, Oklahoma, USA. Bourne, M.C. (1982). Food Texture and Viscosity. New York: Academic Press. Carson, J.K. (2015). Thermal conductivity measurement and prediction of particulate foods. International Journal of Food Properties, 18(12), 2840-2849. Chakraverty, A. (1997). Post Harvest Technology of Cereals, Pulses and Oilseeds (3rd ed.). Oxford & IBH Publishing Co. Pvt. Ltd., New Delhi, India. Chakraverty, A., and Singh, R.P. (2014). Postharvest Technology and Food Process Engineering. CRC Press: New York. Chandramal, B. (1995). Introduction to Soil and Water Conservation Engineering (Surveying, Irrigation, Drainage and Soil Conservation). Kalyani Publishers, New Delhi, India. Dai, F., Han, Z., Zhang, F., Zhao, W., Gao, A and Li, X. (2015). Determination testing of seed hardness of staple breeding wheat seed in gansu province of China. Advance Journal of Food Science and Technology, 7(4), 260-265.