This article throws light upon the four major sub-disciplines of agricultural engineering. The disciplines are: 1. Farm Machinery and Energy in Agriculture (Farm Power and Equipment Engineering) 2. Agricultural Structure and Process Engineering 3. Dairy Engineering 4. Irrigation & Soil and Water Conservation Engineering.
Agricultural Engineering: Sub-Discipline # 1.
Farm Machinery and Energy in Agriculture (Farm Power and Equipment Engineering):
1. First time TRACTOR (1960-61) manufacturing started in India by M/s Eicher Good Earth.
2. Average man power for doing farm work – 0.1 hp (74.6 watts). Average pair of bullock power for usual farm work -1 hp (746 watts)
3. Thermal efficiency for diesel engine – 32 to 38% Thermal efficiency for petrol engine – 25 to 32%
4. Out of the total energy produce in India, the percentage share of thermal power (56%), hydro electrical power (36%), nuclear power (16%) and rest comes from diesel and gas based power.
5. The farm holding in India are classified as (a) marginal – <1 ha, (b) small – 1 to 2 ha, (c) semi medium – 2 to 4 ha, (d) medium – 4 to 10 ha and (e) large – >10 ha.
6. The most popular tractor is found in 30-39 hp segments.
7. 1 H.P. = 75 kg-m/sec or 4500 kg-m/minute
8. 1 H.P. =
Where, P = Mean effective pressure (kg/cm2), L = Length of stock (meter), A = Area of cylinder (cm2), N = No. of revolution, n = no. of cylinders
9. Indicated Horse Power (IHP) = Break Horse Power + Friction Horse Power (FHP)
10. DBHP =
1. Biomass: mixture of Methane (45-70%) and Carbon dioxide (30-35%)
2. Cattle dung: Water ratio for biogas slurry: 4:5 or 1:1
3. Buffaloes: 15kg dung/day, bullocks or cows: 10 kg dung/day and calves:5 kg dung/day.
4. Suitable condition for biogas production – pH (7-8), temperature (35°C)
5. Biogas calorific value – 4500kcal/m3
a. The speed required for operation of wind mill-10 tol5 km /hr.
b. Two types of wind mill (horizontal axis and vertical axis rotor)
1. Horizontal axis rotor- axis of rotation is parallel to the direction of wind
i. Multi blade
ii. Propeller-most commonly used ii i. Sail type
2. Vertical axis rotor axis of rotation is perpendicular to the direction of wind.
c. Components of wind mill: tower, head, rotor, transmission gear, pump, generator
a. Temperature of sun 5777°K
b. Radiation range from sun, 0.4mm to 2.6 mm-maximum available range, <0.4mm-ultraviolet radiation (8% of total radiation),
0. 4. – 0.7plm visible radiation (46%)
>0.7mm infra red radiation (46%)
c. Solar Constant: solar radiation received per second by surface of unit area held normal to the direction of sun rays at mean earth- sun distance. Its value 1350W/m2 or 1.94cal/s/ml
d. Collection of solar radiation (three ways):
1. By flat plate collector: temp range 40°C to 100°C
2. Focusing or concentrating collector (>100°C)
3. Photovoltaic cell (solar cell): directly convert solar energy into electricity made of silicon separated by thin barrier with conversion efficiency is about 10%.
e. Portable water contained < 550ppm of salt, sea water contained 30,000- 40,000 ppm of salt, ground water contained <2,000-3,000 ppm of salt.
a. Solar still-device converts saline water into portable water.
b. Green house is structure made of polythene / rain forced fibre to provide controlled condition for crop production
h. Energy from Agricultural Waste
i. Thermo chemical process:
1. Direct combustion:
Burning of biomass in excess of air for steam generation
Burning of biomass in limited supply of air at- temp about 1100°C for production of producer gas (CO+H2).
Heating of biomass in absence of air (650-1100°C). Destructive distillation of biomass for production of charcoal
Rapid heating of biomass at low temp to convert it into liquid (acetic acid, acetone, methanol, oils, chars)
j. Biological process:
(1) Anaerobic digestion of biomass
k. Lignin used as binder in briquette.
l. Modes of heat transfer
Take place between particles of body that are direct contact with each other, e.g. solids
Direct movement of particles e.g. fluids (liquid gas)
Heat transfer in the form of electric magnetic waves without any medium
m. Engine (Heat engine): Two types
1. External combustion engine:
Uses heat in the form of steam generated outside in boiler, placed entirely separate from the cylinder.
2. Internal combustion (L.C.) engine:
Heat is generated inside the cylinder by burning of fuel within cylinder
n. Two types of L.C. Engine (petrol Engine and Diesel Engine) –
i. Petrol engine (Otto engine, spark ignition engine): rapid explosion of air-fuel mixture within the cylinder, when it is ignited by spark, is called constant volume combustion.
ii. Thermal efficiency of Petrol engine (n) is given by,
n = l-(L/R) m-1
Where, r = compression ratio = total cylinder volume/clearance volume = v1/v2 m = air constant = Cp/Cv = 1.4, Cp = Sp. Heat at constant pressure. CV = Sp. Heat at constant volume.
iii. Diesel engine: combustion take place by slow burning when the fuel is injected into highly compressed heated air contained in the cylinder. It is also called as constant pressure combustion.
iv. Thermal efficiency of diesel engine (n) is given by,
n = 1 – (L/R) m-1(pm– 1/m (p – D) Where p = cut off ratio
o. When the cycle is completed in two revolutions of the crankshaft, it is called four stroke cycle engines.
Four stroke of the piston:
1. Suction stroke
2. Compression stroke
3. Power stroke
4. Exhaust stroke
p. When the cycle is completed in one revolution of the crankshaft, it is called two stroke cycle engines.
a. Firing Interval:
The interval between successive power strokes in different cylinders of the engine. Bore (D): Diameter of the engine cylinder.
b. Stroke (L):
Linear distance travelled by the piston from top centre (TDC) to bottom dead centre (BDC).
c. Stroke-bore ratio varies from 1-1.45 and for tractor is about 1.25.
d. Power: It is the rate of doing work, S.I. unit Watt=Joule/sec 1 hp=75 kg. m/second
e. Indicated horse power (IHP): It is power generated in the engine cylinder and received by the piston.
f. Brake horse power (BHP): It is the power delivered by the engine and is available at the end of the crankshaft. It is measured by suitable dynamometer.
BHP = IHP-FHP
g. Thermal efficiency: it is the ratio of the horse power output of an engine to the fuel horse power.
h. Mechanical efficiency (%) = (BHP/IHP) x 100
i. Instrument used for power measurement is called dynamometer.
j. Brake dynamometer measures brake or belt horse power and drawbar dynamometer measures drawbar horse power.
k. Calorific value: The heat liberated by combustion of fuel is known as calorific value (kcal/kg).
l. Octane number: measure of knock characteristics of a fuel, used for petrol.
m. Cetane number: Diesel fuels are rated according to cetane number, which is the indication of ignition quality of the fuel.
n. Air-fuel ratio in petrol engine (15:1) for best result.
o. The gravity of fuel/oil is expressed as specific gravity or API gravity, a scale devised by American petroleum Institute.
p. The process of preparing an air-fuel mixture away from the cylinder of an engine is called carburetion and the device in which this process takes pace is called carburetor. Main functions of the carburetor are to mix the air and fuel thoroughly, to atomize fuel and regulate air-fuel ratio.
q. Turbocharger: It is a turbo-compressor driven by the exhaust gases of the engine to supply air under pressure to the cylinders of the engine.
r. Governor is a mechanical device designed to control the speed of an engine within specified limits on tractor or stationary engines for (i) maintaining a nearly constant speed of engine under different load conditions (ii) protecting the engine and attached equipment’s against high speed; when the load is reduced or removed.
s. For tractor engine-variable speed governor (e.g. centrifugal governor) and for stationary engine -constant speed governor are used.
t. Governor hunting is erratic variation of speed governor when it over compensates for changes.
u. Say-bolt Viscometer is used for measure viscosity of lubricating oil.
v. Specific gravity of fully charged battery is 1.280 if sp. gravity below 1.225, it should charge.
w. Classification of tractor:
1. Wheel tractor: pneumatic wheels
2. Crawler tractor: tack type tractor: chain type
3. Power tiller: walking type
x. Tractor Components:
1. I.C. engine:
Most common diesel engine.
Connects and disconnects the tractor engine from the transmission gear and drive wheels. Friction clutch-four wheel tractor dog clutch-power tiller.
3. Transmission gear:
Selective sliding type and constant mesh type.
4. Differential unit:
Differential unit is a special arrangement of gear to permit one of the rear wheels of the tractor to rotate slower or faster than the other.
5. Final drive:
Final drive is a gear reduction unit in the power trains between the differential and the drive wheels.
6. Rear wheels:
Inflation pressure in the rear wheels varies between 0.8 tol.5kg/kg/cm2
7. Front wheels:
Inflation pressure in the rear wheels varies between 1.5 to2.5kg/kg/cm2
8. Slogging/ lugging ability:
In diesel engine, torque is considerably high at lower than rated speed, this behavior is called slogging or lugging ability.
9. Steering mechanism
10. Hydraulic control
11. Hitch system
13. Power take-off unit (PTO)
14. Tractor pully
15. Control pully
y. Japan is the first country to use the power tiller on large scale and power tiller first introduced in India in the year 1963.
z. Hooks law: within elastic limit stress is directly proportional to the strain Brinell hardness test testing machine is used for testing hardness of agricultural implements.
aa. Material used for agricultural machinery (I) Ferrous (1) Non-ferrous
1. Ferrous material
i. Cast iron (2.2 to 4.3% carbon)
ii. Steel is alloy of Iron and Carbon (Low Carbon Steel- <0.25 % Carbon, Medium – Carbon Steel – 0.25 to 0.60% Carbon, High Carbon Steel – 0.6 to 1.5% Carbon).
2. Non-ferrous material
i. Copper, Aluminium, Brass (Copper – 60 to 75%+30 to 40% Zinc),
ii. Bronze (88% Copper+10% Tin+2% Zinc)
ab. Flat belts are use to transmit power between two pulley when distance between them is large.
Ac. V-belts drive is used where less space is available and transmission distance is short, commonly used in agricultural machinery.
Ad. Chain and sprocket drive is used where two parallel shafts are spaced apart at short distance.
Ae. Gears are used to transmit power at uniform angular velocity from one shaft to another.
1. Spur gear: when used two shafts parallel to each other.
2. Worm gear – two shaft right angle to each other but not intersecting to each other.
3. Bevel gear – two shaft right angles to each other and can interact to each other.
4. Helical gear – two shaft parallel to each other but inclined gears teeth.
Mechanical manipulation/practice of modifying of soil to provide favourable condition for crop production.
Physical condition of soil favourable for crop growth.
3. Primary tillage:
Initial soil working operation to open up any cultivable land, reduce soil cover, soil strength, parent material and rearrange aggregates, e.g. ploughing used to break hard span. All ploughs i.e. MB plough, desi plough, disk plough, ridge plough etc are come under primary tillage implements.
4. Secondary tillage:
Tillage operations following primary tillage which are performed to create good seedbed for proper sowing/planting, e.g. harrowing for pulverizing, smoothing and packing of soil for seed bed preparation. All harrows, cultivators, peddlers, roller and hoes are come under secondary tillage implements.
5. Working efficiency of desi plough = 0.32 hp/day
6. Normal ploughing under primary tillage operation is usually done up to 15 cm depth.
7. All Plough and Sub-Spoiler (open up hard span below 40 cm depth) arc the primary tillage implements.
8. Vertical suction/clearance:
Adjustment for depth control in M.B. plough.
9. Horizontal suction/Side clearance:
this suction helps M.B. plough to cut the proper width of furrow slice.
10. through clearance:
It is perpendicular distance between point of share and lower position of the beam of the plough.
Total forced required to pull an implements.
Horizontal component of the pull, parallel to line of motion.
13. Side draft:
Horizontal component of the pull, perpendicular to line of motion.
14. Unit draft:
Draft per unit area.
15. Effective field capacity:
It is the actual area covered by implements, based on its total time consumed and its width (ha/hr.).
16. Theoretical field capacity:
it is the theoretical area covered by implements, based on its total time consumed and its width (ha/hr.).
17. Field Efficiency = (Effective field capacity/ Theoretical field capacity) x
18. Soil pulverization is quality of work in terms of soil aggregates and clod size. This is measured by Penetrometer.
19. Cohesion: force of attraction between similar particles, (e.g. soil and soil)
20. Adhesion: force of attraction between dissimilar particles (e.g. soil and metal)
21. Disc angle: it is angle at which the plane of the cutting edge of the disc is inclined to the direction of travel, e.g. for disc plough (42-45°)
22. Penetration is improved by increasing the disc angle and decreasing the angle tilt angle.
23. Tilt angle:
It is angle at which the plane of the 9utting edge of the disc is inclined to vertical line (for disc plough 15-25°)
24. Share type:
(i) slip share (ii) slip nose (ii) shin (iii) bar point Gathering: whenever a plough works round a strip of ploughed land, it is said to be gathering.
25. Casting: whenever a plough works round a strip of un-ploughed land, it is said to be casting.
1. Broad casting:
Random scattering of seed on the surface of seed bed (high seed rate) by hand.
Placing seed in holes made in seed bed and covering them by using dibbler.
Consists of dropping the seeds in furrow lines in a continuous flow and covering them with soil by using seed drill.
4. Seed dropping behind the plough by using molobansa.
5. Transplanting consist of preparing seeds in nursery and then planting these seedlings in the prepared field, e.g. paddy Trans planter.
6. Hill dropping:
Spacing between plant-to-plant in arrow is constant, e. g. planter.
7. Check row planting: spacing between row to raw and plant-to-plant is constant, e.g. Planter
8. Flu feed type seed metering mechanism is most commonly used in seed drill.
9. Calibration of seed drill:
i. Size of seed drill = no. of furrow openers x distance between two furrow openers
ii. Sowing area in 1 circle of seed drill = Size of drill x p x D
10. Seeds are sown/dropped in 5cm depth of soil and 5cm far from fertilizer.
11. Sprayers are a machine to apply fluid in the form droplets (herbicides, fungicides, and insecticides).
12. Basic components of sprayers are nozzle body, swirl plate; filter, over flow pipe, relief valve, pressure regulator, cut-off valve, spray valve, agitator, spray boom, drop legs, nozzle boss, nozzle disc, nozzle cap, nozzle tip, spray lance, spray gun.
Types of Spray:
1. High volume spray (>400 litres/ha)
2. Low volume spray (5 to 400 litres/ha)
For aerial dose -15-75 litres/ha (used in fruit crops) for ground dose -100-120 litres/ha (used in field crops)
3. Ultra low volume spray (<5 litres/ha)
(a) Most commonly used sprayers are low volume and ultra low volume sprayer.
(b) Nozzles on field sprayers have angle ranges of 60 to 90° but pressure nozzles have smaller angles.
(c) Duster is a machine to apply chemical in dust form.
(d) Mower is a machine to cut herbage and leave them in swath.
(e) Reaper is used to cut grain crops. Reaper binder cuts the crop and ties them into uniform sheaves.
(f) Size of reaper/mower = length of cutter bar
(g) Windrower is a machine to cut crops and deliver them in a uniform manner in a row.
(h) Threshing is a process detaching grain from ear heads or from the plants with using impact or wearing (rubbing) action. Most common threshing machines are olpad thresher, power thresher, threshing by combiner etc.
(i) Size of thresher = size of cylinder x width of winnowing part
(j) Basic components of power thresher:
1. Feeding unit
2. Threshing unit (concave, cylinder on which beaters/spike/rasp bar / hammer are mounted)
3. Cleaning unit with oscillating sieves, fan, air sucking duct (aspirator)
4. Separating unit
5. Collecting unit
(k) Types of thresher (based on cylinder):
1. Rasp bar-shearing action: for paddy
2. Spike tooth – impact and shear action
3. Hammer mill-impact action
4. Syndicator type-cutting action
5. Loop thresher: for paddy
(l) Combine harvester includes cutting mechanism (reel, cutter bar) and convening mechanism and other units are same as power thresher. It harvests the crops, threshing them and winnowing of the threshed crops.
(m) Threshing efficiency: the threshed received from all outlets with respect to total grain input expressed as percentage by mass.
1. Paddy transplanting – manual power tiller, engine operated rice trans-planter
2. Mat type seedling of paddy – self propelled riding type 8-row rice trans-planter.
3. Sugarcane trans-planter – tractor operated semi automatic sugarcane planter and sugarcane sett cutter and planter.
(o) Intercultural Implements are used for removing weeds and creating soil mulch for moisture conservation, i.e. hand hoe (khurpi), harrow etc.
Concave clearance: Clearance between beaters or cylinder tip and concave.
(p) Chaff cutter: machine used for cutting fodder for animal feed.
(q) Duffee formula is used for determine the capacity of chaff cutter.
(r) Land leveling equipment:
2. Bucket scraper
4. Float Leveller
5. Laser Leveller
s) Ergonomics is science which gives relation between man, machine and working environments.
Agricultural Engineering: Sub-Discipline # 2.
Agricultural Structure and Process Engineering:
a. Concrete is usually defined as mixture of cement, sand coarse aggregate (gravel and water in correct proportions and thoroughly mixed so that upon setting, it forms rock-like mass).
b. The slump test is performed to measure the plasticity of the concrete.
c. Water: cement ratio by volume for hydration hardening of cement theoretically works out to be 0.08 but for practically, it is 0.66 to 1.0
d. Curing of concrete is the process of strengthening it through hydration (7 days)
e. Mortar: mixture of cement, sand and water, or lime, sand and water.
f. Compressive strength of concrete ranging between 300 to 700 kg/cm. Seasoning of wood is primary done to get rid of all the surplus sap and moisture, to avoid decay or affected by fungus.
g. Rankine formula/ Airy formula used for determination lateral pressure in shallow bins.
h. Janssen formula used for determination lateral pressure in deep bins.
i. LSU continuous flow dryer is most commonly used in India developed at Louisiana state University Baton Rouge, USA in 1949.
j. Aero and hydrodynamic properties such as Drag Coefficient and Terminal Velocity of agricultural products are important and required of air and water conveying systems and separation equipment.
k. Fourier law is used for heat transfer through conduction.
l. Moisture content (m.c.) of some of the crops at harvest and for safe storage
m. Angle of repose is the angle between the base and the slope of the cone formed on a free vertical fall of the granular material to horizontal plane Tilting top drafting table and circular platform is used for measurement of angle of repose.
n. Refrigeration – process of removal heat from a space at a temperature lower than the surrounding temperature. The principle of refrigeration is based on second law of thermodynamic.
o. Latent heat of fusion of water at atmospheric condition is 80 kcal and Latent heat of vaporization of water at atmospheric condition is 540 kcal.
p. Scalping refers to the removal of few large particles in an initial process e.g. scalper. ‘
q. Cleaning process generally means the removal of foreign and undesirable matter from desired grain/products as much as possible to ensure its purity e.g. cleaner. Cleaning is done on the basis of size, weight and length of impurities.
Types of Impurities:
a. Large impurities – straw panicles, soils, stones, bag strings, iron parts
b. Small impurities – dust, sand soil particles, weed seeds, insects and small stones
c. Same as about grains-empty grains
Cleaning of impurities:
a. Light impurities (in wt.) removed by Aspiration or by sieving
b. Small, large & heavy impurities removed by Sieving
c. Same size but heavy removed by Gravity separation
d. Same size & weight impurities are not easily removed
e. Weed seeds are removed by sieving
f. Iron particles are removed by Gravity separation or Electromagnetic separation method.
g. Air Cleaning Machine (ASM): clean the grain based on size and weight of ASMs perform absorption, main scalping and grading.
h. Absorption – Light wt. materials are removed
i. Main scalping – Grain of other crops removed by screen due to grain shape differences
a. ASMs have 2-8 screens.
b. 3 screens clean small purities, but 4 screens used for desired and more purity.
Types of ASM:
1. Open double sieve cleaner: open, 2 oscillating sieve, 300-400 rpm of transmission shaft.
2. Self cleaning sieve: wooden frame, compartment (20cmx20cm or more), 2 rubber bolls of 1.9 cm and 3.2 cm.
3. Single action sieve
4. Single action Aspirator cleaner: one fan or blower, closed type of cleaner.
5. Double action Aspirator cleaner
6. Single Drum type cleaner: developed by Japan, for stone separation by gravity.
7. Double Drum type cleaner
a. Separation refers to the sorting of cleaned products (grain) according to various physical characteristics i.e. on the basis of size, shape, weight, EC, density, texture and colour, from inert material and other crop seeds, e.g. separator.
b. Grading refers to the removal or separation of smaller (under size), over size (bigger) and shriveled grains from main/ pure/ well fitted (healthy) grain of the same crop depending upon the various commercial values and other uses, e.g. grader.
c. More effective in mixture of grains or mixture of same crop
d. Based on length and shape both (cleaning + separation)
e. ASM used for grading of grains due to air current by fan
1. Same length but different thicknesses –> Rotating graders
2. Different length but same thickness –> Trieurs
3. Different length and different thickness both –> Rotating graders + Trieurs combination
4. Mixture of different varieties with same length & thickness –> Grading Impossible
(A) Rotating Grader:
i. Also called as “Grading reels”.
ii. It grades on the basis of thickness.
i. A rotating indented steel cylinder machine for grading of grains on the basis of length.
ii. It has thousands of pockets (2-8mm) for uploading mixed grain (short & long).
iii. During rotation of cylinder (50 rpm), each pocket upload with grains and short grains fall from higher point and long grains fall first from pockets.
Small broken grains separated, when mixed with short medium but rounded variety.
f. Drying refers to removal of moisture from grains and other products to a predetermined level equilibrium to the surrounding air (10 to 12% normally).
1. Re-circulatory Batch Dryer (PHTC dryer, developed from IIT, Khadagpur, 2 tons capacity)
2. Louisiana State University Dryer (popular in India & USA)
B. Size of rectangular bins – (1) 1.2m x 1.2m (2) 1.5m x 1.5m (3) 1.8m x 1.8m (4) 2.1m X 2.1m
C. Air distribution from ‘V shaped channels.
h. Conditioning is the process of maintaining uniform moisture and temperature of stored agriculture produce by moving a small amount of air through it.
i. Moisture measurement method:
1. Oven dry method -> 130°C±2°C for 1 hrs
2. Chemical method use of Calcium Carbide
j. Equilibrium Moisture Content (EMC): when a grain (product) exposed to a continuous supply of air at a constant temperature and humidity under partial pressure, grain losses the m.c. from surrounding air, until the vapour pressure of grain and air come to equal.
k. Henderson equation is most popular equation for determining of EMC.
l.EMC curve or Isotherm: a plot of EMC and ERH (Equilibrium Relative humidity) at a particular temperature (25°C).
1. Grain isotherm is commonly in S-shaped.
2. Henderson equation of grain isotherm –> 1-RH = eCTMn
Where, RH = Relative humidity, c = grain constant (Kelvin), T = temperature of air (°K), M = EMC of grain on dry basis (%), n = grain constant (dimensionless)
m. Psychrometric chart is graphical representation of thermodynamic properties of air at 1 atm pressure.
n. The thickness of grain in thin-layer drying is normally up to grain to 15 cm.
o. The deep bed drying grain depth is ranges from >15 to <45 cm. A Storage structure:
Traditional storage structure:
(a) Morai (Eastern & Southern India)
(e) Kuthla, Muda (Bihar)
(f) Kanaj (Karnataka, Maharashtra)
Improved storage structure:
(a) Pusa bin-mud, plastic & brick
(b) Brick and Cement bin
(c) Bunker storage
(d) CAP-cover and plinth
Modern storage structure:
(a) Deep and shallow bin
(c) Vertical silo
p. Shallow bin: a bin whose relative dimensions are such that the plane of rupture meets the grain surface before it strikes the opposite side.
q. Deep bin: a bin whose relative dimensions are such that the plane of rupture meets the opposite side before it emerges from the grain
r. Parboiling: it is the pre-milling (optional) hydro thermal treatment (heated water treatment at 70°C) given to paddy prior to its milling to achieve maximum recovery to head rice (1 to 2% more) and minimize breakage. In parboiling, gelatinization starch takes place.
s. Parboiling improves vitamin B12 in rice grain.
t. Parboiling of paddy is carried out in three steps (1) Soaking (2) Steaming (3) Drying
u. CFTRI method of parboiling is most commonly in India.
v. Grain handling mechanical devices:
1. Belt conveyor-longer distance
2. Bucket elevator – very efficient for vertical conveyance (<50 meter)
3. Screw conveyor – used for short distance
4. Pneumatic conveyor – the material is carried in pipelines either by suction or blowing pressure stream.
w. Triple point of water lie at 0°C and 4.59 mm of mercury, at this point three phases of water viz. solid ice, liquid water and water vapour coexist at equilibrium.
Agricultural Engineering: Sub-Discipline # 3.
a. The plate type heater exchange is mostly used in large sizes dairies.
b. Brine-concentrated CaCl or NaCl solution is used for cooling water or milk directly.
c. Solid CO2 is called Dry ice.
d. Pasteurization (3 types)
1. Batch pasteurization – milk heated at 61″C for 30 minutes
2. HTST – milk heated at 7r’C for 15 seconds
3. Ultra HTST – milk heated at 135″C for 2 seconds or no holding time at all
4. Vacreator – used for conditioning and pasteurizing of cream milk.
e. Two most commonly used refrigerators are Ammonia and Freon-10.
f. Hoinogenization is mechanical treatment used to reduce diameter of the fat globule by a factor 10.
g. Sterilization: milk is heated at temperature above 100″C and packed in air tight condition.
h. Types of dairy barns:
1. The stanchion barn (general purpose barn) – cow are housed and milked in the same building.
2. Loose housing barn with milking room (milking house system – cows are covered in covered or partially covered yard, but milked in batches in a special milking house called the milking parlour.
3. The open air barn (loafing barn system) does not have any cover.
4. Pen barns are structures for sheltering and restricting dairy animals.
h. Types of poultry houses:
1. Wire floored poultry house – water trough, roosts, nest, feed trough, expanded metal floor roof, egg retainer are the component of house.
2. Deep litter poultry house, keeping poultry inside a shed all the time (floor area per birds – 0.36 m2).
3. Cages house – built in warm climate. The dimensions of a cage for one bird may be 0.6 x 0.2 x 0.45 m.
4. Brooder house are essential in raising and managing chicks.
Agricultural Engineering: Sub-Discipline # 4.
Irrigation & Soil and Water Conservation Engineering:
a. Surveying is a process which determines positions of points on the surface of earth, in horizontal distance.
Objective: to prepare a plan or map
(1) To prepare road
(2) To make irrigation channel
(3) To make channels
(4) To make railway lines
(5) In soil conservation etc.
b. Soil Surveying helps in getting and collecting information’s about soils and preparing an inventory of soil resources of an area.
c. Types of surveying:
1. Reconnaissance soil survey (RSS): helps to identify benchmark soils for delineating problem and potential areas and providing information’s useful for making land use plants and agriculture development.
Scale: 1:50,000 -> 1cm = 0.5km (for state and district level survey)
1:2, 50,000 1cm = 2.5km (for national survey)
2. Detailed soil survey (DSS): helps to understand the soil and land problems and for different conservation measures to control soil erosion, to fix irrigation scheduled, in agriculture and watershed development.
Scale: 1:8,000 1cm = 80mm or 0.08km
1:20,0001cm = 0.2km
1:10,000 for Arial photos
a. Cadastral survey (land survey): determines land boundaries and areas.
b. Topographic survey: determines the shape or relief of the ground and the location of various natural and artificial features.
f. Instruments used in Surveying:
A. Instruments Used for Measuring Distance:
1. Chain: The chain is composed of 100 or 150 pieces of galvanized mild steel wire 4mm in diameter called links.
a. Metric chains: The chains are made in lengths of 20 and 30 meters.
b. Giinter’s Chain: It is 66 fit long and is divided into 100 links. Each link is 0.66 ft. long.
c. Revenue Chain: It is 33 ft. long and divided into 16 links. Each link is 2.0625 ft. long. It is commonly used for measuring fields in cadastral survey.
d. Engineer’s chain: It is 100 ft. long and it is divided into 100 links. Each link is 1 ft. in a length. Used in all Engineering surveys.
2. Arrows (chain pins): also called as marking or chaining pins and are used to mark the end of chain during the process of chaining. The arrows are made 400 mm in length. They are pointed at one end of inserting in to the ground.
3. Tape: Metric, cloth and steel tape.
B. Instruments for marking stations:
1. Wooden Pegs: These are used to mark the positions.
2. Ranging rods: Used for making the positions of stations and for ranging.
3. Ranging Poles: Used in the case of very long lines.
4. Offset Rod: It is used for aligning short offsets.
5. Plumb Bob: It is also used for testing the verticality of ranging poles.
g. Contour line: an imaginary line of constant elevation on the surface of the ground.
h. Contour interval: the vertical distance between two consecutive contours.
i. Theodolite is a device used for measuring horizontal and vertical angles.
j. Hydrology is the earth science dealing with the occurrence and movement of water upon and beneath the land areas of globe.
k. The average & annual rainfall of India is about 119.4 cm.
l. Gross Command Area (G.C. A): total area which can be irrigated by a certain channel or a project.
m. Culturable Command Area (C.C. A): it is the portion of the G.C. A which is Culturable or cultivable.
n. C.C. A. = G.C.A. – uncultivable area in the G.C. A.
o. The common practice in northern India for distribution of water through canal to farmer is Warabandi (numbers of turns).
p. Aquifer: A porous soil or geological formation which will yield significant quantity of water.
q. Unconfined aquifer is also known as a free, phreatic or non-artesian aquifer, is one overlying an impervious stratum, in which the water is not under pressure.
r. Confined aquifers: also known as artesian or pressure aquifers lie below an impervious layer and the water in them is under pressure.
s. Manually operated water lifting devices: Swing basket (lift – 1 to 1.2m), Counter poise lift (2-3 m), don (1.2m), Archimedean screw (lift 0.5-1.2 m). Paddle wheel (lift <1.2 m).
t. Animal powered operated water lifting devices: Rope and bucket lift (15m), Persian wheel (lift <10 111), Chain pump (lift<6 m).
Types of pumps for Irrigation:
1. Displacement pumps (reciprocating pumps and rotary pump): operating pressure (atm pressure i.e. 1 kg/cm^ water lift <10m, best result-7mi
2. Centrifugal pump (suction Iift<4.5m, Maximum suction head is taken as 6 m, but beyond about 4 m the efficiency of pump drop down substantially.). Impeller and casing are two parts of centrifugal pumps.
3. Turbine pumps (Deep well turbine pumps and submersible pump) – suction lift >7.5 meters.
4. Propeller pumps (axial flow and mixed flow) -Suction lift 1-2.5 meters.
5. Airlift pumps
6. Jet pump (suction lift 12-18m)
a) The interrelationship of capacity, head, power and efficiency – are best shown graphically and these curves are called the “characteristics of the pumps”.
b) Priming is the process of removing air from pump casing and suction pipe by filling water in the suction pipe.
c) Static bead = Static suction head + Static discharge head
d) Total head = Static head + Friction head + Velocity head
e) Water is measured under two conditions: at rest and in motion. Hence, the s commonly used in measuring water is in unit flow and unit of volume.
f) The commonly used units of water at rest are the litre, cubic meter and hectare- centimeter.
g) The commonly used units of water in motion are in m3/s and It/s.
h) Orifices, Weirs, Notches and Parshall flumes are used to measure the rates of flow (discharge) of water.
i) The basic formula for calculating the discharge through a weirs is Q = CLHm
Where, C = a coefficient, depending on the nature of the crest and approach conditions
L = length of crest cm,
H = head of the crest cm,
m = exponent depends on the type weir opening
j). Types of weir based on their shape:
1. Rectangular weir
(a) Suppressed Rectangular Weir (Francis formula)- Q = 0.0184LH-”^2
(b) Contracted Rectangular Weir Q = 0.0184(L-0.1nH) H^/^ zvhere, n= numbers of end contractions
2. Cipolletti weir – trapezoidal weir (slope H: V=l:4) Q=0.0186LH 3/2
3. 90″V notch weir (triangular shape) Q = 0.0138 H’-‘^
k) Bernoulli’s theorem is application of the law of conservation of energy to fluid flow.
l) Total energy (head) = Pressure energy (head) + Velocity energy (head) + Elevation head energy
m) Darcy’s law is applicable to groundwater flow and drainage problems,
n). Hydraulic radius is ratio between the cross-section (a) of the stream and its wetted perimeter (p).
o). Soil texture refers to the relative proportion of the various size groups of mineral particles in a given.
p). Soil structure refers to the manner in which the soil particles are arranged in groups or aggregates.
q). A typical Si.t loam soil contains about 50% solids, 30% water and 20% air.
r). Clay soils contain more than 40% of clay particles and 45% sand or silt.
s). Hygroscopic water: water held tightly to the surface of soil particles by adsorption forces.
t). Capillary water: water held by forces of surface tension in continuous films around soil particles and capillary space.
u). Gravitational water: water that moves freely in response to gravity and drains out of the soil.
v). Percolation is the downward movement of water through the soil profile.
w). Seepage is the lateral movements of water from water sources such as a reservoir or irrigation canal.
x).Tensiometers, electrical resistance measuring devices and neutron moisture meter are used for measurement of soil moisture.
y). Evaporation is the process of vaporization by which water is transferred into the atmosphere.
z). Transpiration is the discharged of water as vapour into the atmosphere by the leaves and stems of living plants.
Irrigation efficiency is the ratio usually expressed as per cent, of the volume of the irrigation water transpired by plants, plus that evaporated from the soil, plus that necessary to regulate the salt concentration in the soil solution, and that used by the plant tissue to the volume of water diverted, stored, or pumped for irrigation.