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Technical Manual on Conventional and Automated Drip Irrigation

Author(s): Vikas Sharma, Jalgaonkar Bhagyashri Ramesh, Yadvendra Pal Singh, Mukesh Kumar Mehla
Abstract:
Technical Manual on Conventional and Automated Drip Irrigation
(Installation, Operation and Maintenance)
Authors
Vikas Sharma
Ph.D. Research Scholar, Department of Soil and Water Engineering, College of Technology and Engineering, Udaipur, Rajasthan, India
Jalgaonkar Bhagyashri Ramesh
Ph.D. Research Scholar, Department of Soil and Water Engineering, College of Technology and Engineering, Udaipur, Rajasthan, India
Yadvendra Pal Singh
Ph.D. Research Scholar, Department of Soil and Water Engineering, College of Technology and Engineering, Udaipur, Rajasthan, India
Mukesh Kumar Mehla
Ph.D. Research Scholar, Department of Soil and Water Engineering, College of Technology and Engineering, Udaipur, Rajasthan, India
Publication Month and Year: December 2019
Pages: 34
E-BOOK ISBN: 978-81-943354-7-4
Academic Publications
C-11, 169, Sector-3, Rohini, Delhi, India
Website: www.publishbookonline.com
Email: publishbookonline@gmail.com
Phone: +91-9999744933
Preface
Drip irrigation play an important role in conservation of irrigation water and further increases the water use efficiency.
This manual covers all the technique related to drip irrigation in modern agriculture. It includes all inclusive technical details of conventional as well as automated drip irrigation system.
This is anticipated as a laboratory manual for students of irrigation and agricultural engineering. It will provide as practical manual for students of engineering at undergraduate, postgraduate and useful for Ph.D. students of agricultural engineering. In addition, the manual will be a valuable reference to professional and agricultural scientists working in the field of micro irrigation.
It is hope that farmers, undergraduate, postgraduate and Ph.D. students of agricultural engineering will find this manual quite useful. In preparation of this manual, authors have received help, suggestions and encouragement from several individuals. The authors would like to express their gratitude to Dr. Ajay Kumar Sharma, Dean, College of Technology and Engineering and Dr. Mahesh Kothari, HoD, Department of Soil and Water Engineering for their encouragement and providing all necessary support in preparation of this manual. The authors are also grateful to all colleagues of Department of Soil and Water Engineering for their assistance and having useful discussions in preparation of this manual.
We hope that readers would provide the scope for future alteration and improvement of this manual by their valuable comments and suggestions.
Vikas Sharma
Ms. Jalgaonkar Bhagyashri Ramesh
Yadvendra Pal Singh
Mukesh Kumar Mehla
Content
S. No.ChapterPage No.
1.Drip Irrigation System01-04
2.Automated Drip System05-09
3.Design of Drip System10-17
4.Installation and Commissioning of Micro Irrigation18-20
5.Maintenance of Drip System21-25
6.Concept of Crop Water Requirement26-31
References32-32
Chapter - 1
Drip Irrigation System
Drip Irrigation
Drip irrigation is defined as regulated and slow application of irrigation water through dripper or emitters at frequent intervals near the plant root zone over long period of time.
Principals of Drip Irrigation: Mainly drip irrigation system characterized by following features.
Irrigation water is applied at low rate
Water is applied to crop for long period of time
Irrigation water is applied at frequent intervals
Types of drip irrigation system
Emitter/Dripper or Online Drip Systems
This system is widely used in orchards, vineyards, landscaping and nurseries. Emitters or drippers are installed at predetermined spacing on laterals or drip line.
Line Source Drip System
This is an inexpensive plastic hose with built-in orifices spaced along its length It provide a continuous wetted strip and is widely used for row crops such as sugarcane, tomatoes, strawberries, vegetables, cotton etc.
Available with various types of diameters and discharges of coverage.
Benefits of Drip Irrigation
Drip Systems are designed to provide greater operational ease, minimum maintenance and high efficiency. The various advantage of drip irrigation systems are as follows:
Increased Crop Yields: The system facilitates water application at regular interval thereby maintaining optimum or favorable moisture level in the plant root zone for a longer period thus preventing moisture stress or shock associated with other methods of irrigation. This promotes in higher yield & better quality produce.
Water Saving: Water saving is the main advantage of micro/drip irrigation system. In this irrigation system water losses due to evaporation an percolation are minimum which result more water saving over other method of irrigation.
Quality Improvement and Early Maturity: In case of micro/drip irrigation system the damage and losses due to water contact with fruit or foliage are eliminated which, results good quality of produce.
Controls weed Growth, Saving on Fertilizers and Labour Costs: Water is applied directly in the root zone, wetting only a fraction of the soil; inter space between the rows of plants is not allowed to go beyond the root zone. It results in saving of fertilizer.
Improved Disease Control: Disease control is enhanced under micro irrigation system, because the soil moisture and chemical additive levels can be closely controlled. Ideally Suited for difficult terrain and problematic soils & water Micro/Drip irrigation can convert barren land in to productive purpose. Drip irrigation can be used on saline soil even with brackish water for vegetable and fruit production.
Components of Drip Irrigation Systems
Micro/drip irrigation system mainly consist of different types of component which are used for various purpose. In micro/drip irrigation system all components are connected with one another and form a systematic system. The basic components of drip irrigation are as follows.
Water Source
The source of water can be wells, tube wells, canals, river, reservoir etc. On the availability of existing water source, flow of water through either gravity or lift system will be decide.
Pump
The water from the existing water source has to be supplied under appropriate pressure and discharge. This is usually meet out by selecting a right kind of pump. The size of the pump depends on total required discharge and operating head/required head.
Filters
In drip irrigation system, filtration of water is various essential for proper operation of entire system without chocking of various parts.
Sand Filter
In drip irrigation system, drippers or drip line consisting of small holes are being used. If foreign particles, dust particle, leave, algae etc. coming with water are not filtered, they will clog the dripper and drip tape holes resulting in obstructing the water supply to the plants. In sand filters mainly contain silica sand of size 0.7mm to 1.2mm are used as filter media.
Screen Filter
While majority of impurities are filtered by sand filter, minute sand particles and other small impurities pass through sand filter. They are filtered by screen filter, containing screen strainer of size 100 micron, which filters physical impurities and allows only clean water to enter in the system. In present days invert Y type screen filter is mainly used.
Pressure Gauge
Specially developed three way valve arrangement is used to measure the pressure (inlet and outlet) and the gauge is protected against jerks, pressure surge and vibrations.
Ventury/Fertiliser Tank/Fertigation Pump
Liquid/water soluble fertilizers can be given into the root zone directly by injecting the solution with the irrigation water by using ventury or fertilizer pump. This results in full development of roots and crop & prevents wastage of costly fertilizers. Injection device are also used in acid treatment and chlorination, to clean the drip system & to apply other chemicals.
Valves
Micro/drip system is provided with various types of control valves. To control the water pressure, by pass valve is provided before filter. Gate valve is provided to create the pressure difference for the chemigation and fertigation. At the inlet of submain, control valve (ball valve) is provided and at the end of submain, a flush valve is fitted to facilitate regular cleaning of main and submains. Air release valve is installed at the highest point on the mainline to release the entrapped air during start of the system and to break the vacuum during shutdown of system.
Main Line
This is PVc or HDDPE Pipe line used to carry water from water source to submain. Filter is attached with this pipe so as to provide filtered water to submain.
Submain Line
Submain is also a PVC pipe line that supplies water to the laterals on one or both sides of it. Submains are buried at 30-45cm in the soil to enable cultivation operations in the field. Size of submain varies 25 to 45 mm.
Laterals/Drip Line
These are either line source or blind pipe and are made up of LLDPE which is quite flexible and strong. These convey water from submain lines to root zone via drippers. They are spread in open field & their spacing is decided on the basis of row to row distance of the crop.
Drippers
Water coming from the laterals reaches the plant root zone through drippers. Type of crop, soil and crop water requirements are deciding factors for dripper spacing on the lateral. Drippers may be pressure compensating or non-pressure compensating and inline dripper or online dripper depending upon field topography and type of crop required to irrigate respectively.
Flush Valve
At its tail end, flush valve is provided for cleaning of main and submains.
Chapter -2
Automated Drip System
Automation
Automationofanirrigationsystemreferstooperationofthesystemwithnoorminimum manual intervention. The introduction of automation into irrigation system has increased application efficiency and drastically reduced labour requirement.
Components of Drip Irrigation Systems
Time based system
Quantity based system
Moisture sensor based system
Total area to be irrigated is divided into small segments called irrigation blocks or zones and these zones are irrigated in sequence according to the flow of water available from the water source.
In time based system, time is a basis of irrigation. Time of operation is calculated according to volume of water required and the average flow rate of water.
In volume based system, the preset amount of water can be applied in the field segments by using automatic volume controlled metering valves. Sequencing of metering valves can also be done automatically.
The moisture sensing system is the extension of time based system. Operation of irrigation valves are controlled by the moisture sensors placed directly in to the root zone.
Benefits of Automation
Control over the entire irrigation system-Increased yield due to production factors
Conservation of water, labour and energy-No need for manual operation to open and close valves, especially in intensive irrigation processes
Flexibility-Possibility to change frequency of the irrigation and fertilization processes and also to optimise these processes
Precision and Ease in Operation-Precision in providing water-fertilizers proportions; usually the operator is busy with other tasks and therefore misses his time schedule
Adoption of advanced crop systems and new technologies especially new crop systems that are complex and difficult to operate manually
Use of water from different sources and increased efficiency of water and fertilizer use
System can be operated at night, thus all day can be utilized for other agricultural practices
Automation Equipments and Their Applications
Main components of an Automatic Irrigation System are,
Controller
This device is the heart of the automation, which co- ordinates operation of the entire system. The controller is programmed to run different field for their required duration. In some cases moisture sensors are used with it which gives feed back to the controller about field moisture level. The controller has in built 24-hr clock. There is an option to have different scheduling of irrigation for different days of the week. These are mostly multistation controller i.e. they can control 4/6/8/12 and even more number of solenoid valves through this irrigation controller. Other facilities available with the controllers are, Option to connect moisture sensors, temperature sensors, or other sensors having analog output. The some popular irrigation controller are as follows:
The ESP-RZXE Controller
The Pro-C Hydrawise™ combines the power of Wi-Fi-based irrigation management and the convenience of modular functionality into one next-generation controller.
Number of Stations: 4-16
Start Times: 36
Number of Sensor Inputs: 1
Transformer Input: 120 VAC or 230 VAC (international model)
Transformer Output (24 VAC): 1 A
Station Output (24 VAC): 0.56 A
Plate 1: ESP-RZXe irrigation controller
Control Valves
Replacement of conventional manual valve by either solenoid valve or hydraulic valve is necessary for a complete automation.
Hydraulic Valves
These valves are operated on hydraulic pressure. The operation of a hydraulic valve depends on the type of valve and whether it is NC (Normally closed) or NO (Normally open) in principle. A command can be transmitted to these hydraulic valves by means of control tubes and solenoid coil. These solenoid coils are mounted on the main line and connected to the valve by control tubing.
Plate 2: Irrigation controller
Solenoid Valve
Solenoid coil is used to translate electric pulses into hydraulic pulses which enable opening and closing of specific hydraulic valves.These solenoid coil requires 24 V AC input for its operation. Solenoid coil when mounted on the valve are connected to controller by standard wire. The size of the standard wire is the function of the distance between solenoid valve and the controller.
Master Relay
This relay controls function of pump whenever any of the solenoid valve is switched on, one pulse is sent to activate master relay which in turn starts the pump through pump starter.
Plate 3: Solenoid valve 12VAC operated
Programming Schedule and Working of Time Based System
The first step to programme the irrigation system is to determine the duration of irrigation required for each section. The duration of individual valves are fed in the controller along with the system start time. Clock of the controller is set with the current day and time. As the clock of the controller synchronized with the start time of the programme, controller starts sending 24 V AC current to the first solenoid valve in the programme sequence through the wire and also the same current reaches the master relay to start the pump. The solenoid/hydraulic valve, thus activated, comes to open position. As soon as duration of valve no 1. Is over the controller switches valve no.2 and soon the process repeated till all the valves are activated one after the other. When operation of the last valve is over, controller stops sending current to solenoid and master relay, the pump is switched off. The same process is repeated at the next run.
During operation of automated drip irrigation system different types of technical fault and technical occurs in irrigation controller and valve mechanics. Some common trouble shooting regarding irrigation controller and valve are given below along with their remedy.
Chapter - 3
Design of Drip System
The long run and safe operation of drip irrigation mainly depends on their appropriate design procedure with respect to standard formulas
Design Inputs
Drip system are designed to provide high irrigation efficiency and uniform distribution of water and nutrients for high value crops as compared to conventional flood irrigation system. In case a larger system is required by the farmer tailor made to his field conditions it can be designed within allowable discharge variation limit by using following procedure. The inputs required to make a good design of micro irrigation system are as follows:
Layout of the area
Details of the water source and soil type
Agronomical details (plant spacing, crop period, season, canopy, etc.)
Climatic data (rainfall, temperature, evapotranspiration etc.)
A survey questionnaire is provided in the annexure, which can be used to get specific information on above inputs. All the information is not required for designing basic layout of drip System and determining pipe sizes. However by using above information complete micro irrigation system can be designed which will give following outputs:
Design Outputs
Detail layout of the system in the field
Emitter selection and placement
Size and length of mainline, sub main and lateral pipes
Pumping and filtration requirement
Operating Schedule (Irrigation Scheduling)
Bill of material and cost estimate
System design starts with selection of suitable emitter depending on type of crop, water requirement, operating time, soil type, water quality etc. Length and size of lateral is determined from the table based on lateral flow rate, field size etc. Similarly size and length of sub main is determined. Each sub main is individual unit with a control valve. Whole area is then divided in to different sub main units and number of sub main units operating at a time are selected based on existing pumping/water source capacity. Each operating section is decided so that discharge is more or less similar for all the sections. The mainline is then planned connecting all the sub mains by taking shortest possible route and its size is determined from the table based on the flow rate so that frictional head loss is with in limit and total pressure head required for the system is within pump/water source capacity. If there is no pump then pump requirement is worked out from total discharge and pressure head required for the system. Depending on flow rate and water quality suitable filtration device is selected. Total quantity of all the components is calculated from the layout to prepare bill of quantity and cost estimate.
Survey
To prepare accurate layout of any area (size, shape and slope), survey inputs that are required to make a layout(e.g. ABCD) for design of micro irrigation system are described as given below.
Straight Distance: Between points at the corners (e.g. AB, BC, CD & DA). It can be measured with a metallic tape in a straight line with corner points duly identified by putting stones or sticks.
Angle at the Corner: For three cornered area distances of three sides is enough to make the layout. For four-cornered area any one angle has to be measured along with distances of the sides. For five cornered figure two consecutive angles will be required and so on for multiple sides. Distance of 10 meters is marked from the corner on each line forming the angle and then a tie length is measured between these points. The angle then can be determined from the table for tie length and corresponding angle as given in the annex.
Elevation: Slope of the ground surface may be judged with naked eye for small plots wherever possible and taken in to consideration while designing the drip system. If the ground surface is too undulating and slope is difficult to be judged by naked eye, then levels should be taken with leveling instrument and contours drawn on the map to make proper design of the drip system.
Water Source: Position of water source (Tank, well, reservoir, pond, river, stream, existing pump, pipe line etc.) should be marked on the map and following details should be noted.
Size, Volume, flow rate etc. of water source and its height above ground level or depth from ground surface
Pump details for existing pump viz. suction, delivery, actual discharge & head, operating time, pump HP, expected discharge & head etc.
Quality of water, impurities in water (algae, sand/silt etc.). If water analysis report is available it should be enclosed with the survey report or if possible farmer should try to get it analyzed from local laboratory
Agro-Climatic Details: The details of existing crops or crops to be planted should be noted viz. specific area under particular area, crop spacing (plant to plant distance x row to row distance), no of plants and no. of rows, crop duration, expected canopy, rainfall, evapotranspiration etc.
Soil Details: The details of soil quality visible to naked eye should be noted viz. heavy soil or light soil depending on soil texture (proportion of clay, silt & sand). If soil analysis report is available it should be enclosed with the survey report or farmer try to get it analyzed from local laboratory.
Permanent Details: Like farm house, large tree, huge rock etc. should be marked by taking angular measurements from minimum two points so that it can be plotted accurately on the survey plan.
Survey Plan: From above information (1 to 6) plan of the area surveyed can be prepared on 1: 1000 scale. For smaller area scale can be used depending on size of the area. Design of drip system (layout) can be prepared on this plan and then it can be used for installation purpose.
Water Requirement
Water Requirement of plants depends on many factors viz. temperature, humidity, soil type, wind velocity, growth stage, shade/sun etc. Plants absorb soil moisture and transpire it to the atmosphere during the process of photosynthesis. Some amount of water is retained in the plant tissue and rest of the soil moisture gets evaporated to the atmosphere. Drip Irrigation involves frequent application of water, even on a daily basis. Therefore water requirement of the plant per day is equivalent to the rate of potential evapotranspiration (PET) per day. Evapotranspiration is the quantity of water transpired by the plants plus quantity of water retained in the plant tissue and water evaporated from the soil surface. The values for reference evapotranspiration are normally available for particular area at the nearest meteorological observatory.
Water requirement can be calculated as:
WR (Liters per day) = ET x Kc x Cp x Area
Where,
ET is evapotranspiration (mm per day)
Kc is crop factor
Cp is canopy factor
Area in sq. meter
If specific crop factor values are not available then it can be assumed as one.
Canopy factor is the percentage area covered by plant canopy (foliage). It varies as per the growth stage of the plant. Area in case of orchard plant is the multiplication of the distance from plant to plant (m) and distance from row to row (m). In case of row plantation unit area can be taken to calculate water requirement.
Example: Calculate Peak water requirement for grapes planted at the spacing of 2 m by 2m. Assume peak ET for the area as 6 mm per day, crop factor for grape 0.8 and canopy factor 0.8.
Water requirement per day = 6 x 0.8 x 0.8 x 2 x 2
= 15.36 liters per day per plant
It is called as peak water requirement because it is calculated on the basis of highest rate of evapotranspiration which normally occurs in high temperature and windy conditions in summer. However daily water requirement will depend on daily rate of evapotranspiration. It will be less during winters and more in summer. The drip system has constant discharge at the given pressure. Therefore operating time can be varied to provide required amount of water depending on the season.
Operating Time/Irrigation Scheduling
Operating (Irrigation) time is the duration for which the irrigation system is run to provide required amount of water for the plants. It can be calculated as following:
Irrigation time (hrs / day)=(Water requirement (liters per day))/( Application rate (liters per hour))
Example: 1
Calculate Irrigation time for a mango tree with daily water requirement of 10 liters per day per plant and provided with microtube system with discharge rate of 4 liters per hour.
Irrigation time (hrs/day)=10/( 4)= 2.5 hrs/day
Example: 2
Calculate Irrigation time for a okra plot of size 100 sq. meter with daily water requirement of 400 liters per day and provided with microtube system with discharge rate of 200 liters per hour.
Irrigation time (hrs/day) =400/( 200)= 2hrs/day
Selection of Emitter
Emitter is the most important part of a drip system through which water is delivered at desired rate to the plant and uniformity of water application is maintained all over the irrigated area. Therefore an emitter should match particular conditions existing at the field viz. type of crop, spacing of the plants, terrain, water requirement, water quality, operating time, pressure head etc. Some of the criteria that can be applied to the selection of dripper are given below:
Reliability against clogging and malfunctioning
Emission Uniformity
Simple to install and maintain
Permissible variation of pressure head (Pressure compensating in case of undulated terrain)
Percentage area wetted
Flow rate
Operating pressure
Cost
Design of Lateral
The most of the drip systems LLDPE laterals of 12 mm and 16 mm size are used. For micro tube system 12 mm LLDPE lateral is used and for Baffle hole drip system 8 mm PVC lateral is used. There are some important points to be considered while designing the lateral pipe as given below:
If the average slope of the field is less than 3% in the direction of the lateral, it can be used at equal length on both sides of sub main pipe
If the slope of the field is more than 3% laterals should be used along the contours as far as possible
If it is not possible to use laterals along the contours on sloping surface due to plant spacing etc., the length of laterals on downside of the sub main should be more than laterals on the upside. For higher slopes laterals only on downside should be used
It is important to find out how long a lateral can be used on each side of the sub main so that variation in discharge due to friction loss is within allowable limit. The desirable limit for emitter flow variation is less than 10% but depending on the crop, variation of 10 to 20% is acceptable. For 10% variation in discharge, approx. 20% variation in the available head is acceptable. Accordingly allowable length of lateral can be calculated from flow equations like Hazen-Williams (using C = 150) as given below:
Where Hl is pressure loss due to friction (m),
Hl = 5.35 × Q1.852/( D 4.871) × LQ is total discharge of lateral (lps),
L is length of lateral (m) & D is inside diameter (cm).
Design of Mainline and Submain Line
The layout of mainline and submain depends upon physical factor like shape and size of the area, other obstacles and topography of field. In design of mainline and submain line the calculation of head losses in pipe are most important factor. The head losses in pipe mainly calculated by following formula:
Darcy-Weisbach
h=f (lv^2)/2gd
Where,
F = Friction factor
L = Length of pipe
D = Diameter of pipe
f=0.3164/Re^0.25 (For turbulent flow)
f=64/Re(For laminar flow)
Willian-Hazen
The William-Hazen equation for smooth pipe (using C=150 usually for plastic pipe) is as follows;
h = 15.27 ×Q^1.852/D^4.871 × l
Where,
H = Head loss in m
Q = Total discharge in lps
L = Length of pipe in m
D = Internal diameter of pipe in cm
When C is given, the total head loss can be calculated by following equations;
h=K(Q/C)^1.852×D^(-4.871)×l ×F
Where,
H = Head loss in m
K = Constant (1.21 〖×10〗^10)
Q = Total discharge in lps
L = Length of pipe in m
D = internal diameter of pipe in mm
F = Outlet factor
C = Coefficient of friction for continuous section
Selection of Filter
Filtration requirement depends on size of flow path in the emitter, quality of water and flow in the mainline. Screen filter is used in case of AMIT Kits as water is stored in a storage tank. For large system, depending on water quality, different filters or combination of filters can be used. For large flow requirements filters can be connected in parallel using manifolds so that pressure loss across the filter is within limit. Four types of filters are mainly available in different sizes (filtration area) as described below,
Screen (Mesh) Filter: It is made of plastic or metal and different sizes are available for different flow rates from 1 m3/hr to 40 m3/hr. It is used for normal water with light inorganic impurities. It is called surface filter.
Sand (Media) Filter: It is made of M.S. metal and available in different sizes similar to screen filter. It is used for water with suspended particles and organic impurities like algae. Either sand or gravel can be used as media for filtration. It is also called as depth filter. It is used in series with the screen filter.
Disc Filter: It is made of plastic and has round discs with micro water path, staked together in a cylinder so that impurities cannot pass through the discs. It gives combination of surface and depth filters.
Hydro-Cyclone: It is made of M.S. metal and has a conical shaped cylinder to give centrifugal action to the flow of water so that heavy impurities settle down. It is used in case of sandy water along with the screen filter.
Selection of Pump/Total Head Requirement
Head (pressure) required at the inlet of the mainline or filter is given below:
Head (m) = Operating pressure (m) + Mainline friction loss (m) + fittings loss (m)+ Filter loss (m) + (-) Elevation difference (m).
In case of centrifugal pump total head requirement is as given below:
Total Head (m) = Suction head (m) + Delivery head (m) + Operating pressure (m) +Mainline friction loss (m) + fittings loss (m) + Filter loss (m) + (-) Elevation difference (m).
Horse Power Requirement:
Horse Power (HP) = ( Flow (lps) x Total Head (m))/( 75 x Motor efficiency x Pump efficiency)
Efficiency of the motor and pump differ for different model and make. Approximately motor efficiency can be taken as 80% and pump efficiency as 75% for mono-block pump. However in order to procure pump from the market, required flow and total head should be mentioned to the supplier/ manufacturer so that he can select suitable model from the same or lower horse power category.
Chapter - 4
Installation and Commissioning of Micro Irrigation
System
The installation of Drip System some basic data are required. These data are collected at the time of survey of the field and then system is designed on technical and commercial parameters.
Following are the various steps in installation of the system:
To collect information of farmer and farm
To survey the field and preparation of rough drawing
To collect and study the agro climatic data i.e. rainfall, temperature, evaporation, sunshine hours etc.
To collect the soil and water samples and analyse them in the laboratory
To make recommendation for chemical treatments
To fix the irrigation and fertigation schedule
To study the inter-relationship between crop, water, soil and agro-climatic factors and accordingly selection of type of system is done
To fix the irrigation and fertigation schedule
To study the inter-relationship between crop, water, soil and agro-climatic factors and accordingly selection of type of system is done
To select the length and diameter of main and submain lines by keeping in view the discharge of well, existing pump capacity, existing pipe line (if any), and peak water requirements of the crop
To suggest proper pump
After studying all the above factors, final engineering design is prepared on computers
After preparing the complete proposal with all technical details, short quotation including major items and assuming certain percentage of fitting and accessories, is submitted to the farmer which indicates ruling prices.
Installation Drip/Drip Tape System can be divided into Three Stage
Fitting of filter station/control valves
Connecting mains and submains
Laying of drip tape or lateral with drippers
Fittings of Filter Station
For sand filter, a hard base or concrete base should be made.
Once the sand/screen filters are installed in the correct position, arrangement of backwash and bypass are done according to farmer's convenience
It is thoroughly checked and ensured that all the fittings are done properly
Mains & Submains Connections
Mains and submains are PVC/HDPE pipe lines. PVC pipelines are laid underground at the depth of more than 1.5 feet so as to avoid damages during intercultivation
First filter fitting is done and then main lines are connected starting from the filter, and followed by the submains as per installation sketch
A ball valve is provided at the inlet of the submain. After the ball valve, an air release valve is provided on the drip tape submain
A flush valve facing the slope of the submain is provided at the end of each submain to facilitate submain flushing
Laying of Drip Tape or Lateral with Drippers
Once the gromate take offs are fixed upon the submain, lateral/polytube laying is done as per the design. For this, holes are drilled on submain pipe, according to the size of gromate take off (GTO) i.e. ø 11.9mm drill for 8mm ID GTO & 16.5mm drill for 13mm ID GTO. Then gromates are fixed in it and on these takeoffs are fixed. Lateral is fixed to one end of take off
Lateral placement is done according to row distance, with sufficient shrinking allowance and extra lateral provided at the end
Drip tape should be laid straight. Its outlets should always face upwards
Drip tape should be in between two crop rows and that too in the centre exactly. Otherwise, one row would receive more water and the another less
Commissioning
After installation, the testing/commissioning should be done in the following way
Backwash the sand filter for the removal of dirt, algae, organic matter etc. through backwash valve
See that all the control valves and flush valves are open before testing
Close the flush valve after the submain is completely flushed
When drip tape/laterals are completely flushed, close their ends with the help of end caps
Check the pressure on the gauges installed at the inlet and outlet of the filter
Chapter - 5
Maintenance of Drip System
Periodic Preventive Maintenance Is Very Essential for the successful working of drip irrigation system. Following are the things to be done on daily, weekly and monthly basis, to ensure the proper working of the system.
General Maintenance
Check for lateral/drip tape functioning, wetting zone, leakages of pipes, valves, fittings etc.
Check The Placement of Drippers, in case the placement is disturbed. Put drippers to the proper location by moving the 6 mm extension polytube/Microtube removing excessive snaking
Check for leakages through filter gaskets in the lids, flush valves & fittings etc.
Maintenance of Filtration System
In order to get maximum efficiency and optimum result it is necessary to prevent emitter, sprinkler and laterals from clogging. Hence, filtration system is the heart of irrigation systems. Properly Maintained Filters Will Ensure Maximum efficiency of irrigation systems, by avoiding clogging.
Removal of Sand from Sand Filter
Maintenance of Sand Filters
Over a period, the contaminants in water accumulate and clog more space in the sand bed and thus reduce the efficiency of filter. Daily Backwashing of Yours and Filter is Very Important.
Screen Filter Backwash
Backwash of Sand Filter
Back washing is the process which water flow is reversed and sand bed is lifted and expanded allowing it to release the collected dirt. The dirt is then carried away through back washing valve.
Backwash Flow Should be Adjusted Properly, because excessive backwash flow will lead to removal of sand itself out of the filter and insufficient backwash flow will not clean the sand properly. The sand filter should also be cleaned regularly as follows
Open the lid of sand filter as illustrated
Allow the water to come out through the lid (flow should be such that no sand comes out)
Stitches and Thoroughly By Moving the hand in between the black filter candles without disturbing their positions
Maintenance of Screen Filter
Flushing at scheduled daily interval is necessary to maintain your screen filter. It is recommended to flush your screen filter, if pressure drop more than 0.5Kg/cm2 (5matwater). The pressure difference can be observed by checking inlet and outlet pressure by using a single 3-way control valve.
Flushing can be done by simple opening of the drain valve, allowing the force of water to flush the dirt out through drain valve. It is also necessary to clean the screen at regular interval. Procedure of cleaning is very simple, open the screen filter lid, remove the screen & clean it in flowing water by rubbing with cloth or soft nylon brush cleaning of screen filter.
Submain and Lateral/Drip Tape Flushing
Most of the silt, dirt, foreign bodies coming with water are entrapped and removed by sand and screen filter. Still some silt passes onwards come in sub mains and laterals/drip tapes. Also sometimes algae and bacteria lead to the formation of slime/paste the pipes and laterals/drip tape. To remove these silts and slimes, the submains should be flushed by opening their closed ends. By flushing, even the traces of accumulated salts will also be removed. The flushing can be stopped, once the water coming out is clean
Flushing of Submain and Lateral Pipe
Chemical Treatment
Physical treatment will not remove bacteria or microscopic algae and these can grow within the system at very high rate or can interact with particles silt and clay and form clusters or can catalyst precipitation of salts. Therefore chemical treatment of water either at the source or within the system is the most useful method of preventing or curing such problems. The treatment generally involves use of chlorine or acid intermittently or continuously.
Acidification of Drip Irrigation System
The injection of acid into drip irrigation system is primarily carried out to lower the pH of the irrigation water and prevent the precipitation of salts. Precipitation of salts such as calcium carbonate, magnesium carbonate or ferric (iron) oxide can cause either partial or complete block age of the Drip Systems. Acid may also be used to lower the pH of the water in conjunction with the use of chlorine injection to improve the effectiveness of the chlorine as a biocide. Acid may also be effective in cleaning systems which are already partially blocked with precipitates of salts. The most reliable step for deciding on acid treatment is a water analysis. Soil and water samples are collected during the survey and then analysed to recommend acid or chlorine treatment perthes water quality. Ventury, Fertilizer Pump or Fertilizer Tank is used for chemigation &fertigation
Chlorine Injection
Chlorine may be injected as continuous or intermittent treatment. Either type of injection is effective.
It is very important to treat the system regularly to prevent blockage.
Frequency of treatment depends on the level of contaminants in the water
System should be chlorinated at the time of shut down and prior to use in the next season to keep lateral/drip tape lines sterilized
Continuous Treatment
Chlorine is injected continuously at a level sufficient to maintain the residual free chlorine at the end of the system (i.e. 10 to 20mg/lit).
Common Chlorine Source
Calcium Hypochlorite (Bleaching powder): It is available commercially in a dry form as a powder or as granules. Also known as "Bleaching Powder" and contains 65% freely available chlorine.
A known weight of bleaching powder can be added to the measured quantity of water. It must be stirred vigorously to break the lumps.
Procedure for Chemical Treatments
Example: If water analysis report recommends the mixing of 50ml of HCL with 100 Litres of water and 2" screen filter of capacity 25 m3/hr exists for the drip irrigation system; quantity of acid required will be 4.8 Litres. The volume of water required is (20-4.8) = 15.20 Litres. Prepare the solution of volume 20 Litres by adding 4.8 Litres of HCL in 15.20 Litres of water.
Connect the ventury tube to the manifold of the filter Immerse the suction pipe of venturi tube into the water.
Regulate the main valve of filter manifold gradually in such a way that the suction is created in the suction pipe of ventury
Find out the minimum and maximum pressure and suction rate of ventury
Fix the desired suction rate and pressure
Pass the prepared solution through the ventury into the micro irrigation system
After the treatment is over, shut off the system for 24 hours.
Flush out the whole irrigation system with water after 24 hours.
Precautions
Do not provide acid and Chlorine treatment at the same time
Acid is harmful and it must be handled with care
Never add water into acid, always add acid into water
Ensure equipments used to handle the acid are resistant to corrosion.
Chapter - 6
Concept of Crop Water Requirement
The water requirement of crops is basically is the amount of water that is required to fulfill the evapotranspiration rate so that crops may thrive. The evapotranspiration rate is the amount of water that is lost to the atmosphere through the plant leaves as well as the surface of soil.
The major climatic factors (see Fig. 4) which influence the crop water needs are:
Sunshine
Humidity temperature
Winds peed
Table 1: Effect of main climatic factors on crop water requirement
Climatic FactorCrop water need
HighLow
TemperatureHot conditionCool condition
Humiditylowhigh
Wind speedHigh windlittle wind
Sunshinesunnycloudy
The highest crop water requirement is found in area which is hot, dry. The lowest values are found when it is cool, humid and cloudy with some wind. The influence of the climate on crop water requirement is given by the Reference Crop evapotranspiration (ETo). The ETo is expressed in mm/day, mm/month, or mm/season. The reference crop which having height 0.12 m, surface resistance 70 sec/m and albedo 0.2.
Methods to Measure the Evapotranspiration Rates of Crops
Pan Evaporation Method
Evaporation pans provide a measurement of the combined effect of temperature, humidity, wind speed and sunshine on the reference crop evapotranspiration ETo (see fig 1).
Fig 1: Pan evaporation method
Many other types of pan are used in India. The best known pans are the Class A evaporation pan (Fig. 1a) and the Sunken Colorado pan (square pan) (Pig. 1b).
Fig 1a: Class a evaporation pan
Fig 1b: Sunken Colorado pan
The principle of the evaporation pan is the following:
The pan is mainly installed in the field
The pan is filled with a fresh quantity of water
The filled water is allowed to evaporate during a certain period of time (usually 24 hours). Each morning at 7 o'clock a measurement is taken. The rainfall, if any, is measured simultaneously
The remaining quantity of water (water depth) is measured after 24 hours
The amount of evaporation per time unit (the difference between the two measured water depths) is calculated; this is the pan evaporation: E pan (in mm/24 hours)
The E pan is multiplied by a pan coefficient, K pan, to obtain the ETo.
Formula: ETo = K pan × E pan
Where,
ETo: Reference crop evapotranspiration
E pan: Pan evaporation
K pan: Pan coefficient
If the depth of water in the pan reduces too much (due to lack of rain), water is added and the before and after the water is added the water depth is measured.
The Penman-Monteith Equation
The reference evaporation rate, ET0, is calculated using the Penman Equation by using different climatic parameters of temperature, solar radiation, wind speed and humidity.
Where
ETo = Reference evapotranspiration [mm day-1]
G = Soil heat flux density [MJ m-2 day-1]
Rn = Net radiation at the crop surface [MJ m-2 day-1]
u2 = Wind speed at 2 m height [m s-1]
T = Air temperature at 2 m height [°C]
es = Saturation vapour pressure [kPa]
ea = Actual vapour pressure [kPa]
es - ea = saturation vapour pressure deficit [kPa]
G = Psychrometric constant [kPa °C-1]
D = [slope vapour pressure curve [kPa °C-1]
Growth Stages for CWR
The crop water requirement mainly depends on crop growth stage. The stage of crop growth indicates phonological properties of plant and their duration after germination. Basically the growing period of plant divided in to three stage which is given below:
The Initial Stage: This is the period from sowing or transplanting until the crop covers about 10% of the ground.
The Crop Development Stage: This period starts at the end of the initial stage and lasts until the full ground cover has been reached (ground cover 70-80%); it does not necessarily mean that the crop is at its maximum height.
The Mid-Season Stage: This period starts at the end of the crop development stage and lasts until maturity; it includes flowering and grain-setting.
The Late Season Stage: This period starts at the end of the mid-season stage and lasts until the last day of the harvest; it includes ripening.
Determination of Crop Factors for Estimation of CWR
To find out the crop water requirement crop coefficient at different stage plays an important role. The Kc values for each of the four growth stages of different crops are summarized in following table.
Table 2: Values of the crop factor (kc) for various crops and growth stages
CropInitial StageCrop Dev. StageMid-Season StageLate Season Stage
Barley/Oats/Wheat0.350.751.150.45
Bean, green0.350.701.100.90
Bean, dry0.350.701.100.30
Cabbage/Carrot0.450.751.050.90
Cotton/Flax0.450.751.150.75
Cucumber/Squash0.450.700.900.75
Eggplant/Tomato0.450.751.150.80
Grain/small0.350.751.100.65
Some Important Terminology
Irrigation: It is the artificial application of water to the soil in order to maintain optimum moisture content for plant growth.
Capillary Water: Water which is retained by a soil due to force of surface tension after draining all gravitational water. This water resides in the pore of soil where capillary forces balance gravity forces such that a negligible amount of further drainage of water takes place. This water is available for beneficial use of plant and exists in the soil under suctions in the range of 0.1 to 31 bars.
Evapotranspiration: It is combined losses of water due to crop transpiration and evaporation from the soil surface upon which the crop is grown. Potential evapotranspiration (ET) is basically maximum amount of evapotranspiration.
Effective Rainfall: The portion of a rainfall after initial losses that is effectively used by the plant is known as effective rainfall. During a rainfall event, some part of the rain water will run off the surface of the soil, or percolate through the bottom of the root zone and get trapped in the foliage. This amount of water is not available for plant growth and, therefore, is not taken as effective rainfall.
Gravitational Water: Water that moves into, though, or out of a soil under the influence of gravity forces. Gravitational water drains rapidly from the soil and is not considered to be available for plant use. Generally, this water exists in a soil profile at suctions less than field capacity (i.e. less than approximately 0.1 to 0.33 bars).
Hygroscopic Water: Water that is highly bound to the soil particles at suctions greater than 31 bars. This portion of irrigation water cannot be used by plants.
Irrigation Interval: The time duration in days between the start of successive irrigations.
Precipitation: It is defined as all form of water that comes from atmosphere on the soil surface is known as precipitation. The some form of water is rain, sleet, hail, snow, or mist (fog). The noun form of the term precipitation is generally associated with the depth or volume of water that fell over a unit area.
Soil Water Terms
Field Capacity (FC): The water content of the soil in the root zone of crop after most gravity drainage has occurred, generally 24 to 48 hours after irrigation, or in the range of 0.10 to 0.33 bars suction.
Permanent Wilting Point (PWP): It is also called the wilting point, PWP is the water content of the soil in the root zone of crop when the crop can no longer extract water from the soil. When soil water contents goes down from this level, then damage of crop occurred. Soil suctions at PWP are generally greater than 15 bars.
Total Available Water (TAW): The total water in the root zone of crop that is available for beneficial use by crop. TAW is the difference between field capacity (FC) and the permanent wilting point (PWP) multiplied by the depth of the root zone.
Deep Percolation: It is the volume of water that drains vertically through the bottom of the crop root zone such that it is lost with respect to potential crop use.
Infiltration: It is a just entry of water in to the soil.
References
American Society of Agricultural Engineers. 1985. ASAE Standards. ASAE EP405. ASAE, St. Joseph, Michigan.
Kaur, M., Sharma, V., Singh, Y.P. and Paradkar, V.D. 2019. Effect of Textile Waste Water on Seed Germination and Some Physiological Parameters in Vegetable Crop under Drip Irrigation. Int. J Curr. Microbiol. App. Sci. 8(07):2006-2009.
Margdarshika. 2017. JISL, MH.
Sharma, V., Singh, Y.P., Gunjan P., Singh, P.K..2017. Effect of Different Level of Irrigation on Biometric Parameters and Estimation of Crop Water Requirement for Summer Rice Crop under Drip Irrigation in Tarai Region of Uttarakhand, Int. J. Pure App. Biosci. 5(6):730-739. doi: http://dx.doi.org/10.18782/2320-7051.6050
Sharma, V., Gunjan, P., Singh, Y.P. and Singh, P.K. 2019. Growth, Yield and Yield Contributing Factors of Rice Crop as Influenced by Different Level and Methods of Irrigation in Tarai Region of Uttarakhand, India. Int. J. Curr. Microbiol. App. Sci. 8(04): 1088-1098. doi: https://doi.org/10.20546/ijcmas.2019.804.126
Sharma, V, Singh, P.K, Bhakar, S.R, Yadav, K.K. & Lakhawat, S.S. (2019). Integration of Soil Moisture Sensor Based Automated Drip Irrigation System for Okra Crop. Indian Journal of Pure and Applied Biosciences. 7(4), 277-282.
Sharma, V., Singh, P.K & Singh, Y.P. (2019). Application of Moisture Sensor with Micro Irrigation for Water Conservation in Smart Irrigation and Precision Agriculture, proceeding of all India seminar organized by The Institution of Engineer at Kota.
Yadav, D, Awasthi, M.K., Nema, R.K. 2017. Estimation of Crop Water Requirement of Micro Irrigated Orchard Crops for different Agro-Climatic Conditions of Madhya Pradesh. Int. Arch. App. Sci. Technol, 8 (3): 18-24.
About The Authors
Vikas Sharma is Ph.D. Scholar of the Department of Soil and Water Engineering, College of Technology and Engineering, Maharana Pratap University of Agriculture and Technology, Udaipur. He did his B. Tech. (Agriculture Engineering) from Uttar Pradesh Technical University (UP) and M. Tech. (Irrigation and Drainage Engineering) from College of Technology, G.B Pant University of Agriculture and Technology, Pantnagar. He has qualified GATE 2014, AIEEA-PG 2014 and ASRB-NET in year 2018. Mr. Vikas Sharma was awarded with Bronze Medal for standing third in order of merit in B.Tech (Agricultural Engineering) in year 2014. He has published 11 papers, 10 abstracts and 4 articles in various journals and proceedings. He is a Member of Indian Society of Agrometeorologist, Anand.
Jalgaonkar Bhagyashri Ramesh is PhD Scholar of the Department of Soil and Water Engineering, College of Technology and Engineering, Maharana Pratap University of Agriculture and Technology, Udaipur. Ms. Jalgaonkar Bhagyashri Ramesh did her B. Tech. (Agriculture Engineering) from College of Agricultural and Engineering, Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth, Dapoli (MS) and M. Tech. (Irrigation and Water Management Engineering) CTAE, MPUAT, Udaipur. Ms. Jalgaonkar Bhagyashri Ramesh was awarded with Jain Irrigation Medal for standing second in order of merit in M. Tech. (Irrigation and Water Management Engineering) in year 2017. She has published 3 papers, 5 abstracts and 3 articles (Marathi language) in various journals and proceedings. She is Life Member of Indian Society of Agrometeorologist, Anand and Indian Society of Agricultural Engineers, New Delhi.
Yadvendra Pal Singh is Ph.D. Research Scholar of the Department of Soil and Water Engineering, College of Technology and Engineering, Maharana Pratap University of Agriculture and Technology, Udaipur. Mr. Yadvendra Pal Singh obtained his B. Tech (Agricultural Engineering) from Uttar Pradesh Technical University, Lucknow and M. Tech. (Irrigation and Drainage Engineering) from College of Technology and Engineering, G. B. Pant Agriculture University, Pantnagar (Uttarakhand). He has published 12 papers and 8 abstracts in various journals and proceedings. He has also Co-author and author of three book Chapters related subjective. He is Life Member of Indian Society of Agro meteorologist, Anand
Mukesh Kumar Mehla is Ph.D. Scholar in the Department of Soil and Water Engineering, College of Technology and Engineering, Maharana Pratap University of Agriculture and Technology, Udaipur. He did his B.Tech. (Agricultural Engineering) and M. Tech Agril. Engg. (Soil and Water Engineering) from College of Agricultural Engineering and Technology, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana, India. He has been Awarded ICAR-JRF/SRF (PGS) fellowship during Ph.D. He has qualified GATE 2017, AIEEA-PG 2017 and AICE-JRF/SRF (PGS) 2019. He has published 3 papers in various journals and 8 abstracts in conference proceedings. He is Life Member of Indian Society of Agricultural Engineers, New Delhi.
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