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Farm Irrigations Systems Design Manual

Author(s): Mukesh Kumar Mehla, Yadvendra Pal Singh, Jalgaonkar Bhagyashri Ramesh, Vikas Sharma
Abstract:
Farm Irrigations Systems Design Manual
Authors
Mukesh Kumar Mehla
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
Jalgaonkar Bhagyashri Ramesh
Ph.D. Research Scholar, Department of Soil and Water Engineering, College of Technology and Engineering, Udaipur, Rajasthan, India
Vikas Sharma
Ph.D. Research Scholar, Department of Soil and Water Engineering, College of Technology and Engineering, Udaipur, Rajasthan, India
Publication Month and Year: January 2020
Pages: 62
E-BOOK ISBN: 978-81-944644-4-0
Academic Publications
C-11, 169, Sector-3, Rohini, Delhi, India
Website: www.publishbookonline.com
Email: publishbookonline@gmail.com
Phone: +91-9999744933
Preface
“Farm Irrigations Systems Design Manual” is primarily intended for students of Agricultural Engineering, Agriculture and Horticulture for understanding the different methods of irrigation used on farm and their design. This manual will also be valuable for reference to professionals, extension workers and agrarians working in the field of agriculture. There are number of people who helped in preparation of this manual, authors are obliged to thank everyone who in one way or other helped creation of this manual through their support, help, suggestions and encouragement.
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 indebted to all colleagues of Department of Soil and Water Engineering for their support 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.
Mukesh Kumar Mehla
Yadvendra Pal Singh
Jalgaonkar Bhagyashri Ramesh
Vikas Sharma
Index
S. NoChapterPage No.
1.Introduction01-07
2.Irrigation Requirement08-15
3.Design of Basin Irrigation16-19
4Design of Furrow Irrigation20-22
5.Design of Border Irrigation23-26
6.Design of Sprinkler Irrigation System27-40
7.Design of Drip Irrigation System41-49
8.Fertilizer Application in Irrigation System50-52
9.Modern Advances in Irrigation53-57
References58-59
Further Reading60-60
List of Figures
S. NoFiguresPage No.
1.Different Methods of Irrigation03
2.Phases of Surface Irrigation Event04
3.Schematic Representation of the Water Balance09
4.Schematic of a Unit Volume of Soil10
5.Phase Relations (Vs = 0)12
6.Schematic Representations of Field Capacity and Permanent Wilting Point Soil Moisture Content13
7.Pressure Profile in a Lateral Laid Uphill33
8.Representation of Tensiometer Working (a) and in Onion Field (b)54
9.Controller Box of the Automatic Irrigation System54
10.Different Components of the Automatic Irrigation Systems55
List of Tables
S. NoTablesPage No.
1.Irrigation Efficiencies for Different Methods of Irrigation (Percentage)02
2.Basin Areas for Different Soil types and Rates of Water Flow (Booher, 1974)18
3.Maximum Width of Basin or Terrace Based on Land Slope (Booher, 1974)18
4Maximum Furrow Lengths Based on Slope, Stream Size, Soil Type, and Net Irrigation Depth (Booher, 1974)21
5.Recommended Furrow Spacing Based on Soil Type21
6.Maximum Border Lengths and Widths24
7.Typical Values of C for use in Hazen-Williams Equation31
8.General Guidelines for Understanding the Meaning of Tensiometer Reading54
Chapter - 1
Introduction
Concept of Irrigation
We have seen great expansion in use of land and water resources in recent time with ever increasing population depending upon agriculture for food, which make sustainable use of the same a big priority. Historically, number civilizations have been dependent on irrigated agriculture and have flourished in presence of sustainable system of irrigation to ensure food security for them consequently due to limitations in understanding the complex soil-water-plant relationships which were either completely ignored or due lack of planning, the productivity of irrigated agriculture declined eve leading to fall of civilisations. The ancient civilization of Mesopotamia flourished in the Tigris-Euphrates valley 6000 years ago and then stumbled when the soil became saline due to poor irrigation practices and a lack of proper drainage. Availability of a reliable and suitable supply of water for agriculture can result in enormous improvements in agricultural production and productivity. Along with that effective agronomic practices like as fertilization and crop rotation should be followed also soil reclamation and management, erosion control, and drainage practices must applied according to local needs. But better water management is the key to a success of an irrigation project.
Irrigation water management is done with main objective maximizing the efficiencies and minimize the labour and other costs while maintaining a favourable environment for growth of the plant. This depend on type of irrigation system (sprinkle, drip, or surface irrigation) and the design of the system, and other factors like the reuse of field tail water, soil type, topography, frequency of irrigation, depth of water to be applied, and measures to increase the uniformity of applications such as land levelling or shaping.
Selecting a suitable irrigation method
Various methods can be employed to supply irrigation water to plants and each method has its inherent advantages and disadvantages. These should be taken into account when choosing the appropriate method best suited to given field conditions and circumstances. There are a large number of considerations that should be taken into account when selecting an irrigation system. These considerations vary in importance depending on location and crop to be grown the factors like topographic limitations, soil properties, land preparation, economics (expected life, fixed and operational costs), cultivation and harvesting practices etc. For instance, some sprinkler systems can be operated on slopes up to 20% or more, but furrow or border irrigation is usually limited to a maximum slope of around 2 to 6%. Drip irrigation can be used on slopes up to 60%. Similarly, soil characteristics like soil type, soil moisture-holding capacity, the intake rate, and effective soil depth are also criteria for selecting suitable irrigation system for example, sandy soils having a high intake rate will require high-volume sprinklers but that would be unacceptable for a clay soil. The moisture-holding capacity will influence the size of the irrigation sets and frequency of irrigation, as evidenced by in case of sandy soil which has low moisture-holding capacity and requires light applications of water at frequent interval. There are numbers of factors that should be considered when selecting suitable type of irrigation system and selection should be made such that it will be most advantageous for the particular situation.
Table 1: Irrigation Efficiencies for Different Methods of Irrigation (Percentage)
Irrigation EfficienciesMethods of Irrigation
SurfaceSprinklerDrip
Conveyance efficiency40-50 (canal)/60-70 (well)100100
Application efficiency60-7070-8090
Surface moisture evaporation30-4030-4020-25
Overall efficiency30-3550-6080-90
Types of irrigation methods
Irrigation is the purposeful application of water in suitable amount of water that promotes normal plant growth and development. It is purposeful in the sense that it is carefully planned in advance based on the concept of application of the ‘right amount’ of water at the ’right time’ through the ‘best and appropriate method’ for given field condition, type of crop, level and type of technology, required depth of application, required labour, inputs, and economy etc. Different irrigation methods frequently used are given in Figure 1.
Fig 1: Different Methods of Irrigation
Surface irrigation
The term "surface irrigation" refers to a broad class of irrigation methods in which water is distributed over the field by a free-surface, gravity flow. A flow is introduced at a high point or along a high edge of the field and allowed to cover the field by overland flow. The rate of coverage is dependent almost entirely on the quantitative differences between inlet discharge and the accumulating infiltration. Secondary factors include field slope and length as well as surface roughness. The practice of surface irrigation is thousands of years old and together the different methods of surface irrigation represents are the ones most commonly used today.
They can be broadly classified into:
Basin irrigation
Border irrigation
Furrow irrigation
Flood irrigation
As noted previously, there are two features that distinguish a surface irrigation system:
The flow has a free surface responding to the gravitational gradient
The on-field means of conveyance and distribution is the field surface itself
Surface irrigation is the application of water to the surface of the field by gravity flow. The flow is introduced at one side of the field until the whole field is gradually watered. This can be done either by flooding the entire field at once, or by feeding water into small area.
A surface irrigation event is composed of four phases as illustrated vividly in Figure 2. When water is applied to the field, it 'advances' across the surface until the water extends over the entire area. It may or may not directly wet the entire surface, but all of the flow paths have been completed. Then the irrigation water either runs off the field or begins to pond on its surface. The interval between the end of the advance and when the inflow is cut off is called the wetting or ponding phase. The volume of water on the surface begins to decline after the water is no longer being applied. It either drains from the surface (runoff) or infiltrates into the soil. For the purposes of describing the hydraulics of the surface flows, the drainage period is segregated into the depletion phase (vertical recession) and the recession phase (horizontal recession). Depletion is the interval between cut off and the appearance of the first bare soil under the water. Recession begins at that point and continues until the surface is drained.
Fig 2: Phases of Surface Irrigation Event
Advantages of surface irrigation methods
Requires minimal understanding for effectively operating and maintaining the system
Can be easily developed at the farm level and requires Minimal capital investment
Doesn’t require complicated and expensive equipment
Lower operation and maintenance costs
The control and regulation structures are simple, durable and easily constructed
Better able to utilize water supplies that are available less frequently, more uncertain, and more variable in rate and duration
Disadvantages of surface irrigation methods
Loss of water through deep percolation
Loss of nutrients through leaching beyond root zone
Ground water pollution through leaching of agrochemicals beyond root zone
Surface water pollution through runoff water
Salinization/alkalization of soil
Plant suffers from water stress due to both water scarcity and water logging
Nutrient uptake may not be ideal due to unfavorable soil water regime in the root zone
Plant is more susceptible to soil borne diseases
More Insect pest attack
Labor intensive
Less efficient than pressurized irrigation systems
Flood irrigation
Flood irrigation is a practice in which an entire field is covered with water. It is the conventional method of irrigation in India and can be highly inefficient where flow rates are inadequate to complete the irrigation quickly. The inefficiency is due to deep drainage below the root zone. Flood irrigation also causes temporary waterlogging, with adverse effects on crops like wheat, maize, and legumes. Waterlogging is more prolonged and more severe on heavy textured soils, and on soils used for rice culture because of the well-developed, shallow, hard pan (low permeability) as a result of puddling.
Basin irrigation
Basins are flat areas of land, surrounded by low bunds. The bunds prevent the water from flowing to the adjacent fields. Basin irrigation is commonly used for rice (paddy) grown on flat lands or in terraces on hillsides. Trees (e.g. citrus, banana) can also be grown in basins, where one tree is usually located in the middle of a small basin (check basin). This method is suitable for crops that are unaffected by waterlogging over longer periods.
Furrow irrigation
Furrows are small channels, which carry water down the land slope between the crop rows. Water infiltrates into the soil as it moves along the slope. The crop is usually grown on the ridges between the furrows. This method is suitable for all row crops and for crops that cannot stand in water for long periods (e.g. 12-24 hours).
Border irrigation
Borders are long, sloping strips of land separated by bunds. They are sometimes called border strips. A sheet of water flows down the slope of the border, guided by the bunds on either side. When the desired amount of water has been delivered to the border, the stream is turned off. However, if the flow is stopped too soon, there may not be enough water in the border to complete the irrigation at the far end. If it is left running for too long, the water may run off the end of the border and be lost in the drainage system. Borders can be up to 800 m or more in length and 3-30 m wide depending on a variety of factors.
Border slopes should be uniform, with a minimum slope of 0.05% to provide adequate drainage and a maximum slope of 2% to limit problems of soil erosion. Deep homogenous loam or clay soils with medium infiltration rates are preferred. On heavy clay soils, border irrigation may cause problems because of the low infiltration rates (basin irrigation is more suited on these soil types). Close growing crops such as pasture or alfalfa are preferred.
Sprinkler irrigation
In the sprinkler method of irrigation, water is sprayed into the air and allowed to fall on the ground surface somewhat resembling rainfall. The spray is developed by the flow of water under pressure through small orifices or nozzles. The pressure is usually obtained by pumping. With careful selection of nozzle sizes, operating pressure and sprinkler spacing the amount of irrigation water required to refill the crop root zone can be applied nearly uniform at the rate to suiting the infiltration rate of soil.
Drip irrigation
It is also called trickle irrigation and involves dripping water onto the soil at very low rates (2-20 litres/hour) from a system of small diameter plastic pipes fitted with outlets called emitters or drippers. Drip irrigation system delivers water to the crop using a network of mainlines, sub-mains and lateral lines with emission points spaced along their lengths. Each dripper/emitter, orifice supplies a measured, precisely controlled uniform application of water, nutrients, and other required growth substances directly into the root zone of the plant. Water is applied close to plants so that only part of the soil in which the roots grow is wetted, unlike surface and sprinkler irrigation, which involves wetting the whole soil profile. With drip irrigation water, applications are more frequent (usually every 1-3 days) than with other methods and this provides a very favourable high moisture level in the soil in which plants can flourish.
Assignment
What are the advantages and disadvantages of surface irrigation methods?
Define and contrast the three methods of surface irrigation.
Give examples when to use or employ each method.
Summarize briefly the design criteria of the three surface irrigation methods.
Chapter - 2
Irrigation Requirement
The irrigation systems are usually not expected to supply all of the moisture required for the crop production. Doing so would ignore the valuable contribution of other water sources such as rain and thereby force the irrigation systems to be larger and more expensive than required. Definitely we need to maximize the fraction of water that is supplied to be beneficially used, but this fraction or irrigation efficiency cannot be 100% without other serious problems getting developed. For arriving at requirement of water by the plant that needs to be fulfilled by an irrigation system there are four major factors required to be considered:
The concept of water balance in the region encompassing the plant environment.
The body of soil supplying moisture, nutrient, and anchorage for the crop and the associated characteristics of this porous medium.
The crop water requirements, including drainage for aeration and salt leaching.
The efficiency and uniformity of the irrigation system.
Water balance
The employment of a water balance is a useful concept for characterizing, evaluating, or monitoring any irrigation system. A graphical representation of the water balance is shown in Figure 3.
Fig 1: Schematic Representation of the Water Balance
The term ‘water balance’ refers to the accounting of water going into and out of an area. The quantity of water added to, subtracted from, and stored within a set volume of soil during a given period of time is considered. It is assumed that in a given volume of soil, the difference between the amount of water added Win to the soil and the amount of water removed Wout from the soil during a certain period is equal to the change in soil water content ∆W during the same period of time. All quantities in equation are expressed in terms of volume of water per unit area of soil (that is equivalent depth units) during the period considered.
ΔW=Win−Wout
Considering the various individual factors influencing the water balance of the root zone per unit area of field. Thus, the root zone water balance is expressed as:
(ΔS+ΔV) = (RF+IR+UP) − (RO+DP+E+T)
Where,
∆S is change in root zone soil moisture storage
∆V is increment of water incorporated in the plants
RF is rainfall
IR is irrigation water
UP is upward capillary flow into the root zone
RO is runoff
DP is downward drainage out of the root zone
E is direct evaporation from the soil/water surface
T is transpiration by plants
Soil characteristics
Soil characteristics of particular importance to irrigated agriculture include
The capacity of the soil to hold water and still be well drained.
The flow characteristics of water in the soils.
The physical properties of the soil matrix, including the organic matter content, soil depth, soil texture, and soil structure.
Soil chemical properties, including the translocation and concentration of soluble salts and nutrients due to the movement, use, and evaporation of the soil water.
Knowledge of all these relationships and how they influence each other is critical for improving irrigation practices and obtain the best, most efficient use of water. A view of basic representation of a unit volume of soil, which contains solids (soil particles), liquid (water), and gas (air), is shown in Figure 4.
Fig 4: Schematic of a Unit Volume of Soil
Water content (w) is a measure of the water present in the soil expressed as percentage. It is defined as:
w=M_W/M_S ×100
Void ratio (e) is a measure of the void volume. It is defined as:
e=V_V/V_S
Porosity (n) is also a measure of the void volume, expressed as a percentage. It is defined as:
n=V_V/V_T ×100
Degree of saturation (S) is the percentage of the void volume filled by water which is the portion of the pore space filled with water. It is defined as:
S=V_W/V_V ×100
Bulk density (m) is the density of the soil in the current state. It is defined as:
ρ_m=M_T/V_T
Dry density (d) is the density of the soil in dry state. It is defined as:
ρ_d=M_S/V_T
Saturated density (sat) is the density of the soil when the voids are filled with water and Submerged density (') is the effective density of the soil when it is submerged. It is given as:
' = sat - w
Unit weight (γ) of a soil is simply the weight per unit volume.
 =  x g
Bulk unit weight (γm), which is also known as total, wet or moist unit weight. It is the total weight divided by the total volume, and is defined as:
_m=M_t/V_t
Dry unit weight (γd) is the unit weight of the soil when dry. It is given as:
_d=M_s/V_t
Saturated unit weight (γsat) is the bulk unit weight of a soil when it is saturated and Submerged unit weight (γ') is the effective unit weight of a submerged soil, and is given by:
γ' = γ sat - γ w
Where, γw is the unit weight of water, which is 9.81 kN/m3.
Phase relations
Fig 5: Phase Relations (Vs = 0)
w=M_W/M_S =Se/G_S
n=V_V/V_T =e/(1+e)
ρ_m=M_T/V_T =(G_S+Se)/(1+e) ρ_█(&W@&)
ρ_sat=M_T/V_T =(G_S+e)/(1+e) ρ_W
ρ_d=M_S/V_T =G_S/(1+e) ρ_W
Example: A cylindrical specimen of moist clay has a diameter of 38 mm, height of 76 mm and mass of 174.2 grams. After drying in the oven at 105℃ for about 24 hours, the mass is reduced to 148.4 grams. Find the dry density, bulk density and water content of the clay.
Assuming the specific gravity of the soil grains as 2.71, find the degree of saturation.
Solution
Volume of the specimen (Vt) = π x (1.9)2 x (7.6) = 86.2 cm3
Mt = 174.2 g
Ms = 148.4 g
∴ρ_d=M_S/V_T =148.4/86.2 = 1.722 g/cm^3
ρ_m=M_T/V_T =174.2/86.2 = 2.021 g/cm^3
w=M_W/M_S ×100=(174.2-148.4)/148.4×100 = 17.4%
Using,
ρ_d=G_S/(1+e) ρ_W
∴e=((2.71)×(1))/1.722-1.0=0.574
Using,
w=Se/G_S
∴S=((0.174)×(2.71))/0.574=0.821 or 82.1%
Therefore, degree of saturation for the cylindrical specimen is 82.1%.
Soil moisture
Crop growth is retards both in the case of presence of excessive water (waterlogging) or insufficient water in the root zone. The available soil moisture for plant use is held in the range of negative apparent pressure of one-tenth to one-third bar (field capacity) and 15 bar (permanent wilting point). The soil moisture content within this pressure range will vary from 25 cm per meter of soil depth for some silty loams to as low as 6 cm per meter for some sandy soils. A graphical representation of field capacity and permanent wilting point is given in figure 6.
Fig 6: Schematic Representations of Field Capacity and Permanent Wilting Point Soil Moisture Content
Field capacity (Wfc)
It is defined as the moisture fraction of the soil after being allowed to freely drain and further drainage occurs at a very slow rate. For a soil that has been fully irrigated time required to reach filed capacity is approximately 1 day for a "light" sandy soil and 3 days for a "heavy" soil. This corresponds to a soil moisture tension of 1/10 to 1/3 atm (bar).
Permanent wilting point (Wwp)
It is defined as the soil moisture fraction at which plants permanently wilts and application of additional water cannot relieve the wilted condition. This corresponds to a soil moisture tension of 15 atm bar.
Total available water (TAW)
It is given as the difference of the volumetric moisture contents at field capacity and permanent wilting point multiplied by the depth of the root zone (D). It is given as:
TAW = (θfc – θwp) x D
Management allowed deficit (MAD)
It is the degree to which the volume of water in the soil is allowed to be depleted before the next irrigation is applied. It corresponds to a soil moisture content between field capacity and permanent wilting point this is primarily dependent on type of crop and crop growth stage. It is given as:
MAD = f x TAW
Soil moisture deficit (SMD)
It is the depletion of soil moisture below field capacity at the time with respect to a particular soil moisture content (θ) at that time. It is given as:
SMD = (θfc – θ) x D
Infiltration
It is the most crucial factor affecting surface irrigation. This single parameter basically controls not only the amount of water entering the soil, also the advance rate of the overland flow. Infiltration in borders and basins is determined using the Kostiakov equation:
Z= kτa
Where,
Z is the cumulative infiltration in m3/m/m.
τ is the “intake opportunity time” in minutes.
k and a are empirical coefficients.
Evapotranspiration (ET)
Evapotranspiration depends upon climatic conditions, crop variety and stage of growth, soil moisture depletion, and various physical and chemical properties of the soil. Procedure for estimating ET includes two steps first is determining the seasonal distribution of reference crop "potential evapotranspiration", ETp, which can be computed with standard formulae and then ETp is adjusted for crop variety and stage of growth. Other factors like moisture stress can be ignored for the purposes of design computations.
Drainage requirements
Some irrigation water should be applied in excess of the storage capacity of the soil to leach salts from the root region, although this does not have to be achieved during each irrigation event. It can usually be applied on an annual basis. Normally deep percolation occurs under most surface irrigation systems which exceeds the leaching fraction necessary for salt balance. But still some irrigated areas require consideration for drainage to maintain proper salt balance in the root zone.
Assignment
A 75 mm (internal diameter) thin walled sampling tube is pushed into the wall of an excavation and a 200 mm long undisturbed specimen, weighing 1740.6 g, was obtained. When dried in the oven, the specimen weighed 1421.2 g. assuming that the specific gravity of the soil grains is 2.70, find the void ratio, water content, degree of saturation, bulk density and dry density.
(Ans. 0.679, 22.5%, 89.5%, 1.970 g/cm3, 1.608 g/cm3)
Find the weight of a 1.2 m3 rock mass, having a porosity of 1%. Assume that the specific gravity of the rock mineral is 2.69.
(Ans. 31.35 kN)
Chapter - 3
Design of Basin Irrigation
Basins are flat areas of land, surrounded by low bunds. The bunds prevent the water from flowing to the adjacent fields. Basin irrigation is commonly used for rice (paddy) grown on flat lands or in terraces on hillsides. Trees (e.g. citrus, banana) can also be grown in basins, where one tree is usually located in the middle of a small basin (check basin). This method is suitable for crops that are unaffected by waterlogging over longer periods.
Design criteria of basin irrigation
Topography
The basin shall be nearly if not completely level to prevent tailwater. A difference of 6 cm to 9 cm between the highest and lowest elevations may be allowed such that it is less than one-half of the net depth of application.
Soil type
Clay and loamy soils are preferred for basin irrigation. Sandy soils or fine-textured soils that crack when dry shall be avoided because the basin ridge or bund height will be unreasonably high.
Application rate
Irrigation water shall be applied at a rate that will advance over the basin in a fraction of the infiltration time.
Irrigation volume
The volume of water applied shall be equal to the average gross irrigation application.
Intake opportunity time
The intake opportunity time at all points in the basin shall be greater than or equal to the time required for the net irrigation to infiltrate the soil. The longest intake opportunity time at any point in the basin area shall be sufficiently short to avoid scalding and excessive percolation losses.
Depth of water
The depth of water flow shall be contained by the basin dikes.
Design application efficiency
The minimum design application efficiency shall be 70 percent. Thus, the minimum time required to cover the basin shall be 60 percent of the time required for the net application depth to infiltrate the soil.
Basin dikes
Top width of the basin dike shall be greater than or equal to the height of the dike. The settled height shall be at least equal to either the gross application depth or the design maximum depth of flow plus a freeboard of 25 percent, whichever is greater.
Supply ditches
Supply ditches shall convey the design inflow rate of each basin or multiples of the design flow rate where more than one basin is irrigated simultaneously. The water surface in the ditch shall be 15cm to 30 cm above the ground surface level in the basin depending on the outlet characteristics. The ditches shall be constructed with a 0.1 percent grade or less to minimize the number of check structures and labour requirements.
Outlet location
One outlet shall be installed for basin widths of up to 60 m and flow rates up to 0.4 m3/sec. multiple outlets at various locations may be installed depending on the rate of flow require and the width of the basin.
Drainage
Surface drainage facilities shall be provided for basins with low or moderate intake soils and in high rainfall areas.
Erosion
The maximum water flow velocity into the basin shall be less than or equal to 1 m/sec to avoid scouring and erosion.
Agricultural practice
The width of the agricultural machinery or implement to be used in the basin shall be considered in finalizing the width.
Layout of basin irrigation
The design procedure is based on the objective to flood the entire area in a reasonable length of time so that the desired depth of water can be applied with a degree of uniformity over the entire basin. Table 2 shows the suggested basin size for different soil types and flow rates. Values are based on practical experience, and have been adjusted in particular to suit small-scale irrigation conditions. The shape and size of basins are mainly determined by land slope, soil type, flow rate, required depth of application, and farming practices. The main limitation on the width of a basin is the land slope. If the land slope is steep, the basin should be narrow, otherwise too much earth movement will be needed to obtain level basins. Table 3 provides guidance on the maximum width of basins or terraces based on the land slope. The dimensions obtained from tables are the maximum values. Basin can be made smaller than this if required and still be irrigated efficiently with the available stream size or flow rate.
Table 2: Basin Areas for Different Soil types and Rates of Water Flow (Booher, 1974)
Flow rateSoil type
SandSandy loamClay loamClay
l/secm3/secBasin area (m2)
50.00535100200350
100.01065200400650
150.0151003006001000
300.0320060012002000
600.06400120024004000
900.09600180036006000
1200.12800240048008000
1500.1510003000600010000
1800.1812003600720012000
2100.2114004200840014000
2400.2416004800960016000
2700.27180054001080018000
3000.30200060001200020000
Table 3: Maximum Width of Basin or Terrace Based on Land Slope (Booher, 1974)
Slope (%)Maximum width (m)
AverageRange
0.24535-55
0.33730-45
0.43225-40
0.52820-35
0.62520-30
0.82215-30
1.02015-25
1.21710-20
1.51310-20
2.0105-15
3.075-10
4.053-8
Example: Estimating the basin size Estimate the dimensions of a basin, when the soil type is a deep clay loam and the land slope is 1 percent. The available stream size is 30 li/sec.
Solution
From Table 2, the recommended maximum basin area for a clay loam soil with available flow rate of 30 l/sec is 1200m2.
From Table 3, the maximum basin or terrace width for a slope of 1 percent is 25 m (range 15 to 25m).
If the total basin area is 1200 m2 and the width is 25 m, the maximum basin length is 1200/25 = 48m.
The dimensions of the basin shall be 25m x 48m.
Assignment
Estimate the most efficient dimensions (length and width) of the rice paddy (basin irrigation), when the soil type is sandy loam and the average slope is 0.5 percent. The available flow rate from the adjacent NIA irrigation canal is 0.15 m3/sec.
Chapter - 4
Design of Furrow Irrigation
Furrows are small channels, which carry water down the land slope between the crop rows. Irrigation water flows from the field channel into the furrows by opening up the bank of the channel or by means of siphons or spiles. Water infiltrates into the soil as it moves along the slope. The crop is usually grown on the ridges between the furrows. This method is suitable for all row crops and for crops that cannot withstand waterlogging for long periods. There are two types of furrow irrigation systems namely:
Corrugation furrow
Zigzag furrow
In corrugation furrow the water flows down the slope in small furrows called corrugations or rills which is used for germinating drill-seeded or broadcasted crops. The zigzag furrow makes possible to increase the length that the water must travel to reach the end of irrigation run thus, reducing the average slope and velocity of the water. Zigzag furrow irrigation is also suited to the growing of tree crops.
Design criteria of furrow irrigation
Slope
The minimum grade shall be 0.05 percent to facilitate effective drainage following irrigation and excessive rainfall. If the land slope is steeper than 0.5 percent, furrows shall be set at an angle to the main slope or along the contour to keep furrow slopes within the recommended limits.
Soil type
Furrows shall be short in sandy soils to avoid excessive percolation losses; while furrows can be longer in clayey soils.
Stream size
If the furrows are not too long, 0.5 li/sec of stream flow shall be adequate for irrigation but the maximum stream size shall largely depend on the furrow slope.
Irrigation depth
Larger irrigation depths shall allow longer furrows.
Cultivation practice
Compromise shall be made between the machinery available to cut furrows and the ideal plant spacing while ensuring that the spacing provides adequate lateral wetting on all soil types.
Layout of furrow irrigation
Furrows must be in consonance with the slope, stream size, soil type, and net irrigation depth. These factors impact furrow length. Table 4 shows the recommended furrow length based on these parameters.
Table 3: Maximum Furrow Lengths Based on Slope, Stream Size, Soil Type, and Net Irrigation Depth (Booher, 1974)
Furrow Slope (%)Maximum Stream Size (l/sec) per furrowClayLoamSand
Net Irrigation Depth (mm)
507550755075
Furrow Length (m)
0.03.010015060903045
0.13.0120170901254560
0.22.51301801101506095
0.32.015020013017075110
0.51.215020013017075110
However, it may be practical to make the furrow length equal to the length of the field in order to avoid land wastage. Similarly, the length of field may be much less than the maximum furrow length. This is not usually a problem as furrow lengths are made to fit the field boundaries. The spacing of furrows is influenced by the soil type and the cultivation practice. As a rule of thumb, for sandy soils the spacing should be between 30 cm for coarse sand, and 60 cm for fine sand. On clay soils, the spacing between two adjacent furrows should be 75 to 150 cm. As shown in Table 5.
Table 4: Recommended Furrow Spacing Based on Soil Type
Soil typeFurrow spacing (cm)
Coarse Sand30
Fine Sand60
Clay75-150
Example: Determine the length and number of furrows on a relatively flat fine sandy soil when the net irrigation depth is 75 mm applied at a rate of 3.0 l/sec. The field is a rectangle with dimensions of 90 m x 200 m planted lengthwise with tobacco as shown in the figure below.
Solution
From Table 4, the recommended maximum length of furrow is 45 m for a sandy soil that requires 75 mm net irrigation depth application at a rate of 3.0 l/sec.
Since the planting orientation is lengthwise, the furrows should be set along the 200 m length. Thus, the number of furrows along this length is computed as
200 m/45 m = 4.4. Round this off to the next higher whole number, so the number of furrows along this 200 m length = 5 furrows. Therefore, there will be 5 furrows, 40 m long along the 200 m field length.
From Table 5, the recommended furrow spacing for fine sand along the 90 m field width is 60 cm or 0.6 m. Thus, the number of furrows along this width is computed as 90 m/0.6 m = 150 rows of furrows.
If the number of furrows along the 200 m length is 5 and the number of furrows along the width is 150, the total number of furrows in the said field is 5 x 150 = 750.
The field should be provided with 750 furrows having a length of 40 m per furrow, wherein there will be a series of 5 furrows along the 200 m length, and 150 rows of furrows spaced 0.6 m apart along the 90 m width.
Assignment
Determine the length and number of furrows on a 10.0 ha clayey corn field with 0.3 percent slope. The required depth of irrigation water application is 75 mm to be applied at a rate of 0.002 m3/sec. The field is a rectangle with dimensions of 200 x 500 m planted crosswise with corn.
Chapter - 5
Design of Border Irrigation
Borders, sometimes called border strips, are usually long, uniformly graded strips of land, separated by earth bunds. In contrast to flooding or basin irrigation, these bunds are not to contain the water for ponding but to guide it as it flows down the field. Irrigation water can be fed to the border in several ways: opening up the channel bank, using small outlets or gates or by means of siphons or spiles. A sheet of water (called water front) flows down the slope of the border, guided by the bunds on either side. Border strip irrigation comes in two types:
Open-end border system
Blocked- end border system
The open-end border system is usually applied to large borders where the end borders are provided with openings to accommodate free flow of water for drainage. In contrast, the blocked-end border system is usually applied to small borders where the end borders restrict the further downward flow of water.
Design criteria of border strip irrigation
Crop
All close-growing, non-cultivated, sown or drilled crops, except rice and other crops grown in ponded water can be irrigated by border irrigation.
Topography
Areas shall have slopes of less than 0.5 percent. For non-sod crops, slopes of up to 2 percent may be acceptable and slopes of 4 percent and steeper for sod crops.
Soil type
The soil shall have a moderately low to moderately high intake rate which is 7.6 to 50 mm/hr. Coarse sandy soils with extremely high and those with extremely low intake rate shall be avoided.
Stream size
The stream size shall be large enough to adequately spread water across the width of border.
Irrigation depth
A larger irrigation depth shall be aimed by making the border strip longer in order to allow more time for the water to reach the end of the border strip.
Cultivation practices
The width of borders shall be a multiple of the farm machinery used in the field.
Border strip layout
The dimensions and shape of borders are influenced in much the same way as basins and furrows by the soil type, stream size, slope, irrigation depth and other factors such as farming practices and field or farm size. Table 6 provides a guideline to determine maximum border dimensions. It must, however, be stressed that this table is for general guidance only as the values are based on field experience and not on any scientific relationships.
Table 6: Maximum Border Lengths and Widths
Soil TypeBorder Slope (%)Stream Flow (l/sec per m)Border Width (m)Border Length (m)
Sand0.2-0.410-1512-3060-90
Infiltration rate greater than 25 mm/hr0.4-0.68-109-1260-90
0.6-1.05-86-975
Loam0.2-0.45-712-3090-250
Infiltration rate of 10 to 25 mm/hr0.4-0.64-66-1290-180
0.6-1.02-4690
Clay0.2-0.43-412-30180-300
Infiltration rate of less than 10 mm/hr0.4-0.62-36-1290-180
0.6-1.01-2690
Operation
Borders are irrigated by diverting a stream of water from the channel to the upper end of the border where the water flows down the slope. When the desired amount of water has been delivered to the border strip, the stream is turned off. This may occur before the water has reached the end of the border. There are no specific rules controlling this decision. However, if the flow is stopped too soon there may not be enough water in the border strip to complete the irrigation at the far end. If it is left running for too long, then water may run off the end of the border and be lost in the drainage system. As a guideline, the inflow to the border can be stopped as follows:
On clay soils, the inflow is stopped when the irrigation water covers 60 percent of the border. If, for example, the border is 100 m long a stick is placed 60 m from the farm channel. When the water front reaches the stick, the inflow is stopped.
On loamy soils, it is stopped when 70 to 80 percent of the border is covered with water.
On sandy soils, the irrigation water must cover the entire border before the flow is stopped.
Example: Determining border strip width and length, distance of water front from the source and total stream flow. Given a grass pasture on clayey soil with 0.3 percent slope that requires a 3.5 l/sec irrigation water application rate:
What will be the maximum width and length of the open-ended border strip irrigation system?
At what distance in meters the irrigation water would have reached along the direction of flow from the source to downstream so that the flow can be stopped to prevent over-irrigation?
What is the corresponding total stream flow to satisfy the desired irrigation depth?
Solution
From Table 5, the maximum width and length of border strips are 30 m and 300 m, respectively.
From the guidelines in Section D (Operation) above, it is recommended that on clayey soils, the inflow is stopped when the irrigation water covers 60 percent of the border strip length. Thus, the source should be closed when the flow has reached 180 m downstream, that is, 300 m x 0.6 = 180 m.
Per notation for column 3 of Table 5, the stream flow is given per meter width of the border strip. Thus, the total stream flow into a border is equal to the unit flow (the value given in the table) multiplied by the border width (in meters). Hence, the total stream flow = 3.5 l/sec/m x 30 m = 105 l/sec.
The pasture area should be provided with 30 x 300 m border strips with application rate of 105 l/sec, which should be stopped when the water front has reached 180 m downstream.
Assignment
Given a Centrosema forage production area (border irrigation) with loamy soils and 0.25 percent slope that requires a 0.006 m3/sec irrigation water application rate:
What will be the maximum width and length of the open-ended border strip irrigation system?
At what distance in meters the irrigation water would have reached along the direction of flow from the source to downstream so that the flow can be stopped to prevent over-irrigation?
What is the corresponding total stream flow to satisfy the desired irrigation depth?
Chapter - 6
Design of Sprinkler Irrigation System
In the sprinkler method of irrigation, water is sprayed into the air and allowed to fall on the ground surface somewhat resembling rainfall. The spray is developed by the flow of water under pressure through small orifices or nozzles. The pressure is usually obtained by pumping. With careful selection of nozzle sizes, operating pressure and sprinkler spacing the amount of irrigation water required to refill the crop root zone can be applied nearly uniform at the rate to suiting the infiltration rate of soil.
Advantages of sprinkler irrigation
Elimination of the channels for conveyance, therefore no conveyance loss
Suitable to all types of soil except heavy clay
Suitable for irrigating crops where the plant population per unit area is very high. It is most suitable for oil seeds and other cereal and vegetable crops
Water saving
Closer control of water application convenient for giving light and frequent irrigation and higher water application efficiency
Increase in yield
Mobility of system
May also be used for undulating area
Saves land as no bunds etc. are required
Influences greater conducive micro-climate
Areas located at a higher elevation than the source can be irrigated
Possibility of using soluble fertilizers and chemicals
Less problem of clogging of sprinkler nozzles due to sediment laden water
General classification of different types of sprinkler systems
Sprinkler systems are classified into the following two major types on the basis of the arrangement for spraying irrigation water.
Rotating head or revolving sprinkler system.
Perforated pipe system.
Rotating head
Small size nozzles are placed on riser pipes fixed at uniform intervals along the length of the lateral pipe and the lateral pipes are usually laid on the ground surface. They may also be mounted on posts above the crop height and rotated through 90 0, to irrigate a rectangular strip. In rotating type sprinklers, the most common device to rotate the sprinkler heads is with a small hammer activated by the thrust of water striking against a vane connected to it.
Perforated pipe system
This method consists of drilled holes or nozzles along their length through which water is sprayed under pressure. This system is usually designed for relatively low pressure (1 kg/cm2). The application rate ranges from 1.25 to 5 cm per hour for various pressure and spacing.
Based on the portability, sprinkler systems are classified into the following types
Portable system: A portable system has portable main lines, laterals and pumping plant
Semi-portable system: A semi portable system is similar to a portable system except that the location of water source and pumping plant is fixed.
Semi-permanent system: A semi-permanent system has portable lateral lines, permanent main lines and sub mains and a stationery water source and pumping plant.
Solid set system: A solid set system has enough laterals to eliminate their movement. The laterals are positions in the field early in the crop season and remain for the season.
Permanent system: A fully permanent system consists of permanently laid mains, sub mains and laterals and a stationery water source and pumping plant.
Components of sprinkler irrigation system
A sprinkler system usually consists of the following components:
A pump unit
Tubings-main/submains and laterals
Couplers
Sprinkler head
Other accessories such as valves, bends, plugs and risers
Sprinkler system design parameters
Sprinkler discharge considering area of coverage
The actual selection of different components of the sprinkler system is based on specifications furnished by the manufacturers of the equipment. The selection depends on wetting diameter of nozzle, at a given operating pressure at nozzle, sprinkler discharge, combination of sprinkler spacing and lateral moves, application rate suiting to soil and wind conditions. The required discharge of an individual sprinkler is a function of the water application rate and the two-way spacing of the sprinklers. It may be determined by the following equation:
Where,
q = required discharge of individual sprinkler (l/s)
S1 = spacing of sprinklers along the laterals (m)
Sm= spacing of laterals along the main (m)
I = optimum application rate (mm)
Height of sprinkler riser pipes
Sprinklers are located just above the crops to be irrigated and, therefore, the height of the risers depend upon the maximum height of the crop. To avoid excessive turbulence in the riser pipes the minimum height of riser is 300 mm for 25 mm diameter and 150 mm for 15 mm to 20 mm diameter.
Sprinkler spacing
The uniformity of water distribution from sprinklers depends on the operating pressure, wind velocity, rotation of sprinklers, spacing between sprinklers and laterals. The spacing of sprinklers on laterals and the laterals spacing are adjusted for obtaining maximum uniformity for given condition. Greater depth of water accumulate near sprinkler head and depth decreases gradually with distance from the sprinklers. Therefore, there is a necessity of overlapping of the spray pattern of the individual sprinkler, to obtain uniform depth of water application. Sprinklers are arranged along a lateral such that the diameter of the water spread area of sprinkler is overlapped.
Capacity of sprinkler system
The capacity of a sprinkler system is a important design parameter. This is estimated after knowing the total area to be irrigated by a sprinkler irrigation system. The formula to compute system capacity is given by:
Q = 2780 (A×d)/(F×H×E)
Where,
Q = Discharge capacity of the pump (l/s)
A = Area to be irrigated (ha)
d = Net depth of water application (cm)
F = Number of days allowed for the completion of one irrigation
H = Number of actual operating (hours/day)
E = Water application efficiency (per cent)
Sprinkler discharge
The discharge of a sprinkler is estimated by knowing the diameter of nozzle and operating pressure available at the nozzle by following formula:
Q=CA√2gh
Where,
Q = Discharge (cm3 s-1)
C = Sprinkler discharge coefficient which vary from 0.80 to 0.95
A = Cross-sectional area of nozzle or orifice (cm2)
g = Acceleration due to gravity (cm s-2)
h = Pressure head (cm)
Area covered by sprinkler
The area covered by a rotating head sprinkler can be estimated as:
R=1.35√dh
Where,
R = Radius of the wetted area covered by sprinkler (m)
d = Diameter of nozzle (m)
h = Pressure head at nozzle (m)
The maximum coverage is attained when the jet emerges from the sprinkler nozzle at angle between 300 and 320.
Hydraulic design of pipe network
Pipe network in the sprinkler irrigation system consists of the lateral, sub main and main pipeline. The sprinkle nozzles are mounted on the laterals; laterals are connected to the sub main and sub main to the main. Main pipe line takes water from the source through the pump. It is desired to design the pipe network appropriately for uniform water application and economical system cost. As the sprinkler system requires pressure to operate, both uniformity water application and system economy are affected by the frictional head loss through the pipes. Large variation in friction head loss in the lateral or sub main reduces the uniformity in water application on the other hand too small variation results in high uniformity, which requires larger pipe size makes system more expensive. Hence it requires optimal combination of hydraulic and economic consideration. The Hazen-Williams equation is commonly adopted for that and it is given by:
H_f (100)= K (Q/C)^1.852/D^4.87
Where,
Hf (100) = A friction loss per 100 m of pipe (m/100 m)
C = A friction coefficient which is a function of pipe material characteristics
Q = The flow of water in the line (L s-1)
D = The inside pipe diameter (mm)
K = A constant which is 1.22 × 1012 for metric units
Table 5: Typical values of C for use in Hazen-Williams equation
S No.Pipe materialC
1Plastic150
2Epoxy-coated steel145
3Cement asbestos140
4Galvanized steel135
5Aluminum (with coupler every 9.0 m)130
6Steel (new)130
7Steel (15 years old) or concrete100
Allowable head loss in sprinkler pipe
Pressure loss occurs due to friction and joints. This should not exceed practical value. Normally it should be between 15 and 20 per cent of the total head. The recommended practice to design the sprinkler lateral is not to exceed the pressure variation more than 20% of the higher pressure. The difference in elevation head is considered while determining the variation in pressure. This may be paying of laterals in upward slope or down slope. While the lateral is laid on up slope direction, the less pressure is available at the nozzle while lateral laid on down slope direction, the additional pressure is available at the sprinkler nozzle due to gain in energy.
Pipe with multi outlet
When there are no outlets along the length of the lateral or sub main (usually called as closed pipe line or blind pipe), the head loss due to friction can be computed by Hazen-William formula. However, in sprinkler lateral or sub main, outlets along the length of the pipe are given as sprinkler heads or sprinkler laterals as the case may be. Flow of water through the closed or blind pipe of a given diameter causes more frictional head loss compared to that of a pipe with number of outlets along the length of the pipe which is due to the fact that the flow rate decreases with every passing outlet. To accurately compute friction loss in the lateral with multi outlet, start at the last outlet on the pipe line and work back to the head of the pipeline, computing the friction head loss between each outlet for the flow rate between two outlets. In case of multiple outlets, the frictional head loss through the blind pipe is computed for the given flow rate and then multiply with reduction factor (F) due to reducing flow rate. The reduction factor depends on the number of equally spaced outlets on the lateral. Assuming first sprinkler is at the same as other sprinklers located on the lateral, The F can be computed using following expression:
F =
Where,
F = Reduction factor
N = Number of outlets
M = Exponent used in the head loss equation (In Hazen-William’s equation the m = 1.852 and for Darcy’s Weisbach equation m=2)
For N>10, the last term in equation can be omitted.
Jensen and Fratini (1957) modified the above expression for F to account for the first sprinkler being located one-half the sprinkler spacing from the supply line. They assumed that no water flows past the last sprinkler. The modified expression indicates that the F factor is more than 5 percent larger for N<20.
Design of sprinkler laterals
In the design of sprinkler laterals the pressure variation should not exceed more than 20% of the higher pressure. The design capacity for sprinklers on a lateral is based on the average operating pressure.
Fig 7: Pressure Profile in a Lateral Laid Uphill
Source: Michael, 2010
Pressure required at the main to operate the system is given by:
Where,
Ha = Average pressure (m)
Hf = Head loss due to friction in lateral pipe (m)
Hn = Pressure required at the main to operate (m)
He = Maximum difference in elevation between the first and last sprinkler on a lateral pipe (m)
Hr = The riser height (m)
The term is positive if lateral is laid up slope and negative, if lateral is laid down slope
Design of main pipe
Sub main pipe supplies the water to sprinkler lateral and main supplies water to the sub main. If more numbers of sub mains are operated simultaneously at same time (a case for the large field) the procedure described for the design of the lateral may be used. However, when a single sub main is operated, the size of sub main and main pipe line is selected such that the annual operating cost and initial cost of the sub main line and mainline should be low. Normally friction loss of 3 m for small sprinkler system and 12m for large sprinkler systems are used in design of main pipe line.
Pumps and power units
The suitable size of pump is selected considering the maximum total head against which the pump expected to operate and deliver the required discharge. This is be determined by:
Where,
Ht = Total design head against which the pump is working (m)
Hn = Maximum head required at the main to operate the sprinklers on the lateral at the required average pressure, including the riser height (m)
Hm = Maximum friction loss in the main and in the suction line (m)
HJ = Elevation difference between the pump and the junction of the lateral and the main (m)
Hs= Elevation difference between the pump and the source of water after drawdown (m)
The discharge required to be delivered by pump is determined by multiplying the number of sprinklers that are operated at any given instant of time by the discharge of each sprinkler. Once the head and discharge of the pumps are known, the pump may be selected from rating curves or tables provided by the manufacture.
Power requirement of pump
It is given by
h_p=(Q_t×H_t)/(75×n_p )
Where,
Qt = total discharge (l s-1)
Ht = total head (m)
np = efficiency of pump
Example: Design a sprinkler irrigation system to irrigate 5 ha Wheat crop.
Assume the following
Soil type = silt loam, Infiltration rate at field capacity = 1.25 cm h-1, Water holding capacity = 15 cm m-1, Root zone depth = 1.5 m, Daily consumptive use rate = 6 mm day-1, Sprinkler type = Rotating head.
Solution
Step I
Given infiltration capacity =1.25 cm h-1
Hence maximum water application rate = 1.25 cm/h
Step II
Total water holding capacity of the soil root zone = 15 x 1.5 = 22.5 cm
Let the water be applied at 50% depletion, hence the depth of water to be applied = 0.50 x 22.5 = 11.25 cm
Let the water application efficiency be 90 per cent
Depth of water to be supplied = 11.25 / 0.9 = 12.5 cm
Step III
For daily consumptive use rate of 0.60 cm
Irrigation interval = 11.25 / 0.6 = 19 days
In period of 19 days, 12.5 cm of water is to be applied on an area of 5 ha. Hence assuming 10 hrs. of pumping per day, the sprinkler system capacity would be
Step IV
Let the spacing of lateral (Sm) = 18 m,
Spacing of Sprinklers in lateral (Sl) = 12 m
This selection is based on using following consideration:
Operating pressure of nozzle = 2.5 kg cm-2
Maximum application rate = 1.25 cm h-1
For nozzle size (5.5563 x 3.175 mm) operating pressure and application rate is:
Operating pressure: 2.47 kg cm-2 and
Application rate 1.10 cm hr-1 (which is less than the maximum allowable application rate of 1.25 cm h-1)
Diameter of coverage: 29.99 ≈ 30.0 m
Discharge of the nozzle: 0.637 l s-1 = 0.637 x 10-3 m3s-1
Step V
Total no. of sprinkler required = = 14.12 ≈ 14 sprinklers
Considering two sprinkler laterals, therefore 7 sprinklers on each lateral.
Step VI
Using the sprinklers spaced at 12 m intervals on each lateral. The lateral lines will be at 18 m spacing.
Step VII
Total length of each lateral = 12 x 7 = 84
Operating pressure = 2.47 kg cm-2
Total allowable pressure variation in the pressure head is 20%, hence maximum allowable pressure variation in pressure = 0.2 x 2.47 = 0.494 kg/cm2 = 4.94m
Assume pressure variation due to elevation = 2 m
Permissible head loss due to friction = 4.94 – 2 = 2.94 m
Total flow through the lateral = 7 x 0.637 x 10-3 = 4.459 x 10-3 m3s-1
Reduction factor (F) = = 0.333 + 0.071 + 0.0034 = 0.407
Head loss due to friction using Darcy’s weisbach equation and reduction factor.
Hf =
Or 2.94 =
Hence diameter of lateral = 63mm
Assume height of riser pipe =1m
The head required to operate the lateral lines (Hm) = 24.7+2.94+2+1 = 30.6m
Frictional head loss in main pipe line (Hf) = 30.6 0.2 = 6.12m
Calculating in the same way as done in case of lateral
Or
D = 69.10 ≈ 75 mm
Total design head (H) = Hm+ Hf +Hj +Hs
Where,
Hj = Difference in highest junction point of the lateral and main from pump level = 0.5 m (assumed)
Hs = Suction lift (20 m, assumed)
H = 30.6 + 6.12 + 0.5 + 20 = 57.22 m
The pump has to deliver 0.009 m3s-1 of water against a required head of 57.22 m
Hence, the horse power of a pump at 60% efficiency
=
Pump with horse power of 12 Hp would be sufficient for the system.
Uniformity coefficients (Cu):
It is a measurable index of the degree of uniformity obtainable for any size sprinkler operating under given conditions. This uniformity coefficient is affected by the pressure nozzle size relations, sprinkler spacing and by wind conditions. The coefficient is computed from field observations of the depths of water collected in catch cans or collectors placed at regular intervals within a sprinkled area as per procedure described in preceding sections. It is expressed by the equation developed by Christiansen (1942):
Where,
M = Average value of all observations i.e., average application rate (mm)
N = Total number of observation points
X =Numerical deviation of individual observation s from the average application rate (mm)
A uniformity coefficient of 100 per cent (obtained with overlapping sprinklers) is indicative of absolutely uniform application, whereas the water application is less uniform with a lower value of coefficient. A uniformity coefficient of 85 per cent or more is considered to be satisfactory.
Pattern efficiency
The pattern efficiency (also known as distribution efficiency) is calculated with the total depths of water collected at each of the catch cans placed at the grid points. The minimum depth is calculated considering average of the lowest one fourth of the depths collected in catch cans used in a particular test. The pattern efficiency is useful in calculating the average depth to be applied for a certain minimum depth. The pattern efficiency is influenced by the wind conditions. Pattern efficiency is given by:
Application efficiency
The application efficiency is calculated by minimum rate water to the average rate applied. The application efficiency is influenced by the wind conditions. It is given by:
Example: Determine the uniformity coefficient, Pattern and application efficiencies from the following data found from a field test on a square plot bounded by four sprinklers:
Sprinkler nozzle dimension (S)-4.76 x 3.2 mm nozzles at 2.8 kg/cm3
Spacing-16m x 12m, Wind-5 km/hr from south-west
Humidity-49%, Time of test-2 hour
S9.48.17.1S
8.68.110.410.78.8
9.49.69.69.99.4
9.98.49.69.19.6
S8.47.17.3S
Solution
ObservationFrequencyApplication rate x frequencyNumerical deviationsFrequency x deviations
10.7110.71.61.6
10.4110.41.31.3
9.9219.80.81.6
9.6438.40.52
9.4328.20.30.9
9.119.100
8.818.80.30.3
8.618.60.50.5
8.4216.80.71.4
8.1216.212
7.317.31.81.8
7.1214.224
21188.5ΣX=17.4
Mean = 188.5/21 = 8.97
Uniformity Coefficients (Cu) =
= 100 (1- 17.4/21*8.97) = 90.76%
Total catch cans at 21 locations = 188.5 mm in 2 hours
Average catch (188.5/21) = 8.97
Average of the lowest one fourth of the cans (5 out of 21)
= (37.7/5) =7.54 mm or 3.77 mm/hr
Pattern efficiency = (7.54/8.97) *100= 84 percent
Average rate applied = 0.45 cm/hr
Application efficiency = (0.377/0.56) x 100= 83.77 percent
Chapter - 7
Design of Drip Irrigation System
Micro irrigation is frequent application of water directly on or below the soil surface near the root zone of plants. It delivers required and measured quantity of water in relatively small amounts slowly to the individual or groups of plants. Water is applied as continuous drops, tiny streams, or fine spray through emitters placed along a low-pressure delivery system. Such system provides water precisely to plant root zones and maintains ideal moisture conditions for plant growths.
Advantages of micro irrigation
Water saving
Enhanced plant growth and yield
Uniform and better quality of produce
Efficient and economic use of fertilizers
Less weed growth
Also suitable to waste lands
Possibility of using saline water
No soil erosion
Flexibility in operation
Easy installation
Labour saving
Suitable to all types of land terrain
Saves land as no bunds etc. are required
Minimum diseases and pest infestation
Types of micro irrigation system
The basic types of micro irrigation system are as follows:
Surface system
It is the system in which emitters and laterals are laid on the ground surface along the rows of crops. The emitting devices are located in the root zone area of trees.
Sub-surface system
It is a system in which water is applied slowly below the land surface through emitters. Such systems are generally preferred in semi-permanent/permanent installations.
Bubbler system
In this system the water is applied to the soil surface in a small stream or fountain. Bubbler systems do not require elaborate filtration systems. These are suitable in situations where large amount of water need to be applied in a short period of time and suitable for irrigating trees with wide root zones and high water requirements.
Micro and mini sprinklers
These are small plastic sprinklers with rotating spinners. The spinners rotate with water pressure and sprinkle the water. These are available in different discharges and diameters of coverage and can operate at low pressure in the range of 1.0 to 2kg/cm2. Water is given only to the root zone area as in the case of drip irrigation but not to the entire ground surface as done in the case of sprinkler irrigation method.
Pulse
Pulse system uses high discharge rate emitters and consequently has short water application time. The primary advantage of this system is a possible reduction in the clogging problem.
Biwall
It is extruded dual chamber micro-irrigation tubing manufactured from Linear Low Density Polyethylene (LLDPE). This system is suitable for all closely spaced row crops like sugarcane, cotton, vegetables, onion, tea etc.
Components of micro irrigation system
The components of Micro irrigation system can be grouped into two major groups viz.
Head control unit
Distribution network
Head control unit
The head control unit of micro irrigation System includes the following components.
Pump/overhead tank: It is required to provide sufficient pressure in the system. Centrifugal pumps are generally used for low pressure trickle systems. Overhead tanks can be used for small areas or orchard crops with comparatively lesser water requirements.
Fertilizer applicator: Application of fertilizer into pressurized irrigation system is done by either a by-pass pressure tank, or by venturi injector or direct injection system. The detailed description of fertilizer application system is presented in subsequent section s(1.6.2).
Filters: The hazard of blocking or clogging necessitates the use of filters for efficient and trouble free operation of the micro irrigation system. The different types of filters used in micro irrigation system are described below.
Gravel or media filter
Media filters consist of fine gravel or coarse quartz sand, of selected sizes (usually 1.5-4mm in diameter) free of calcium carbonate placed in a cylindrical tank. These filters are effective in removing light suspended materials, such as algae and other organic materials, fine sand and silt particles. This type of filtration is essential for primary filtration of irrigation water from open water reservoirs, canals or reservoirs in which algae may develop. Water is introduced at the top, while a layer of coarse gravel is put near the outlet bottom. Reversing the direction of flow and opening the water drainage valve cleans the filter. Pressure gauges are placed at the inlet and at the outlet ends of the filter to measure the head loss across the filter. If the head loss exceeds more than 30 kPa, filter needs back washing.
Screen filters
Screen filters are always installed for final filtration as an additional safeguard against clogging. While majority of impurities are filtered by sand filter, minute sand particles and other small impurities pass through it. The screen filter, containing screen strainer, which filters physical impurities and allows only clean water to enter into the micro irrigation system. The screens are usually cylindrical and made of non-corrosive metal or plastic material. These are available in a wide variety of types and flow rate capacities with screen sizes ranging from 20 mesh to 200 mesh. The aperture size of the screen opening should be between one seventh and one tenth of the orifice size of emission devices used.
Centrifugal filters
Centrifugal filters are effective in filtering sand, fine gravel and other high-density materials from well or river water. Water is introduced tangentially at the top of a cone and creates a circular motion resulting in a centrifugal force, which throws the heavy suspended particles against the walls. The separated particles are collected in the narrow collecting vessel at the bottom.
Disk filters
Disk filer contains stacks of grooved, ring shaped disks that capture debris and are very effective in the filtration of organic material and algae. During the filtration mode, the disks are pressed together. There is an angle in the alignment of two adjacent disks, resulting in cavities of varying size and partly turbulent flow. The sizes of the groove determine the filtration grade. Disk filters are available in a wide size range (25-400 microns). Back flushing can clean disk filters. However, they require back flushing pressure as high as 2 to 3 kg/cm2.
Pressure relief valves, regulators or bye pass arrangement: These valves may be installed at any point where possibility exists for excessively high pressures, either static or surge pressures to occur. A bye pass arrangement is simplest and cost-effective means to avoid problems of high pressures instead of using costly pressure relief valves.
Check valves or non-return valves: These valves are used to prevent unwanted flow reversal. They are used to prevent damaging back flow from the system to avoid return flow of chemicals and fertilizers from the system into the water source itself to avoid contamination of water source.
Distribution network
It mainly constitutes main line, submains line and laterals with drippers and other accessories.
Mainline: The mainline transports water within the field and distribute to submains. Mainline is made of rigid PVC and High-Density Polyethylene (HDPE). Pipelines of 65 mm diameter and above with a pressure rating 4 to 6 kg/cm2 are used for main pipes.
Submains: Submains distribute water evenly to a number of lateral lines. For sub main pipes, rigid PVC, HDPE or LDPE (Low Density Polyethylene) of diameter ranging from 32 mm to 75 mm having pressure rating of 2.5 kg/cm2 are used.
Laterals: Laterals distribute the water uniformly along their length by means of drippers or emitters. These are normally manufactured from LDPE and LLDPE. Generally, pipes having 10, 12 and 16 mm internal diameter with wall thickness varying from 1 to 3 mm are used as laterals.
Emitters/drippers: They function as energy dissipaters, reducing the inlet pressure head (0.5 to 1.5 atmospheres) to zero atmospheres at the outlet. The commonly used drippers are online pressure compensating or online non-pressure compensating, in-line dripper, adjustable discharge type drippers, vortex type drippers and micro tubing of 1 to 4 mm diameter. These are manufactured from Poly- propylene or LLDPE.
Online pressure compensating drippers: A pressure compensating type dripper supplies water uniformly on long rows and on uneven slopes. These are manufactured with high quality flexible rubber diaphragm or disc inside the emitter that it changes shape according to operating pressure and delivers uniform discharge. These are most suitable on slopes and difficult topographic terrains.
Online non-pressure compensating drippers: In such type of drippers discharge tends to vary with operating pressure. They have simple thread type, labyrinth type, zigzag path, vortex type flow path or have float type arrangement to dissipate energy. However, they are cheap and available in affordable price.
In-line drippers or inline tubes: These are fixed along with the line, i.e., the pipe is cut and dripper is fixed in between the cut ends, such that it makes a continuous row after fixing the dripper. They have generally a simple thread type or labyrinth type flow path. Such types of drippers are suitable for row crops. Inline tubes are available which include inline tube with cylindrical dripper, inline tubes with patch drippers, or porous tapes or biwall tubes. They are provided with independent pressure compensating water discharge mechanism and extremely wide water passage to prevent clogging.
Other accessories are take-out/starter, rubber grommet, end plug, joints, tees, manifolds etc.
Planning and design of drip irrigation system
The planning and design of drip irrigation system is essential to supply the required amount of irrigation water. The water requirement of the plant per day depends on the water that is taken by the plant from the soil and the amount of water evaporating from the soil in the immediate vicinity of the root zone in a day. The plant intake is affected by the leaf area, stage of growth, climate, soil conditions etc. The water requirement and irrigation schedule can be determined from the soil or plant indicators-based methods or soil water budget method, but the simplest and most commonly method is to use pan evaporimeter data. To apply the required amount of water uniformly to all the plants in the field, it is essential to design the system to maintain desired hydraulic pressure in the pipe network. The design of Micro irrigation system is essentially a decision regarding selection of emitters, laterals and manifolds, sub main, main pipeline and required pumping unit. The steps needed to be followed for designing the Micro irrigation system are given below:
Collection of general information
Layout of the field
Crop water requirement
Hydraulic design of the system
Pump horse power requirement
Design of drip irrigation system
The steps necessary for the design of a micro irrigation system include:
Step 1: Determine net depth of application
Step 2: Emitter design
Step 3: Determine flow per lateral, submain, and mainlines.
Step 4: Determine total system capacity to meet design plant evapotranspiration.
Step 5: Size laterals, submains, and mainlines.
Step 6: Determine pump size needed.
Detailed design steps are explained with the help of example.
Example: Design a drip irrigation system for a citrus orchard of 1 ha area with length and breadth of 100 m each with a well located at one corner of the field. Citrus has been planted at a spacing of 5 m x 5.5 m. The maximum pan evaporation during summer is 8 mm/day. The other relevant data are given below:
Land slope = 0.40% upward slope from S-N direction
Water source = A well located at the S-W corner of the field
Soil texture = Sandy loam
Clay content = 18.4%
Silt = 22.6%
Sand = 59.0%
Field capacity= 14.9%
Wilting point = 8%
Bulk density = 1.44 g/cc
Effective root zone depth= 120 cm
Wetting Percentage = 40%
Pan coefficient = 0.7
Crop coefficient = 0.8
Solution:
Step 1: Estimation of water requirement, Evapotranspiration of the crop (ET) = Open pan evaporation x Pan Coefficient x Crop coefficient
= 8 x 0.7 x 0.8
= 4.48 mm/day
Volume of water to be applied = Area covered by each plant x Wetting fraction x ET
= (5 x 5.5) x 0.40 x 4.48
= 49.28 l/day or 50 l/day
Step 2: Emitter selection and irrigation time emitters are selected based on the soil texture and crop root zone system. Assuming three emitters of 4 lph, placed on each plant in a triangular pattern are sufficient so as to wet the effective root zone of the crop.
Total discharge delivered in one hour = 4 x 3 = 12 lph
Irrigation time = 50/12 = 4 h 10 minutes
Step 3: Discharge through each lateral
A well is located at one corner of the field. Submains will be laid from the centre of field. Therefore, the length of main, submains, and lateral will be 50 m, 97.25 m, 47.5 m each respectively. The laterals will extend on both sides of the submains. Each lateral will supply water to 10 citrus plants.
Total number of laterals = (100/5.5) x 2 = 36.36 (Considering only 36)
Discharge carried by each lateral, Qlateral = 10 x 3 x 4 = 120 lph
Total discharge carried by 36 laterals = 120 x 36 = 4320 lph
Each plant is provided with three emitters,
Therefore, total number of emitters will be 36 x 10 x 3 =1080
Step 4: Determination of number of manifolds
Assuming the pump discharge = 2.5 lps = 9000 lph
Number of laterals that can be operated by each manifold = 9000/120 = 75.
So, only one manifold or submains can supply water to all the laterals at a time.
Step 5: Size of lateral
Once the discharge carried by each lateral is known, then size of the lateral can be determined by using the Hazen- Williams equation. The reduction factor (F) can be estimated as
F =
= 0.54m
H_f= K (Q/C)^1.852/D^4.87 L F = 0.26m
For D = 16 mm, = 0.063m
The permissible head loss due to friction is 10% of head of 10 m (head required to operate 4 lph emitters) is 1 m, therefore 12 mm dia lateral size is selected.
Step 6: Size of submain
Total discharge through the submain
= Qlateral x Number of laterals
= 120 x 36
= 4320 lph = 1.2 lps
Assuming the diameter of the submain as 35 mm. Head loss for 97.25 m of pipe length by using the Hazen- Williams equation,
H_f= K (Q/C)^1.852/D^4.87 L F = 1.70
Therefore, frictional head loss in the submain = 0.30m
Head at the inlet of the submain = H emitter + H lateral + H submain + H slope
= 10 + 0.26 + 1.70 + 0.40 = 12.36m
Pressure head variation = 17%
Design pressure head variation is 17% which is within the recommended 20% variation, Hence, size of the sub main line is adequate.
Step 7: Size of the main line
Assuming the diameter of main as 50 mm
Discharge of main, Qmain = Discharge of submain (Qsubmain) x no. of submians =1.2 lps
Using Hazen- Williams equation,
H_f= K (Q/C)^1.852/D^4.87 L F= 0.42m
Step 8: Determining the horse power of pump
Assuming that the head variation due to uneven field variations and the losses due to pump fittings, etc. as 10% of all other losses.
Hlocal = 10% of all other loss
Total dynamic head =(Hemitter + H lateral + H submain + H main+ Hslope) + Hstatic + Hlocal
= 12.36 + 0.42 +10 +1.28
= 24.06 m
Pump Horse power,
h_p=(Q_t×H_t)/(75×n_p )
= 0.64 = 1.0
Hence, 1 hp pump will be adequate for operating the drip irrigation system for irrigating 1 ha area of citrus crop.
Chapter - 8
Fertilizer Application in Irrigation System
Fertigation is the method of application of soluble fertilizer with irrigation water. Fertigation is a prerequisite for drip irrigation. Since the wetted soil volume is limited, the root system is confined and concentrated. The nutrients from the root zone are depleted quickly and a continuous application of nutrients along with the irrigation water is necessary for adequate plant growth. Fertigation offers precise control on fertilizer application and can be adjusted to the rate of plant nutrient uptake.
Advantages of fertigation
Several distinct advantages of fertigation in comparison with conventional application methods are as follows:
The supply of nutrients can be more carefully regulated and monitored.
The nutrients can be distributed more evenly throughout the entire root zone or soil profile.
The nutrients can be supplied incrementally throughout the season to meet the actual nutritional requirements of the crop.
Nutrients can be applied to the soil when crop or soil conditions would otherwise prohibit entry into the field with conventional equipment.
Soil compaction is avoided, as heavy equipment never enters the field.
Crop damage by root pruning, breakage of leaves, or bending over is avoided, as it occurs with conventional chemical field application techniques.
Less equipment may be required to apply the chemicals and fertilizers.
Less energy is required in applying the chemical. Usually less labor is needed to supervise the application.
Criteria for chemicals application through irrigation systems:
Avoid corrosion, softening of plastic pipe and tubing, or clogging of any component of the system.
Safe for field use.
Soluble or emulsifiable in water.
Should not react adversely to salts or other chemicals in the irrigation water.
Equipment and methods for fertilizer injection
Injection of fertilizer and other agrochemicals such as herbicides and pesticides into the drip irrigation system is done by:
By-pass pressure tank
Venturi system
Direct injection system
By-pass pressure tank: This method employs a tank into which the dry or liquid fertilizers kept. The tank is connected to the main irrigation line by means of a by-pass so that some of the irrigation water flows through the tank and dilutes the fertilizer solution. This by-pass flow is brought about by a pressure gradient between the entrance and exit of the tank, created by a permanent constriction in the line or by a control valve.
Venturi injector: A constriction in the main water flow pipe increases the water flow velocity thereby causing a pressure differential (vacuum) which is sufficient to suck fertilizer solution from an open reservoir into the water stream. The rate of injection can be regulated by means of valves. This is a simple and relatively inexpensive method of fertilizer application.
Direct injection system: With this method a pump is used to inject fertilizer solution into the irrigation line. The type of pump used is dependent on the power source. The pump may be driven by an internal combustion engine, an electric motor or hydraulic pressure. The electric pump can be automatically controlled and is thus the most convenient to use. However its use is limited by the availability of electrical power. The use of a hydraulic pump, driven by the water pressure of the irrigation system, avoids this limitation. The injection rate of fertilizer solution is proportional to the flow of water in the system. A high degree of control over the injection rate is possible, no serious head loss occurs and operating cost is low. Another advantage of using hydraulic pump for fertigation is that if the flow of water stops in the irrigation system, fertilizer injection also automatically stops. This is the most perfect equipment for accurate fertigation.
Two injection points should be provided, one before and one after the filter for fertigation. This arrangement helps in by-passing the filter if filtering is not required and thus avoids corrosion damage to the valves, filters and filter-screens or to the sand media of sand filters.
The capacity of the injection system depends on the concentration, rate and frequency of application of fertilizer solution.
Chapter - 9
Modern Advances in Irrigation
Use of tensiometer for irrigation scheduling
A tensiometer is a simple and relatively low-cost tool that can be used to schedule irrigation in crops. Tensiometers continuously measure soil water potential or tension, which is a measure of soil moisture or soil water content. This is generally expressed in centibars (CBAR) on a tensiometer vacuum gauge. If the tension in the soil is high, plants have to use more energy to extract soil water. If tension in the soil is low, then plants have lower energy requirements to extract soil water. A typical tensiometer is a water-filled tube with a porous ceramic cup at the lower end. After it is installed in the soil, water moves from the tensiometer through the cup into the unsaturated soil. This process continues until the negative pressure inside the tensiometer equals the negative pressure in the surrounding soil. The pressure inside the tensiometer is then in equilibrium with the pressure in the soil and can be measured by reading a vacuum gauge on the tensiometer. A pictorial representation of tensiometer in field is given in Figure 7.
Fig 8: Representation of Tensiometer Working (a) and in Onion Field (b)
Table 8: General Guidelines for Understanding the Meaning of Tensiometer Reading
ReadingRemarks
0-5 CBARSoils are saturated or nearly saturated as a result of irrigation or rain. Discontinue irrigation to prevent wasting water and leaching nutrients from the root zone.
10-15 CBARCrops should be irrigated as soon as possible. Irrigation should be initiated at 10 CBAR during the flowering and fruit set, and at 15 CBAR for the rest of the growing season.
25 CBAR and higherPlants show symptoms of water stress. The tensiometers may soon lose vacuum and require servicing to restore accurate performance.
Automatic irrigation system
An automatic irrigation system can be used to control time of irrigation with the help of controllers and valves which operate the system, run according to feeded time. A picture of the automatic irrigation system and its different component is shown in Figure 9 and 10.
Fig 9: Controller Box of the Automatic Irrigation System
Fig 10: Different Components of the Automatic Irrigation Systems
In the automatic controller system, several functions have a significant role to apply the irrigation automatically through the drip system in the micro plots.
Functionality of automatic irrigation system
Set time and date
Set programme start times
Set watering days
Set station run times
Special features (seasonal adjustments, remote access etc.)
Program display
Manual program operation
Water Level Sensor
Programmable fertigation
Use of modelling in irrigation water management
There are various computer programs available which are based on analytical or numerical solutions that can simulate water uptake, water dynamics in the soil and wetting patterns in root zones in surface and subsurface irrigation systems e.g.: Wet Up (Cook et al., 2003) based on analytical solutions and HYDRUS 2D/3D (Simunek et al., 2008), So-WaM (Wesseling et al., 2009), Neuro-Drip (Hinnell et al., 2010), Coup Model (Jansson, 2012) and Drip-Irrigation (Arbat et al., 2013) which are based on numerical solutions. Models use the information about the soil and the root system properties, the climate, and the plant/emitter configuration of the irrigation system and simulate soil water status in the active root zone. DIDAS (Friedman, 2016) is similar computer software based on analytical solutions of the Richards equation for steady and unsteady water flow in point and line source emitters/sources from surface and subsurface in semi-infinite soil domain. (Mehla and Singh, 2019) used DIDAS software for optimizing emitter spacing for Onion crop by running simulation for different lateral spacing and compare results by comparing relative water-uptake rate (RWUR, ratio between water uptake rate and irrigation rate for different spacing at different depth to determine optimal lateral spacing for Onion crop. Modelling can be used for evaluating existing system designs and irrigation schedules. These softwares are especially useful as they decrease the need of costly and time consuming field trails and experiments.
Experimental research on automation in irrigation
The various research experiments were conducted on response of crop under drip irrigation as well as effective water management. (Sharma et al., 2019) conducted a field experiment to investigate the response of different level of irrigation on crop growth, yield and water use of summer rice crop as well as estimation of crop water requirement for summer rice under drip irrigation system. The results were compared with the surface irrigation treatments. The result revealed that more water saving occurs in drip irrigation. The growth parameters such as plant height, number shoot per m2 were found maximum in the surface irrigation treatments followed by drip irrigation treatment. The maximum yield and water use efficiency was found under drip irrigation treatment. The result shows effective use of water through drip irrigation. (Sharma et al, 2019b) the average values of all performance evaluation parameters except DC, were found to be highest for automated drip system. The values of EU were more than to design criteria of 90% in each condition (Keller and Karmeli, 1974) for installed drip irrigation systems, which indicate that both drip systems operated excellently. (Mehla and Kumar, 2019) conducted a research on drip irrigation system in Kinnow Orchard and found that the performance evaluation parameters DC and EU varied as distance on submain increased and also along the laterals. (Sharma et al, 2019c) conducted a field experiment for automated drip irrigation with soil moisture sensor for growing okra. The result shows good correlation between values of soil moisture content obtained by gravimetric method and sensor output voltage as well as good correlation between soil moisture by measured by sensor and soil moisture content by gravimetric method. The system found very convenient to switch on and switch off the pump when the water is applied, especially when farmer are busy in other agricultural operation. This technique saves large amount wastage of water as well as wastage of power and increases yield of okra crop by maintaining optimum moisture content in root zone during whole crop period. (Sharma et al, 2019d) conducted a experiment to study the effect of different level of irrigation growth, yield and yield attributes and water use efficiency under surface and subsurface drip irrigation. The results show that the plant height, number of tillers per plant, plant dry matter and LAI for rice crop were found maximum in the subsurface drip. Whereas, the water use efficiency for treatments under drip irrigation was significantly superior to the treatments under conventional irrigation. (Sharma et al, 2019d) conducted a field experiment at to investigate the effect of chemical fertilizer scheduling on growth and yield performance of okra (Abelmoschus esculentus L.) under Sensor Based Automated Drip and Conventional Drip System Plasticulture Farm, CTAE, MPUAT Udaipur in year 2019. The fertilizer use efficiency was also found higher in sensor based drip irrigation treatments, it was probably due to less leaching of irrigation water with chemical fertilizer because of frequent irrigation as per plant need.
References
Arbat, G., Puig-Bargués, J., Duran-Ros, M., Barragan, J., Ramirez de Cartagena, F. (2013). Drip-Irriwater: computer software to simulate soil wetting patterns under surface drip irrigation. Comput. Elect. Agric. 98, 183–192.
Booher. (1974). Surface irrigation. FAO Agricultural Development Paper 95. Rome, Italy: Food and Agriculture Organization.
Cook, F.J., Thorburn, P.J., Fitch, P., Bristow, K.L., (2003). WetUp: a software tool to display approximate wetting patterns from drippers. Irrig. Sci. 22, 129–134.
Friedman, S.P., Communar, G., and Gamliel, A. (2016). DIDAS - User-friendly software package for assisting drip irrigation design and scheduling. Comput. Elect. Agric., 120:36-52.
Hinnell, A.C., Lazarovitch, N., Furman, A., Poulton, M., Warrick, A.W., (2010). Neuro Drip: estimation of subsurface wetting patterns for drip irrigation using neural networks. Irrig. Sci. 28, 535–544.
Jansson, P.E., (2012). Coup Model: model use, calibration, and validation. Trans. ASABE 55, 1337–1346.
Mehla M. K. and Kumar A. (2019). Drip Irrigation System Evaluation in Kinnow Orchard. International seminar on “Sustainable Environment & Agriculture under Global Climate Change-2019” at MDU, Rohtak, Haryana, India, 94-95.
Mehla M. K., Singh K., 2019. Optimizing Drip Irrigation System Design for Onion Crop Using DIDAS Software. Bulletin of Environment, Pharmacology and Life Sciences, 8(2),64-69.
Sharma, V., Singh, Y.P., Gunjan P. and 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., Singh Y.P, Kaur M. and Paradkar, V.D. (2019). Estimation of Different Uniformities and Distribution Characteristic of Automated and Conventional Drip Irrigation Systems for Okra Crop under Field Condition. Int. J. Curr. Microbiol. App. Sci. 8(07): 2330-2333. doi: https://doi.org/10.20546/ijcmas.2019.807.285
Sharma, V., Singh, P.K., Bhakar, S.R., Yadav, K.K. and Lakhawat, S.S., (2019). Integration of Soil Moisture Sensor Based Automated Drip Irrigation System for Okra Crop, Ind. J. Pure App. Biosci. 7(4), 277-282. doi: http://dx.doi.org/10.18782/2320-7051.7642
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, Yadav, K.K, Lakhawat, S.S. and Bhakar, S.R. (2019). Effects of chemical fertilizer scheduling on performance of okra (Abelmoschus esculentus L.) crop under soil moisture sensor based automated drip and conventional drip irrigation system. International Journal of Chemical Studies 2019; 7(4): 3189-3191.
Sharma, V., Ramesh J.B., Singh, Y.P. and Mehla M.K. (2019. Technical Manual on Conventional and Automated Drip Irrigation (Installation, Operation and Maintenance). Academic Publications, November, 2019.
Simunek, J., van Genuchten, M.T., Sejnac, M., (2008). Development and applications of the HYDRUS and STANMOD software packages and related codes. Vadose Zone J. 7, 587–600.
Wesseling, J.G., Ritsema, C.J., Oostindie, K., Stoof, C.R., Dekker, L.W., (2009). A new, flexible and widely applicable software package for the simulation of one dimensional moisture flow: SoWaM. Environ. Model. Software 24, 1127–1132
Further Reading
ASABE, Design & operation of farm irrigation system, 2nd edition. Finkel HJ 1983. Handbook of Irrigation Technology. Vols. I-II. CRC Press.
Michael, A.M., 2008, Irrigation Theory & Practices, Vikas Publishing House Pvt. Ltd., New Delhi.
Mane & B. L. Ayare, Design Operation of Drip Irrigation, Jain Publications.
Mane & B. L. Ayare, Design Operation of Sprinkler Irrigation, Jain Publications.
Schwab, G.O., D.D. Fangmeier, W.J., Elliot & R.K. Frevert, 1993. Soil & Water Conservation Engineering. Fourth Edition, John Wiley & Sons, Inc. New York.
About the Authors
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 Member of 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
Jalgaonkar Bhagyashri Ramesh 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. 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. 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.
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. 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.
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