Levelling

2. “Plant is not a fish,
Soil is not a Camel”

3. Major Water application Techniques
Irrigation Methods
Surface Irrigation Sub surface irrigation Pressurized irrigation
Border
basin
Furrow
Natural
Artificial
Sprinkler
Drip/Trickle

4. 4.1 Introduction to Surface
Irrigation System
The term 'surface irrigation' refers to a broad
class of irrigation methods in which water is
distributed over the field by overland flow.
A flow is introduced at one edge of the field and
covers the field gradually.
Surface irrigation offers a number of important
advantages at both the farm and project level.
Because it is so widely utilized, local irrigators
generally have at least minimal understanding of
how to operate and maintain the system.

5. 1. Basin Irrigation
Basin irrigation is the most common form of
surface irrigation, particularly in regions with
layouts of small fields.
If a field is level in all directions, is
encompassed by a dyke to prevent runoff, and
provides an undirected and uncontroled
flow of water onto the field.
 A basin is typically square in shape but exists
in all sorts of irregular and rectangular
configurations.
It may be furrowed or corrugated, have raised
beds for the benefit of certain crops

6. Generally basin irrigation is used
Salt affected area
For closely spaced crop and sensitive
to flooding
Soil with low infiltration rate
Slope less than 0.1% flat lands
is suited to different crops, such as,
rice, cotton, groundnuts etc.

8. 2. Border Irrigation
 Border irrigation can be viewed as an extension of basin
irrigation to sloping, long rectangular or contoured field shapes,
with free draining conditions at the lower end.
 In a border irrigation, controlled and directed surface flooding
is practiced whereby the field is divided up into strips by parallel
ridges or dykes
 It can be used for all crops that can withstand flooding for a short
time e.g. wheat.
 It is suited to soils very low infiltration rates.

9. ….continue
 The land between two levees is called a border strip, simply
called a border
 Border irrigation is a more controlled version of wild
flooding with additional field ditches that serve as supply
sources for applying water to the field.

10. Border Irrigation

11. 3.Furrow Irrigation
In furrow irrigation, water no longer flows over
the entire soil surface but is confined to small
channels (furrows) between the crop rows. It
is then gradually absorbed into the bottom and
sides of the furrow to wet the soil.
Water infiltrates through the wetted perimeter and
spreads vertically and horizontally to refill the soil
reservoir.

12. There are several disadvantages with furrow irrigation.
these includes:
 an accumulation of salinity between
furrows
 an increased level of tail water losses
 the difficulty of moving farm equipment
across the furrows
 the added expense for furrow
construction
an increase in the erosive potential of the
flow

13. ….continue

15. 4.3 Pressurized irrigation
 Water is put into pipes, pressurized and precisely
delivered to plants. This method saves much more water
than traditional surface flow irrigation
 Advantages
Pressurized irrigation systems avoid the water loss of
open surface flow irrigation
Estimates indicate that pressurized irrigation efficiency is
75 to 95 percent
Pressurized irrigation systems need from one-tenth to one-
quarter of the man hours open systems require,
Pressurized irrigation is especially valuable in arid and
semi-arid areas.

16. …Continue
Disadvantages
Water quality is crucial to the prolonged operation of
pressurized irrigation systems
Water high in dissolved minerals leads to frequent
blocking of emitters
Routine maintenance is needed to unblock delivery
fittings
water needs to be filtered before entering the
irrigation system to remove suspended solids such as
silt, algae, sand and dust, which will clog emitters

17. Types of Pressurized Irrigation systems
1. Sprinkler irrigation
Sprinkler irrigation is a method of applying irrigation
water which is similar to natural rainfall.
Water is distributed through a system of pipes usually by
pumping
It is then sprayed into the air through sprinklers
The pump supply system, sprinklers and operating
conditions must be designed to enable a uniform
application of water.

18. Adaptability of Sprinkler Irrigation
 Some of the conditions which favour sprinkler irrigation
are as follows.
Soils too porous for not good distribution by surface
methods.
Undulating land too costly too level sufficiently for good
surface irrigation
Land having steep slopes and easily erodible soils.

19. …..Continue
Irrigation stream too small to distribute water efficiently
by surface irrigation.
Land needs to be brought in to top production quality.
Sprinkler systems can be designed and installed quickly.
Soils with low water holding capacities and shallow
rooted crops which require frequent irrigation.

20. Sprinkler Irrigation versus Surface irrigation
Sprinkler systems can be designed so that
less interference with cultivation and other
farming operations occurs and less land is
taken out of production than with surface
methods.
Frequent and small depth of water can
readily be applied by sprinkler systems.
Higher water application efficiency can
normally be obtained by sprinkler
irrigation.

21. …Continued
For areas requiring in frequent irrigation,
sprinkler irrigation can be provided
Water measurement is easier with
sprinkler than with surface methods.
Whenever water can be delivered to the
field under gravity irrigation, sprinkler
irrigation is particularly attractive.
When domestic and Irrigation water
come from the same source, a common
distribution line can be frequently used.

22. Limitations of sprinkler Irrigation
Wind distorts sprinkler pattern and causes uneven
distribution of water
Ripened soft fruits may be affected by spraying
water.
Water must be clean and free of sand, debris and
large amount of dissolved salts.
High initial investment as compared to surface
irrigation.
High power requirements
Fine textured soils with slow infiltration rate can
not be irrigated efficiently in hot windy areas.

23. Sprinkler Irrigation- artificial rain

24.  Suitable crops
 Sprinkler irrigation is suited for most row, field and tree
crops and water can be sprayed over or under the crop
canopy large
 sprinklers are not recommended for irrigation of
delicate crops such as lettuce because the large water
drops produced by the sprinklers may damage the crop.
 Suitable slopes
 Sprinkler irrigation is adaptable to any farmable slope,
whether uniform or undulating
Suitable soils
 Sprinklers are best suited to sandy soils with high
infiltration rates although they are adaptable to most
soils.

25. Suitable irrigation water
A good clean supply of water, free of suspended
sediments, is required to avoid problems of sprinkler
nozzle blockage and spoiling the crop by coating it with
sediment.
Sprinkler System Layout
A typical sprinkler irrigation system consists of the
following components:
Pressure generating unit(Pump unit)
Water carrier unit(mainline,submain line,latterals)
Water delivery units(rises pipes &sprinkler)
 Quality improvement subunit(screen, Desilting basins

26. 2. DRIP IRRIGATION
 Drip irrigation is sometimes 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.
 Water is applied close to plants so that only part of the soil in
which the roots grow is wetted

30.  Suitable slopes
Drip irrigation is adaptable to any
farmable slope.
 Suitable soils
Drip irrigation is suitable for most soils.
On clay soils water must be applied
slowly to avoid surface water ponding
and runoff.
Suitable irrigation water
One of the main problems with drip
irrigation is blockage of the emitters.
Thus it is essential for irrigation water
to be free of sediments.

31. Drip System Layout
A typical drip irrigation system consists of the following
components:
 The pump unit:- takes water from the source and provides the
right pressure for delivery into the pipe system.
 The control head:-consists of valves to control the discharge
and pressure in the entire system. It may also have filters to clear
the water.
 Mainlines, sub mains and laterals:- supply water from the
control head into the fields. They are usually made from PVC or
polyethylene hose .
 Emitters or drippers:- are devices used to control the discharge
of water from the lateral to the plants. They are usually spaced
more than 1 meter apart with one or more emitters used for a
single plant such as a tree.

32. Criteria for Selection of Various Methods
 The selection of the methods are depend on
the f.f factors
 Type of crop
Type of technology
Previous experience with irrigation
required labor inputs
Costs and benefits.
The natural conditions such as soil type, slope,
climate, water quality and availability, have the
following impact on the choice of an irrigation
method

33. …Continued
Soil type:- Soils which have a low water
storage capacity and a high infiltration
rate need frequent but small irrigation
applications. Under these circumstances,
sprinkler or drip irrigation are more
suitable than surface irrigation.
Slope:-Sprinkler or drip irrigation are
preferred above surface irrigation on
steeper or unevenly sloping lands as they
require little or no land levelling.

34. …Continued
Climate:-Strong wind can disturb the
spraying of water from sprinklers. Under
very windy conditions, drip or surface
irrigation methods are preferred.
Water availability:-Water application
efficiency is generally higher with sprinkler
and drip irrigation than surface irrigation
and so these methods are preferred when
water is in short supply.

35. Land Levelling
 Land leveling is reshaping of the field surface to a
planned grade.
 It is necessary in making a suitable field surface to
control the flow of water, to check soil erosion and
provide surface drainage.
Land leveling operations may be grouped into three
phases:
 Rough grading
Land leveling
Land smoothing

36. Rough grading
Is the removal of abrupt irregularities such as mounds, dunes
and rings, and filling of pits, depressions and gullies.
Land leveling
 It means land grading or land forming or land shaping
 It requires moving large quantities of earth over
considerable distance
Land smoothing
which is the final operation in land leveling.
Leveling operations leaves irregular surfaces due to
dumping the loads. These irregularities are removed
and a plane surface obtained by land smoothing

37. Criteria for land leveling
 Land leveling is influenced by
 the characteristics of the soil profile,
 prevailing land slope,
 rainfall characteristics,
 cropping pattern,
 methods of irrigation,

38. Land leveling Design
 The following is the procedure
for land leveling design.
• Determining the centroid of
the filed: The distance of the
centriod from the reference
line is then obtained by
dividing the sum of the
products by the total number
of stakes
• Determining the average
elevation of the field: This is
obtained by adding the
elevations of all grid points in
the field and dividing the sum
by the number of points.
• Compute the slope of the plane

39. The slope of the best fit line through the average X-
direction elevation (Ej) is A and is found by:
For the best fit slope in the Y-direction, the slope, B, is
 
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
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
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N
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Y
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B
1
2
1
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1
1
1
/
/

40. EXAMPLE
Determine the centroid of the field, average elevation of
the field, cut and fill volume, if the field have down field
slope of 0.2%. also compute the best fit slope of the field.
The elevation of the field are as follows.Distance b/n stakes
are 25m.