Upload
madhujegathish
View
83
Download
1
Tags:
Embed Size (px)
Citation preview
Irrigation water can be applied to the land in several different
ways, and the choice among alternative irrigation methods,
depends upon many factors, including:
• economics
• crop type
• soil type
• water availability and quality
• farming practices
• legal considerations and others
Uncontrolled surface flooding
It consists of applying water to the field without any bunds to guide the flow of water
wetting the soil surface completely.
This method is most commonly used for irrigation of crops sown by broadcasting
method viz., rice, low value pastures, lawns and millets etc.
Advantages
1. No land levelling & land shaping
2. Low labour and land preparation costs
3. Less skill required by irrigator
Disadvantages
1. Applied water is lost by deep percolation &
surface runoff
2. Low irrigation application efficiency
Controlled flooding
Check basin methodIn this method the field is divided into square or rectangular plots of 4 to 4000 m2
guided by bunds on all the sides. v
Advantages1. Water can be applied uniformly.
2. Even small streams can be used for irrigation of crops efficiently.
3. Simple and cheap when equipment is used for constructing bunds
Disadvantages1. Unless the land is levelled, distribution of water in plot is uneven.
2. Considerable area is lost under field channels and bunds i.e.
nearly 30% of area.
3. Bunds interfere in working of inter-cultivation equipment
4. More labour is required for field layout and irrigation
Ring basin methodThis method is a modification of check basin method and is suitable for sparsely grown
orchard crops and cucurbits.
Border strip methodThe cultivated field to be irrigated is divided into a number of long parallel
strips, generally 3 to 15 m in width and 75 to 300 m in length separated by small
border ridges or low dykes of about 15 cm high, laid out in the direction of the
slope.
Traditional meethodsLevee: holds the water back
Canal: allows the water to be brought to drier areas
Dam: controls the flow of water
Subsurface drip
Water applied through small emitter openings below the
soil surface
Basically a surface system that's been buried
(few inches to a couple feet)
Permanent installation
Subsurface Drip Irrigation
Advantages
• High & uniform water application
• Lower pressure & power requirements
• No dry corners
• Adaptable to automation
Disadvantages
• High initial cost
• Water filtration required
• Complex maintenance requirements
Flushing, Chlorination and Acid injection
Salt movement under irrigation with saline water
Salt accumulation leached
downward by successive water
applications
Salt accumulation leached
radially outward from drip
tubing
Subsurface Drip Sprinkler/Flood
Micro spray/ micro jets
Discharge: 1gal/min/spray applicator
Low operating pressure requirements of from 0.8 to 1.5
kg/cm2, low water application rates and suitability for stony
or very coarse sandy soils
Objective: To emit water in the form of small droplets
without causing any misting
Micro sprinklers
• These are highly useful for high discharge requirements in case
of orchards and also where the crop canopy as well as the root
zone spread is more
• They are normally, designed to spray water to cover an area of
1 to 6 meters with a flow rate varying from 20 lph to 120 lph
Rain gun
• Most suitable for a variety of climates liketropical, temperate and humid climates as inIndia
• Light in weight and easy to install
• Uniform distribution profile with adjustable jet
• Long life span and low maintenance
• Better pattern coverage & good performance inwindy conditions
Possibilities of adapting micro irrigation
Drip irrigation
All type of crops except some close spaced crops
Well and tank irrigation
Suitable for all types of soils – sandy, clay and saline
Sprinkler irrigation
Close spaced crops
Well, tank and canal irrigation
Suitable for all types of soils –coarse sandy soils