Introduction MCQ Quiz in मल्याळम - Objective Question with Answer for Introduction - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Concept:

Drip irrigation

• It is also called trickle irrigation is used in areas with water scarcity and salt problems.
• It involves the slow application of water, drop by drop to the root zone of a crop,  water seeps from these holes drop by drop, hence the name drip irrigation.
• Water-saving 50-70% as compared to surface irrigation.
• The difference in water delivery rate between extreme emitters should not exceed 10%
• Water discharge rate is generally 1-4 lit/hr. at 1.5-2.5 kg/cm2 pressure.
• The water use efficiency of drip irrigation is 95%
• Most suitable for widely spaced crops, orchards trees, and greenhouses.

Advantage of drip irrigation:

• ​​Increased water use efficiency
• High crop yield
• Uniform and better quality of the produce
• Efficient and economic use or fertilizer through fertigation
• Less weed growth
• Minimum damage to the soil structure and reduction in soil erosion
• Usage in undulating areas and slowly permeable soil
• Low energy requirement i.e. labor-saving

Explanation:

Uncontrolled or wild flooding: 

Surface flooding in which water is diverted to non-prepared areas and is let to flow down the natural slopes without controlling its distribution. Also referred to as “mountain flooding”.

As compared to sprinkler irrigation, the water application efficiency of the uncontrolled flooding method is low and the cost of labor is high.

There are mainly 3 types of irrigation used in agriculture, namely

1) surface irrigation,

2) sub-surface irrigation and

3) sprinkler irrigation:

Surface Irrigation Consists of Flood, Basin, Border, Furrow

• Flood
  • Water is left in the fields from a channel without any control from any side from flow.
  • It covers the entire field without any restrictions.
  • Water application efficiency is low and the cost of land preparation is low but the cost of labor is high.
  • Used for rice and more crops.
• Basin
  • These are small walls that are covering a flat area
  • These walls are being set up to ensure that the water stays within the desired area.
  • They can be filled to desired  depth so that water can be retained for a long duration
• Border
  • Land is divided into long parallel strips
  • Borders are separated by low walls
  • Having a very uniform slope in the direction of irrigation
• Furrow
  • Small channels that can carry water towards land slope between the crop
  • Water infiltrate within the soil because of movement within the slope
  • Crops grow on ridges between the furrows
  • It is for the crops that cannot handle water for more than 24 hours

Subsurface

• The application of water into fields is below the ground surface so that it is supplied directly to the root zone of the plants. 
• Water is applied beneath the ground by maintaining an artificial water table, usually 25 to 70 cm, below the ground surface. 
• Water moves upwards towards the land surface through capillary action to meet the requirements of the crops in plant roots.  
• Water may be obtained from wells, streams, lakes etc. It can be divided as 
  1. Natural Subsurface
  2. Artificial subsurface

Sprinkler Irrigation

• In this method of irrigation, water is delivered through a network of pipes and pumps.
• Water is available in form of the spray.
• It also reduces seepage losses and other losses.
• Sprinkler method of irrigation has a higher water application efficiency.
• The cost of land preparation and labor is less.

Concept:

Irrigation Projects in India are classified into three major aspects:

• Major Irrigation Projects: A project having a cultivable command area(CCA) of more than 10,000 hectares.
• Medium Irrigation Projects: A project having CCA between 2000 and 10,000 hectares.
• Minor Irrigation: A project with is designed to irrigate an area of 2000 hectares or less is classified as a minor irrigation 

Cultivable command area = Total command area - Area utilizing surface water resource = 10000 - 2000 = 8000 hec

So, from the above, we can say that, the irrigation project comes under medium irrigation project

Note:

Whereas major and medium irrigation works are meant for tapping surface water (e.g., rivers), minor irrigation mainly involves groundwater development, e.g., tube-wells, boring works, etc.

Concept:

Surface Irrigation System:

We have two sources of water to be used as irrigation water one is ground water and other is flowing water. Based on the source of water used as irrigation water, water irrigation system is mainly divided in to two categories:

1. Lift irrigation – when ground water lifted up to be used as irrigation water
2. Flow irrigation – when flowing water is used as irrigation water.

These are further classified as below – 

Flow irrigation:

These are also called gravity irrigation. It is the type of irrigation in which water is available at a higher level as to enable supply to the land by gravity flow.

It is further divided into two categories

a) Inundation irrigation: It is done canal taking off from a river in flood without any diversion head work. It depend on the periodical rise in water level of the river and supply is drawn through open cuts in the river bank or creeks which are called heads. Inundation canals usually flow during the summer months and bring in large quantity of silt beneficial to crops. e.g. river canal irrigation.

b) Perennial Irrigation: In this system assured supply of water throughout the crop period to irrigation requirement of the crops is made available to the command area through storage of water done at dam or diversion supply made by means of head works at the off take point of the canal. Perennial irrigation may be either direct (e.g reservoir or tank), storage (indirect) or combined.

Note:

Methods Irrigation systems:

Irrigation water may be applied to the crops by three basic methods:-

1. Surface Irrigation method

2. Sprinkler irrigation method

3. Sub-surface irrigation method

In the financial year 1978-79, Planning Commission classified the irrigation projects on the basis of Cultural Command Area (CCA) as follows:

• Minor Irrigation Project: With CCA up to 2,000 hectares.
• Medium Irrigation Project: Have CCA between 2,000 hectares and 10,000 hectares.
• Major Irrigation Project: With CCA more than 10,000 hectares.

Other than this irrigation projects can also be classified on the basis of the type of flow:

• Gravity Irrigation: In this type of project water is stored at height gravity makes it flow down to the required destination.
• Lift Irrigation: In this type of project water is made to flow against gravity from a lower level to some height with the help of some external means.

Explanation:

Gross Crop Area:

• Gross Cropped Area (GCA) is the total area sown once as well as more than once in a given year ( particular year). When the crop is sown on a piece of land twice, the area is counted twice in the gross cropped area (GCA), or counting the area as many times as the number of crops sown (or grown) on the same land.

Additional Information

Gross Command Area: 

• Gross command area is the total area enclosed within the project's irrigation boundary that can be economically irrigated regardless of the amount of water available.
• Gross command area includes culturable area and unculturable area. Examples of unculturable area include ponds, residential areas, reserved forests, and roads.

Cultivated Command Area:

• The cultivable command area is also called a culturable command area. This is defined as the cultivable part of the gross command area. This is that area where cultivation is possible. 

Net Crop Area:

• The physical extent of land on which crops are sown and harvested is known as net cropped area. Or in other words, Net Crop Area is defined as the area sown once as well as more than once in a given year but counted only once.

Concept:

Surface Irrigation System:

We have two sources of water to be used as irrigation water one is ground water and other is flowing water. Based on the source of water used as irrigation water, water irrigation system is mainly divided in to two categories:

1. Lift irrigation – when ground water lifted up to be used as irrigation water
2. Flow irrigation – when flowing water is used as irrigation water.

These are further classified as below – 

Flow irrigation:

These are also called gravity irrigation. It is the type of irrigation in which water is available at a higher level as to enable supply to the land by gravity flow.

It is further divided into two categories

a) Inundation irrigation: It is done canal taking off from a river in flood without any diversion head work. It depend on the periodical rise in water level of the river and supply is drawn through open cuts in the river bank or creeks which are called heads. Inundation canals usually flow during the summer months and bring in large quantity of silt beneficial to crops. e.g. river canal irrigation.

b) Perennial Irrigation: In this system assured supply of water throughout the crop period to irrigation requirement of the crops is made available to the command area through storage of water done at dam or diversion supply made by means of head works at the off take point of the canal. Perennial irrigation may be either direct (e.g reservoir or tank), storage (indirect) or combined.

Note:

Methods Irrigation systems:

Irrigation water may be applied to the crops by three basic methods:-

1. Surface Irrigation method

2. Sprinkler irrigation method

3. Sub-surface irrigation method

Concepts:

On the basis of the arrangements adopted for spraying irrigation water, sprinkler systems are classified into three types, such as:

 i) Fixed nozzles attached to a pipe,

 ii) Rotational head /revolving sprinkler, and

iii) Perforated pipe system.

1. Fixed Nozzle System

Parallel pipes are installed about 15m apart which are supported on rows of posts. Water is discharged at right angles to these pipes. The entire 15 m space between pipe lines may be irrigated by turning the pipes through 135⁰ about respective longitudinal axes.

2. Revolving Sprinkler System

This system is further divided into three types, such as:

a) Conventional system / small rotary sprinkler- Small size nozzles are placed on riser pipes that are fixed at uniform intervals along the length of a lateral pipe. In this method, the most common device to rotate the sprinkler head is a small hammer actuated by the thrust of the water striking against a vane connected to it.  

b) Boom type and self propelled- This system employs one boom sprinkler in each lateral. A boom is basically a nozzle, slowly rotating from a pipe sprinkler which is moved by towing the towers to the next position along the laterals with a tractor.

c) Mobile raingun / large rotary sprinkler- The system operates at a high pressure to irrigate comparatively large areas, because it is able to throw a large quantity of water over wide areas.  

3.  Perforated System

Explanation:

Methods of Irrigation

Sprinkler system:

• A Sprinkler system of irrigation is best for an uneven ground surface as it does not need investment in leveling work. Also, it conveys water evenly throughout the surface with the help of sprinkler heads like rain falling on the surface. 
• In this method of irrigation, the water is applied to the land in the form of a spray and it can be used for all types of soil and for any topography. It is highly recommended for soils having large undulations and easily erodible soils and it is mostly adopted in tea and coffee gardens.
• There is no erosion of soil and fertilizers are used economically since they can be injected through the water.
• Even though it reduces various leakages but the evaporation loss is always there
• Power required is less.

Other Methods of Irrigation: