Ranks Country/Region

Ranks	Country/Region	Irrigated land (km²)
1	China	690,070
2	India	667,000
3	United States	264,000
4	Pakistan	202,000

The earliest known systems of irrigation began in 6000 BC in Egypt and Mesopotamia.

Surface irrigation

Water is distributed over and across land by gravity, no mechanical pump involved.

(It is normally used when conditions are favorable: mild and regular slopes, soil type with medium to low infiltration rate, and a sufficient supply of surface or groundwater. Surface irrigation is widely utilized and therefore a well-known system which can be operated without any high-tech applications)

Localized irrigationgf

Water is distributed under low pressure, through a piped network and applied to each plant.

Localized irrigation is a method of applying water that results in wetting only a small area of the soil surface and sometimes only part of the root zone. Water is applied near the base of the plant so that the application is concentrated in the root zone.

Drip irrigation

A type of localized irrigation in which drops of water are delivered at or near the root of plants. In this type of irrigation, evaporation and runoff are minimized.

Drip irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surface. The goal is to place water directly into the root zone and minimize evaporation

Sprinkler irrigation

Water is distributed by overhead high-pressure sprinklers or guns from a central location in the field or from sprinklers on moving platforms.

Sprinkler irrigation is a method of providing rainfall-like irrigation to the crops. Water is distributed through a system of pipes usually by pumping. Spray heads at the outlets distribute the water over the entire soil surface.

Lateral move irrigation (Center pivot irrigation)

Water is distributed through a series of pipes, each with a wheel and a set of sprinklers, which are rotated either by hand or with a purpose-built mechanism. The sprinklers move a certain distance across the field and then need to have the water hose reconnected for the next distance. This system tends to be less expensive but requires more labor than others.

Center-pivot irrigation, also called water-wheel and circle irrigation, is a method of crop irrigation in which equipment rotates around a pivot and crops are watered with sprinklers. A circular area centered on the pivot is irrigated, often creating a circular pattern in crops when viewed from above

Sub-irrigation

Water is distributed across land by raising the water table, through a system of pumping stations, canals, gates, and ditches. This type of irrigation is most effective in areas with high water tables.

Subirrigation also known as seepage irrigation, is a method of irrigation where water is delivered to the plant root zone. The excess may be collected for reuse.

Manual irrigation

Water is distributed across land through manual labor and watering cans. This system is very labor intensive

Manual irrigation is by far the most common form of irrigation as anyone physically able to, can manually irrigate their crops. Manual irrigation is you moving water from plant to plant. This is very labour and time intensive and is usually done with a hose or bucket, so it is only suitable for smaller areas

1. 
   For watering large areas of farmland, drip irrigation is the most efficient irrigation system for reducing water and fertilizer loss. By filtering the water down through the soil and into the root system, some of the water percolates down into the groundwater system to be reused for irrigating in future years.
   
2. 
   Surface irrigation is the oldest form of irrigation and has been in use for thousands of years. In surface ( flood, or level basin) irrigation systems, water moves across the surface of an agricultural lands, in order to wet it and infiltrate into the soil.
   
3. 
   Irrigation schemes in the world use about 3 500 km3 water per year, of which 74% is evaporated by the crops. This is some 80% of all water used by mankind (4 400 km3 per year).
   
4. 
   Improper drip irrigation installation often culminates into poor root development and dieback. For example, looping your tubing too wide or installing a small quantity of water emitters creates drought conditions where roots continually grow – they may resort to shallow growth to find moisture and die back.
   
5. 
   Furrow or flood irrigation is widely used in many parts of the world, including the US, but is the least efficient, losing about 50 percent of water applied. This loss can be reduced by leveling fields, practicing surge flooding and capturing and reusing runoff.
   
6. 
   Indonesia tops the chart showing countries with the largest overall area, with 225,000 square kilometres taken by permanent cropland, or 12.4% of its total. Second on the list is China, with 160,000 sq km – some 1.7% of its total land area.
   
7. 
   Unlike other forms of irrigation, such as sprinklers that are only 65-75% efficient, drip irrigation 90% efficient at allowing plants to use the water applied. And, it reduces runoff and evaporation. Drip irrigation applies the water slowly at the plant root zone where it is needed most.