1. Methods of Irrigation Presented by : Prof. S. P. Jadhav

3. Requirements of an irrigation method 1. The method should be such that uniform water distribution with as small as 6 cm water depth is possible. 2. Also it should be possible to keep heavy uniform application of water with 15 to 20 cm of water depth. 3. It should allow use of large concentrated water flows for reduction in conveyance losses. 4. It should be suitable for use with economic conveyance structures. 5. It should be such that mechanized farming is possible. Good irrigation method results in increased crop yield, conservation of resources with soil productivity maintained and makes economical use of water.

4. Uncontrolled or Wild flooding In this method, water is spread or flooded on a rather smooth land, without much control or prior preparation. This method is generally used in the inundation irrigation system in which water is forced to spread over vast tracts of land during the season of high stream flow. It is wasteful use of water, and is practised largely where irrigation water is abundant and inexpensive.

5. Uncontrolled of Wild Flooding

6. Controlled Flooding In the controlled Flooding water is spread over the land with proper methods to control the depth of application. Types of controlled flooding -- Controlled flooding is classified into the following types: i. Free floodingii. Border flooding iii. Check floodingiv. Basin flooding v. Contour lateralsvi. The Zig Zag method

7. Contour laterals This is a special case of free flooding in which the field channels or laterals are aligned approximately along the contour lines. This method is applicable to steeper terrain.terrain The field is cut by a relatively dense network of small contour laterals, the spacing of which depends upon the prominent grade of field between two adjacent ditches or laterals, the uniformity of slope and the soil type.

8. Free Flooding The free flooding technique is performed by excavating ditches in the irrigation land. As shown in the figure, from the main supply ditch, water is collected in the subsidiary or lateral or contour ditches. These subsidiary ditches are excavated either along the contour or above or below the slope of the area. The water from the lateral ditches is allowed to flow freely without any sort of control and hence it is also called wild flooding.

9. Free flooding The wild flooding technique is best suitable for crops or pastures that are cultivated closely. The contour ditches excavated in free flooding techniques are mostly spaced at a distance of 20 to 30m. This merely depends on the type of soil, type of crop, soil texture, etc. It performs well when employed on a sloped land or an irregular land. This method is not preferred where checks, basins, border or furrows are feasible.

10. Border strip Irrigation Fig. 2

11. Border strip Irrigation Border flooding method involves dividing the irrigation land into several strips of width around 10 to 20 m and length of 100 to 400m. Each strip is separated by a border or levees. The ridges constructed between the borders must have sufficient height to prevent overtopping during the irrigation. As shown in the figure-2, the water is allowed to flow from the supply ditch to each strip. So to prevent water to concentrate in one area, the surface must be leveled in the direction perpendicular to the flow of water. As the water flows through the strip, it infiltrates at the lower end. At this point, the supply is closed. High efficiency is gained when the strips are short and narrow.

12. Check flooding Fig. 3

13. Check flooding Check flooding is a method similar to flooding where the water is controlled by the surrounding check area that is formed by the construction of levees. These levees can be short or long which are constructed along the contour. Most of the check area has a measure varying from 0.2 to 0.8 hectares. In check flooding, the water from the supply ditch is allowed to move to the check area and is held for a period until desirable infiltration takes place. Check flooding is suitable for both permeable and less permeable soil. If applied for permeable soils, the water is quickly spread to the soil. While in case of less permeable soil, the water is allowed to stay for longer period to ensure adequate penetration.

14. Basin Flooding Basin flooding is a special type of check flooding as shown in figure-4. Here, the subsidiary ditches receive water from the mains supply ditch. Each subsidiary ditch is connected to a basin that occupies one or more trees. This method is especially followed for orchard trees. Ring basins are formed for each tree; in some cases, one ring basin may be formed for two or more trees. Water is supplied to these basins through a supply ditch. In some cases, a number of ring basins are interconnected. Portable pipes or large hoses may also be used in place of ditches. Fig. 4

15. Basin Flooding

16. Zig zag Method It is special method of flooding where water takes circuitous route before reaching the dead end of each plot. The whole area is divided into a number of square or rectangular plots; each plot is then subdivided with the help of low bunds or levees. This method is suitable for relatively level plots. It is, however, highly unsuitable for farming operations with modern farm machinery.

17. Zig zag Method

18. Furrow Irrigation Method – Types, Uses, Advantages and Disadvantages

19. Furrow Irrigation What is furrow irrigation? A Furrow irrigation system is a surface irrigation system. In this method, furrows are developed in rows during the planting and cultivation process in which gravity plays the main role and water is efficiently applied for the plant to grow. Water can infiltrate through furrow irrigation and reach up to the root of the crop. This irrigation method is very water-efficient compared to other surface irrigation systems. The size and shape of the furrow are depends upon which type of crop or plant or tree is grown and the spacing needed between them. Water infiltrates in soil due to gravity and spread up to its roots. This method is most suitable for plants or trees grown in rows.

20. Main Points in furrow irrigation system Furrows are small, parallel channels, made to carry water in order to irrigate the crop. The crop is usually grown on the ridges between the furrows. Furrow irrigation is suitable for a wide range of soil types, crops and land slopes. Furrow irrigation is suitable for many crops, especially row crops. Crops that would be damaged if water covered their stem or crown should be irrigated by furrows.

21. In summary, the following crops can be Irrigated by furrow irrigation. row crops such as maize, sunflower, sugarcane, soybean. crops that would be damaged by inundation, such as tomatoes, vegetables, potatoes, beans; fruit trees such as citrus, grape; broadcast crops (corrugation method) such as wheat.