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Irrigation water management

1. Flood System: When the land is flat, the entire area is

flooded by letting in water. This system is commonly practiced in canal or tankard areas, in wet lands for banana, and other crops.

This is a water method as the water is supplied in excessive quantity.

The entire area is allowed to saturate with water and the interval between two irrigations is kept fairly long. It also causes stagnation in shallow and ill drained soils.

Flood irrigation

2. Basin System: This system is widely practiced on large scale all

over the world. A basin is a small patch or land bounded around a tree.

It is usually a square with the tree in the centre. The soil gradually slopes down from, the base of the tree to the edge of tile basin, resulting in a trough.

Circular basins are also made sometimes. Water let In from the main water channel first reaches the periphery, soaks the outer area and "gradually spreads towards the trunk, and thus is prevented from coming in contact with the tree trunk. This system is useful for loamy soils.

Basin irrigation

3. Furrow System: Furrow system of irrigation is commonly practiced in

orchards in Western countries. The entire orchard is ploughed up and divided into furrows.

The number of furrows between the rows of trees depends on the age of the plantation . When trees are young, a single furrow is sufficient, A furrow is ordinarily about 200 to 300 feet long about 18 inches wide at the top and 6 inches deep, with sloping sides.

The size of the furrow varies with the type of soil and slope of the land, Furrow run at right angles to the slope or gradient of the land. When the land is highly sloppy the length of the furrow is reduced.

Normally, for every. 100 feet of the length of the furrow a six inch gradient of fall is adequate. Furrows are kept hallow so that water may spread quickly all over the area. When furrows are deep the water is likely to be absorbed by deeper layers or the soil and water intake becomes high, Thus by adjusting the depth of furrows, the quantity of water to be applied to crops can be controlled.

Furrow irrigation

4. Ring System: In this system the water is applied in a ring around

the tree. The method is recommended for coconut or areca nut trees, is in this system the water is not allowed to touch the bark of the tree thereby reducing the chances or nut splitting to which the trees are susceptible. The size of the ring will increase as the trees grow.

In applying water to crops, care should be taken to see that the optimum quantity is applied at proper interval. The water applied should reach the entire root zone of the tree. For this it is necessary to study the relationship between the spread of trees and root penetration.

Ring system of irrigation

5. Border Strip or Modified Furrow System:

A better system of irrigation is the modified furrow system. Water is applied from one main channel simultaneously into several furrows.

It is let out first in a main feeder channel where it rises up and flows uniformly into all the furrows at the same period A good initial preparation of land is necessary. The land should be perfectly leveled with a gently slope.

In this system, water penetrates quickly into the deeper layers, the horizontal movement is slow. There is thus deep penetration of water into the entire root zone of the crop.

Erosion is almost eliminated due to slow flow of water supervision is easy, the main feeder or head channel alone has to be regulated and this saves considerable amount of labour

Border strip or modified furrow system of irrigation