Orchard Management (1+1)

SYSTEMS OF IRRIGATION

Introduction:

• Despite the fact that nearly 75% of the total area on the earth’s surface is occupied by water. This can be traced to the fact that 97.3% of the water is in oceans and seas. Only 2.47% is the fresh water. Water is a vital factor and natural resource for the growth of any living organism, and is a limiting factor for plant growth. It is the most important in supporting all forms of life.
• Plants also require water for their better growth and production.
• Where there is shortage of water, particularly during critical stages like flowering and fruiting, there can be drastic reduction in yield. Hence, the necessity of irrigation is to make up this deficiency of water. The water needs of any orchard depend upon.

1. Annual rainfall
2. Periods of water shortage
3. Types of crops and cropping
4. Expected increase in production with irrigation
5. Type of soil
6. Annual rainfall
7. Periods of water shortage
8. Types of crops and cropping
9. Expected increase in production with irrigation
10. Type of soil

• Availability of water for irrigation has an enormous impact on the success of commercial fruit growing.
• However, where rainfall is normal and well distributed, it is also feasible to grow certain fruit crops under rain-fed conditions.
• In India, temperate fruit cultivation is mostly confined to such areas, which is the main cause of low productivity.
• However, proper management of rain water by using appropriate water harvesting techniques, its judicious use and moisture conservation practices can increase water use efficiency and consequently productivity.
• Where irrigation water is available, its optimum use shall determine the tree’s performance in terms of growth, vigour and yield. Therefore, water management practices such as irrigation; rain water harvesting and moisture conservation practices should be followed on scientific lines to get maximum return from the orchard.

Irrigation:

• It is defined as the artificial supply of water to support plant growth and production in absence of adequate supply of water through rainfall is known as irrigation.
• Irrigation is very important in fruit crops as sufficient moisture must be maintained in soil for obtaining yield of good quality fruits. There are three important aspects of irrigation:

i) Time of irrigation
ii) Quantity of water in required.
iii) Appropriate System irrigation

Systems of Irrigation:

• Several methods of irrigation are employed in orchard depending upon age of the trees, topography of soil and availability of irrigation water. Descriptions of commonly adopted methods of irrigations are outlined below:

1. Surface irrigation: Flood system, basin, boarder method, Furrow method etc.
2. Sub-surface irrigation: Drip irrigation
3. Overhead irrigation: Sprinkler irrigation

Flood system: In this system, whole orchard area is irrigated through one head i.e. without sub- division of the unit area into small plots (Plate 8.1).

• Follow this method if the land is flat and levelled and plenty of water is available.
• The method is useful where intercrops or green manuring crops are grown in the orchard.
• In this system, wastage of water is more; weed growth is excessive, risk of bark diseases like collar rot or foot rot exist as the tree trunk remain in contact with water for a longer time.
• It is suitable for orchard attaining more than 8-10 year of age.

Plate 8.1: Flood irrigation in tomato field Plate 8.2: Furrow irrigation in tomato field

Advantages:

• The entire soil gets fully saturated with water without leaving any dry pocket in it.
• As involvement of labourer is less, the operational cost is also less in this method.
• Rodents are controlled to considerable extent.
• By flooding trees are well protected from frost as the latent heat of water is more.

Disadvantages:

• The orchard trees badly suffer due to over-irrigation if the irrigation water is not drained off quickly and timely.
• The method can’t be used unless the land is even.

Check basin:

• Prepare basins of desired size and shape (circular, rectangular, square) around each plant depending upon age of the plant and topography of land.
• After the rains, trenches are formed between the rows of banana plants (Figure 8.1).
• In some cases (In Poovan and Monthan, in Tanjore area) 60 cm wide and 45 cm high trenches are dug between alternate rows of plants.
• Irrigation water should not directly touch the trunk as there is a risk of disease infection. In tree fruit crops (citrus), heaping of soil around the trunk should also be avoided as it keeps the wet soil in contact with scion portion leading to soil borne diseases like gummosis.
• The basins should, therefore, be made slopping downwards from the tree trunk.

Figure 8.1: Check basin system of irrigation Figure 8.2: Basin system of irrigation in fruit crops

Advantages:

• The distribution of water takes place more uniformly.
• The chance of over-irrigation is less as the entry of irrigation water in the beds is regulated.
• The soil is made to saturate more evenly.

Basin system.

• In this system, basins around the trunk are linked directly with one another through strait channel (Figure 8.2).
• Water wastage and weed growth are less in this system. However, water passing through the channel touches the tree trunk directly and hence risk of spreading of bark diseases is more.
• Water flows also draw away the manure from the tree basin and deposits it at the end of channel. This system is suitable for young fruit trees.

Advantages:

• Helpful especially in loose textured soil where flooding or furrow method has limitation.
• Water stagnation in a basin dose not takes place as the excess water flows to the next basin and is finally drained off.

Disadvantages:

• The nutrients present in the soil in a basin are washed away and move to the next basin.
• The soil-borne pathogens, if exist in the soil of a basin are carried to the other basins and thereby, the soil of those basins are also contaminated.

Modified basin system.

• This is an improved system over the basin system.
• In this system, main channel runs in between the tree lines and the basins are linked independently through small sub channels.
• Attention should be paid to block the sub channels after basin has received adequate water. The size of basin is increased with the increase in tree canopy size every year.
• This is a good system of irrigation for young orchard up to 6-8 years of age and also for arid regions, having water shortage. Incidence of bark diseases are less and intercropping is possible.

Furrow method:

• This system suitable for vegetable crops (Plate 8.2) and in sloppy orchard land areas, particularly for old orchard.
• Make 20-30 cm deep furrows on either side of the tree at proper distance depending upon age and spread of the plant.
• Restrict the furrow length to 80-100 feet only to avoid wastage of irrigation water.
• In this system, the water moves slowly in furrows in the area between the rows. The trees are fed through the lateral movement of water.
• The consumption water is less in this system and there is no risk of bark diseases.
• Saturation of root zone is comparatively less. Not suitable for intercropping and green manuring.

Advantages:

• Evaporation loss of water is less.
• The irrigation water is able to reach greater depth of the soil.
• For such fruit crops which are needed to be earthed up occasionally as in banana, the method is preferable. This is because, earthing-up is done automatically while opening the furrows.
• Where the soil is of higher clay content, the method is considered to be particularly suitable.

Disadvantages:

• The method is not suitable in porous soil for high vertical percolation.
• Many feeder roots lying close to the soil surface may be damaged or cut off while opening the furrows.

Border Method:

• This method is also called as the Sara method.
• To irrigate by this method, the land is divided in to long strips by relatively broad ridges.
• Each strip is then irrigated with a water channel unless it is thoroughly saturated.

Pitcher system.

• Pitcher with a hole at the bottom is buried in the tree basin where feeder roots are confined (Figure 8.3).
• When it is filled with water, water is released slowly as droplets, which meet the water requirement of plant.
• Number of pitcher per tree depends upon the spread of the tree. However, 4 to 5 pitchers per tree are sufficient for the tree having 3 m spread.
• This system is highly a boon in the arid region where availability of water is limited.

Figure 8.3: Pitcher system of irrigation for fruit crops in arid region.