Dripline Irrigation In Kenya

Irrigation methods in Kenya involve drip irrigation, sprinklers, center pivots, rain hose, and button drippers. Simply put, this is the process of supplying crops with water. This is done artificially. Nutrients can also be distributed to crops accordingly.

Sources of water for irrigation include; dams, lakes, boreholes, ponds, wells, and canals.

The frequency and time of irrigation vary for different types of crops. The type of soil is also a factor to consider. Soils hold water at different rates (Soil water retention capacity).

What is the importance of irrigation in Kenya?

  • It increases the availability of water. This in turn increases income to farmers.
  • It helps to bring the vast majority of fallow land under cultivation. Fallow land is land that has been left dormant for over 5+ years.
  • It brings stability to yield levels.
  • It makes it possible to grow more than one crop in different parts of the country.
  • The productivity of irrigated land is higher compared to land that has not been irrigated.
  • Farmers are able to grow their crops during low rain seasons.

What are the types of irrigation?

1. Surface Irrigation

No pumping mechanism is needed in this method. Water is distributed evenly across the land by gravity.

2. Sprinkler Irrigation.

Water distribution is done from a central location. This is achieved by using high-pressure overhead sprinklers or moving sprinklers.

3. Drip irrigation.

Drops of water are delivered near the roots of the plants.

4. Central Pivot irrigation

Water is distributed by a sprinkler system moving in a circular pattern.

EFFECTIVE IRRIGATION METHODS

The two most effective irrigation methods are sprinkler and drip system

1. Sprinkler Irrigation.

In this method, water is applied in a similar manner to natural rainfall. Water is distributed through pipes by a pumping mechanism. It is then sprayed into the air through sprinklers.

What crops are best suited for this method?

  • Row crops – potatoes, sunflower, cotton, maize, dry beans, soy beans, wheat, canola and flax.
  • Field crops – wheat, cotton, corn, rice, soy beans, beans, sugar beets and canola.
  • Tree crops – palm oil, rubber, cocoa, cashew, mango, oranges, plantain, banana, coconut, guava, pawpaw and coffee.

However, large sprinklers are not recommended for delicate crops such as lettuce. This is because the large water droplets will damage their leaves.

Sprinkler Irrigation.

Suitable Slopes.

Sprinkler irrigation is suitable to any farmable slope, be it uniform or undulating. The pipes that supply water are laid out along the land contour where possible (This minimizes pressure changes at the sprinkler)

Suitable soils.

It is best suited for sandy soils with high infiltration rates. It is also adaptable to other soil types.

The application rate from the sprinklers is set in such a way that ponding (accumulation of water) and surface runoff are avoided.

Water supply.

Clean water free of sediments is recommended to avoid the blockage at the sprinklers. The sediments can also coat crops and spoil them.

Sprinkler system layout.

The system typically comprises a pumping unit, mainline and sub-mainlines, laterals, and sprinklers.

The mainline and sub-mainlines combine with the pumping unit carry water to the lateral. They can be laid on the land or buried underground. They can also be temporary and moved from field to field.

Laterals deliver water from the mainlines and sub-mainlines to the sprinklers. They can be permanent or temporary.

How are sprinkler systems operated?

The main goal is to apply water as uniformly as possible.

  • Wetting patterns – Normally the wetted area is circular. The heaviest wetting occurs close to the sprinkler.

The sprinklers need to be operated close to each other so that their patterns overlap. This also helps to reduce the effect of wind and water pressure.

  • Application rate – Rate at which water is sprayed onto the crops. This depends on operating pressure, sprinkler nozzle and distance between sprinklers.

It is best to choose a sprinkler whose application rate is less than the soil infiltration rate.

  • Sprinkler drop sizes – Small drops fall far from the sprinkler compared to large drops. Large drop can damage sprinkler. It is advisable to use small sprinklers.

Use small nozzle sprinklers operating at the recommended pressure.

What affects sprinkler systems the most?

  1. The labor force required to move the pipes and sprinklers around the field is large.
  2. The wetting pattern from a single sprinkler is not very uniform.
  3. Affected by wind and water pressure.

2. Drip Irrigation

It can also be referred to as trickle irrigation. It involves dropping water at very low rates from a system of small diameter pipes. The pipes are fitted with emitters or drippers.

Water is applied close to the plants near the roots only. This is different from sprinkler irrigation where the whole soil surface is wetted.

Water application is more frequent, usually 1-3 days. This provides a more favorable condition where crops can flourish.

Drip Irrigation using drip lines.

What crops are best suited for this method?

  1. Row crops – Tomato, Chilly, Capsicum, Cabbage, Cauliflower, Onion, Okra, Cucumber, Peas, Spinach, Pumpkin.
  2. Tree crops – Grapes, Banana, Pomegranate, Orange, Citrus, Mango, Lemon, Custard Apple, Sapota, Guava, Pineapple, Coconut, Cashew,
    Papaya, Watermelon.
  3. Vine crops
  4. Flowers.
  5. Cash crops.
  6. Spices.

Suitable slopes.

Adaptable to any farmable slope. The is crop is planted along contour lines and the water supply is laid along the contour.

This will minimize the changes in emitter discharges as a result of land elevation changes.

Suitable soils.

Suitable for most soils. On clay soils, the water is applied slowly to avoid surface runoff and ponding.

For sandy soils though, a higher emitter discharge rate is needed. This ensures adequate lateral wetting of the soil.

Suitable irrigation water.

Clean water is needed to avoid blocking the emitters. The water needs to be free of sediments, algae, fertilizer deposits, and dissolved chemicals.

Drip system layout.

The system typically consists of a pumping mechanism, control head, main and sub-main lines, laterals, emitters, and drippers.

The pump delivers water into the piping system. The control head has valves that control discharge and pressure. It also has a filter to clean the water. A fertilizer tank may also be added to inject fertilizer during irrigation.

Mainlines, sub mains, and laterals supply water from the control head into the field. They should be buried below the ground because they degrade easily when exposed to solar radiation.

Emitters or drippers discharge water from the laterals to the plant. Usually, they are spaced 1meter apart. More than one emitter is used for tree plants.

For row crops, closely spaced emitters are used to wet the soil.

How are drip systems operated?

Drip systems are usually permanent. This means it can be easily automated. It is very useful when labor is scarce or very expensive to hire.

Water can be applied frequently (daily) when required. This provides favorable conditions for crop growth.

  • Wetting patterns – Unlike sprinkler irrigation, drip irrigation only wets part of the root soil zone. This depends on the discharge rate and type of soil.

Although only the root zone is wetted, it is still important to meet the water requirements of the soil.

 Drip irrigation is not a substitute for other proven methods of irrigation. It is just another way of applying water to crops.

Where is drip irrigation best suited?

  • Land is steeply sloping
  • Water quality is marginal
  • When water and labor is expensive
  • Where high value crops require to be watered frequently.

How much is drip irrigation in Kenya?

Drip irrigation in Kenya.

One acre drip irrigation in Kenya costs between K.sh 80,000.00 to K.sh 150,000.00 based on design and the number of driplines per bed. The price of drip irrigation in Kenya per acre varies due to the topography of the land, the location of the farm, and the quality of the drip line.

Who makes the best drip irrigation system?

Who makes the best drip irrigation system?

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