Low cost irrigation systems, continued

A simple irrigation system can consist of a storage tank  a main hose and lateral hoses with small holes or inserted micro tubes. The technologies described here are:

  1. The Nica drip
  2. The Micro tube drip
  3. The two tank system

 

Nica drip and Micro tube drip can be connected directly to the outlet of a pump (minimum height of pump outlet approx. 0.7m above drip system level) or be combined with a water storage tank  of around 0.9 m high that than can  be filled up directly with, for instance, a rope pump. To achieve maximum pressure, it is advised to install the well and water storage tank at the highest possible place.

The lay-out of the system depends on a number of variables, such as:

  1. The available manpower to pump and work on the land;
  2. The type of products that are grown;
  3. The soil and climate conditions.
  4. The slopes and height differences of the ground surface

It is best to ask assistance of agricultural experts from the region in designing the optimal lay-out.

Typical plot area that can be irrigated by these drip systems with help of a hand pump is between 1/8  to 1/4 ha.

Another advantage of drip irrigation is that nutrients can be added to the water which then enter directly into the soil around the plants. A manure “tea” can be made from animal manure or green plants. This liquid should be diluted in order to avoid burning the plants. Correct irrigation avoids that nutrients are washed away by rains or transformed by micro-organisms.

 "Micro-tube Drip"

The "Micro-tube Drip" system is a modification of the Drum kit or Baffle drip system as supplied by the organisation IDE (International Development Enterprise). The drum kit has a water storage drum placed quite high, and these systems require an operating head of 1 to 2 meter.

The micro-tube system uses parts of the Drum kit system like the so-called “lay flat” hose for mains and laterals which reduce cost and transport volume compared to the Nica drip.

Also the connectors and micro tubes used to make the drippers are used.

The length of the drippers is 0.3 to 0.5 meter which is shorter than in the Drum kit  and therefore easier to clean and less water height is required (0.5 to 0.9 meter).

Water output flow from the drippers can be altered by making the micro tube longer or shorter.

The micro-tubes of the lowest placed laterals should be longer than those of the laterals placed higher up. The lengths of the drippers can be varied, on an experimental basis, to get the same amount of water out of all the drippers.

If the land is sloping it is best to let the laterals run along the contours, so that the pressure is the same within the lateral.

trialchim

irrigclose

First trial system in Chimoio

Close up of the flow from the microtube dripper

 

 

hrptank

Hand rope pump with tank, connected to the micro-drip system,

see also picture at the right.

The micro-drip system with tomato plants, Nov 2007.

 

The two tank system

A very simple system is the satellite tank system. The installation consists of two small tanks (up to maximally 2 m3 each), one near the HRP and the other further in the field up to 50 m away, connected with a hose. With the hand rope pump the tanks can be filled up, and the watering of the plants can be done by hand with watering cans, from the tanks. The tanks make the work much lighter, because of easy and close-by access of water, reducing walking distances and reducing labour costs without having to adjust micro-tube systems to the plants. Mind the second tank upper left in the field

twotanksyst

The two tank system demonstrated at the  EPF workshop.