an adequate water supply is important for plant growth.
when rainfall is not sufficient, the plants must receive additional water from irrigation.
REASONS WHY IRRIGATION IS CARRIED OUT IN EAST AFRICA
- Existence of gently sloping land which favours irrigation by gravity flow of water e.g. at Mwea-Tebere.
- The existence of modern technology ensures the use of irrigation e.g. overhead sprinkling at Kilombero.
- The existence of extensive free land due to the sparse population in dry areas has also led to the use of irrigation.
- Presence of rivers that provide permanent sources of water for irrigation e.g. river Malaba for Doho irrigation scheme.
- Availability of adequate capital to buy the machines e.g. water pumps and to extend social infrastructures e.g. railway lines e.t.c.
- In many parts of East Africa, rainfall is inadequate hence the need for adding water artificially e.g. in Kasese.
- There is a need to increase food production through irrigation to sustain the ever-increasing population.
- Some crops need too much water which can be easily provided through irrigation e.g. rice, sugarcane, yams e.t.c.
- Irrigation is carried out to maintain moisture in the soil in order to help in the maintenance of soil fertility.
- Some areas receive very hot temperatures, and they lose a lot of water through evaporation in the dry season hence the need for irrigation e.g. Kasese and Mobuku valleys.
- The government policy of opening up remote areas and improvement of agricultural productivity has also led to irrigation.
points to consider for irrigation decision
- land suitability for irigation for example slope
- method of irrigation to be used
- when to irrigate: decide based on soil, crop and climatic condition
- how much to irrigate: decide based on crop water requirement
- quality of irrigation water
- effective rainfall: part of total rain is useful for crop production