What is Irrigation?
In simple terms, irrigation refers to the process of facilitating the supply of water to crops through pipes, ditches, and sprinklers. Irrigation system helps farmers to have less dependency on rainwater. Having an irrigation system is an important factor for assured crop production. It allows proper utilization of all the production factors and leads to increased yield. The irrigation system also provides optimum moisture to crops and provides farmers with better yield per unit of land. Irrigation begins during the rainy season and is continued in a controlled fashion, as needed.
Types of Terrace Irrigation Practiced in Different Parts of the World
- Bench terraces: These are conservation structure where a slope is directly or slowly converted into a series of level steps (like staircase on slope) and ledges. The flat areas between the terraces are used for growing crops such as grass and legumes. The grasses and legumes capture water and nutrient runoff and are used for animal feed. The terrace is then closed by growing grass on the last flat area at the bottom of the terrace.
- Fanya juu: It is the practice of throwing the soil upwards. For this kind of terrace, a ditch is dug and the soil from uphill is thrown to form a ridge. The ditch traps the water and allows the water to infiltrate slowly into the soil. The ridge also prevents the soil from moving downhill. It is mostly used in the highlands where the speed of the water is high. There should be a ridge at the bottom of the terrace to close off this fanya juu terrace.
- Fanya chini: A practice of irrigation where the soil is thrown downhill. To make this kind of terrace, farmers dig a ditch and throw the soil downhill to establish a ridge. They grow tree or fodder on the ridges and close off the terrace with a final ridge. This form of terrace farming is often used in the lowlands with moderate slopes.
- Water terraces: Water terraces are built in flood-prone areas by farmers to cope with flowing water. To deal with water masses, water speed, and to change the water direction. Water terraces are similar to bench terraces, except that at the end of the trench, there is no final ridge for stopping the flow of water. Instead, furrows are constructed under the benches to catch runoff water.
- Stone terrace: In stone terraces, stones are used to create strong embankments on steep slopes. The stone terraces have the potential to slow down runoff, increase water infiltration, and form the basis for improved production in semi-arid areas. By using the contours of low slopes, water harvesting is improved and crops can be grown in low rainfall areas.