Irrigation agriculture is the type of agriculture which involves the artificial application of water to soil or land for farming purposes.
Irrigation is mainly practiced in areas where there is insufficient rainfall like in Egypt and Sudan (Nile Basin) which make use of water from the River Nile and; in Mali, Northern Nigeria (Niger Basin) which make use of water from River Niger.
These countries, especially Egypt and Sudan are in the desert; hence, the need for irrigation agriculture.
NEED OR REASONS FOR IRRIGATION
These are some of the reasons for the need of irrigation in both the Nile Basin and the Niger Basin:
- Rainfall is low and unreliable.
- High rate of evaporation creates water deficit in the soil.
- Both areas are dry and arid.
FACTORS WHICH FAVOUR IRRIGATION AGRICULTURE
- Presence of rivers like River Nile in Egypt and Sudan and Niger in West Africa.
- Presence of fertile alluvial soils (or plain).
- Incidence of low rainfall or unreliable rainfall.
- Incidence of high rate of evaporation.
- Resourcefulness of the people.
- Presence of large population and the need for increased food production.
- The need for agricultural raw materials.
- The need to control flooding.
IMPORTANCE OF IRRIGATION
- It makes the farmers to be less dependent on rainfall.
- Irrigation makes early planting possible.
- It enables farmers to cultivate one crop twice or thrice on the same piece of land in a year.
- It increases the yield of crops.
- It helps to reduce salt concentration in the soil by diluting and dissolving some out of the soil.
The areas covered by irrigation schemes or where irrigation agriculture is practiced are:
- In the Nile Basin are:
- The Nile Delta.
- The Nile valley.
- The lake shores.
- Aswan (Egypt).
- Khasimel Girba (Egypt).
- Senna (Sudan).
- Kenena (Sudan).
- The Geriza plain i.e. the Managil extension.
- In the Niger Basin are:
- Inland Niger Delta (in Mali).
- The Niger valley.
- The lake shores e.g. Kainji Lake.
SIMILARITIES BETWEEN THE NILE AND NIGER IRRIGATION PRACTICES
- Both the Nile and the Niger irrigation practices depend on large dams.
- Both practice perennial irrigation i.e. building of dams and barrages.
- Both use canals to channel water to the farms.
- Manual method is used in both areas.
- They both grow food crops e.g. cereals and vegetables.
- Both have small and large farms.
- Irrigation farms in both areas are owned by government and individuals.
- They both grow cash crops e.g. sugar cane on the Niger and cotton on the Nile.
REASONS WHY IRRIGATION IS MORE IMPORTANT IN THE NILE BASIN THAN THE NIGER BASIN
- The Nile Basin occupies a desert area, especially in Egypt. It supplies virtually all the water requirements while, the Niger areas receives more rainfall.
- Presence of richer alluvial flood plains in the Nile which is better for agriculture than in the Niger Basin.
- There is higher population in the Nile Basin than in the Niger Basin. This leads to greater demand for food production.
- The Nile Basin is used more for cash crop production than in the Niger Basin.
- There is more intensive use of land on the Nile Basin than on the Niger Basin.
METHODS OF IRRIGATION IN USE
The methods employed in both the Nile and Niger Basins are the same and they include:
- Shaduf method: This involves a hand operated lever lifting buckets of water from the river and tipping or dropping them into narrow channels running along the ridges or patches of cultivation.
- Perennial method: This involves the use of dams, barrages and canals. Water is usually stored in dam reservoir and released during farming season. It promotes the growth and cultivation of crops all year round.
- Basin irrigation method: This occurs during the flooding of the rivers. When flood occurs, water is held back by building up some embankments or barriers. This water is later released during dry season.
- Use of pumps: It involves the use of generators or pumping machines to get water out from rivers or wells to farmlands. This at times is also referred to as sprinkler irrigation.
- Manual method (use of buckets): This involves the fetching of water with buckets from rivers and wells and getting them to farmlands.
- In the Nile Basin: Crops cultivated include cotton, sugar cane, millet, wheat, maize and rice.
- In the Niger Basin: Crops cultivated include groundnut, maize, guinea corn, onions, sugar cane and rice.
CONTRIBUTIONS OF IRRIGATION SCHEMES TO ECONOMIC DEVELOPMENT
- It has led to the production of food crops.
- It has led to the production of cash crops.
- It provides income to farmers.
- It generates revenue for government.
- It leads to production of industrial raw materials.
- It provides employment to people.
- Fishing is also carried out in the schemes.
- It has led to the growth of settlements.
- It has boosted tourism in the areas.
PROBLEMS OF IRRIGATION
- The construction of dams has led to the displacement of people from their original homes and lands. This leads to high cost of resettlement.
- Fluctuations in the volume of water in rivers also result in low yield of crops.
- Irrigation equipment is expensive to purchase and maintain.
- Lack of technical know-how on the establishment and operations of irrigation scheme.
- Excessive dissolution of salts in irrigated area or increase in salinity prevents proper growth of crops.
- There is the problem of silting of dams.
- There are social problems arising from the displacement of people or settlement.
- Most dams may collapse.
- Breeding of diseases associated with stagnant water e.g. Bilharzia and River blindness.
- Disasters can occur as a result of flooding.
- It can result in the growth of water weeds.