In irrigated agriculture, water taken up by crops is partly or totally provided through human intervention. Irrigation water is withdrawn from a water source (river, lake, aquifer or reservoir) and applied to the farm through an appropriate conveyance infrastructure. To satisfy their water requirements, irrigated crops benefit from both more or less unreliable natural rainfall, and from irrigation water. Irrigation provides a powerful management tool against the vagaries of rainfall and makes it economically attractive to grow high-yield seed varieties and to apply adequate plant nutrition as well as pest control and other inputs, thus giving room for a boost in yields. Figure 3 illustrates the typical yield response of a cereal crop to water availability and the synergy between irrigation, crop variety and inputs. Irrigation is crucial to the world’s food supplies. In 1998, irrigated land made up about one-fifth of the total arable area in developing countries but produced two-fifths of all crops and close to three-fifths of cereal production.
Irrigation plays a key role in stabilizing food production in a number of countries by either supplementing or replacing the need for natural precipitation for the purpose of food production. Irrigation stabilizes farm production by protecting against drought and by increasing crop yields and quality when rainfall is insufficient. It permits farmers to grow moisture-sensitive, high-value crops and crops that will improve their diet. In some areas with proper climates, irrigation allows farmers to raise two or three good crops in a year. It allows them to plant on time, thus optimizing market conditions and produce surplus to meet manufacturing needs.
The availability of water confers opportunities to individuals and communities to boost food production, both in quantity and diversity, to satisfy their own needs and also to generate income from surpluses. Irrigation has a land-augmenting effect and can therefore mean the difference between extreme poverty and the satisfaction of the household’s basic needs. It is generally recognized that in order to have an impact on food security, irrigation projects need to be integrated with an entire range of complementary measures, ranging from credit, marketing and agricultural extension advice to improvement of communications, health and education infrastructure
Community-managed small-scale irrigation systems, by improving yields and cropping intensities, have proved effective in alleviating rural poverty and eradicating food insecurity. Marketing of agricultural produce, both locally and at more distant places when adequate transport and communication infrastructure is available, can make a significant contribution to the income of farmers. Bank deposits and credits, as well as crop insurance, can be used to finance agricultural operations and buffer against climatic risk.
The productivity boost provided by irrigated agriculture results in increased and sustained rural employment, thereby reducing the hardships experienced by rural populations that might otherwise drift to urban areas under economic pressure. Growth in the incomes of farmers and farm labourers creates increased demand for basic non-farm products and services in rural areas. These goods and services are often difficult to trade over long distances. They tend to be produced and provided locally, usually with labour-intensive methods, and so have great potential to create employment and alleviate poverty.
Agriculture sustains not only the economy but also the livelihood of Kenyans. Any strategy for economic transformation and prosperity will not be achieved without investing resources and efforts towards enhancing agricultural productivity to attain food security. Similarly, agricultural value addition has the potential to act as a catalyst for Kenya’s industrial take-off. It is the policy of the Government that all Kenyans, throughout their life-cycle enjoy at all times safe food in sufficient quantity and quality to satisfy their nutritional needs for optimal health.
Further to this, the growth in manufacturing sector will also be heavily driven by the increase in agro-processing ventures in the country to be achieved through surplus production. Irrigation increases predictability, allows for production planning and it is very well targeted through contract farming noting that irrigation schemes have a very high level of farmers’ organization. For instance, sugar can yield increase by over 200% under irrigation as compared to rainfed irrigation. As an example, in Kenya under rainfed conditions, a well-managed sugarcane field should yield roughly 45-53 tonnes per hectare however under irrigation 110 to 150 ton/ha can be achieved in the sub-tropics. This is then a good solution to increasing the volume of sugarcane to spur growth of the sugar sector in Western Kenya. Many other crops fall under this category that include cotton, tomatoes, fruits, palm oil, macadamia, soya beans, cashew nuts among others.