Zones Agriculture
Irrigated agricultural system
THE IRRIGATED AGRICULTURE SYSTEM
Irrigation is an artificial system of applying water to the soil. This system is very useful in areas where there is very little rainfall and during dry seasons. Irrigation is also used to prevent soil consolidation, suppress the growth of weeds in grain fields, and to protect plants against frost.
Irrigation also refers to application of water by human agency to assist the growth of crops and grass. The system is for example is practiced in the southern parts of Uganda to supply water at critical times during the plant growing season. This system takes place in arid and semi-arid areas where rainfall totals are very low.
Today 10% 0f the worlds cultivated land is irrigated. And the significance of irrigation varies from country to country. Among the developing countries, 100% of the arable in Egypt is irrigated,75%in peru,45% in Iraq,41% in Mexico, and 38% in Pakistan.
Only 17% of all croplands are under irrigation, but these lands produce over one-third of the world’s food (68). During the 1960s and 1970s the amount of cropland under irrigation expanded by 2% to 4% annually. Since then, expansion has slowed to an annual pace of 1% or less, not enough to keep up with the growing food needs of developing countries where population is growing rapidly.
Fully 70% of all fresh water used every year throughout the world is used for irrigated agriculture (9). Only about half of all water withdrawn for irrigation, however, reaches the crops (41). The rest soaks into unlined irrigation canals, leaks out of pipes, or evaporates on its way to the fields due the poorly built irrigation systems.
Aims and Objectives of irrigation system.
To supply moisture for plant growth and this also transports essential nutrients.
To cool the soil and the atmosphere to create a more favorable environment for plant growth.
To improve on agricultural output since frequent water is availed to the plants.
To provide constant water supply to the agricultural fields.
The types of irrigation system and how there are practiced include the following;
Surface irrigation is an irrigation system in which gravity flow is applied to move water across the land in order to infiltrate and wet it. Surface irrigation is further classified as border strip, basin or furrow irrigation. Surface irrigation is the most commonly used method of irrigation and represents as much as 95 percent of common irrigation activity today. This system is being practiced at kibimba rice scheme.
Advantages of surface irrigation
With this system there is efficient distribution of water to the crops and it’s the most efficient system. In so doing good yields of crops are produced which may boost the economy of a given country. For example in Uganda, kibimba is almost the leading producer of Rice.
Surface irrigation can be developed at the farm level with minimum capital investment, so its cheap for farmers compared to other Irrigation Agriculture systems like sprinkler irrigation system.
Surface systems is less affected by climatic and water quality characteristics. Even moderate winds can reduce the effectiveness of sprinkler system but may aid the performance of surface systems.
Under surface system salinity is less experienced than either of the pressurized systems.
Surface irrigation systems are better able to utilize water supplies that are available less frequently, more uncertain, and more variable in rate and duration.
Disadvantages of surface irrigation system.
Land leveling costs can be high, so surface irrigation practice tends to be limited to land already having small, even slopes.
Under surface irrigation system, it is situated on lower lands with heavier soils and they tend to be affected by water logging and soil salinity if adequate drainage is not provided.
Surface irrigation methods are difficulty in applying light, frequent irrigations early and late in the growing season of several crops. For example, in heavy calcareous soils where crust formation after the first irrigation and prior to the germination of crops, a light irrigation to soften the crust would improve yields substantially.
Surface irrigation system tends to be labor intensive. This labor need not be overly skilled. But to achieve high efficiencies, the irrigation practices imposed by the irrigator must be carefully implemented.
Sprinkler or overhead irrigation is an irrigation system in which water is distributed throughout the field by the aid of high-pressure sprinklers in order to simulate rainfall during dry weather. Sprinkler irrigation systems are better than surface irrigation in leaching out salts from the soil, and they are not affected by uneven land distribution. For example it is being practiced at kakira sugar cane plantation in jinja an eastern region of Uganda It include merits and demerits as shown below;
Advantages of over head irrigation
System losses are (runoff, seepage) substantially reduced.
Over irrigation is completely eliminated and uniformity of application is high.
Irrigation water requirement is reduced as compared to other methods.
No land leveling is required in the field and land use for productive purposes can be maximized.
Fertilizer can be injected in the irrigation water to reach the root zone directly.
The system allows better weed control since this method is not affected by uneven land distribution..
Disadvantages of overhead irrigation system
Poor uniformity and application efficiency in high wind regimes and / or dry and hot conditions.
Capital cost is high with greater operational costs due to higher energy requirements.
Not suitable for paddy crops for example rice because such crops require a lot of water which may be availed by surface irrigation method.
Crops are prone to diseases due to moist environment because moist places are bleeding places for organisms which spread diseases.
Water with impurities and sediments may damage the system making it inefficient.
Drip irrigation is an irrigation system in which water is delivered at the root of the plant, drop by drop. It is also known as trickle irrigation. In this type of irrigation, pipes are laid in between the plants and during irrigation; water goes directly to the plants.
Advantages of drip irrigation
It is the most water efficient method of irrigation because there is even distribution of water to the crops hence high yields obtained.
Drip irrigation helps in the maintenance of soil moisture reservoir increasing on the decomposition of micro-organism in the soils.
The surface of the soil is dry which enables harvesting and transfer work to be executed more and with minimum effort.
When water resources are scarce and costly, much larger highly-targeted zone can be watered rather than covering the field with water.
The required moisture level in the root zone is maintained and the plants get its water from the soil without using much energy and this facilitates effective growth.
If managed properly, evaporation and runoff are minimized. Since drip irrigation is often combined with plastic mulch, it helps to reduce evaporation.
Disadvantages of drip irrigation
Drip irrigation is most expensive and least aesthetically pleasing method because all the plastic lines which have to be installed must be close to each other on the ground.
Drip irrigation tends to be labor intensive. This labor need not be overly skilled. But to achieve high efficiencies the irrigation practices imposed by the irrigator must be carefully implemented.
In drip irrigation system, droppers get clogged. To prevent this, water must be very well filtered and chemicals must be issued to clean the system.
Because the surface is not watered with drip irrigation system method, there is certain degree of salting. The salt is washed away if the zone receives more than 300mm yearly. If this isn’t the case with the location of the field, supportive watering methods must be employed.
Factors put into consideration in selection of an irrigation system
Compatibility
The irrigation system for a field must function alongside other farm operations such as land preparation, cultivation, and harvesting. The use of the large mechanized equipment requires longer and wider fields. The irrigation systems must not interfere with these operations and may need to be portable or function primarily outside the crop boundaries. Smaller equipment or animal-powered cultivating equipment is more suitable for small fields and more permanent irrigation facilities
Economics
The type of irrigation system selected is an important economic decision. Some types of the systems have high capital and operating costs but may utilize minimal labor and conserve water.. Other systems are relatively less expensive to construct and operate but have high labor requirements. Some systems are limited by the type of soil and the topography found on a field. The costs of maintenance and expected life of the rehabilitation along with an array of annual costs like energy, water, depreciation, land preparation, maintenance, labor and taxes should be included in the selection of an irrigation system
Topographical characteristics
Topography is a major factor affecting irrigation, particularly surface irrigation. Of general concern are the location and elevation of the water supply relative to the field boundaries. Field slope and its uniformity are two of the most important topographical factors.
Water supply
The quality and quantity of the source of water can have a significant impact on the irrigation practices. A water supply with a relatively small discharge is best utilized in an irrigation system. A poor quality water supply must be utilized more frequently and in larger amounts than one of good quality.
Soils
The soil’s moisture-holding capacity, intake rate and depth are the principal criteria affecting the type of system selected. Sandy soils typically have high intake rates and low soil moisture storage capacities and may require an entirely different irrigation strategy than the deep clay soil with low infiltration rates but high moisture-storage capacities. Sandy soil requires more frequent, smaller applications of water whereas clay soils can be irrigated less frequently and to a larger depth. Other soil properties influence the type of irrigation system to use. The physical, biological and chemical interactions of soil and water influence the hydraulic characteristics.
External influences
Conditions outside the sphere of agriculture affect and even dictate the type of system selected. For example, national policies regarding foreign exchange, strengthening specific sectors of the local economy. Since many irrigation projects are financed by outside donors and lenders, specific system configurations may be precluded because of international policies and attitudes
Crops
The yields of many crops may be as much affected by how water is applied as the quantity delivered. Irrigation systems create different environmental conditions such as humidity, temperature, and soil aeration. They affect the plant differently by wetting different parts of the plant thereby introducing various undesirable consequences like leaf burn, fruit spotting and deformation, crown rot, etc. Rice, on the other hand, thrives under ponded conditions.
Irrigation agriculture system has impacts to the environment which may be positive and negative as shown below:
Positive impacts of irrigation agricultural system to the environment
There is increased land being cultivated. In desert areas for example the use of irrigation system allows cultivation to take place in a place where it would not otherwise be possible and it also carried out all the year round and not only during rainy seasons but also dry season. This increases on the crop yields.
Irrigation water supplied by river in flood time often carries much silt, which adds to the fields increasing on the fertility of soil. With increased soil fertility will mean increased crop yields.
Double cropping is made possible. Farmers in this case are able to produce more than one crop a year and this increases farmer’s income because irrigation system will give to good crop yields.
Creation of employment opportunities in the construction of dams, canals, tanks. Many of the people earn their living from the jobs got from this system, either during construction or after construction.
Generation of government revenue: Government revenue is generated either directly or indirectly. This can help to balance and improve government expenditure. It can be through direct taxing of such farmers or payment of some services offered to them in an indirect way.
There is significant amount on nitrogen which is fixed in most water logged fields by algae, which may float on the surface of irrigation water. With the fixation of nitrogen the fertility of the soil and crop yields are maintained.
Provision of water: The practice has generated constant water supply not only to the farmers but also to other community members. Water is also used for domestic purposes like for animal to drink.
Boosted tourism industry: Some farmers have large farms with good quality plants which may be different from other farms, and this attracts tourists to tour the farm in either way borrow information to be applied on their different farms. With the tourists it has helped to increase on their local incomes and national income (gross domestic products).
Irrigation agriculture as a system has improved quality of food supplied to the farmers and the community around. Due to double cropping there is constant supply of food season after season. Constant supply of food has helped to check some mulnutritional deficiencies like kwashiorkor.
Negative impacts of irrigation agriculture system on the environment
The development of irrigation system has lead to the spread of diseases such as Bilharzia.since fast moving water cannot make the snails to survive in such conditions; irrigation canals provide an ideal habitat for it.
Irrigation system has mostly engaged in the production of agricultural products for example cotton, sugarcane, wheat and other products whose prices at the world market keep on fluctuating. With constant price fluctuations the farmers and government income is affected.
Pollution of water: Due to siltation of rivers, erosion problems affects water quality thus rendering it unhealthy for consumption (man) and indirectly when used by plants. This affects the environmental health conditions as it can cause some diseases like diarrhea (got from taking unclean water).It also increases on soil salinity due to higher rates of evaporation.
Generation of water weeds: water weeds have become a serious problem to the environment. Some water weeds like the water hyacinths tend to compete with crops for the soils nutrition and sometimes it chokes the canals
Due to constant water generation: This has lead to continuous sedimentation which is a serious problem throughout river channels, overhead channels. With this there is destruction of water resources.
Alternation of soil p.H: Irrigation done with water containing a lot of sodium may damage soil structure owing to formation of alkaline soils which may hinder decomposition of some organic matter by the micro-organisms with in the soil.
Irrigation agricultural system may involve use of some organic fertilizers, such fertilizers may be a threat to the environment as it depletes the ground aquifers and this may be an affect to the water cycle.
Problems of irrigation agriculture system in most African countries
It is an expensive system to install. Starting an irrigation system is an expensive venture which requires a lot capital to start. So most agriculturalists have remained on the local agriculture methods which slowly boost a country’s economy.
Poor technology: Due to poverty in most African countries they are not able to buy advanced equipments which are suitable for irrigation system. Most irrigation systems need modern technology because water may be trapped with the use of poor technology for example overhead irrigation system needs advanced technology.
Lack of skilled labor: Due to lack of trained personnel’s makes irrigation systems unsuccessful because those personnel who may be employed to manage the system may not know how to assess the environment impacts as a result of the system; instead they tend to neglect them.
Political instability: Some African countries for example Somalia it is very hard to build canals and redirect water for irrigation due to the fact that most of its areas are desert .Due to severe instabilities underground pipes may be destroyed during explosions.
Water scarcity: Some areas are desert for example southern parts of Sudan, north eastern parts of Uganda (karamoja region). Accessibility to water is a serious problem recorded from the past experiences. Much as the farmers wish to have such a system, water supply becomes an issue.
Solutions to the above problems.
Establish agricultural cooperatives: This helps farmers in many ways to solve various problems during the practice. This co-operatives lend money inform of loans to farmers to boost or set up irrigation schemes. They also call for training workshops to educate them new techniques about the existing schemes.
Lack of skilled manpower: This has been solved through calling for the training of local or village farmers on how to deal with the irrigation systems. With the training acquired, it can improve on their skills.
Technological advances: Encouraging people to adopt modern technological methods for example the use of machines like tractors, off-loading graders can help to solve the problem of poor technology of using local tools like hoes,pangas,axeswhich may make the work monotonous.
Insecurity like wars, tribal conflicts, cattle’s rustling makes the system unsuccessful in some areas in a given country. This makes their lives very hard and they end up in camps which may be very difficult for them to practice this irrigation system. So there is need for provision of security personnel’s to guard such region with irrigation schemes. For example in kakira sugar cane plantation there is security officials to guard the scheme.
Scarcity of water has been checked by digging of water sources for example boreholes, dams this will make irrigation system efficient. Also such system should be built near water sources like lakes, rivers.
Recommendations.
Farmers should realize that the investment in an irrigation scheme might be costly at the beginning, but the benefits are tremendous, the money can be quickly recovered. However, there are other cheaper alternatives for instance the wonder water pump which costs 250.000/= is affordable for an ordinary farmer.
Professor Gilbert Bukenya, the vice-president of Uganda says that starting an irrigation system in a country is expensive but tenable. And according to him he spent 16m, 6m on a tank and 10m on other implements like nozzles for ground sprinkling of water and pipes that distribute water around the farm and he emphasized farmers to shift to irrigation form of irrigation.
.Farmers should also emphasize on drip kind of irrigation system. Because here pipes are laid in between the plants and during irrigation water goes directly to the plants.
National agricultural advisory services and other non-government organizations must look forward and come in to help farmers with advisory services, support them through providing them with loans in form of funds because this can uplift their system of agriculture.
In conclusion: Many farmers depend on rain. For example According to a 2007 report by the Internal Food Policy Research Institute, sugarcane and rice are the most irrigated crops in Uganda. The report reveals that the rest of the crops are rain-dependent. Most African countries should adopt irrigation because that is where the future of agriculture lies. The master plan envisages that to popularize irrigation, demand-driven demonstrations will be necessary. And once farmers see that irrigation can be the difference between a good harvest and starvation, the uptake will be expected to increase. So with this system agriculture will be diversified hence a country’s economy will be boosted.
REFERENCES:
State of environment reports. 2000. NEMA publications.
B. Enger, F. Smith, Environment science: study of interrelationship.9th edition. Mc Graw-Hill Publishers.
http/:www.wikipedia.agriculture.com.
Henries. M.Kichodo (2008), world problems and development.3rd edition. Uganda, Kampala
About the Author
Name: Haykal Dahir Omar
Natiionality: Somali
Marial Status: Single
Sex: Male
Birth: 2/3/1985
Occupation: Student, Becholar Of Environmental Science
University: Kampala International University
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