https://drive.google.com/file/d/1rsDjVULf_YzkMXd7650OfAb-vbxA1nyJ/view?usp=sharing
Tuesday, 25 May 2021
AGEN 401 Irrigation II
https://drive.google.com/file/d/138ql3yBl8UdHrSjb1aztPvaxjSexHg42/view?usp=sharingAGEN 401: IRRIGATION II
2 CREDIT UNITS
Year: 2020/2021 Session
Lecturer: M. K. Othman (Professor of Irrigation Water Management), (B.Eng, M.Sc (Agric. Eng), M.Phil (Hydrology/ DEA, National d’Hydrologie: Science de l’Eau et de l’Env. Cont.) France, PhD (Agric. Eng), Adv. Dip.( French Lang), MNIAE, MNSE, FL)
Office: NAERLS, Block A, First Floor
COURSE OUTLINES & LECTURE NOTES
1. Review of Irrigation
2. Design of Irrigation Systems: Border, Furrow, Basin, Sprinkler and Trickle
3. Mitigating Irrigation Problems: Seepage and Channel Lining, quality of irrigation water, salinity, sodicity and leaching requirements, reclamation of saline and sodic lands, and general problems of existing schemes in Nigeria. Farmer Participation in system management, aspects of feasibility studies for irrigation schemes.
Field Trip and Technical Report of the Trip
The class is required to undertake field trip to one or two selected irrigation projects on a study tour. Students are expected to thoroughly study the projects with respect to historical background, project performance (irrigation water management- conveyance, allocation, distribution and application, Cropping intensity, irrigation operation and maintenance, participation of water users association, marketing issues etc), challenges – infrastructure, technical, environmental, etc and way forward
Reference Books
1. Irrigation Theory and Practice by A. M. Michael
2. FAO Training Manuals on Irrigation and Water Managements
3. Technical Handbook No. 24 on Drip Irrigation by Isaya V. Sijali
4. Irrigation Engineering by A. Benami A. Ofen
5. Other lecture and training materials
Review of Irrigation
Definition
Irrigation is defined as the artificial supply/application of water to crops for their optimum growths and yield. There are other definitions more elaborate but with the same meaning
Objectives of Irrigation
• To produce quality crops through the supplemental or total supply of water required by crops to meet their evapotranspiration needs at various stages of growth
• To use the soil as a water storage reservoir without destroying its fertility and structure
• To ensure enough moisture essential for plant life
• To provide means of increasing food production in the country
• To provide employment during dry season period
• To increase cropping intensity of farmland
• Etc
Status of Irrigation in the World
• By 1993, there were 1000 million ha under cultivation in the world, out of this number, about 200 million ha were under irrigation (Malvyn Kay, 1993)
• 95 % of the irrigated land cultivated using surface irrigation methods
• In 1980, 206.88 million ha were cultivated under irrigation and the area was increased to 255.46 million ha (21 % increase by 1995)
• From that year (1995), the irrigated area was expected to increase by 19 % in the next 15 years (i. e. 2010)
Saline and Alkaline Soils
https://drive.google.com/file/d/1vY0EdQj2i8Us7mc2_Q-RTVpmrcRG9cTv/view?usp=sharing
https://drive.google.com/file/d/1VcbIGnS-rN3hn-XcFrJ-Le0hpf1_N0oW/view?usp=sharing
Lecture Notes on Irrigation AGEN 501: Salinity And Water Quality
Prepared by Engr M. K. Othman (PhD)
Sources / Causes of soluble salts in Soils
Salinization is a major problem associated mostly with arid lands. It is estimated that 10 to 50 per cent of all irrigated land in the world is adversely affected by salinity.
Many processes, both natural and man-induced, result in salinization. Salinization requires a source of salt, a process that concentrates the salt and impaired drainage. Sources of salts include the natural weathering of minerals and redeposition of the salts at another location, the importation of salts in water used for irrigation, the deposition of rainfall with low concentrations of marine salts, and the transportation of salts in airborne dust from dry salt beds. Natural weathering of geological salt deposits is a major source of salts in arid regions. The weathering of non-saline minerals can also be important when combined with processes that concentrate the salts. The main origin of salts in the soil is from the weathering of the parent material of soil or rock which include hydration, oxidation, carbonation etc. however, hydrological conditions and poor management of irrigation schemes contribute substantially to the development of soil salinity and alkalinity. (Excess exchangeable salt and excess exchangeable sodium)
These are
1 Use of saline water in irrigation
2 Deposition of salts on the soil surface from the high water table
3 Arid region (high evaporation)
4 Poor drainage (non-leaching)
5 Water backflow or intrusion of seawater in coastal areas
All the above factors either singly or in association with each other are responsible to salt accumulations in soils
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