CONTENT
1. Introduction to Irrigation
- Objective of irrigation
- A wider view
- Water sources
- Improving water quality
- Water quality problems
- Physical impurities -sediment. turbidity, colour
- Chemical impurities -hardness, alkalinity, corrosion, iron, salinity, tastes and odours
- Biological impurities - algae, microorganisms
2. Soil Characteristics
- Understanding soils - sand, silt, clay, organic material
- Naming the soil
- Different soils for different purposes
- Improving soils
- Chemical soil properties - pH, sodicity, salinity
- Physical soil properties - uniformity, available soil water capacity, infiltration, internal drainage
- Kinds of soil moisture
- Gravitational water
- Capillary water
- Hygroscopic water
- Transpiration and Wilting Point
- Feel test for estimating soil moisture
- Fertigation
3. Estimating Plant Needs and Irrigation Scheduling
- When to irrigate
- Symptoms of water deficiency
- Symptoms of water excess
- Checklist for home gardeners
- Timing of irrigations
- Measuring water available to plants
- Calculating field capacity
- Calculating permanent wilting point
- Available moisture range
- Rooting depths of selected plants
- Water extraction by roots
- irrigation calculations
- Irrigation system efficiency
- Estimating water needs
- Estimated water loss under different climatic conditions
- Tensiometers
- Water requirements of turf grasses
- Importance of schedules
- Water volumes and duration
4. Drainage
- Reasons for drainage
- Improving permeability during construction
- Cultivation
- Adding soil ameliorants
- Chemical treatments
- Improving surface drainage after construction -sand slitting, aerating, sub soiling
- Drain layout - herringbone, grid
- Outlet
- Gradients
- Distance between pies
- Drain depth
- Drain types
- Laing drains
- Dams and water storage -site choice, size
- Soil degradation
- Erosion - water, wind, control
- Soil acidification
- Soil compaction
- Chemical residues
- Waste water treatment using reed beds
- Suitable plants
5. Types of Irrigation Systems
- Gravity systems, pressurised systems
- Sub surface systems, surface systems
- Flood irrigation -border check, hillside, furrow
- Pressurised systems - drip, sprinkler
- Conventional systems - portable, semi permanent, permanent
- Mechanised systems - travelling irrigators - soft hose, gard hose, boom types
- Centre pivot irrigation systems
- System components
- Electric drive, hydraulic drive, water drive
- Linear move systems, drive system
- Fixed sprinkler systems -hand move, hose move, permeant
- Quick coupling
- Sprinkler heads - spray, rotating
- Drive mechanisms - impact drive, gear, ball, cam, hex, cam gear drives
- Design considerations
6. Trickle Systems
- Reasons to choose trickle
- Do it yourself micro irrigation for amateurs
- Time duration for watering
- Automated systems
- Microjet irrigation
- Trickle system maintenance
- Cleaning filters
- Flushing
- Using chlorine, doses, continuous chlorination
7. Design Specifications
- System components
- Hydraulics - pressure
- Measuring pressure - bourdon gauge, head of water
- Calculating discharge or flow
- Bernoulli's Equation
- Velocity
- Friction loss in systems
- Water hammer
8. Pumps and Filters
- Types of pumps - piston, radial, mixed flow, axial flow
- Pumps and pressure systems
- Shallow well pumps, deep well pumps
- Pumping mechanisms - piston, centrifugal, turbine
- When a centrifugal pump fails
- Preventing clogging in trickle irrigation
- Controllers - automated, manual
9. Selecting the Right System for a Plant
- Water saving measures
- Filtration
- Flood, sprinkler, trickle irrigation
- Case studies - putting greens, ornamental gardens, etc
10. Design and Operation of Systems
- Cyclic watering
- Pulse watering
- Irrigation schedules
- Sprinkler spacings
- Considering sprinkler performance in design
- Electrical factors
- Electric powered automatic systems
- Design considerations
SUMMARY OF COMPETENCIES DEVELOPED
- Explain the significance of soil in irrigation.
- Explain how to determine when to irrigate in a small scale situation.
- Manage irrigation in a given situation.
- Explain the significance of different aspects of moving water including: drainage, pumps, filters, storage and recirculation.
- Select an appropriate irrigation system for a given situation.
- Explain the principles of design for a simple irrigation system.
- Design a simple irrigation system.
- Oversee the installation of an irrigation system.
WHY IRRIGATE?
The main objective of irrigation schemes or systems is to produce a particular desired pattern of plant growth. Maximum vegetative growth does not necessarily correspond to maximum yield of the part of the plant desired e.g. fruit, nuts, or roots. In addition, achieving maximum yield may require inefficient use of available resources, whether it is land, water, equipment, or labour. 'Optimum yield' is usually the desired objective. This has been defined as the yield at which the benefit/cost ratio is at maximum, although even this may be hard to achieve if any of the resources required for the irrigation system e.g. land, water, or equipment is limited. Therefore, it is important to clearly define the purpose or desired outcome of an irrigation system
The Wider View
Irrigation can be used to produce outcomes in terms of crop production. Irrigation schemes may also have other outcomes. Large-scale schemes may have an impact on human settlement patterns, causing local migrations of labour to or from irrigated areas with subsequent changes in the availability and cost of housing and services. Land prices may also be severely affected as land use patterns change. Impoundment of rivers and streams into dams and lakes can result in major environmental changes (such as changes to river characteristics and to flora and fauna populations) in areas both adjacent and far removed from those features. Small scale, even down to individual garden size systems, can still cause far-reaching changes. For example, the base flow component (year-round flow) of many urban streams derives almost entirely from home irrigation of gardens. If this was to stop these streams would cease flowing for much of the year. In addition, much of the excess water from irrigation systems that flow to streams, rivers and lakes is high in chemicals leached out of gardens or other crop areas. These chemicals, particularly nitrogen and phosphorous from fertilisers and pesticides, can cause major changes in vegetation and animal populations in and adjacent to water bodies.
Benefits of Studying This Course
This course is the perfect course to take for those seeking to develop an understanding of irrigation with a view to installing or maintaining irrigation systems. It guides you through different types of irrigation system and different components of irrigation systems, as well as the relative advantages of each. Learn how to assess a plant's water requirements and adjust irrigation accordingly. This course will appeal to people looking to work in, or broaden their knowledge in, the following areas:
- Irrigation
- Garden Maintenance
- Landscaping
- Nurseries
- Garden Centres
- Parks & Gardens
- Botanical Gardens
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