IRRIGATION - GARDENS

LEARN GARDEN IRRIGATION

• Learn to irrigate plants in gardens
• Learn from highly qualified and experienced professional horticulturists
• A course for nurserymen, gardeners, garden managers, park managers, turf managers and others

Lesson Structure

There are 10 lessons in this course:

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

Aims

• 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
  • 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.

Water is essential to healthy plant growth. It is often the major limitation to a plant's productivity. Irrigation may enable plants or turf to be grown in a dry climate where it would not otherwise be possible. It may also supplement the existing rainfall and improve growth rates by extending the growth period of the plant. It may ensure that there is adequate moisture during critical periods when a plant is growing most rapidly. Irrigation at appropriate times may also improve the quality of turf or the general health of garden plants. The value of irrigation can vary greatly from year to year depending on the distribution of rainfall during the growth season.

This course covers the design, installation, maintenance, operation and evaluation of simple irrigation systems. This course is similar to BHT304 and BAG213, but focuses on irrigation for parks, home gardens, and other ornamental horticulture areas.