Irrigation Management (Horticulture)

Course CodeBHT305
Fee CodeS3
Duration (approx)100 hours
QualificationStatement of Attainment
Become an better Irrigation Manager
  • Learn to manage water better
  • Learn to use water to grow plants in crops, nurseries, gardens

Together with our other Irrigation course, this provides an extensive training for anyone working or wanting to work in the irrigation industry, for:

  • Irrigation Suppliers
  • Irrigation Istrallers
  • Irrigation Managers

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Lesson Structure

There are 8 lessons in this course:

  1. Water management
  2. Irrigation scheduling
  3. Drainage
  4. Irrigation controllers
  5. Irrigation maintenance
  6. Fertigation
  7. Design evaluation
  8. Irrigation design

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

What You Will Do

  • Contact your regional or local water authority.
  • Ask them for information on their water restriction policy.
  • When are water restrictions enforced and how do they affect water users?
  • Focus mainly on the problems experienced by agricultural users.
  • Consider ways that users can minimise their dependence on water access?
  • Write a brief report on your findings and submit with your assignment.
  • Visit a property that uses irrigation.
  • Discuss with the manager the methods that are used to decide when to water and how much ater to use.
  • Is irrigation an important element in the success or otherwise of the property?
  • Choose a drainage system to which you can get access.
  • Remember a drainage system is designed to cope with most situations.
  • They are many examples in your local everyday environment.
  • Some examples might include the guttering on your house or even on your car.
  • Discuss how the system operates and include sketches to show design features.
  • Contact a number of companies that offer computerised and technology solutions to irrigation.
  • Obtain prices and information if possible on appropriate working installations of their product.
  • If possible try a follow up visit at least one (1) operation and discuss the product with a user as well as a retailer. If distance or transport is a problem then you could try writing for this information, which would be suitable for the purpose of this set task.
  • Visit a property that uses large irrigation systems.
  • Enquire about the maintenance of their systems.
  • Consider how is water quality monitored and maintained?
  • Investigate at least two irrigation supply companies.
    • Observe how they service customers.
    • Consider: are there any other services they provide?

Water is Important to Plant Growth

Water is a major component of all plant growth. In succulent, leafy plant material the water content may be as high as 85 - 95%. Of all materials taken in by a plant, water is absorbed in the largest quantities. Generally less than 5% of the water taken in by the plant is used within the plant. In some cases the amount used is as little as 1%. The water remaining in the plant is used mainly in the cell tissues which are 75 - 90% water, as a carrier of foods and growth regulants from the leaves via the transport system (vascular system), and in very small quantities as part of the photosynthetic process.

 

The remaining 95% or more acts as a carrier of nutrients. Once it has carried these nutrients up through the plant, it becomes surplus and is disposed of to the atmosphere through the leaf stomata (leaf pores). This loss of water also helps to keep the leaf canopy cool reducing the likelihood of leaf burning or desiccation. This upward movement of water from the roots through the stems via the vascular system to the leaves is sometimes known as the transpiration stream.

 

Transpiration is the principal method of water movement into and through the plant. This is a physical process powered by the evaporation of water as a vapour into the atmosphere from the plant leaf. This water is lost from the outer surface of the leaf mesophyll cells (the spongy interior of the leaf). As the water is lost the cells become dehydrated. This creates a potential difference between the dry mesophyll cells and adjacent moist ones. Because of waters strong cohesive property (strong resistance of water molecules to be pulled apart) water from the adjacent moist cells diffuses through the cell walls into the dehydrated cells thereby relieving the pressure differential. The continued loss of water molecules from the leaves by evaporation creates a continual flow of water throughout the plant. This results in the pulling of replacement water from the soil via the roots and up the plant stem into the leaf.

 

Evaporation from the crown of the plant is roughly proportional to the size of the crown. Wind is the major cause of evaporation as it removes the moisture-laden air around the leaves creating a strong gradient between the moisture-laden leaf and the drier atmosphere surrounding the leaf. Increasing temperature will also increase the rate of evaporation. During winter transpiration is generally small, however in spring and early summer the amount of water transpired can be very large. If the availability of soil moisture is high and other conditions (e.g. light) are favourable the transpiration will be high. If either water supply is limited or other conditions are not favourable then transpiration will be greatly reduced. On a sunny spring day, mature trees can use 250 or more litres of water a day. One hectare of forest in a medium rainfall area may use the equivalent of 1000mm of rainfall per year. In high rainfall areas, such as tropical rainforests, over 2500mm per year may be transpired. In low rainfall areas the figure may be only 250mm per year (500mm of rain per hectare is equivalent to about 5 million litres).

 

TIPS FOR IRRIGATION DESIGN

Before designing an irrigation system you must first consider the following.

 

Water availability

  • What does it cost?
  • Is it available at all times of the year?
  • Do you need to build dams or holding tanks to cope with the times of restricted water supply?

Source and quality of water

  • Is it clean?
  • Does it carry salt, pollutants, diseases etc?
  • What pressure is it supplied at, or do you need to pump it (if so, how far?).
  • Is it from a canal, river, creek, bore, municipal supply, or dam?

Regulations

  • Are there any restrictions on use of water?
  • Are there any restrictions on building dams, canals etc?
  • Are there any drainage regulations etc.?
  • Check with the local council.

Site details

  • You need to know the shape of the site, levels, drainage patterns, locations of buildings, fences, roads walls etc.
  • You need to know the location of plants to be watered.

Finances and labour requirements

  • What money is available to create the system?
  • What manpower is available to operate the system?

 

 

The importance of system design cannot be overly stressed. The effectiveness and overall efficiency of the irrigation project will be largely dependent on system design. Often design is approached from a narrow focus that addresses only certain criteria. While achieving much of the required aims, the system lacks the ability to diversify or ignores minor design issues which have the potential to develop into larger problems at a later date.

 

Design processes can seem initially costly, good design often requires time. This includes, time to evaluate the individual complexities of the project, time to put down potential options by way of rough plans and scenarios, and finally more time to review these options and hopefully select the optimum design for that particular irrigation system. Even small scale irrigation systems are generally costly and intended for long term usage, therefore it is important to get the design process right. The process involves:

 

  1. Initial aims and objectives
  2. Research and consultation
  3. Primary options and design plans
  4. Scenario testing/comment
  5. Secondary options and plans
  6. Design of an appropriate irrigation system. 

 

 

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