Management and operation

Find out about the many benefits of good irrigation management here.

Benefits of good irrigation management

• Protects water quality and quantity.
• Save on pumping costs.
• Protects soil structure and retains valuable nutrients.
• Compliance with conditions of water supply.
• A well-managed system will save on labour and maintenance costs.

Responsibilities of managing an irrigation system

• Understand and work within the conditions or rules that are set by the irrigation scheme or regional council, and govern the supply of water for irrigation.
• Protect water quality.
• Demonstrate and explain good irrigation practices to staff.
• Be as efficient as possible with water and energy use, while maintaining or improving production.
• Ensure any new irrigation is designed with efficient use of water, energy, labour and capital

Understanding the conditions of your water supply

A resource consent or scheme will limit the amount and timing of water available. These are likely to include:

• A limit on the flow (rate of take) such as litres/second, cubic metres/day or week
• A limit on the total volume that can be taken in a month, a season or a year.

As a manager it is your responsibility to have strategies in place to manage the farm when water restrictions occur. Both schemes and individual consents will often have particular limits for stream flows or groundwater levels, which will result in water takes being reduced or cut-off.

Other consent conditions may include defining the area that can be irrigated and the land uses, plus requirements not to water roads, tracks or other non-productive areas.

Know when your resource consent expires and apply for a replacement consent in plenty of time. If the application is submitted at least six months before the existing consent expires you can continue using the consent until the new application is finalised.

Measuring and reporting water use

Your regional council or irrigation scheme will be able to advise what kind of monitoring and reporting is required for your irrigation system.

It is important that owners and managers of irrigated farms establish what their compliance obligations are for water metering and consider what practical steps need to be taken.

Managing water supply restrictions

When river levels are low during the irrigation season, many surface water supplies are either restricted or shut-off completely. Although such water restrictions are generally beyond the control of those on farms, planning to deal with water restrictions can minimise production losses.

Planning ahead

• Consider planting crops in spring when the risk of irrigation restriction is low, enabling good establishment and providing feed in the dry (turnips and kale).
• Prioritise and water the better performing parts of your farm properly and cease irrigating on the poorer performing parts if restrictions come in.
• Make better use of water by evaluating your system to ensure that application uniformity is high and application depth is appropriate.
• Explore options to improve system capacity (on-farm storage, change irrigation type or design).
• Irrigate at night time when ET rates are low.
• Keep an eye on your total annual allocation volume.

Teaching good irrigation practices to farm staff

All staff need to understand what good irrigation means, know their responsibilities and be trained in all aspects of operation, and maintenance. If you are new to the farm it may be useful to contact the previous farm manager for information specific to the farm.

All staff that are operating the irrigation system should attend an IrrigationNZ training day for an overview on irrigation skills and knowledge. This should then be followed up with on-farm training specific to your system.

Ensure your staff know the answers to all these questions

• What is the application depth of the irrigators?
• What should I do if the irrigator or pump breaks down?
• What do I do if a leak is spotted or sprinkler is not working?
• How do I know if the pump or irrigator is operating correctly?
• What are the five most important maintenance jobs on the irrigator?
• When is soil moisture at a level to begin irrigating?
• What determines when we do and don’t irrigate?

Print off this template and fill it out with the relevant irrigation information then hang it up in the shed for staff to refer to.

Irrigation efficiency

Measuring water efficiency

Water use efficiency is the productive return per unit of water applied. In a dairy farm system this is kgDM per millimetre of water applied.

Measuring and monitoring water use helps identify areas in the design or management of irrigation systems that need to change to improve on-farm productivity, such as using less power, growing more grass or less time spent irrigating.

To be able to measure water use efficiency, records need to be kept for:

• annual volume of water used
• how well your system is performing
• pasture grown (from weekly farm walks).
• View water efficiency videos

View irrigation efficiency videos

How do I improve efficiency?

Key methods to better irrigation efficiency are:

• irrigation scheduling (including soil moisture and temperature monitoring)
• improving the performance of the irrigation system
• better matching irrigation system capability to soil type and plant demand

Pump efficiency

For spray irrigators the pump is the centre of the irrigation system and if the irrigation pump is not working properly, the whole irrigation system will suffer.

A pump requires energy to move the water to the irrigator. The force at which the water is delivered is pressure (m, kPa, bar, psi), the amount of water sent to the irrigator is the volume (m3) and the speed at which the water is moving through the pipe is the flow rate (l/sec, m3/hr, gpm).

The pumps role is to supply the irrigator with the correct volume of water at the right pressure level and flow rate, using as little energy as possible. If a leak occurs in the system, the pump will have to work harder (using more energy) to achieve the same amount of pressure.

By having a healthy pump:

• fewer breakdowns will occur
• less energy will be used
• the correct amount of water will be delivered to the irrigator.

Evaluating and improving your system

An evaluation requires knowing what the system is designed to do and checking it is performing to that level. It is about understanding the limiting factors of the system and taking action to fix it.

A detailed system evaluation can be completed by an irrigation consultant or a farmer can carry out their own, using instructions and guidelines developed for farmers. See the Evaluating your system page for more information.