Irrigation planning

Efficient irrigation is essential for productive farming, especially in regions with variable rainfall and increasing climate pressures. 

Whether you're upgrading an existing system or starting from scratch, careful planning ensures your irrigation setup meets crop needs, conserves water, and complies with regulations.

The right choice of irrigation system will depend on your farm goals, for example, increasing pasture growth, reducing labour, or improving water-use efficiency.

Assess system needs

Before selecting an irrigation system, assess:

• crop type and growth stage
• soil characteristics (including texture, infiltration rate, water-holding capacity)
• climate and seasonal rainfall patterns
• water source
• water availability and quality
• topography and field layout
• your labour capacity.

These factors influence how much water is needed, how often to irrigate, and which system will deliver water most efficiently.

You also need tocheck for any required water licensing and approvals.

Monitoring soil moisture

Soil moisture monitoring helps determine when and how much to irrigate. It supports better water use decisions and helps avoid over- or under-irrigation.

Techniques include:

• manual methods to evaluate soil feel and appearance
• sensors and probes to measure moisture at different depths
• tensiometers and capacitance probes provide real-time data.

Irrigation design checklist

Start with a whole farm plan to ensure your system suits your soil, crop needs, and landscape layout. 

The following list of considerations can be used to guide system design and investment decisions.

Site characteristics

Soil survey – soil type is the most significant factor for irrigation. Different soil types have widely varied characteristics which make a big difference to the design and management of irrigation. A comprehensive soil survey providing indications of soil texture, soil structure, infiltration rates, water holding capacity, problem soils and any subsoil constraints is essential. 

Starting without a soil survey means the design and management will be based on guesswork. An electromagnetic induction (EM38) soil survey is a cost-effective method that provides good results for all but very sandy soils.

Topography – all irrigation works best on fairly level, flat land. A topographic survey of the potential irrigation area is essential for good system design. Paddocks may appear to have little variation where they actually vary a lot. Not allowing for this often results in poor irrigation performance. A topographic survey also identifies infrastructure and permanent fixtures such as powerlines, roads, railway lines and fences.

Also consider topsoil management and drainage design as poor drainage can lead to waterlogging, nutrient loss, and plant stress.

Field size and shape – how will irrigation be laid out in the new field? If centre pivot is an option, are you comfortable farming in circles? How will you manage unwatered areas such as corners of square fields?

Vegetation – irrigation areas should be clear of vegetation in the line of planned areas for overhead or travelling irrigators. Investigate if any particular approvals from relevant authorities are needed for the removal of vegetation. Plans should also consider where/how shade shelter and biodiversity areas may be incorporated into areas adjacent to the irrigated site.

Pasture and crop planning – the types of pasture or crop you intend to grow and desired yield levels need to be considered as this will influence the design of the system and perhaps the type of system.

Climatic factors – climate is the main driver of plant water use and this influences most aspects of design and management. Defining the peak and average evapotranspiration for your location for the pasture or crops you intend to grow is important.

Water considerations

Quantity of water available – how many megalitres of water can you reliably access? There is no point having a large irrigable area but insufficient water to supply the plant water requirements.

Water quality – have the water from all your sources tested for quality. Water quality affects the type of plants that can be grown, the type of irrigation system you choose, and may have detrimental effects on soil and irrigation infrastructure. It is better to discover this in advance rather than after you have installed an expensive system that does not work well.

Water availability – can your water supply keep pace with the plants’ water demand? If you have a limited supply rate (for example, from a bore or water delivered from a scheme), the rate of supply may impose a limit on the area of pasture you can irrigate.

How far does the water have to be pumped? If the supply source is a long way from the irrigated field, there will be increased costs in both the pipework required and the annual running costs.

Is on-farm storage needed? If your supply has to be ordered many days in advance or it is not reliable, an on-farm storage might be needed. A storage allows shorter supply paths to the irrigated field, greater flow rates and faster channel/pipe fill, and a collection point for return or storm water.

Infrastructure and equipment

Pump selection and costs – the pump should always be selected as one of the last steps to ensure that it can perform efficiently at the required duty. Pumps are relatively cheap and a small percentage of the overall cost of the irrigation system. If the pump is poorly selected, extra running costs over just a few seasons will almost certainly be more than any saving that might have been made on the purchase price.

Monitoring system – methods of monitoring water and energy efficiency should be planned from the start. This means fitting appropriate meters and gauges. Having them with the capacity to be read remotely encourages collecting and using the data.

• For electrically driven pumps, install a pressure gauge at the pump, a water meter, and use the power meter readings.
• For diesel driven pumps, install a pressure gauge at the pump, a water meter, and a diesel fuel flow meter.

Information from these can be used to monitor pump efficiency and cost per ML. Observations over time will indicate where there is a problem and when it is cost-effective to renovate the pump or other components.

Monitoring of soil moisture – what soil moisture monitoring system will you install and how will you make your irrigation scheduling decisions?

Cost

Capital costs and operating costs – the irrigation layout must be beneficial for your business so insist on detail of the running costs as well as the capital costs so you can determine what is optimal for you. There is often a trade-off between these where a small increase in capital cost results in a large reduction to operating costs.

Labour availability – some systems (for example, surface systems, hand-shift, traveller) require high labour input. Other systems (centre pivot, drip) require more skilled labour. Labour and training costs need to be considered.

Installation – the type of system and layout will require different labour, equipment and timeframes to install. Also consider flow-on effects and disruption to infrastructure availability and daily routines around the farm during installation.

Water efficiency and productivity – can be monitored by recording yield from the irrigated area, the water meter readings and rainfall. Indicators such as Irrigation Water Use Index (IWUI) and Gross Production Water Use Index (GPWUI) can be easily calculated at the end of each season to evaluate the annual water and economic efficiencies of the system.

Choosing the right irrigation system

Common irrigation methods include:

• Surface irrigation – Water flows across the soil surface (e.g. furrow, border strip).
• Sprinkler systems – Water is sprayed over crops using pressurised nozzles.
• Drip/trickle irrigation – Water is delivered directly to the root zone via emitters.
• Travelling irrigators – Mobile systems that move across paddocks.

Each system has pros and cons depending on crop type, water availability, and land conditions.

Cost and performance

Irrigation is only viable if the cost is matched by productivity.

The recommendation is to keep total irrigation costs below 25% of gross income, including:

• Fixed charges – Infrastructure, licences.
• Variable costs – Water, energy, labour.

Improving system efficiency or spreading capital costs over more hectares can reduce cost per megalitre and improve return on investment.

Sprinkler systems

The following are sprinkler systems, meaning they distribute water by spraying it over the surface of the crops using pressurised nozzles or emitters.

Below the table you can find more detail on each system:

Centre Pivot and Lateral Move (CPLM)

CPLM systems are widely used across NSW for pasture and crop production.

These overhead irrigation systems rotate or move laterally across fields, providing uniform water distribution.

They offer high efficiency and automation benefits, making them suitable for large-scale operations. However, they require regular maintenance, seasonal checks, and careful scheduling to avoid issues like the "green drought"—a period of under-watering that can significantly reduce pasture growth.

To help assess suitability, maintenance needs, and seasonal readiness, see the checklist.

Bikeshift

Bikeshift irrigation involves manually shifting lightweight sprinkler lines across paddocks, often using a bike or quad bike. 

While more labour-intensive than automated systems, bikeshift setups are flexible and cost-effective for smaller farms or irregular paddock shapes.

To help assess suitability, maintenance needs, and seasonal readiness, see the checklist.

K-line

K-line irrigation uses a series of connected low-pressure sprinklers mounted on pods, which are dragged into position using a quad bike or tractor.

This system is particularly suited to undulating terrain and rotational grazing setups.

K-line systems are valued for their adaptability, ease of movement, and relatively low infrastructure costs.

They are commonly used in dairy and livestock operations across NSW.

To help assess suitability, maintenance needs, and seasonal readiness, see the checklist.

Getting a quote or hiring a contractor

• Engage an independent irrigation designer — not just a supplier.
• Request a performance specification before seeking quotes.
• Match system type to crop and soil conditions.
• Consider future expansion and seasonal variability.

After installation

• Ensure the system performs to design specifications.
• Test pressure, flow and application rates.
• Train operators and document procedures.

Seasonal timing and efficiency

Starting irrigation too late can lead to a “green drought” when pasture or crop growth slows due to soil moisture falling below the root zone. Even full irrigation may not quickly restore optimal conditions.

To avoid this:

• monitor soil moisture early and regularly
• start irrigation before soil moisture drops below the readily available water (RAW) range
• maintain systems so they’re ready to operate when needed
• don’t delay irrigation due to energy or labour costs as the cost of lost production may be higher.

Irrigation training and support

Local Land Services offers a range of support for irrigators across NSW. Whether you’re new to irrigation or refining an existing system, there are training opportunities, technical resources and industry contacts to help.

• Field days and workshops - covering topics like crop rotation, soil health, pest management and irrigation scheduling. Visit our events page to find out more.
• Technical advice. Local Land Services ag officers and Drought Adoption Officers can provide technical advice.