Identify sources and their limitations
Compare mains water, abstraction and harvested water against peak daily demand and annual requirements. Audit use, improve application uniformity and repair leaks before increasing supply capacity.
The crop, rootstock and root-zone depth determine the area that drip irrigation must wet.
The English abstraction threshold
In England, withdrawals above 20,000 litres per day are likely to require an Environment Agency abstraction licence. The exemption for smaller operations aggregates abstractions at multiple points on the same source. Use the linked national routes for Scotland, Wales and Northern Ireland.
Compare mains supplies, private abstraction, harvested or recycled water, storage and emergency tankered supplies. Private sources can include rivers, streams, ponds, wells, boreholes and drains.
Daily demand governs the delivery needed during a busy period, whereas annual demand governs the total available across the season. An annual surplus does not guarantee adequate daily flow during a dry spell. Conversely, a high-capacity pump does not show that the permitted seasonal supply can sustain continuous use.
Audit efficiency and resilience
Audit water use by production area, harvesting or recycling opportunities, storage capacity, irrigation efficiency, scheduling and the interruption the crop can tolerate. Uniform application, avoiding runoff and repairing leaks can conserve water without purchasing an entirely new installation.
Recycled irrigation water typically needs treatment and should not be used where potable water is required. Reservoirs can buffer a low-flow source and store winter abstraction or rainfall.
Irrigation pump: flow, head and backwash
Select the agricultural irrigation pump for the system's flow and head requirements, including filtration backwash. Pipe layout and size affect pump efficiency and head loss. Include filter backwash demand when specifying the pump and motor.
Diesel and electric irrigation pumps use different power arrangements, but each must match the layout's delivery duty. Catalogue capacity has to be compared with the operating requirement through pipes, valves and filters.
Impeller design and diameter, total head, speed and flow all affect performance. Reducing pipe diameter can raise head loss, pressure requirements and pumping-energy costs, even when the initial installation is cheaper.
Solar powered irrigation pump and portable pump
A solar-powered irrigation pump, solar irrigation pump or solar powered irrigation system needs solar power available across the required operating window. A portable irrigation pump needs abstraction arrangements at each source.
Expansion changes the design question
Expanding a planting while retaining the original pump can compromise delivery. Soil, rootstock, wetted depth, irrigation shifts and topography remain relevant when converting or extending an existing installation.
For a drip layout, see the dedicated design guide.
Deep irrigation starts from root depth
Deep irrigation is a question of root depth: crop variety, rootstock and likely root-zone depth are inputs when planning a system. Sub-surface drip places the water inside the root zone, so it keeps losses down.
Types of farm irrigation systems
Four methods are in common use for irrigating potatoes: overhead rain guns, boom irrigation, sprinkler systems and drip irrigation. The sections below take them in turn, then the systems for pasture, orchards and vineyards. Whichever you choose, the pump and abstraction questions above and the application records below stay the same.
Overhead irrigation: rain guns and sprinklers
Overhead irrigation puts the water over the crop through a rain gun, a boom or sprinklers. An overhead rain gun (raingun) is the main method of application in potato crops and is cheap and versatile. It is prone to uneven application, which can lead to over-watering in some areas, so pressure, nozzle size and gun angle have to be managed. A travelling gun or boom irrigator is uneven at the start and end of each run, and a boom gives better uniformity than a gun.
Farm sprinkler systems cut the labour needed during the season and give better uniformity and the ability to apply small doses frequently (pulse irrigation), but their capital cost is higher. Fixed or portable solid-set sprinklers take substantial labour to set up and retrieve and very little once set up, and they suit high-value intensive vegetable and herb crops; fixed systems suit perennials. For a commercial tripod sprinkler or any other temporary set-up, allow for the labour of laying and retrieving the lines.
Boom irrigation: uniformity against layout
A boom irrigation system, compared with a rain gun, improves uniformity of application, especially for scab control, but topography, layout, field furniture and soil type can restrict its use, and high application rates can lead to run-off, soil slumping and ridge erosion. Boom systems use lower pressure than guns. Both are most suited to annual crops, including pastures, with low water requirements.
Pressurised irrigation and gravity-fed irrigation
In a pressurised irrigation system a hard-hose gun needs high pressure and loses more to friction. A gravity-fed irrigation system needs no pump, but it needs significant head, so measure the fall between the source and the field before relying on it. Dripper and micro-spray systems work at low pressure, but they need a filter and fairly clean water.
Field irrigation system: centre pivot and lateral move for large areas
For a commercial irrigation system on a large field, a centre pivot is best suited to large areas of crops with high water requirements or high value, and it is robust on rolling terrain. It may need an end gun to cover the corners of a square paddock, and the uniformity under the end gun is low. A linear (lateral) move machine is suited only to rectangular areas.
Keep your spray records in one place. Free to start.
Pasture irrigation: sprinkler lines, guns and border strips
For pasture irrigation, a long-lateral pasture sprinkler line (K-line type) has a low capital cost but high labour requirements, is suited to pasture only, and suits irregular or undulating ground. A travelling gun or boom also works on pasture, and sub-surface drip is suitable for pasture if it is properly designed. Strip (border-check) irrigation is suited to areas of even slope.
Vineyard and orchard irrigation: micro-sprays and drippers
Micro-sprays and mini-sprinklers suit vine and tree crops, with accurate control of irrigation if they are paired with good scheduling. Under-canopy micro-sprinklers or drippers are a common choice for orchards, and the same design stage should settle whether frost protection in winter or cooling in summer is wanted. For a mist irrigation system, say at the design stage whether the aim is cooling or frost protection.
Subsurface irrigation: drip tape below the ground
Sub-surface drip, the underground irrigation system, puts permanent drip tape below the ground, which supplies water directly to the crop root zone. Nothing runs off the surface and there is no crusting or ponding. Its high capital cost is the main obstacle. It is common for vegetables and tomatoes, and it may need an additional system for germination. For the pipework and filtration of an underground irrigation system, see the drip design guide. If the water only tops up the rain, as in supplemental irrigation, keep the same source, volume and timing record for each application (see Fresh Produce irrigation evidence below).
Irrigation controllers and rain sensor
An irrigation controller runs the schedule. A rain sensor connected to it is designed to interrupt the cycle of an automatic irrigation system when a specific amount of rainfall has occurred. Whatever the controller does, the application still has to be recorded as source, volume and timing.
Choosing sprinkler heads and nozzles
Irrigation sprinkler heads, also called spray heads, are the nozzles that decide how the water lands, so choose them with the system, not separately. On a rain gun, pressure, nozzle size and gun angle all have to be managed. A sprinkler layout gives high uniformity if it is properly designed with appropriate spacings, which means the head, the spacing between heads and the operating pressure are specified together. Micro-spray and mini-sprinkler heads are low-pressure heads and need a filter and fairly clean water.
Fresh Produce irrigation evidence
Red Tractor Fresh Produce standard PR.IG.5 requires irrigation records showing the source, volume and timing of each application. A water-test result does not contain those application details.
The related requirements are distinct:
- PR.IG.3 requires a documented Water Management Plan to improve efficiency and reduce waste.
- PR.IG.4 bases crop irrigation on an identified need, using evidence such as moisture measurements, scheduling, physical inspection or weather-station data.
- PR.IG.1 links microbiological testing frequency and E. coli thresholds to the crop category.
- PR.IG.1.1 requires controls and test results to be retained and reviewed, with improvement actions recorded.
- PR.IG.1.2 specifies a UKAS-accredited laboratory or another ISO 17025 standard, with water E. coli testing in its accreditation scope.
- PR.IG.6 requires the relevant water licence or permit and compliance with its volume and timing conditions.
For Red Tractor Fresh Produce members, PR.RA.1.f requires assessment of microbiological, chemical and physical water risks.
Sprinkler pump, irrigation well pump and diesel water pump: pump, drive and source
Match the pump to the actual delivery circuit, whether it supplies drip irrigation or a sprinkler irrigation system. The best irrigation pump or best sprinkler pump is the one whose pump curve meets that circuit's duty, whether it is an irrigation well pump, a diesel water pump for agriculture or a solar pump for farms. These systems can have different operating duties; layout, flow, head loss and filtration demand together set the motor.
A pump drawing lake water needs a water-quality and filtration assessment.
Descriptions such as 12v, 3 hp, PTO or diesel identify a power supply, rating or drive. They do not specify the complete pump duty, which includes the required operating head even for a small irrigation pump.
A Berkeley pump, a submersible agricultural pump or a booster pump is judged by its pump curve, drive and the connected installation.
Agricultural irrigation systems: compare the complete cost
Pipe size and layout affect head loss and pumping costs, so the installation price has to be compared with the resulting operating duty. A PVC irrigation system or poly tubing irrigation is a choice of pipe material, and pipe material, diameter and class affect capital and running costs.
For small farm irrigation systems, crop area, source, changes in elevation and irrigation shifts set the pump duty. The drip guide covers emitter and filtration questions.
Smart irrigation system and soil moisture sensor: what the records still need
Moisture measurements from a soil moisture sensor can serve as the evidence of need that PR.IG.4 asks for. An automatic irrigation system or smart irrigation system still has to leave the PR.IG.5 record of source, volume and timing of each application.
Irrigation water meter and application records
Red Tractor requires the source, volume and timing of each application to be recorded; an irrigation meter reading gives the volume.
Rainwater and the proposed delivery system
When rainwater feeds a drip system, plan storage, water quality and filtration together; harvested roof water can require treatment first.
Next step
See the drip-design guide and, for scheme records, batch traceability.