‘One drop at a time’, part 4: Why drip remains an outsider in North American potato country

From the Columbia Basin and Idaho’s Snake River Plain to southern Alberta and Prince Edward Island, potato growers are under pressure to extract more value from every unit of water. Drip irrigation offers impressive control, but it must compete against deeply established—and increasingly precise—centre-pivot systems.

By Lukie Pieterse, Editor/Publisher of Potato News Today

Editor’s note: Lukie Pieterse is a former South African potato grower who produced drip-irrigated potatoes for several of the country’s major processors at the time, including McCain Foods, Frito-Lay and Heinz. His interest in drip irrigation is therefore grounded in first-hand farming experience.

Drip irrigation has many of the biological characteristics a potato crop appears to need.

It can deliver small amounts of water frequently, maintain relatively stable moisture inside the ridge, support carefully timed fertigation and avoid routinely wetting the canopy. It can also reduce wind drift, surface evaporation and runoff when compared with poorly designed or poorly operated overhead systems.

Yet anyone travelling through the major irrigated potato regions of North America will see far more centre pivots than drip lines.

That is not because North American growers have failed to recognise drip’s potential. It is because irrigation technologies do not compete on agronomy alone. They compete as complete farming systems.

Across Idaho, Washington, Oregon, North Dakota, Manitoba and Alberta, centre pivots already serve large fields and rotational crops with comparatively little annual installation and retrieval labour. Pumps, electrical services, wells, pipelines, roads and management practices have been developed around them.

Drip therefore enters these regions not as an obvious replacement for an inefficient past, but as a challenger to an increasingly sophisticated incumbent.

The important question is no longer whether drip irrigation can grow potatoes. It can. The more difficult North American question is where drip offers enough additional value to justify the disruption, expense and management demands of changing the system.

North America is not one irrigation environment

Any continental discussion must begin by recognising that North American potato production spans very different water realities.

In the Columbia Basin, Idaho and other western production areas, irrigation is generally a fundamental part of commercial potato production. Seasonal rainfall cannot reliably meet crop demand, and irrigation infrastructure is built into the economics of the farm.

Southern Alberta occupies a similarly irrigation-dependent environment, with intensive processing-potato production concentrated within established irrigation districts.

The situation changes moving east. Manitoba combines substantial irrigated production with variable summer rainfall. Prince Edward Island, New Brunswick, Maine and other humid regions have traditionally depended more heavily on precipitation. There, supplemental irrigation may be needed intensively during a dry season and scarcely at all during a wet one.

Canada’s production geography illustrates the importance of these differences. According to Agriculture and Agri-Food Canada’s 2023 national potato crop profile, Prince Edward Island and Manitoba each accounted for approximately 21% of the country’s harvested potato area, while Alberta represented approximately 20%.

Three provinces with broadly similar shares of national production consequently face very different irrigation, water-supply and investment decisions.

A system that makes sense for a grower irrigating every year in southern Alberta may be difficult to justify on a PEI farm where its value depends heavily on when rain falls.

The scale of existing irrigation matters

The latest national figures show how deeply irrigation is embedded in American agriculture.

The USDA’s 2023 Irrigation and Water Management Survey recorded 212,714 farms with 53.1 million irrigated acres. Producers applied approximately 81 million acre-feet of water.

The survey covers all irrigated agriculture rather than potatoes alone, but it provides important context. American farmers irrigated 12.6 million more acres with sprinkler systems than with gravity irrigation. Five states—Arkansas, California, Idaho, Nebraska and Texas—accounted for approximately half of irrigated acreage and more than half of all water applied.

Farmers and ranchers spent about $3 billion during 2023 on irrigation equipment, facilities, land improvements and computer technology. Pumping energy cost another $3.3 billion.

Those figures demonstrate why growers are interested in water and energy efficiency. They also show why wholesale conversion is difficult. North American agriculture has enormous amounts of capital tied up in existing systems.

For a potato business with functional pivots, the relevant comparison is not between drip and an imaginary farm without irrigation. It is between drip and the equipment the grower already owns.

The pivot has earned its place

Centre pivots became dominant in much of western North American potato country because they fit large-scale field agriculture.

Once installed, a pivot can irrigate potatoes and many rotational crops without placing and removing lateral lines every season. One operator can supervise several machines, particularly where remote controls and telemetry are available. Fertilisers and some crop-protection inputs can be delivered through suitable systems, subject to regulations and label requirements.

Pivots also avoid placing plastic laterals directly in the zone disturbed by potato planters, hillers and harvesters.

Their circular pattern leaves corners or irregular areas outside the principal irrigated circle, and poor design or maintenance can reduce uniformity. Wind drift, evaporation, wheel-track problems and canopy wetting remain legitimate concerns.

But the modern pivot should not be confused with older high-pressure sprinkler systems operating without monitoring.

Lower-pressure packages, improved nozzle selection, closer sprinkler spacing, drop tubes, variable-speed drives, pressure regulation, remote control and variable-rate irrigation are all improving the performance of overhead systems.

University of Idaho guidance on low-elevation spray application in potatoes explains how lowering sprinkler heads from the conventional mid-elevation position to approximately one or two feet above the ground or canopy can reduce the time droplets spend in the air. This can limit wind drift and evaporation while allowing lower operating pressures.

Lower pressure can reduce pumping costs, but it also changes application intensity. If water is delivered faster than the soil can absorb it, runoff and ponding may result. Soil texture, slope, surface condition and sprinkler spacing must therefore remain part of the design.

The lesson is that pivots are not standing still. Drip must compete not only with the conventional pivot of yesterday, but with a more closely monitored and increasingly variable system.

Precision irrigation in Alberta may strengthen the pivot

Southern Alberta offers one of the clearest examples of this evolution.

A four-year project entitled Towards Climate-Robust Irrigation Water Management for Potato Production is investigating whether precision irrigation can improve water-use efficiency and potato yield.

As reported by Alberta Agriculture through Potatoes in Canada, the project was in its second year in 2025. Researchers are examining which fields are most likely to benefit from precision technology and how that technology should be managed.

Modern variable-rate equipment can control individual sprinklers or groups of sprinklers along a pivot. Rather than treating the field as one uniform soil, the system can alter application according to mapped zones.

Willemijn Appels, Mueller Applied Research Chair in Irrigation Science at Lethbridge Polytechnic, has explained that the practical benefits of such technology under Alberta conditions still need to be established. Water availability is not expected to increase during the coming decade, while potatoes remain both high-value and sensitive to water supply.

This research has direct implications for drip.

If variable-rate pivots can respond successfully to differences in soil, topography and crop requirement, growers may be able to obtain part of drip’s precision advantage without abandoning their existing field-scale infrastructure.

On the other hand, the Alberta research programme has also examined subsurface drip in controlled soil bins, according to the Mueller Irrigation Research Group. That work recognises that drip remains a legitimate candidate where water must be placed precisely below the surface.

The likely outcome may not be a simple victory for one technology. Research may instead identify particular soils, slopes, fields or crop situations for which each system is best suited.

The Pacific Northwest has already investigated drip

Oregon State University has developed extensive potato-specific guidance on drip irrigation.

Its peer-reviewed Drip Irrigation Guide for Potatoes addresses bed configuration, pumps, filters, system maintenance, chemigation and other design requirements. Companion guidance covers scheduling through evapotranspiration estimates and soil-water tension.

This research base demonstrates that drip is agronomically viable in the Pacific Northwest. It also reveals the complexity of doing it properly.

Emitter spacing, line placement and flow rate must match soil texture. Water quality determines filtration needs. Tape must be protected from damage but remain within reach of the active root zone. Long runs, changes in elevation and inadequate pressure can reduce uniformity.

Permanent subsurface drip presents a further problem in potato rotations. Lines buried deeply enough to escape tillage and harvest machinery may be too far from the shallow potato root zone, especially in coarse soils with limited lateral water movement.

Shallow annual tape solves part of that problem but creates another: it must be installed, monitored and retrieved each season.

Growers must consequently compare a pivot that remains in the field for many years with laterals that may become an annual production input.

Pivot corners could offer drip a foothold

The most logical North American opportunity may not be replacing complete pivots. It may be supplying areas pivots cannot reach.

A centre pivot irrigates a circle within a square or irregular field. Corner arms can increase coverage, but some land may remain outside the wetted area. Drip can potentially bring those sections into production without requiring another overhead machine.

University of Idaho has discussed both shallow annual tape and more deeply buried drip for pivot corners. Some of its published cost estimates are decades old and should not be used as current budgets, but the concept remains relevant.

A corner installation changes the economic comparison. Drip is no longer being asked to replace a functioning pivot. It is being evaluated against leaving land unirrigated, planting a lower-value crop or accepting less reliable production.

The same principle applies to narrow fields, awkward parcels, land near obstructions and locations where overhead irrigation could affect neighbouring property or infrastructure.

This may be drip’s most realistic path into established western systems: not as a revolution across every acre, but as a targeted solution to the acres conventional equipment handles poorly.

Prince Edward Island tells a different story

In Atlantic Canada, the main question is often not how to replace an existing pivot. It is whether installing supplemental irrigation can be justified at all.

A peer-reviewed study published in Potato Research evaluated supplemental irrigation on commercial PEI potato farms between 2019 and 2022. Four to five fields were involved annually, using six commonly grown russet cultivars.

The treatments included rainfed production, conventional supplemental irrigation, irrigation guided by soil-moisture monitoring, and soil-moisture-guided irrigation combined with a 20% reduction in fertiliser input.

Supplemental irrigation significantly increased marketable yield in 2019 and 2020, when periods of inadequate rainfall limited crop water supply.

During 2021 and 2022, rainfall was more sufficient and evenly distributed. Growers either did not irrigate or applied relatively small amounts, and marketable-yield responses were negligible.

Across the study, irrigation helped reduce annual variation in potato yield. Its profitability, however, depended on equipment and water-supply costs, field scale, operating expenses and rainfall distribution.

That is a crucial finding. Irrigation can possess genuine biological and risk-management value while producing an uncertain annual financial return.

PEI has since made a supplemental irrigation calculator available to help growers estimate an appropriate moisture range and irrigation rate according to soil parameters and crop growth stage.

This movement toward evidence-based scheduling is important regardless of whether water is delivered through drip, travelling guns or another system. In humid production regions, the ability to avoid unnecessary irrigation may be as valuable as the ability to irrigate during drought.

An Iowa trial illustrates the insurance dilemma

A farmer-led experiment in Iowa provides another instructive example.

After several hot, dry summers, grower Lee Matteson tested drip irrigation on Red Pontiac and Kennebec potatoes in 2024. According to Practical Farmers of Iowa, tape was installed in June, with irrigated and non-irrigated treatments included for both varieties.

The season then turned wet. Soil moisture did not fall to a level requiring irrigation, and the system was operated only twice to apply fertiliser. No statistically significant irrigation effect on marketable yield was found.

It would be easy to dismiss this as an unhelpful result. In fact, it captures one of the central economic challenges confronting supplemental irrigation.

The grower must invest before knowing whether the season will create an opportunity to earn a return. Equipment purchased after drought begins is unlikely to arrive, be designed and become operational in time to prevent early crop damage.

Irrigation in a variable climate therefore has an insurance value. The difficulty is assigning a price to that protection and determining how many dry years are needed to recover the investment.

Fertigation could strengthen drip’s case

Drip may become more competitive where it performs more than one job.

Applying soluble nutrients through the system allows the seasonal requirement to be divided into smaller applications. This can improve the alignment between nutrient availability and crop demand and may reduce the quantity of mobile nitrogen present before the crop can use it.

On coarse soils, smaller and more frequent applications may reduce the risk of nitrate moving below the active root zone.

That benefit must be measured rather than assumed. Fertigation requires suitable injection equipment, backflow protection, water testing, compatible fertilisers and effective flushing. Errors in concentration can affect an entire irrigation block, while precipitation inside lines can obstruct emitters.

The financial case should therefore compare the complete nutrient programme under drip with the farm’s existing practice. Potential savings in fertiliser, application passes, fuel and labour belong in the calculation, but so do injection equipment, monitoring and maintenance.

Plastic remains an unresolved cost

Annual drip tape creates a physical waste stream that pivots do not.

Tape removed from potato fields may be wet, stretched and contaminated with soil. Collection, transport and recycling can be difficult, and the availability of agricultural-plastic recycling varies considerably by region.

Fragments left in the field can interfere with equipment and contribute to long-term plastic contamination.

Thicker reusable laterals may reduce annual waste, but they cost more and still require retrieval and storage. Permanent subsurface systems avoid yearly collection, yet must survive field traffic, tillage and rotation while maintaining hydraulic performance.

Any credible environmental comparison must therefore examine more than water savings. It should consider energy use, equipment life, fertiliser losses, plastic manufacture, retrieval and end-of-life handling.

Drip may still deliver a favourable result, but water efficiency alone does not settle the sustainability question.

Where drip has the strongest North American prospects

Drip is most likely to establish a larger role where several advantages coincide:

Water allocation or pumping capacity is genuinely restrictive.
The crop carries a high value or strict market specification.
Field shape makes pivot or linear-move coverage inefficient.
Wind materially reduces sprinkler uniformity.
Soil provides sufficient lateral movement from emitters.
Fertigation creates measurable nutrient and labour benefits.
The farm can integrate tape installation and retrieval with existing machinery.
Several crops in the rotation can use the infrastructure.
Bringing previously unirrigated land into reliable production creates additional revenue.
Water and quality records are detailed enough to demonstrate a return.

Its weakest case is likely to be on large, regular fields where an existing pivot already delivers uniform applications efficiently and serves the complete rotation.

The future may be hybrid rather than revolutionary

The North American irrigation debate should not be reduced to drip versus pivot.

A grower might use a variable-rate pivot across the main field while drip serves corners or irregular sections. Drip could be reserved for high-value varieties, seed production or research blocks. Overhead irrigation might establish the crop and wet the complete ridge, with drip used later for precise water and nutrient delivery.

Sensors, weather data, crop models and flow monitoring can improve both systems. The most important innovation may not be the application device itself, but the information used to decide when and where water is needed.

North American growers will not abandon decades of infrastructure simply because another system appears more efficient in a research comparison. Nor should they.

Drip will earn a place only where it solves a defined production problem more profitably and reliably than the alternatives.

That may prevent it from becoming the dominant irrigation method across the continent’s largest potato regions. It does not make drip irrelevant.

Its future may lie precisely in the places where the pivot reaches its limits: outside the circle, across variable soils, within restricted water allocations and in crops where each improvement in marketable yield carries substantial value.

The winner will not necessarily be the system that applies the fewest litres per hectare. It will be the one that places available water where the potato crop can use it, protects quality, fits the rotation and leaves the farm financially stronger.