Precision spraying and weed control: getting more from every litre

Four levels of precision

Precision spraying is not one product. It is a ladder, and each step removes a different kind of waste. It helps to know which step you are on before comparing brochures.

• Rate control: a controller holds the target litres per hectare as forward speed changes, so turning and slowing no longer over-apply.
• Section control: GPS switches boom sections off over ground already sprayed, on headlands and in point rows, removing most overlap.
• Individual nozzle control: pulse-width modulation or nozzle-by-nozzle switching gives very fine section widths and can compensate for speed differences across the boom when turning.
• Spot spraying: cameras or sensors detect weeds and fire only the nozzles above them, so herbicide goes on green plants rather than the whole field.

What camera spot spraying really saves

Spot spraying produces the largest headline savings, and the claims deserve careful reading. John Deere's See & Spray fires individual nozzles when boom-mounted cameras identify a weed. In September 2024 Deere reported that customers achieved an average 59% herbicide saving across maize, soya bean and cotton fields that season, compared with broadcast spraying, over more than one million acres. The company also cited an Iowa State University extension study with 76% average product savings across its test fields.

The saving is largest where weeds are patchy, and small where they are everywhere. Residual herbicides that must cover the whole soil surface cannot be spot-applied at all. The technology is also crop-specific: Deere lists maize, soya beans, cotton and fallow. In England, the SFI26 guidance for action PRF2 notes that camera recognition is currently available for docks and nettles in grass or clover leys, all weeds in maize, certain wide-row crops such as potatoes, and green growth on stubbles.

So the right question is not 'what does the system save?' but 'how much of my herbicide spend is post-emergence, on crops the system recognises, in fields where weeds are patchy?' Multiply the saving by that share, not by your whole chemical bill.

The UK rules precision kit has to work within

Spray drift near water is controlled by buffer zones printed on product labels. HSE's Local Environment Risk Assessment for Pesticides (LERAP) scheme lets users of horizontal boom sprayers reduce a 5 m aquatic buffer zone for eligible products after carrying out a risk assessment that takes account of watercourse size, dose and drift-reducing equipment with a recognised LERAP star rating. Buffer zones greater than 5 m for horizontal booms cannot be reduced, and you must record the decision, whether you reduce the buffer or use the full label distance, in your spray records.

Sprayer condition is regulated too. The UK Pesticides National Action Plan 2025 confirms that professional application equipment must be inspected under the National Sprayer Testing Scheme, and that people applying professional products need an accredited certificate unless supervised by a certificate holder. A camera system on a boom that bounces or a pump that cannot hold pressure will not deliver its promised savings, so boom stability and a current test certificate come before any upgrade.

The direction of policy is clear. The NAP sets a target to reduce each of the 20 metrics of the UK Pesticide Load Indicator by at least 10% by 2030, against a 2018 baseline. Precision application is one of the practical ways farms can contribute without giving up effective control.

Support for precision kit in England

The Farming Equipment and Technology Fund (FETF) 2026 productivity list included several spraying items, each with an expected average cost used to set the grant. Examples were a 24 m camera-guided spot sprayer (FETF425, expected average cost £46,000, 50% grant rate), automatic spray boom height control (FETF418, £10,495, 40%), camera-guided inter-row sprayers at 3 m and 6 m (FETF216 and FETF217, 50%) and closed transfer systems for loading chemicals (FETF419 and FETF420, 50%). FETF 2026 closed to applications on 12 May 2026 and Defra has said it was the final standalone round in its current form.

Under SFI26, action PRF2 paid £43 per hectare per year for camera or remote sensor guided herbicide spraying, and CIPM4 paid £45 per hectare per year for not using insecticide on arable and permanent crops. Both SFI26 application windows are now closed, with Defra planning a 2027 scheme.

A setup checklist before you spend on technology

Many of the gains from precision spraying come from getting the basics right on the sprayer you already own. Work through this list first; it is cheap and the savings are immediate.

• Calibrate: check each nozzle's output against the chart and replace any more than 10% above the mean flow.
• Match nozzles to the job: use LERAP-rated low-drift nozzles near watercourses and check the product label for any nozzle or droplet requirements.
• Set boom height to the nozzle manufacturer's recommendation and keep it there; automatic height control helps on uneven ground.
• Check GPS accuracy and field boundaries before relying on section control.
• Keep a written record of product, rate, water volume, nozzle, wind speed and any LERAP decision for every application.
• Confirm the sprayer's National Sprayer Testing Scheme certificate is in date.

Choosing between upgrading and replacing

Section control and rate control can usually be retrofitted to a sound sprayer at modest cost. Individual nozzle control and camera systems often need a newer boom, electrics and a compatible controller, which can push the decision towards a new or late-model sprayer.

Work out the saving per hectare on the products the system can actually target, multiply by your sprayed hectares, and compare it with the annual cost of the upgrade including any per-hectare fee. If you also contract-spray for neighbours, the extra hectares can change the answer. When you are comparing complete machines, the FarmFleets search lets you check tank size, boom width, pump output and the tractor power needed to carry a mounted or trailed unit, and the compare tool puts the options side by side.

Sources

Sources checked 2026-09-25

• John Deere, See & Spray customers see 59% average herbicide savings in 2024 (18 September 2024) — checked 2026-09-25
• HSE, Local Environment Risk Assessment for Pesticides (LERAP) — checked 2026-09-25
• GOV.UK, UK Pesticides National Action Plan 2025 — checked 2026-09-25
• GOV.UK, Productivity items and specifications, FETF 2026 — checked 2026-09-25
• GOV.UK, SFI26 actions (print version) — checked 2026-09-25

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