PRF1Variable rate application of nutrients

What it actually is

You apply all your major nutrients, nitrogen, phosphorus, potassium and magnesium, whether they come as manufactured fertiliser, solid manure, slurry or digestate, through variable rate application equipment. The kit is driven one of two ways: pre-programmed with a variable rate file built from zonal soil or crop testing or remote sensing data, or connected to crop reflectance sensors on the tractor or sprayer, and either way it varies the rate across the field automatically. One exception is written in, and it is confined to arable crops: an initial wake-up dose of nitrogen on an arable crop in late winter or early spring may go on flat rate through equipment that is not variable rate. On grassland and permanent crops there is no such exception. Micronutrients and lime are outside the requirement.

The zonal soil data underneath it must cover phosphorus, potassium, magnesium and pH as a minimum, and existing analysis counts if it is less than 5 years old.

GOV.UK's stated aim is precision equipment applying the major nutrients at rates that automatically adjust to match crop requirements across different areas of land, reducing over-application, improving yields through more uniform growth, and improving water and air quality.

The land entered has to be receiving at least one major nutrient above the thresholds the page sets, 100 kg of nitrogen, 40 kg of phosphorus or 40 kg of potassium per hectare a year, so this is an action for fed ground, not fallows. It is rotational or static.

Source: GOV.UK, PRF1 action page, checked 23/08/2026.

What it pays, and what that comes to

The rate is in the panel at the top of this page. Multiplied out:

Source: arithmetic on the payment rate shown at the top of this page, which comes from Tilth's copy of the GOV.UK action catalogue and carries its own last-checked date. The 200 hectares is an illustration.

Is it worth it on your ground?

The question splits into the two farms this action meets.

The farm already running variable rate. The costs already exist in your business: the spreader or sprayer that can do it, the zonal sampling round, the files or the sensor subscription. The action adds the discipline of running all four major nutrients and the organic manures through it, the wake-up nitrogen on arable crops aside, plus the record keeping below. If that describes your system already, the payment is close to clean money, and the only real check is whether the muck side of your operation can truly apply to a file, because the requirement covers slurry and solid manure, not just the bag, and it has to hold in practice, not on paper.

The farm thinking of starting for the payment. Be careful with the arithmetic here, because the best available British evidence puts a number on what variable rate nitrogen earns, and it is smaller than the folklore. ADAS ran trials across 11 commercial farms over 5 years, with hundreds of small plots at different nitrogen rates inside single fields of wheat, barley and oilseed rape, and found variable rate application would have raised yields by about 0.05 tonnes a hectare on average, worth roughly £10 a hectare in profit. Their conclusion was that most of the value lies in getting close to the right average rate for the field, not in varying the rate within it. Set that £10 beside this action's payment and beside the cost of zonal sampling, files and capable kit, and the payment is doing most of the lifting in the sum, which is a fragile place for a three year commitment to stand.

Source: ADAS, report on in-field variable rate nitrogen trials, 27/07/2026, checked 23/08/2026. The sampling, file and kit costs are your own figures, priced by your supplier.

Does it work, and what makes it work better

This section is what we have found in published sources about the practice this action pays for. It is not scheme guidance, it is not Defra's or the RPA's view, and it adds no requirement beyond what the GOV.UK action page sets out. We have named every source and given the date we checked it. What it means for your ground is your decision.

Conservation Evidence, whose graded assessments anchor most evidence sections on this site, hold no assessment of variable rate nutrient application, so this page rests on agronomic sources rather than a graded panel, and there are two worth having.

The ADAS work is the substantial one, and it is fresh, reported in July 2026: 11 commercial farms, 5 years, hundreds of within-field plots across winter wheat, winter barley and oilseed rape. The finding was that variable rate nitrogen would have increased yields by about 0.05 tonnes a hectare on average, roughly £10 a hectare of profit, and that applying the right uniform rate for the field achieved nearly the same result as varying the rate within it. Their stated conclusion is that the greatest value of variable rate nitrogen lies in helping get as close as possible to the field's average optimum rate, which is hard to estimate, rather than in the within-field variation itself.

AHDB's guidance on variable rate nitrogen makes the environmental case qualitatively: emissions associated with fertiliser application can be limited, and nitrate leaching is prevented where land is not carrying more nitrogen than it needs. They give no figures, and they stress that accurate data, testing and calibration come before any of it.

Source: ADAS, report on in-field variable rate nitrogen trials, 27/07/2026, and AHDB, variable-rate nitrogen application to reduce emissions, both checked 23/08/2026.

What we have not found. Any published British measurement of what variable rate application does to nitrate leaching or emissions in practice, which is the half of the action's aim the payment is presumably buying. Anything on variable rate phosphorus, potassium or magnesium outcomes, as against nitrogen. And nothing measuring PRF1 itself.

What the sources say makes it work better. The ADAS conclusion doubles as the practical steer: the money is in the accuracy of the underlying numbers, not the cleverness of the variation. Soil assessment and decision support to estimate the right optimum come first, which sits neatly beside this action's own requirement for zonal soil data no more than 5 years old covering phosphorus, potassium, magnesium and pH. AHDB's advice points the same way: test, calibrate, and plan before varying anything.

Source: ADAS and AHDB, as above, checked 23/08/2026.

What follows is Tilth's own reading of how those findings sit against this action, and it adds no requirement beyond what the GOV.UK action page sets out.

The honest position is that the yield case for variable rate is weak on the best British evidence, the environmental case is plausible and unmeasured, and the action pays a small amount for equipment discipline either way. That is not a criticism of the technology so much as a description of where the evidence has got to. The farms with most to gain are the uneven ones, and the work that earns the money on any farm is the unglamorous part, current zone maps and honest soil data, because a variable rate file built on stale or thin data just moves the wrong rates around the field with more precision.

What you actually have to do

Apply all major nutrients, nitrogen, phosphorus, potassium and magnesium, in manufactured fertilisers, solid manures, slurry and digestate, to the entered land using variable rate equipment that either runs a variable rate file built from zonal soil or crop testing or remote sensing, or is connected to tractor or sprayer mounted crop reflectance sensors, varying the rate automatically in a way that can reasonably achieve the action's aim. The initial wake-up nitrogen application to arable crops in late winter or early spring may go on flat rate through non-VRA equipment; there is no such exception on grassland or permanent crops. Zonal soil data must cover phosphorus, potassium, magnesium and pH as a minimum, and existing analysis under 5 years old counts. Micronutrients and lime are outside the requirement. Do this in each year of the three year duration.

Source: GOV.UK, PRF1 action page, checked 23/08/2026.

Where it can go, and what rules it out

Agricultural land below the moorland line: arable land with crops, temporary grassland, fallow arable land, improved permanent grassland, and permanent horticultural crops, registered and declared with compatible codes. The land must be receiving at least one major nutrient above the page's thresholds, 100 kg of nitrogen, 40 kg of phosphorus or 40 kg of potassium per hectare a year. SSSIs need Natural England's consent first, and land with historic or archaeological features needs its HEFER. Rotational or static, so the action can follow the fed ground around the rotation.

Source: GOV.UK, PRF1 action page, checked 23/08/2026.

Things worth watching

This section is Tilth's own reading of where this action is easy to get wrong. It is not scheme guidance, it is not sourced from Defra or the RPA, and none of it adds a requirement beyond what the GOV.UK action page sets out.

All means all, and muck is the hard one. The requirement covers slurry, solid manure and digestate as well as the bag. Variable rate spreading of granular fertiliser is mature kit; variable rate muck is a much rarer machine. If your organic applications cannot in truth vary to a file or a sensor, that conversation is better had before entering than during an inspection.

Check the soil data's birthday. The 5 year allowance on existing zonal analysis is generous, but a farm entering in 2026 on zones sampled in 2022 will need a resampling round mid-agreement. Price it into the decision now.

The wake-up exception is one application, early, and arable only. Late winter or early spring, the first dose, on an arable crop. Everything after it goes variable, including the main nitrogen splits, and on grassland and permanent crops every application goes variable from the start, which is where a farm with a flat-rate habit will slip.

Contractors need to be in on it. If spreading or spraying is contracted, the as-applied records this action leans on come off the contractor's kit, and their invoice is named in the evidence list. Whether their machine can log and hand over as-applied data is worth asking before you commit.

The threshold gates the land, not the farm. Only land receiving a major nutrient above the thresholds is eligible, so low-input grass and unfed fallows are out. Match the entered area to the ground you actually feed.

Keeping the evidence

Also Tilth's own reading. GOV.UK sets the requirements; what follows is a practical suggestion about record keeping.

GOV.UK's list is longer here than on most actions: invoices for the zonal soil testing, the variable rate files uploaded to the equipment, as-applied variable rate records at land parcel level, records of the flat-rate wake-up nitrogen where used, field operation records with invoices, and contractor invoices where relevant.

The habit that covers it is keeping the pair together: the file that went into the machine and the as-applied record that came out of it, per parcel, per application. Modern terminals export both. Add the soil analysis and its invoice at the start, and the wake-up dressing noted as such, and the year audits itself.

Tilth holds soil test results against fields, records applications at parcel level with dates and rates, and stores documents against the farm, so the files, the as-applieds and the analyses live in one place.

The part only your own ground can answer

Whether your fields are uneven enough for varying the rate to matter. The ADAS average says the typical field gains little, and an average is exactly the thing your own farm is not. Yield maps that show the same zones underperforming year after year, and soil analyses that disagree from one end of a field to the other, are the case for this action; uniform maps are the case against. Tilth holds your yields, your soil results and your NDVI imagery field by field, and lets you build variable rate maps from what they show, which is the groundwork this action pays you to stand on. Request an invite.