Your spreader, set for the fertiliser in your shed.
An NSTS fertiliser spreader test: we check the machine, analyse your fertiliser, then tray test the spreader across its full width, with trays every metre, and adjust it until the pattern is right.
What happens on the test
An SCS engineer comes to you with the trays, the kit and an iPad to record everything. Here’s what they do.
Your machine gets an MOT
Every working part is checked before a granule goes in, including the discs and vanes, and the tractor’s PTO speed against what the cab says.
Your fertiliser gets analysed
Bulk density, crush strength and granule size, from the bags you’ll be spreading. It’s how we catch a batch that won’t behave.
The full-width tray test
Trays every metre across the whole spread. We drive through, collect what lands, work out the CV at your bout width, adjust the spreader and go again until the pattern is right.
You get the NSTS report
Settings, photos and the conditions on the day, emailed to you and uploaded to the NSTS database. If the first run was off, the report estimates what it was costing you.
That matches what NSTS sets out for a fertiliser spreader test: an inspection including the discs and vanes, tray testing across the working width, adjustment for the best CV for each product, and an electronic report.1
- Product
- AN 34.5% N, batch B
- Bout
- 24 m, trays every 1 m
- First run
- CV 24.3%
- After adjustment
- CV 3.1%
- Evidence
- Photos, settings, conditions on the day
Uploaded to the NSTS database
Why we test your fertiliser first
Fertiliser changes from one delivery to the next. Larger, heavier granules fly further. Smaller or softer ones fall short, or break up on the discs.
A spreader’s setting chart is right for the fertiliser it was made with. But fertiliser is a commodity, made all year round in different plants and batches, so the bags in your shed may not be the fertiliser the chart was drawn up for. Two batches of the same product can need different settings.2
So before we touch the spreader, we test the fertiliser you’re actually going to spread.
| Measure | How we test it | What it changes |
|---|---|---|
| Granule size | Sorted through a grader box | How far each granule flies |
| Bulk density | A tube of known volume, filled and weighed | How it flows and how hard it’s thrown |
| Crush strength | A random sample crushed in a strength tester | Whether it shatters on the vanes and drops short |
How often to test
No UK law requires a spreader used only for fertiliser to be tested. The floor is set by farm assurance: a yearly calibration, with a record.
The advice from AHDB and the industry asks for more, because the thing that changes most often isn’t the spreader. It’s the fertiliser.
| Who | What they say | How often |
|---|---|---|
| The law | No testing duty: the inspection rules don’t cover equipment that isn’t used for pesticides.3 In NVZs and in Wales, nitrogen must be spread as accurately as possible.45 | None set |
| Slug pellets | Red Tractor and SQC count a fertiliser spreader used for slug pellets as a pellet applicator, so it needs an NSTS test.67 See slug pelleter testing. | By 5 years old, then every 6 |
| Red Tractor: Crops, Beef & Lamb, Dairy, Fresh Produce and Pigs | All manufactured fertiliser application equipment maintained and calibrated, with records kept (CR.EC.10, B.EC.10, DR.EC.10, PR.EC.10, PG.EC.10). No independent test is required.689101112 | Every year |
| Scottish Quality Crops | Spreaders maintained and calibrated, with records kept (1.11). No independent test is required.712 | Every year |
| Quality Meat Scotland: cattle and sheep | Application equipment checked for accurate application (10.15).1312 | Every year |
| AHDB, RB209 | Calibrate for rate every spring and when the fertiliser type changes; check the pattern with catch trays.14 | Rate each change; trays yearly |
| AIC | Tray test for every new type, brand or batch, after servicing or new parts, and with headland equipment.15 | Every change |
Test before your first pass of the season, with the fertiliser you’re going to spread. Most of our tests happen between January and May, so book a few weeks ahead. How often should a spreader be tested?
What you get
A dated record of the machine check, the rate and the spread pattern, with the settings for each fertiliser we tested.
Every NSTS test carries the NSTS certification fee. It’s what keeps the assurance inspector happy. For our prices, see what an NSTS spreader test costs.
How long the test takes depends on the spreader’s width and how many fertilisers we test. We’ll give you an idea when we book, so you can plan the day.
- The NSTS report, emailed to you. The settings for each fertiliser, the CV before and after adjustment, photos and the conditions on the day.
- Two fertilisers in every test. Each gets its own tray test, settings and CV on the report.
- A record on the NSTS database. You, your assessor or a buyer can check a test online by entering its certificate number on the NSTS website.16
- What it was costing you. If the first run was off, the report estimates the money the uneven spreading was losing.
Questions.
Does a new spreader need testing?
Yes. A new spreader comes with the manufacturer’s settings, but not with your tractor, your fertiliser or your fields. Our full guide to testing a new spreader sets out the evidence.
Is a fertiliser spreader test a legal requirement?
Not for a spreader used only for fertiliser. The legal duty is about the result: in NVZs and in Wales, nitrogen must be spread as accurately as possible.45 Slug pellets are different: pellet applicators must be tested by law,17 and Red Tractor and SQC count a fertiliser spreader used for pellets as a pellet applicator.67
Does Red Tractor require an NSTS spreader test?
No. Standard EC.10 asks for fertiliser application equipment to be maintained and calibrated at least annually, with a calibration record. It doesn’t name a tray test or an NSTS test.6 An NSTS test report is a dated record of the machine check, the rate and the spread pattern, so it covers the requirement and more.
Do I need to recalibrate for every fertiliser?
For the rate, yes: RB209 says to calibrate whenever the fertiliser type changes,14 because different products flow through the spreader at different speeds. For the spread pattern, RB209 asks for a tray check every year; the AIC advises one for each new type, brand or batch.15 A sensible middle course is a full test each year with your main products, and a quick check whenever a delivery looks different.
Which spreaders do you test?
Farm-scale twin-disc spreaders and broadcasters, down to the small spreaders used on orchards and greens. For pedestrian spreaders on turf, see golf, sport and turf.
Book a fertiliser spreader test
Most of our tests happen between January and May, so book a few weeks ahead of your first application.
- The make of spreader and the bout width you work at
- The fertilisers you’ll use, and have them on site on the day
- Your postcode, so we can send the nearest engineer
Or email info@spreadcheck.com. We’ll ring you to fix a date. Nothing is booked until we’ve spoken.
Our other tests
- SprayersKnapsacks to self-propelled
- Slug pelletersRequired by law
- Granular applicatorsPneumatic and placement
- Amenity testsPedestrian and small spreaders for golf, sports pitches, racecourses, schools and turf
- TrialsSpreading trials and product development, for manufacturers and importers
Farm tests: all four machines, and how often each one is due
Sources
- NSTS, Fertiliser spreader test, accessed 2026.
- Yara UK, Spreading preparation, accessed 2026.
- HSE, Guidance on the requirements of the Plant Protection Products (Sustainable Use) Regulations 2012, section 1.10, updated October 2025.
- gov.uk, Using nitrogen fertilisers in nitrate vulnerable zones, 2024.
- legislation.gov.uk, The Water Resources (Control of Agricultural Pollution) (Wales) Regulations 2021, Part 4, 2021.
- Red Tractor, Combinable Crops and Sugar Beet Standards, version 5.1, EC.7 and EC.10, February 2025.
- Scottish Quality Crops, The SQC Standards, 1.11, 2.17 to 2.19, October 2026.
- Red Tractor, Beef and Lamb Standards, EC.10 and guidance, 2025.
- Red Tractor, Dairy Standards, EC.10, 2025.
- Red Tractor, Fresh Produce Standards, version 5.1, EC.7, February 2025.
- Red Tractor, Pig Standards, version 5.1, February 2025.
- SCS, Testing requirements by assurance scheme: a summary of the scheme standards (fertiliser spreaders, slug pellets, granular applicators, sprayers), October 2026.
- Quality Meat Scotland, Cattle and Sheep Assurance Scheme Standards, in force from 1 January 2026.
- AHDB, Nutrient Management Guide (RB209), Section 1: Principles of nutrient management and fertiliser use, 2026.
- Agricultural Industries Confederation, Fertiliser Spreaders: choosing, maintaining and using, 2005, linked from RB209 2026.
- NSTS, Look up your test details, accessed 2026.
- legislation.gov.uk, The Plant Protection Products (Sustainable Use) Regulations 2012 (the UK’s “SUD” rules), regulation 12, 2012.