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Why is my crop striped after spreading fertiliser?

Stripes are the spreader’s pattern written in the crop. Where they fall tells you a lot about what’s wrong, and by the time you can see them, you’ve already lost yield.

By Spreadcheck, NSTS testers. Published . 7 minute read.

The short answer

Stripes mean the spreader is putting too much on some strips and too little on others. The usual causes are a bout width the fertiliser can’t reach, settings made for a different product, worn vanes or a set-up fault; wind, weak granules and blends make it worse.

  • Stripes running halfway between tramlines usually mean the overlap between passes is wrong: too little, and you get pale stripes; too much, and you get dark ones.
  • A change of fertiliser is the commonest trigger. Two batches of the same product can need different settings.1
  • Worn vanes and bearings and the wrong height are common causes of poor performance.2
  • NSTS puts visible striping at above about 20% CV, and a crop with no stripes is no guarantee of even spreading.3
  • The fix is to measure, not to guess: a full-width tray test shows exactly where the pattern is wrong and lets the settings be corrected for that product.

Reading the stripes

Each pass of a spinning-disc spreader lays the heaviest band of fertiliser near the tractor and less towards the edges. The next pass fills in the edges from the other side. When the two meet properly, the field gets an even rate. When they don’t, the crop shows you where.

Even: the passes overlap properly

Even spreading: the rate is close to target everywhere and the crop is one even colour

Not reaching far enough: pale stripes mid-bout

Not reaching far enough: too much on the tramlines, too little mid-bout, so a pale stripe runs between each pair of tramlines

Too much in the overlap: dark stripes mid-bout

Too much in the overlap: too much mid-bout, too little near the tramlines, so a dark stripe runs between each pair of tramlines
Illustrative. Bars show the rate across two bouts, one tray a metre; the dashed line is the rate you set; the band below is the crop, with tramlines marked in brown. All three put on exactly the same total.
  • Pale stripes halfway between tramlines, lush on the tramlines. The fertiliser isn’t reaching far enough for the bout width.
  • Dark stripes halfway between tramlines. Too much is landing in the overlap: the pattern is too heavy at the edges for this width.
  • Every other bout looks different, or one side of each pass. Something is lopsided: the spreader isn’t level, one disc or vane is damaged, the settings differ side to side, or there was a side wind.
  • Stripes only on the headlands or along the boundary. The headland or border settings, or the on-off timing at the ends.
  • Stripes that started with a new delivery. The settings were made for a different fertiliser.

The usual causes

A bout width the fertiliser can’t reach

Not every fertiliser can be spread at every width. Kverneland says its chart widths are the widest that gave under 10% CV in its lab, and that some products can’t reach them.4 Rauch says the wide patterns used at big bout widths are more sensitive to changes in the fertiliser.5 Light products, urea above all, are the first to fall short. See spreading urea: how wide can you go?

Settings made for a different fertiliser

Setting charts are made in test halls with a sample of each product. Yara, which makes fertiliser, says two batches of the same product can need different settings.1 In the 2011 Bygholm test hall trial, one spreader on chart settings gave 13.6% CV; after a tray test with the same fertiliser it gave 5.1%. The chart had been made with a coarser product.6 See are setting charts right for your fertiliser?

Worn or damaged vanes

Fertiliser is abrasive, and the vanes take the wear. Worn vanes and bearings and the wrong height are among the commonest causes of poor spreading,2 and material passing through wears vanes and reduces performance.7 Teagasc says even moderate vane wear changes the throw angle and the distribution, and one worn vane or disc pulls the pattern to one side.8 Look for a rippled or wrinkled working face, a rough leading edge, or a track worn along the lip.9 Rauch says worn vanes must be replaced or the spreading pattern will not be correct.10 After fitting new vanes or discs, the AIC advises a fresh tray test.11

The set-up on your tractor

Working height above the crop, whether the spreader sits level side to side and at the right angle front to back, and the PTO speed at the shaft all move the pattern.11 Teagasc warns that if the machine isn’t level, the spread pattern will be wrong.12

Weak granules and blends

Soft granules break on the vanes, travel less far and cause striping.13 Blends add a twist: ingredients of different size and density land at different distances, so one nutrient can stripe while the overall weight looks even.1415 See how to check fertiliser quality.

Wind

A side wind carries the pattern downwind. Rauch says the wide, flat-topped patterns used at big bout widths, and light or angular products, are more sensitive to side wind and to changes in the fertiliser.5 In New Zealand tray tests, a 6 m/s cross wind cut the usable bout width for DAP from 21 m to 13 m.16 There’s no official UK wind-speed limit; Defra’s code says not to spread in very windy conditions that disrupt the pattern.17

Headlands

Headlands are where the biggest errors hide. Teagasc measured cereal headlands on 17 farms: the first 8 m got about 20% less than target and the next 8 m about 20% more, and some farms had parts of the headland getting almost nothing. Both the border-spreading settings and the on-off timing caused the errors.18 Field edges carry legal limits too: in England, no manufactured fertiliser within 2 m of surface water, or within 2 m of the centre of most hedgerows.1920

You lose yield before you see stripes

Stripes only show once the pattern is well out. NSTS put visible striping at above 20% CV and said a crop with no stripes is no guarantee of even spreading.3 Teagasc and the Fertilizer Association of Ireland say that above 20%, a crop and financial loss will result.21

Under-fed strips lose yield, and the further below the optimum they are, the faster it goes: AHDB’s RB209 shows a cereal crop 40 kg N/ha short of its optimum losing about 0.27 t/ha.22 Over-fed strips don’t win it back. They bring a higher risk of lodging and disease instead.2324

What to do about it

  1. Note where the stripes are. Mid-bout or on the tramlines, every bout or every other one, all over or just on the headlands. It narrows down the cause.
  2. Check what changed. A new delivery, new vanes, a different tractor, a wider bout.
  3. Look at the vanes and discs. Wear, damage and fertiliser build-up all shorten the throw.
  4. Don’t guess at a new setting. Moving a setting by eye can make one side better and the other worse. A full-width tray test shows exactly where the pattern is out, and the settings can be corrected for that fertiliser.

If the crop is already striped this season, it’s worth testing before the next application rather than after harvest. The pattern that striped this pass will do the same on the next one.

Other questions people ask

Why are there pale stripes halfway between my tramlines?

The fertiliser isn’t reaching far enough for the bout width, so the strip where neighbouring passes should overlap goes short. Common causes are a lighter or smaller product than the settings were made for, worn vanes, the spreader set too low, or a bout too wide for that fertiliser.

Why is my crop darker on the tramlines?

It’s the other half of the same problem. If too little reaches mid-bout, too much is landing near the tractor. Check the settings against the product you’re spreading, and check the vanes for wear.

Can wind cause striping?

Yes. A side wind pushes the pattern downwind, so one side of each pass gets more and the other less, and light products like urea suffer most. Rauch says wide-bout patterns, light or angular products are more sensitive to side wind.5 Spread in calm conditions, and narrow the bout for light products if you can’t wait.

Is striping the fertiliser’s fault or the spreader’s?

Usually it’s the match between the two. A spreader set correctly for one fertiliser can stripe with another: in an independent test hall, one spreader gave 13.6% CV on chart settings and 5.1% after a tray test with the same product.6 Soft granules that shatter on the vanes travel less far and cause striping too.13

About this article

Written by Spreadcheck (Spreader & Sprayer Testing Ltd), an NSTS testing company at Rookery Farm, Wheaton Aston, Staffordshire, which wrote the original qualification for fertiliser spreader and slug pelleter testing that NSTS adopted. We sell testing, so every figure here links to its source, and we say where the evidence is mixed.

Checked on 12 October 2026. Rules, prices and guidance change, so follow the links for the latest.

Sources

  1. Yara UK, Spreading preparation, accessed 2026.
  2. Farmers Weekly, How to calibrate your fertiliser spreader for grass (Yara advice), 2008.
  3. Farm Contractor & Large Scale Farmer, AEA to launch National Spreader Testing Scheme, 2015.
  4. Kverneland, Kverneland spreading charts, accessed 2026.
  5. Rauch, Practical test kit operator’s manual, 2024.
  6. Farmers Weekly, Fertiliser spreader test: Amazone ZA-M, 2011.
  7. Farmers Weekly, Correct application makes the most of fertiliser (Ecopt figures), 2012.
  8. Teagasc, Some simple steps before you spread, 2026.
  9. Teagasc, How to cut fertiliser costs without losing out on yields, 2024.
  10. Rauch, AXIS 20.2 to 50.2 instruction manual, section 8.6, 2015.
  11. Agricultural Industries Confederation, Fertiliser Spreaders: choosing, maintaining and using, 2005, linked from RB209 2026.
  12. Teagasc, Fertiliser spreader basic set-up and calibration, leaflet 15, 2025.
  13. Irish Farmers Journal, Is protected urea a runner in 2025?, 2025.
  14. Amazone UK, EasyMix press release, 2019.
  15. Holmes, Ekanayake, Nguyen and Werner, Massey University FLRC, The uniformity of ground spreading common New Zealand blended fertilisers, Occasional Report 36, 2024.
  16. Grafton et al., Massey University FLRC, Occasional Report 29 (NZ Spreadmark field trials in slope and wind), 2016.
  17. Defra, Protecting our Water, Soil and Air: Code of Good Agricultural Practice, paragraph 434, 2009.
  18. Teagasc (Dermot Forristal), Accurate spreading: six steps you need to take, Today’s Farm, 2023.
  19. gov.uk, Rules for farmers and land managers to prevent water pollution, 2026.
  20. gov.uk, Hedgerow management rules: buffer strips, 2024.
  21. Teagasc and the Fertilizer Association of Ireland, Precise Application of Fertiliser, Technical Bulletin 3, 2017.
  22. AHDB, Nutrient Management Guide (RB209), Section 4: Arable crops, 2026.
  23. AHDB, Nutrient Management Guide (RB209), Section 1: Principles of nutrient management and fertiliser use, 2026.
  24. AHDB, An introduction to lodging in cereals, accessed 2026.