WBD3In-field grass strips

What it actually is

You take arable ground you have identified as at risk of erosion or surface runoff, and put a grass strip through the field itself: along the contour of a slope or following a natural drainage pathway, so water running off the cropped ground hits standing grass, slows, and drops its sediment before it reaches a ditch or watercourse. The strip is established within 12 months of the start date, by sowing or natural regeneration, and kept as an intact grass sward all year round, protected from vehicle and stock damage. No fertilisers, manures or pesticides go on it, apart from herbicide spot treatment of injurious weeds, invasives, nettles or bracken, no livestock graze it, and the whole strip is cut once in late summer, after the bird breeding season. Existing in-field strips that meet the requirements can come in.

GOV.UK's stated aim is an in-field grass strip on erosion or runoff-prone land with an intact sward throughout the year, reducing the transport of sediment, nutrients and pesticides, improving water quality, providing wildlife habitat, and supporting integrated pest management.

The action is static, staying put for the whole agreement, and it is one of the limited area actions.

Source: GOV.UK, WBD3 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 strip is an illustration: length times width divided by 10,000, as with the other strip actions.

Is it worth it on your ground?

This action carries one of the higher per-hectare rates on this site, and setting it against the usual benchmark shows why it deserves attention.

Step one: what the ground would have earned. The Farm Business Survey's 2023/24 figures put typical combinable rotation gross margins in the band of £764 to £836 a hectare, and the rate at the top of this page sits level with the bottom of that band. So against an average hectare, this action roughly breaks even before seed. But the action does not want your average hectare: eligibility requires ground you have identified as at risk of erosion or runoff, and the wet flush that gullies every other winter, the slope that sheets soil onto the road, is rarely earning the rotation average. On the ground the action actually targets, the payment will beat the crop more years than not.

Source: Farm Business Survey, Crop Production in England 2023/24, Rural Business Research, checked 02/08/2026. Your own margins on the risk ground are the ones that count, and this comparison is Tilth's arithmetic, not scheme guidance.

Step two: the seed, once. A listed 4/6 metre grass and buffer strip mix runs at £92 per 20 kg at a stated rate of 10 kg an acre, about £113.62 a hectare, a one-off at establishment, or roughly £38 a hectare a year across the agreement. Natural regeneration is allowed where the seedbank suits, which makes even that cost optional on some ground.

Source: ProGreen, own listed price and stated sowing rate, looked up 31/07/2026. Price your own mix; cultivation and drilling are your own cost.

Step three: what the strip is quietly saving. The action's whole purpose is soil staying on the field and out of the ditch, and eroded soil is not free: it takes seed, nutrients and workability with it. We have found no published figure to put on that saving and will not invent one, but on ground that visibly moves in winter, it belongs on the payment's side of the ledger.

Steps one and three are Tilth's own reading and add no requirement beyond what the GOV.UK action page sets out.

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.

The fit note first, and it splits the action's two aims. For the wildlife and pest management half, Conservation Evidence's assessment of planted grass buffer strips and margins reaches this practice well, and it already anchors three other pages on this site. For the erosion and water quality half, the action's headline purpose, Conservation Evidence is a wildlife database and does not assess it, and we have not found an independent source we are willing to cite putting numbers on sediment trapped by in-field strips in British fields. So the best-evidenced part of this page is the action's second aim, and its first aim rests on the mechanism being as plain as it looks: standing grass slows water, and slow water drops what it carries.

The graded assessment. Conservation Evidence, based at the Department of Zoology at the University of Cambridge, summarises the published studies behind individual conservation actions and has independent subject experts score each one. Planting grass buffer strips and margins around arable or pasture fields comes out in their top category, Beneficial, on 69 studies, with 90 per cent for effectiveness, 65 per cent for certainty, and harms not assessed. Effectiveness scores only the size and direction of the reported effects, and they say themselves it does not consider the quantity or quality of the studies. Certainty is the separate score for how many studies there are, how well built they are and how much ground they cover.

Source: Conservation Evidence, action 246, Plant grass buffer strips/margins around arable or pasture fields, Farmland Conservation synopsis, checked 23/08/2026. Cite as Dicks et al. (2020), Farmland Conservation, pages 283 to 321, in What Works in Conservation 2020, Open Book Publishers.

What the studies found. In brief, because our CAHL3 and BFS1 pages carry the full account: nineteen studies from Finland, the Netherlands, Sweden and the UK found grass strips increased arthropod abundance, richness or diversity, nine UK studies found benefits to birds, seven found more plant cover and species, five found benefits to small mammals, against six finding no clear effect on insects, birds or invertebrate pests. Two findings bear directly on a strip in the middle of a field. In south Wiltshire, wheat fields with wide margins of 5 to 6 metres had a higher proportion of grain aphids parasitised than fields with margins under a metre, with the effect measured 20 metres into the crop, and flying predators reducing aphid numbers by 90 per cent and more. And in Oxfordshire, the ground beetle Bembidion lampros, named in the study as an important aphid predator, reached 8 per square metre in recently sown grass margins against 2 to 5 in mature margins and young hedges.

Conservation Evidence say themselves that studies are not directly comparable or of equal value, and that study size, design, reported metrics and relevance to your own situation matter more than "simply counting the number of studies that support a particular interpretation".

Source: Conservation Evidence, action 246, key messages and supporting evidence from individual studies, checked 23/08/2026.

What we have not found. Nothing measuring WBD3 itself. No British field measurement we can cite of how much sediment, nutrient or pesticide an in-field grass strip actually intercepts, which is the action's first-named purpose. And nothing on contour placement against drainage-line placement, which is the main siting choice the advice offers.

What the sources say makes it work better. From the wildlife evidence, width and reach: the aphid parasitism result sat behind margins of 5 to 6 metres, not a mower's width, and its effect reached 20 metres into the crop, which is an argument for generous strips and for the in-field position this action pays for. From the establishment advice on the action page itself: remove subsoil compaction before sowing, except over archaeological features, because water will not soak into a strip sitting on a pan, and cut regularly through the first 12 to 24 months so the sward thickens into the intact carpet the requirement describes.

Source: Conservation Evidence, action 246, supporting evidence from individual studies, and GOV.UK, WBD3 action page, establishment guidance, both 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 shape of this page is an action whose best-measured benefit is not the one on the tin. The wildlife and pest control case for in-field grass is strong, Beneficial on 69 studies, with the distance findings favouring strips inside the field over strips around it. The erosion case is the reason the action exists and the rate is set where it is, and it rests on an unmeasured but bluntly physical mechanism plus your own eyes: if you can see where the water runs and the soil goes, you know better than any study whether a strip across that line will catch it. The action even asks you to write that judgement down, the documented risk identification, which makes your own observation the founding evidence of the agreement.

Siting is where the action is won. A strip on the contour across a long slope, or laid along the wet seam where water already gathers, is doing the job the rate pays for; a straight strip placed for the sprayer's convenience on flat ground is not, and arguably fails the eligibility test before it fails the purpose. The farms that will do best out of WBD3 are the ones that already know exactly which field, and exactly where, before they read this far.

What you actually have to do

Identify the land as at risk of erosion or surface runoff and keep written evidence of that identification. Establish the in-field grass strip within 12 months of the action's start date, by sowing or natural regeneration, and keep it as an intact grass sward throughout the year, protected from damage by vehicles and stock. Apply no fertilisers or manures, and no pesticides beyond herbicide spot treatment of injurious weeds, invasive species, nettles or bracken. Keep livestock off. Cut the whole strip once in late summer, after the bird breeding season, checking for nesting birds first. Existing strips meeting the requirements can be entered. Do this in each year of the three year duration, in the same place, since the action is static.

Source: GOV.UK, WBD3 action page, checked 23/08/2026.

The establishment advice, as advice rather than requirement: place the strip along natural drainage pathways or parallel to the slope's contours, so it slows runoff and traps sediment; remove subsoil compaction before sowing, except on archaeological features; cut regularly in the first 12 to 24 months while the sward establishes; and at the annual cut, take the cuttings off where practical, or fine-chop and spread them where not.

Source: GOV.UK, WBD3 action page, establishment and maintenance guidance, checked 23/08/2026.

Where it can go, and what rules it out

Arable land with crops under AL2 or AL3 codes, temporary grassland under TG01 and fallow arable land under FA01, below the moorland line, on ground you have identified as at erosion or runoff risk and registered with eligible cover.

WBD3 is one of the ten limited area actions under SFI26, sharing the 25 per cent ceiling on your farm's total agricultural area with CIPM2, CAHL1, CAHL2, CAHL3, CIGL1, CIGL2, AHW7, AHW9 and AHW11. How the 25 per cent limit works.

Source: GOV.UK, WBD3 action page, checked 23/08/2026, and GOV.UK, SFI26 scheme rules and guidance, section 4.5, 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.

Write the risk case before anything else. The documented identification of erosion or runoff risk is a named requirement and the natural first artefact of the whole action. Photographs of last winter's rills and the muddy gateway, a line on the map showing where the water goes, and a dated note is all it needs, but it needs to exist, and it is far easier to write while the evidence is on the ground than from memory in year two.

The strip splits the field, so plan the workings. An in-field strip turns one cropped block into two, with the turning, tramlines and drilling patterns that implies. The advice to follow contours or drainage lines will rarely match the straightest working line, and the time to reconcile the two is on the map before establishment, not in the cab at drilling.

Intact sward all year means the strip is not a track. The requirement protects the strip from vehicle and stock damage, and an in-field strip is exactly where a quad, a trailer at harvest, or a short cut in a wet week wants to go. The strips that fail will mostly fail under wheels, not weather.

One cut, late, all of it. Unlike the part-width cut on the arable buffer action, this one cuts the entire strip, once, in late summer. It wants a slot in the plan after harvest pressure eases and before autumn work, and the nesting check before it is the law speaking, not the scheme.

It counts against the 25 per cent. Same arithmetic as the rest of the ten before anything is promised to an agreement.

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 examples are the written erosion or runoff risk evidence, field operation records with invoices, and photographs or other documentation.

Three things carry it: the risk case from before establishment, the establishment record, seed invoice or the note that natural regeneration was used, with the first-year cutting dates, and then one photograph a year of the strip standing green across the slope, ideally one winter shot with water or sediment visibly held, because a picture of the strip doing its job is the whole argument in one frame. The late summer cut goes in the diary each year with its date.

Tilth lets you draw the strip on the field map, attach the risk photographs and notes to it, and record the establishment and cutting operations against the parcel, so the case, the work and the proof stay together.

The part only your own ground can answer

Where the water goes. No survey knows your slopes, your wet seams or which gateway runs brown in November, and the action's own eligibility rests on you documenting exactly that. Walk it in the wet, mark it on the map, and the strip draws itself. Tilth gives you the map, the pins for the problem spots and the photographs against the field, which is the risk case half-written before you start. Request an invite.