AHW4Skylark plots

What it actually is

During autumn and winter you create fallow plots inside a winter cereal crop, and you leave them there until that crop is harvested in the summer. There must be at least two plots per hectare in each land parcel where you do the action. GOV.UK puts the size as needing to be large enough to meet the action's aim, which the page says will usually mean at least 3 metres wide and around 16 square metres in area.

Source: GOV.UK, AHW4 action page, checked 05/08/2026.

What it pays, and what that comes to

The rate is in the panel at the top of this page, and it is paid per plot rather than per hectare. At the minimum of two plots per hectare of winter cereal, that multiplies out to £22 per hectare per year.

Here is the number that makes this action unusual among the ones on this site. Two plots is 32 square metres, which is 0.32 per cent of a hectare. So the payment works out at £6,875 per hectare of ground actually taken out.

Source: plot size and the minimum plot count from the GOV.UK AHW4 action page, checked 05/08/2026. The rest is arithmetic on those figures and 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: 2 × 16 = 32 m²; 32 ÷ 10,000 = 0.32%; £22 ÷ 0.0032 = £6,875.

Is it worth it on your ground?

The arithmetic here is short enough to check in your head, so here it is rather than a verdict. The shape of it is different from every other page on this site, and the reason is set out under the table.

What comes out of production is 0.32 per cent of the hectare. So what you give up is the grain that 0.32 per cent would have grown, worked at the crop's output rather than at its gross margin. The three winter cereals, on Farm Business Survey figures for England, non-organic, in the 2023/24 crop year:

Source: yields and prices from the Farm Business Survey, Crop Production in England 2023/24, Rural Business Research, England, non-organic, 2023/24 column, checked 02/08/2026. The winter wheat figures come from a sample of 572 farms. Output is yield multiplied by price. Grain given up is 0.32 per cent of the yield, its value is 0.32 per cent of the output, and the net figure is that subtracted from the £22 above. Put your own field's yield and your own price into the same sum if you have them.

Two things we have deliberately not done to this sum, and one thing this page does differently from the rest of the site. What follows is Tilth's own reading rather than scheme guidance.

We have not deducted any saving in variable costs. GOV.UK's advice section says that after drilling you can apply fertiliser and spray treatments to the skylark plots as well as to the adjacent crop. Where that is what happens, the fertiliser and the spray still cross the plot, so there is no input bill to take off and the full value of the grain stands. If you would treat the plot differently on your own farm, deduct your own figure.

We have not put a number on the cost of making the plots, because it does not consume an input we could price. The real cost is attention at drilling and the risk of getting the count or the position wrong, and that is your own judgement rather than a figure we are going to invent.

And this page does not use the three-year rotation comparison the other pages use. Everywhere else on this site the comparison is the action's payment against what the ground averages in gross margin across a rotation, because the action takes the ground out for the length of the agreement. This one does not take the ground out. It takes 0.32 per cent of it out, keeps the crop, and keeps the passes that go on the crop. A gross margin is output with the variable costs already removed, and here the variable costs are still being spent on the plot, so a gross margin would understate what is given up. Output is the cautious figure and it is the one used above.

Across a farm. Multiply the net figure by your winter cereal area. On 200 hectares of winter wheat that is £3,320 a year. Read the wording carefully, because it is where this sum goes wrong most easily. That is 200 hectares of winter cereal in the year the plots go in, not 200 hectares of arable land. Plots go in winter cereals only, so ground in a break crop that year carries no plots and earns nothing from this action, and a rotation with a break crop in it never has the whole arable area in winter cereal at once. Two other things come off the eligible area as well: land bounded by tree lines or next to woods is out unless the parcel is over 10 hectares, and the land has to be identified by you as not at risk of soil erosion or surface runoff.

When the answer is no. The £16 to £18 a hectare only exists if the plots go in, in the right places, and stay there until harvest. If drilling is already a scramble and you are not confident that would happen, the sum above is not the sum you would get.

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.

None of the work below is about AHW4 by name. It is about creating skylark plots, and this action is one way of paying for that practice. On this action the practice studied and the practice paid for sit close together. Conservation Evidence define skylark plots as small undrilled patches within cereal fields, given as 4 to 16 square metres, and most of the studies below used 4 by 4 metre patches at two plots a hectare. AHW4 asks for plots at least 3 metres wide and around 16 square metres, at a minimum of two a hectare. So the plots in the research and the plots the action pays for are close to the same object, which is not true of every action on this site.

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. Creating skylark plots comes out in their category Beneficial, on 11 studies. The expert scores behind that are 100 per cent for effectiveness, 80 per cent for certainty, and harms not assessed. Those two scores are not the same thing. Effectiveness scores only the size and direction of the effects that were reported, and certainty is the separate score for how many studies there are, how well built they are, and how much ground they cover. Both being high means the reported effects were large and the panel was reasonably confident they carry across.

Source: Conservation Evidence, action 540, Create skylark plots, in the Farmland Conservation synopsis, checked 05/08/2026. 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, both ways. Four studies from the UK and Switzerland looked at the effect of skylark plots on skylarks themselves, and all four found a positive effect: increases in population size, breeding density, breeding duration or breeding success, or a lower likelihood of skylarks abandoning their territory, relative to fields without plots. A study from Denmark found skylarks used undrilled patches within cereal fields more than an even distribution across the landscape would predict. Four studies looked at wildlife other than skylarks, and those cut both ways: three UK studies found benefits to plants and invertebrates, while two UK studies found no significant differences in the numbers of some invertebrates or of seed-eating songbirds between skylark plots and conventional crop fields. One UK study compared establishment techniques, and found undrilled plots had greater vegetation cover and height than plots established by spraying out with herbicide.

Source: Conservation Evidence, action 540, key messages, checked 05/08/2026.

Some of the individual numbers, so you can see what the effects look like. Morris and others, across 15 sites in northern, eastern and southern England in 2002 and 2003, recorded 0.3 skylark nests a hectare in winter wheat with undrilled 4 by 4 metre patches at two a hectare, against 0.2 in wide-spaced rows or under conventional management, with fewer territorial and nesting birds lost over the season and an average of one more chick per nest by the end of it. Ogilvy and others, on ten farms in the same two years, found 45 per cent of 159 monitored nests were in fields with plots, and by June those fields carried 1 nest a hectare against 0.4 and 1.75 chicks a nest against 0.9. Donald and Morris recorded a Cambridgeshire farm going from 10 territorial males in 2000 to 34 in 2005 after plots were introduced in 2001, though that came alongside 6 metre margins and set-aside, so it belongs to the package rather than to the plots. At the other end, Fischer and others in Switzerland found birds with patches in their territory were less likely to abandon it, but nest productivity was identical at 1.4 chicks a territory either way. Smith and others found invertebrate abundance in undrilled patch fields was not significantly different from conventional winter wheat fields. And Field and others, surveying 100 farms across three English regions in 2007 to 2009, found skylark plots were well used at 1 to 3 seed-eating farmland songbirds a hectare but did not hold significantly more birds than crop fields or fallow plots.

Source: Conservation Evidence, action 540, supporting evidence from individual studies, checked 05/08/2026.

Two things about that list are worth knowing before you weigh it. Four of the 11 studies, Morris 2004, Ogilvy 2006, Smith and Jones 2007 and Smith 2009, are named on the page as part of the same research project, SAFFIE, so they are not four independent looks at the question. And 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". The individual studies listed run from 1997 to 2010, so all of them predate this scheme and this action.

Source: Conservation Evidence, action 540, checked 05/08/2026, including the note under key messages and the project attributions given in the individual study summaries.

What we have not found. Nothing measuring AHW4 itself, which is no surprise given how new it is. Nothing comparing the two plots a hectare this action sets as its minimum against a higher number on the same ground in England. And nothing that puts a figure on what a plot is worth where skylarks are not already in the field.

What the sources say makes it work better. All of the following comes from the studies listed on that same Conservation Evidence page, and it is a description of what was found rather than advice from us.

The clearest practical finding is about how the plot is made. Dillon and others, working in two wheat fields in Cambridgeshire in 2008 and 2009, compared plots left undrilled against plots drilled and then sprayed out with glyphosate. Undrilled plots had 54 per cent vegetation cover by July. Sprayed plots stayed below 30 per cent, and those sprayed in February stayed below 10 per cent. Undrilled plots also carried taller vegetation, 17 to 29 cm against 2 to 13 cm in July. The same study found the extra cover in undrilled plots came from crop and from blackgrass, with blackgrass reaching 40 per cent cover by July, against under 5 per cent in all the sprayed treatments. It also found plots following spring beans tended to carry greater vegetation cover than plots following oilseed rape.

On weeds, Ogilvy and others recorded significantly higher undesirable weed cover in the plots than in the surrounding crop, 6 per cent against 4 per cent, while cover across the field as a whole was no higher, 2 per cent against 1.5 per cent. Smith and others, finding no significant invertebrate response in one of their two years, suggested a critical threshold of weedy cover has to be reached before any significant effect on invertebrates shows up.

On the mechanism, Stoate and Moorcroft reported skylarks raising 49 per cent more young in fields with plots than in fields without, by prolonging the length of the breeding season rather than by doing better in any one attempt.

On size and number, Odderskær and others in eastern Jutland found one 22 hectare field carrying one hundred 40 square metre plots held higher densities of skylarks than four fields averaging seven plots a hectare at 7 square metres each. Those two arrangements differ in both plot size and plot number, so the study does not separate the two.

Source: Conservation Evidence, action 540, background information and supporting evidence from individual studies, checked 05/08/2026.

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 establishment finding is the one that lands directly on a decision this action leaves open. GOV.UK's advice section offers both methods, turning off the drill during sowing or drilling the field and spraying the plot areas out with a non-selective herbicide by the end of December, and the page notes itself that establishing by spraying can reduce foraging opportunities because those areas will not have much vegetation for longer. Dillon's numbers are a measurement of that same point. So the two permitted methods are not equivalent on the evidence we have found, and the page's own advice runs the same way.

The blackgrass number is the other side of it. A cost that shows up in one method and not the other is not in the payment either way, and what 40 per cent blackgrass cover in a 16 square metre patch is worth on your ground depends entirely on what your blackgrass situation already is. We have not found a published figure for that and we are not going to invent one. The rest of it, what the plot follows in the rotation and how weedy the field is to start with, is a decision about the cropping around the plot rather than about the plot. What you are paid against is the GOV.UK page.

What you actually have to do

During autumn and winter, create fallow plots within a winter cereal crop. There must be at least two plots per hectare in each land parcel where you do the action, and GOV.UK says the plots must be large enough to meet the action's aim, which the page puts at usually at least 3 metres wide and around 16 square metres in area. Retain the plots until the winter cereal crop is harvested in the summer.

You also have to identify the land as not being at risk of soil erosion or surface runoff, and keep written evidence that you have.

An existing skylark plot can be maintained and paid for under this action if it meets the action's requirements and is not already being paid for under another environmental land management scheme.

Source: GOV.UK, AHW4 action page, checked 05/08/2026.

What you cannot do on it

You must not locate the plots in tramlines, boundaries or margins. GOV.UK gives the reason on the page: those positions increase the risk of attacks on skylark nests by predators.

You must not do this action on land bounded by tree lines or adjacent to woods, unless the land parcel is larger than 10 hectares.

Beyond that, the action does not restrict what goes on the field. GOV.UK's advice section says that after drilling you can apply fertiliser and spray treatments to the plots as well as to the adjacent crop, that you do not need to keep the plots weed-free, and that you can control weeds such as blackgrass and wild oat by spot spraying with a hand-held device before they flower and set seed. The same section notes that birds, nests and eggs are protected by law, and advises avoiding mechanical weeding of the winter cereal crop between April and harvesting to avoid damage to skylark nests.

Source: GOV.UK, AHW4 action page, checked 05/08/2026.

Where it can go, and any cap

Agricultural land below the moorland line, on arable land, that you have identified as not being at risk of soil erosion or surface runoff. The eligible land covers are arable land used to grow crops, including leguminous and nitrogen-fixing crops, temporary grassland under TG01 and arable land lying fallow under FA01. The action itself has to be done in a winter cereal crop.

The action is rotational or static, which means you can move its location for the second and third years, or do it at the same location each year.

Source: GOV.UK, AHW4 action page, checked 05/08/2026.

AHW4 is not one of the limited area actions under SFI26, so the 25 per cent cap that applies to actions such as CAHL2 and AHW7 does not apply to it. The ten actions that share that cap are CIPM2, CAHL1, CAHL2, CAHL3, CIGL1, CIGL2, WBD3, AHW7, AHW9 and AHW11.

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

What you can stack it with

The compatibility lists are on the GOV.UK action page, set out separately for actions on the same area and actions on boundaries only. On the same area under SFI26 it lists OFC3 and OFM4, and under SFI 2024 it lists CIPM1, CNUM1, CSAM1, OFC3 and OFM4. On boundaries only under SFI26 it lists CHRW2, BND1, BND2 and WBD2. There are further lists for SFI 2023, Countryside Stewardship and Environmental Stewardship agreements.

Source: GOV.UK, AHW4 action page, checked 05/08/2026.

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.

Not in the tramlines, even though that is where the drill is easiest to lift. The prohibition on tramlines, boundaries and margins is explicit, and the tramline is also the convenient place, so the rule and the habit point in opposite directions.

Not every cereal field qualifies. Parcels bounded by tree lines or next to woods need to be over 10 hectares. If a fair amount of your cereals sit in small parcels against woodland, your eligible area is smaller than your cereal area, which matters before you multiply anything by your whole acreage.

The eligible area moves every year. Plots go in winter cereals, so the hectares that carry them are the hectares in winter cereal that year. In a rotation with a break crop, the payment moves round the farm with the cereals rather than sitting still, and the whole-farm figure changes from year to year even though the rate does not.

The shape matters as well as the area. At least 3 metres wide and around 16 square metres together describe a short, wide patch rather than a narrow slot. Worth checking what a brief lift of your own drill actually leaves on the ground against those two figures.

The count is made at drilling and needed at harvest. The payment is per plot and the minimum is per hectare, so how many went in and which fields they are in has to come from a record made at the time.

They stay fallow until harvest. The requirement is to retain them until the winter cereal crop is harvested, so anything that closes them up in spring undoes the action.

Keeping the evidence

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

Two separate records. First, the erosion and runoff assessment, which GOV.UK says you must keep in writing. Second, evidence of what you have done, with field operations at land parcel level and their associated invoices, and photographs or other documentation, given as the examples.

Source: GOV.UK, AHW4 action page, checked 05/08/2026.

What that means in practice is how many plots went in, in which fields, and roughly where. The record is made at drilling and wanted after harvest, which is a long gap to hold anything in your head, and a good argument for marking the plots as you drill rather than counting them afterwards.

The part only your own ground can answer

The net figures above are worked on national average yields and prices, and the number that actually matters is what your own winter cereal ground yields and what you sell it for. Which fields are in cereals in which year is the other half, and that is a rotation question rather than a national one. Tilth keeps both, field by field, alongside the plot count and locations recorded at the moment they exist rather than remembered months later. Request an invite.