CIPM3Companion crop on arable and horticultural land

What it actually is

A crop grown with the crop. GOV.UK's stated aim is that there is a companion crop growing with the main arable or horticultural crop, and the page sets that in the context of an integrated pest management approach, habitat for wildlife, nutrient efficiency and soil protection.

The ground is not taken out. The cash crop still goes in, still gets harvested and still gets sold. GOV.UK names three ways of doing it: trap cropping, inter-cropping and undersowing. It also says the companion crop does not have to be present for the whole growing period, provided the way you manage it can reasonably be expected to achieve the aim.

Source: GOV.UK, CIPM3 action page, checked 02/08/2026.

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 60 hectares is an illustration.

The action is done in each year of the agreement, so the seed cost below recurs annually rather than being spread across three years like the sward actions.

Source: GOV.UK, CIPM3 action page, checked 02/08/2026.

Is it worth it on your ground?

Most action guides on this site compare the payment against what a three-year rotation would have returned on the same hectares, because those actions take the ground out of production. This one does not work that way. The cash crop stays, the field is still drilled and still harvested, and the variable costs on it are spent either way. So there is no rotation to compare against and no break-even yield in the usual sense. What you are risking is that the crop yields a little less than it would have done, and the question turns round: how much yield can the payment absorb before it stops covering itself.

Step one: what the seed costs.

Source: Boston Seeds' own listed price and stated sowing rate, looked up 02/08/2026. The site displays prices with an inclusive and exclusive of VAT toggle and £67.00 was read in the inclusive state. The per-hectare figure is arithmetic on those two numbers. GOV.UK specifies no species and no sowing rate for this action and tells you to ask your seed supplier, so this is one merchant's product at one merchant's recommended rate, not a scheme figure.

Step two: what is left, and what it has to cover.

Source: the payment rate at the top of this page less the seed cost in step one, which comes from Tilth's copy of the GOV.UK action catalogue and carries its own last-checked date. Feed wheat at £206.00/t, AHDB Arable Market Report, 27/07/2026, East Anglia delivered, November 2026 delivery. Worked as £21.50 ÷ £206.00 = 0.104 t/ha. The establishment pass is not included; that is your own figure.

Where does that sit? Defra puts the UK wheat yield at 7.2 t/ha in 2025. 104 kg is under one and a half per cent of that, and your own establishment cost has still to come out of the £21.50.

Source: yield, Defra, Agriculture in the United Kingdom 2025, Chapter 7, checked 31/07/2026. The percentage is arithmetic on that figure and the one above.

The pairing that changes the arithmetic. CIPM4, no use of insecticide, is listed as compatible with this action on the same area. The two rates then land on the same hectares while the ground is still growing and selling a cash crop, and the companion seed comes out only once, so the £33.50 above is deducted from the pair rather than from either one. Both rates are shown at the top of their own guides.

Source: compatibility, GOV.UK CIPM3 and CIPM4 action pages, checked 02/08/2026, where each lists the other as compatible on the same area.

Where that leaves it.

The paragraphs that follow are Tilth's own reading of the arithmetic above. They are not scheme guidance and they are not sourced from Defra or the RPA.

On the merchant price used here, the action pays for its seed and leaves £21.50. What the sum does not capture is the effect of the companion on the cash crop: pest pressure, weed suppression, or nitrogen. If a companion is already part of how you grow the crop, this is a payment for something you were doing anyway and the arithmetic is beside the point. If you would be starting it purely for the payment, £21.50 a hectare after seed is thin, and the case has to rest on what the companion does for the crop.

We are not going to put a figure on that agronomic effect. It varies by crop, by companion, by season and by what your pest and weed pressure actually is, and we have not found a published number we would stand behind on a page about money.

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.

This action is really three actions with one payment on them. GOV.UK names trap cropping, inter-cropping and undersowing, and leaves the choice to you. Conservation Evidence assess all three separately, and the amount of evidence behind them is wildly different. So does the amount of it that has anything to do with an English arable field. That is the most useful thing on this page, so the three are taken one at a time below rather than run together.

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. 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.

Undersowing, which is the one with British evidence behind it. Conservation Evidence assess Undersow spring cereals, with clover for example, which they define as sowing grass or clover beneath a cereal crop, with the undersown crop later ploughed in. It comes out at Likely to be beneficial on 18 studies, with 60 per cent for effectiveness, 43 per cent for certainty, and harms not assessed.

Fifteen of the studies, from the UK, Austria, Denmark, Finland and Switzerland, looked at effects on biodiversity. Eleven found benefits to some birds, plants, insects, spiders or earthworms, including higher densities of singing skylark and nesting dunnock, higher arthropod abundance and species richness, and higher numbers of bumblebees, butterflies, earthworms, ground beetles, spiders or springtails. Five, from Austria, Finland and the UK, found no benefit to invertebrates, plants, grey partridge population indicators, or to the nesting densities of two out of three farmland bird species. One UK study found only one of five bird species turning up more frequently on undersown wheat stubbles than on conventionally managed barley.

Source: Conservation Evidence, action 136, Undersow spring cereals, with clover for example, Farmland Conservation synopsis, checked 22/08/2026. Cite as Dicks et al. (2020), Farmland Conservation, pages 283 to 321, in What Works in Conservation 2020, Open Book Publishers.

Inter-cropping, which has not been assessed at all. Conservation Evidence hold an action called Plant more than one crop per field (intercropping) and its category is Evidence not assessed, on 5 studies, with no effectiveness, certainty or harms score against it.

What those five studies found: three replicated, controlled and randomised studies from the Netherlands, Poland and the UK found intercropping cabbage with French beans or clover raised ground beetle abundance. A trial in Switzerland found more earthworms in a maize plot immediately followed by a rye grass crop. A review found ground beetle numbers enhanced by intercropping against single crops.

Source: Conservation Evidence, action 124, Plant more than one crop per field (intercropping), Farmland Conservation synopsis, checked 22/08/2026.

Trap cropping, which scores best and fits worst. The nearest assessment is Combine trap and repellent crops in a push-pull system, which Conservation Evidence describe as intercropping the main crop with plants repellent to pests while growing attractive trap crops around it. It comes out at Beneficial, their top category, on 10 studies, with 70 per cent for effectiveness, 68 per cent for certainty and 5 per cent for harms. They note they are presenting evidence from 10 of 13 studies.

The findings are strong and they include the thing the money section on this page could not answer. Two randomised, replicated, controlled studies from Kenya found higher parasitism of stem borer larvae. Two from Kenya and South Africa found more natural predators. Two of three studies in Ethiopia, Kenya and South Africa found fewer pests, and two found fewer witchweeds. Two of three found less pest damage. Four of five found higher yields and one found no effect. Two studies in Kenya and a review found greater economic benefits, with one recording higher production costs in the first year and equal or lower costs across the following five.

Then the fit. Conservation Evidence state the crops studied were maize and beans, and the work is in Kenya, South Africa and Ethiopia. The pests are stem borers and witchweed. None of that is an English cereal field.

Source: Conservation Evidence, action 753, Combine trap and repellent crops in a push-pull system, checked 22/08/2026.

The mechanism underneath all three. Conservation Evidence also assess Grow non-crop plants that produce chemicals that attract natural enemies, at Likely to be beneficial on 4 studies, with 68 per cent for effectiveness, 40 per cent for certainty and 0 per cent for harms, presented from four of six studies. All four found a fall in either pest numbers or pest damage where the attractive plants were grown. Three found higher numbers of natural enemies. One found higher crop yield. The crops studied were lettuce, orange, safflower and sorghum, in China, Germany, India and Kenya.

Source: Conservation Evidence, action 724, Grow non-crop plants that produce chemicals that attract natural enemies, checked 22/08/2026.

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".

What we have not found. Nothing measuring CIPM3 itself. Nothing on trap cropping or companion cropping in English combinable crops, which is what most readers of this page will be doing. And no figure for the effect of a companion on the cash crop's yield in a British rotation, which is the number the money section further up this page says it will not invent. The push-pull yield results exist and they are about maize and beans in East Africa.

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

The clearest steer is about which method rather than how to do it. Undersowing is the only one of the three with an assessment resting on studies from Britain and northern Europe in cereals. Trap cropping in a push-pull system carries the strongest scores of the four and rests on tropical maize and beans. Inter-cropping has no assessment at all, and its five studies are largely about cabbage.

On what the companion is doing, the natural enemy work is consistent as far as it goes: in all four studies, growing plants that attract natural enemies was followed by fewer pests or less damage. Three of the four also recorded more natural enemies present.

On cost over time, the one finding on this runs in a helpful direction. In the push-pull work, production costs were higher in the first year and equal or lower across the following five.

Source: Conservation Evidence, actions 136, 124, 753 and 724, key messages and supporting evidence from individual studies, all checked 22/08/2026.

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.

Our reading is that the method you choose decides whether there is evidence behind what you are being paid for, and the page above is where a farmer would go to make that choice. If you are growing cereals in England and you want to do this action on ground where somebody has actually measured something similar, undersowing is the answer. It is the only one of the three assessed on studies from this part of the world, in the crop most readers grow.

The push-pull results are the most impressive on the page and we would not lean on them. Beneficial on 70 per cent effectiveness with a 68 per cent certainty score is a strong assessment by the standards of this site. It is also about controlling stem borers in maize in Kenya. The mechanism is the same idea CIPM3 is built on, and a mechanism working on one continent in one crop is not a result about your oilseed rape.

There is one honest note about the undersowing evidence too. Conservation Evidence define the assessed practice as an undersown crop that is later ploughed in. CIPM3 does not require that, and it says the companion does not have to be present for the whole growing period. So even on the method with the best fit, what was measured and what is being paid for are not quite the same thing.

The cost finding is the one we would keep in mind against the arithmetic further up this page. That work found production costs higher in the first year and equal or lower for five years afterwards. This action runs for three. If a companion crop takes a year to learn, the payment is arriving during the expensive part and stopping around the time it gets easier, which is a shape worth noticing on an action paying a small amount for something that changes how you grow the crop.

What you actually have to do

Establish a companion crop growing with the main arable or horticultural crop, by trap cropping, inter-cropping or undersowing, and manage it so that it could reasonably be expected to achieve the aim. The companion crop does not have to be present for the whole growing period.

On areas identified in your HEFER record as containing historic or archaeological features, GOV.UK says to avoid deep-rooted companion crop species. An existing companion crop that meets the requirements is eligible.

You must do this action in each year of its three-year duration. If the start date makes it too late in the first year, you must start within 12 months of the action's start date. GOV.UK gives no calendar establishment window and no removal or destruction date.

Source: GOV.UK, CIPM3 action page, checked 02/08/2026.

Where it can go

Agricultural land below the moorland line, on arable land, temporary grassland (TG01), fallow land (FA01) or permanent horticultural crops (TC01). The action is rotational or static. SSSIs and land with historic or archaeological features are eligible with the appropriate consent or HEFER record in place.

Source: GOV.UK, CIPM3 action page, checked 02/08/2026.

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.

GOV.UK sets no species, no rate and no dates, and that is worth knowing before you plan round it. There is no list of permitted companions, no sowing rate, and no stated point at which the companion has to be established by or removed. The page tells you to ask your seed supplier. CNUM3 and CSAM3, by comparison, write species minimums into their requirements and set establishment windows. That leaves room to fit this action to how you already farm, and it leaves the choices with you.

"Does not have to be present throughout" is not the same as "does not matter". The permission is tied to managing it in a way that can reasonably be expected to achieve the aim. Those two clauses travel together on the page and it is the second one that does the work.

The seed cost is annual, not one-off. This runs in each year of the three, so the £33.50 recurs. On the sward actions the seed is spread across the agreement; here it is not.

A product name is not a compliance statement. Because GOV.UK sets no species list for this action, a mix sold for companion cropping is the merchant's proposition rather than a prescribed one. The judgement about whether what you sowed is a companion crop growing with the main crop, managed so it can reasonably be expected to meet the aim, is yours to make and yours to justify.

Deep-rooted species and HEFER features. If your record identifies anything, the species choice is constrained before you get to the agronomy, and that is a decision made at ordering rather than at drilling.

It only makes sense if it does something for the crop. £21.50 a hectare after seed is a small enough number that one extra establishment pass can absorb it. The action earns its place where the companion is doing something for the crop and the payment is a contribution, rather than the other way round.

Compatible on the page is not the same as compatible on your parcels. GOV.UK lists CIPM4 as compatible with this action on the same area, and the pairing above rests on that. The land eligibility conditions of both actions still have to hold on the ground you have in mind, and that is a check against your own parcels rather than against the list.

The merchant prices above were read inclusive of VAT. Merchant sites can display either basis, and a quote you are given may be on the other one. Worth settling before the figures go into a budget.

Keeping the evidence

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

The action page asks for evidence of what you have done, with field operations at parcel level and their invoices, and photographs or other documentation, given as examples.

Because GOV.UK sets no species list and no dates, the record is the only thing that shows what you decided to do and when, as well as that you did it. The seed invoice with the species on it, the establishment operation for the companion recorded at parcel level with its method, and photographs of the two crops growing together are the three things that make the case. Photographs are worth taking while both crops are standing, because a companion crop is temporary by nature and by harvest there may be nothing left to look at.

Since the action recurs each year, all of that needs doing three times, and on three different parcels if you move it round the rotation.

The part only your own ground can answer

The £21.50 above is the easy half of the sum. The half that decides it is what the companion does to the yield of the crop it is growing with, and the only place that answer exists is in your own field records, compared against the same field in a year without one. Tilth keeps the companion establishment, the seed invoice and the yield against the same parcel, so the comparison is there to make. Request an invite.