SOH3Multi-species summer-sown cover crop

What it actually is

This is the summer member of the cover crop family, and unlike its spring-sown sibling SOH2, it is in the current SFI 2026 offer, so it is open to new applications as well as held in existing agreements.

Source: GOV.UK, SOH3 action page, which is published as an SFI26 action, and GOV.UK's SFI 2024 actions print version, page 25, which is where SOH2 stands now that GOV.UK have taken its action page down, both checked 23/08/2026.

In the summer months, which GOV.UK gives as typically June to August, you sow a rapid-germinating cover crop you will not harvest, in the window between harvesting one cash crop and either sowing the next main crop or establishing a winter cover crop. The mix must contain at least four species from two or more of four plant families: brassicas, legumes, cereals and grasses (grasses capped at 25 per cent by weight), and herbs, with the same short list of prohibited species as the other cover actions, including maize, sorghum and miscanthus. You keep it growing with leafy cover and minimal bare soil, for a duration that can reasonably achieve the aim, which GOV.UK puts at typically around 8 consecutive weeks. You do not cut it, graze it or apply fertilisers or manures to it by machine, and you destroy it no more than 2 weeks before the next main crop is established, minimising compaction, runoff and erosion as you do. On horticultural permanent crops, it can go around or between fruit or nut trees.

GOV.UK's stated aim is a well-developed summer-sown cover crop protecting the soil surface, promoting root growth, improving soil structure and biology, reducing nutrient leaching and erosion, and building organic matter.

Source: GOV.UK, SOH3 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 15 hectares is an illustration.

Is it worth it on your ground?

Step one: the seed. An annual cost, re-sown each year. Listed prices for mixes sold for this action:

Source: Boston Seeds, own listed prices and stated sowing rates, looked up 23/08/2026. Price your own mix, and check it against the action's rules yourself: at least four species, two or more families, grasses no more than 25 per cent by weight, none of the prohibited species.

Step two: putting it in and taking it out. The same contractor figures as the other cover pages: direct drilling at £77.69 a hectare, broadcasting at £35.93 plus £35.19 rolling, and a spraying pass at £16.97 before chemical. Seed plus establishment plus a sprayed destruction lands somewhere around £135 to £170 a hectare at contractor rates, against the rate at the top of this page, so at full contractor prices the payment roughly buys the job, and with your own kit or a lighter establishment off the back of the combine it comes out in front.

Source: NAAC contractor price survey 2026 to 2027, published by Farmers Weekly, checked 23/08/2026. Averages of member responses; your own figures are the ones that count.

Step three: what the window was worth otherwise. For a summer cover the honest answer on many fields is a stubble, some volunteers and a flush of blackgrass, because the gap between an early harvest and an autumn drilling was not earning anything anyway. Where the sum needs care is where the gap is only long enough because drilling is being pushed later, and where the cover's thirst meets the seedbed, which the evidence section below takes up.

Step four: the stacking arithmetic. The action page lists CSAM2, the winter cover crop action, as compatible on the same area, and this action's own aim names winter cover establishment as one of its two endpoints. Run the two in sequence on the same hectare and the payments stack across the year. What the rules of your own agreement allow is for your agreement documents to say, but the pages are written so the summer cover can hand over to the winter one.

Steps three and four are Tilth's own reading, and add no requirement beyond what the GOV.UK action pages set out. The rotation call is yours.

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 evidence base is the same one behind the winter and spring cover pages on this site, CSAM2 and SOH2, and the season note bites hardest here. Conservation Evidence's five assessments cover the general practice of growing cover crops. One, Grow cover crops when the field is empty, in their Soil Fertility synopsis, is defined by the empty field rather than the calendar and draws on studies from the UK, Denmark, Turkey, the USA, Australia and Japan. The other four, all called Grow cover crops in arable fields, sit in their Mediterranean Farmland synopsis, from dry-summer climates and heavily in irrigated vegetables, and their studies are overwhelmingly of winter covers. The single study of summer cover crops we found among them reported inconsistent differences in the following crop's yields. Everything below therefore describes the practice, measured mostly in a different season and, for four of the five assessments, a different climate.

The graded assessments. 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.

Growing cover crops when the field is empty comes out as Beneficial, their top category, on 12 studies, with 75 per cent for effectiveness, 67 per cent for certainty and 16 per cent for harms. The four Mediterranean assessments each score one outcome of the same practice:

Source: Conservation Evidence, action 898, Soil Fertility synopsis, and actions 1345, 1351, 1357 and 1394, Mediterranean Farmland synopsis, all checked 23/08/2026. Cite the first as Key et al. (2020), Enhancing Soil Fertility, pages 613 to 634, in What Works in Conservation 2020, Open Book Publishers, and the other four as Shackelford et al. (2017), Sustainable Agriculture in California and Mediterranean Climates, University of Cambridge.

What the studies found. The full account is on our CSAM2 page; the short version. The soil case is strong: more organic matter under covers in a meta-analysis and ten replicated controlled studies, more microbial biomass in five, less erosion, more stable aggregates, and, in the soil fertility evidence, a British study on sandy soils finding a winter cover cut nitrate leaching by 79 per cent at one site and 42 per cent at another against fallow. The following crop is the weak case: lower yields after covers in six studies in some comparisons, higher in three, mixed in eight, no different in seven, with legume covers beating non-legumes on following yield in eight studies. The water assessment is a trade-off: covers used water and left less in the soil in several comparisons while cutting leaching, runoff and, in one French study, herbicide loss.

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, actions 898, 1345, 1351, 1357 and 1394, key messages and supporting evidence from individual studies, all checked 23/08/2026.

What we have not found. Anything measuring SOH3 itself, or a summer-sown catch crop of this design in Britain. Any measurement of the 8 week duration the guidance suggests. And nothing on the handover this action's aim describes, a summer cover giving way to a winter one, anywhere in the evidence.

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. Legumes remain the consistent lever: better following yields in eight studies, more soil nitrogen in five, greater carbon input in a review's account. And time in the practice matters: the review found longer-term cover cropping produced considerably larger soil carbon gains, and a Spanish study found higher soil quality under long-term covers than short-term.

Source: Conservation Evidence, actions 898, 1345, 1351 and 1357, key messages and supporting evidence from individual studies, 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 leaching findings fit this action's timing better than any other cover page on this site. The nitrate a British field loses goes with the autumn and winter drainage, and it is the flush released after harvest that a summer-sown cover is stood there to catch. The British result, a cover cutting leaching by 42 to 79 per cent, was measured over exactly the months this action's cover, or the winter cover it hands over to, would occupy. If reducing nutrient loss is the reason on the GOV.UK page you care about, the timing of this action is the right one.

The water trade-off is this page's caution, and it lands on the seedbed. A cover drinking through August and September is drinking the moisture the next crop's seedbed wants, and the two-week destruction window means it stops drinking only a fortnight before drilling. In a wet autumn that is nothing; in a dry September on heavy land wanting a timely wheat seedbed, it is a real trade, and the Mediterranean studies are the only measurements anyone has of it. This is the one cover action where the destruction date is agronomy first and compliance second.

And the establishment risk is the mirror of the payment's generosity. A rapid-germinating mix into an August seedbed lives or dies on moisture that week, and a cover that never establishes is a cost with no action behind it. The species lists this page's mixes carry, buckwheat, vetch, linseed, phacelia, are quick, but no mix germinates in dust. Sowing off the back of the combine into whatever moisture the straw left is the version of this action that works with the season rather than against it.

What you actually have to do

Each year of the three year duration, establish a rapid-germinating multi-species cover crop during the summer months, which GOV.UK gives as typically June to August, that will not be harvested as a commercial crop. The mix must contain at least four species, including species from two or more of these families: brassicas, legumes, cereals or grasses, and herbs, with grasses no more than 25 per cent of the mix by weight. The mix must not contain Japanese reed millet, maize, miscanthus, reed canary grass, sorghum, artichokes or sweet fennel, and deep-rooted species must be avoided on areas with identified historic or archaeological features.

Maintain the cover for a duration that can reasonably achieve the action's aim, which GOV.UK puts at typically around 8 consecutive weeks, well established with leafy vegetation protecting the soil and minimal bare patches. Do not cut it, graze it with livestock or apply fertilisers or manures by mechanical means, except as part of destruction. Destroy it no more than 2 weeks before the next main crop is established, and minimise compaction, poaching, runoff and erosion when you do.

Multi-species temporary grass leys used for grazing, multi-species crops grown for harvest, and existing cover crops that are not overseeded do not count. If the agreement's start date is too late for the first summer, establish within 12 months of the start date. In the final year, continue until the next main crop is sown or the action's end date, whichever comes first.

Source: GOV.UK, SOH3 action page, checked 23/08/2026.

The sowing advice, as advice rather than requirement: drilling for germination reliability, broadcasting for cost, rolling for seed contact and moisture, species that germinate and grow in cooler conditions where the growing season runs short, and no cultivation or fertiliser or pesticide application within 2 metres of the centre of a hedgerow, which is the law regardless of this action.

Source: GOV.UK, SOH3 action page, checked 23/08/2026.

Where it can go, and what rules it out

Agricultural land below the moorland line, on arable land with crops under arable or leguminous crop codes, fallow arable land under FA01, and horticultural permanent crops under TC01, including around and between fruit and nut trees. SSSIs need Natural England's consent first, and land with historic or archaeological features needs its HEFER checked before the mix is chosen. You can enter the total or part of a parcel, and the action is rotational or static.

Source: GOV.UK, SOH3 action page, 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.

Moisture decides the sowing date, inside the window. June to August is the rule; the seedbed is the reality. The mix has to germinate rapidly to do its job, and an August drought can hold seed in dry soil until the window and the 8 weeks both stop adding up. If the moisture is there at harvest, going straight in behind the combine banks it.

Count the eight weeks before you promise the field to a wheat. Sown mid August, an 8 week cover runs to mid October, and destruction can only come within 2 weeks of establishing the next crop. Fields earmarked for early-drilled autumn cereals are a tight fit; fields going to later drillings, or handing over to a winter cover, fit easily. The calendar sum belongs in the cropping plan, not in September.

If it hands over to CSAM2, you are running two rulebooks on one field. The summer action bans grazing; the winter action allows it. The summer action's destruction rule points at the next main crop; the winter cover has its own establishment and destruction rules. The handover date decides which rulebook you are under, so write it down when it happens.

The grass cap is by weight, and summer mixes lean on oats. Black oats at 35 per cent of a mix is fine if oats are counted as a cereal, but the cap on grasses is by weight and the invoice's percentages are what anyone will look at. If a mix leans heavily on any one grass, ask the merchant to confirm how it sits against the action's wording before it goes in the drill.

No grazing, even though it is standing feed in October. A well-grown summer cover in a dry autumn is the best-looking keep on the farm, and it is off limits except in destruction. The winter action is the one that feeds sheep; this one just feeds the soil.

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 field operation records at parcel level with the invoices detailing the seed mix, and photographs and supporting documentation.

The dates carry it, same as the other cover actions: sowing, which must sit in the summer months, destruction, and the next crop's establishment, which together prove the two-week rule. Where the cover hands over to a winter cover instead, the winter cover's establishment date closes this action's record. The invoice carries the species, the families and the grass percentage, and a dated photograph at the cover's best covers the well-established requirement.

Tilth records operations against the parcel with dates, holds invoices against jobs, and lets you attach photographs, so the dates, the mix and the proof sit together.

The part only your own ground can answer

Which fields have the window. Harvest dates, drilling intentions and soil moisture are the whole decision, and all three are yours. After that, the question the literature cannot answer, what the following crop did after a summer cover on your soil, sits in your own yield records within a couple of seasons. Tilth holds your cropping, your operations and your yields in the same place. Request an invite.