Cover crops: the equipment that makes them work

Why the machinery matters

A cover crop is grown to protect and improve the soil rather than to be sold. USDA's Natural Resources Conservation Service describes its Cover Crop practice (code 340) as planting grasses, legumes or other herbaceous plants to protect and improve soil during periods when cropland would otherwise be bare, with benefits including reduced erosion, more soil organic matter, better nutrient cycling and improved infiltration.

Those benefits depend on biomass, and biomass depends on timing. A cover sown late into a cold seedbed produces little growth and little benefit, while a cover left too long can compete with the following crop, lock up nitrogen and leave a seedbed that is hard to drill. The two machinery jobs that decide success are therefore establishment and destruction.

Getting it in the ground

An AHDB-funded review of cover crop evidence (research review RR90) concluded that the most important agronomic factor in getting benefits from cover crops is to establish them early, in late summer or early autumn. The best method depends on how quickly the cash crop comes off and how much time and labour are available at harvest.

SARE's 'Managing Cover Crops Profitably' notes that drilling gives the most uniform depth and seed-to-soil contact, broadcasting requires higher seed rates than drilling, and aerial seeding into a standing crop as it dies back in late summer is used on larger farms. In the US, where maize and soya bean harvests can run late, seeding into the standing crop or immediately behind the combine is common because there is little time left before frost.

• Drilling after harvest: most reliable establishment; needs a drill that handles residue and small seeds.
• Low-cost air seeders on a cultivator, drill or combine header: spread seed in the same pass as another job.
• Broadcasting followed by a light rolling: fast and cheap, but uses more seed and establishment is less even.
• Inter-seeding or aerial seeding into a standing crop: gains time where harvest is late, with more variable results.

Checking a drill or seeder for cover crops

Cover crop mixes often combine large seeds such as beans or oats with very small ones such as clover or phacelia. That puts demands on metering and placement.

• Metering range: can the unit meter small seeds at low rates accurately, and does it have separate hoppers or a small-seed box?
• Seed mix separation: mixed seed of different sizes can separate in the hopper; ask whether an agitator is fitted.
• Residue handling: row cleaners, sharp coulters and enough downforce help place seed through straw, as SARE's guide on conservation tillage notes.
• Calibration: do a static calibration test for each mix, not just the main species.
• Work rate: width and forward speed decide whether you can seed straight behind the combine.

Destroying the cover crop

AHDB's guidance on cover crop destruction sets out the main options. Non-selective herbicides such as glyphosate kill cover crops and weeds, with glyphosate plus 2,4-D suggested for legumes; AHDB notes a typical rate of at least 4.5 litres per hectare of 360 g/l glyphosate. Rolling and crimping work best in frost, around minus 4°C. Discs tend to deal with residues better than tines. Well-managed grazing can reduce bulk and help residues break down. Frost alone gives only partial kill, and ploughing is possible but risks damaging soil condition.

Timing matters as much as method. AHDB's rule of thumb is to terminate cover crops six to eight weeks before the intended drilling date of the next crop, because destroying them later risks yield losses. Early, even pre-Christmas, destruction leaves most time for residues to break down. Heavy soils benefit from earlier destruction so the surface can dry before drilling, while light and medium soils give more room for mechanical options. Even with mechanical methods, AHDB notes that some herbicide will usually still be needed at some stage, and you must always follow product intervals before drilling the following crop.

Where a roller-crimper is used as the main termination tool, SARE's guidance is that results are best once the cover has finished vegetative growth, with rolling delayed until flowering or later. Rolling too early lets the cover recover.

The scheme rules in England

The Sustainable Farming Incentive 2026 action CSAM2, multi-species winter cover crop, paid £129 per hectare per year over a three-year action. The seed mix had to contain at least two species from two or more of these families: brassicas, legumes, cereals or grasses, and herbs. The cover had to be well established over winter, normally early December to late February, with leafy growth protecting the soil surface and minimal bare soil. Fertilisers and manures could not be mechanically applied to it, and it could not be destroyed before the end of winter unless an early-sown spring crop was being established, and then not more than six weeks before that crop. Grazing was allowed as long as the cover stayed well established. Evidence to keep included field operation records, seed invoices showing the mix, and photographs.

Both SFI26 windows had closed by 22 September 2026, and Defra plans an SFI scheme for 2027 whose details are not yet published. The FETF 2026 productivity list included an air drill for establishing cover crops (FETF207, expected average cost £3,150, 50% grant) and a cover crop roller (FETF110, £4,880, 40%); that round is also closed.

Matching tractors and kit

Most cover crop work is light draft, so the pressure point is timing rather than horsepower. A seeder mounted on a machine that is already working at harvest often beats a separate pass with a larger drill. For destruction, a roller or disc behind a mid-sized tractor is usually enough, but weight on wet autumn or spring soils needs watching. Check operating weight, tyre options and hydraulic outlets for fan-driven seeders on the FarmFleets tractor category page, and compare candidates in the compare tool.

Sources

Sources checked 2026-09-25

• AHDB, How to destroy cover crops — checked 2026-09-25
• AHDB, A review of the benefits, optimal crop management practices and knowledge gaps associated with different cover crop species (RR90) — checked 2026-09-25
• SARE, Managing Cover Crops Profitably: Managing cover crops in conservation tillage systems — checked 2026-09-25
• USDA NRCS, Cover Crop (Ac.) (340) Conservation Practice Standard — checked 2026-09-25
• GOV.UK, SFI26 actions (print version) — checked 2026-09-25

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