With minimal soil disturbance at establishment looking likely to play a role in future crop support payments, what might those still relatively inexperienced in min- or no-till need to be prepared for?
Among those not using minimal or no-tillage practices, the prospect these systems might count towards future support payment qualification means they may now have to look at what steps could be necessary to adopt such measures. But while the switch may appear challenging, advice from agronomists and adopters suggests preparation and planning can counter this.
Harry Henderson, AHDB East Midlands knowledge exchange manager, says: “In 1977, 205,226 hectares were direct drilled, rising 27 per cent to 260,044ha the following year.
“But just a few years later plough sales rose sharply, with a 1988 HGCA report attributing direct drilling’s decline to three main problems: grass-weed control, compaction in a succession of wet autumns, and the ban on straw burning. Aside from the latter, those are things which today we recognise and are equipped to deal with. This is about more than just the drill.”
The most difficult soils on which to achieve a successful switch, particularly to no-till, are the heaviest clays, largely because they are most likely to suffer from surface smearing, poor drill slot closure, hair-pinning of straw in the drill slot and impaired water infiltration, points out Dick Neale, Hutchinsons’ technical manager. Stony soils also present unique difficulties, limiting drill choice to tine coulter types due to the propensity of discs to ‘ride’ stones.
“While a new drill may be necessary, machinery which works best in your particular circumstances will repay its investment, with a potential trade-off in lower overall farm power requirements,” he says.
“Moving less soil means there is less need for a big tractor or it allows wider widths with the same tractor, with knock-on benefits for reduced compaction.”
One of the primary issues on heavy clays is closing drill slots or filling them with loose soil, he points out, but there are solutions.
“In soils with more than 35 per cent clay, most direct drills work best in a tickle of surface soil, more than a simple straw rake creates on these soils. There are an increasing number of tined implements which can work at 30-50mm to create this, while spreading straw and chaff, disrupting slug activity and encouraging a weed flush for spraying off. The heaviest clays may need several years to transition to no-till.”
Farmers who trial a field using a dealer’s or contractor’s direct disc or strip-till drill often dismiss the results when the crop initially turns out to look less impressive than a conventionally-established one, says Mr Neale.
“But analyse what is happening under the surface. Ploughing and deep non-inversion oxygenates topsoil, encouraging a burst of microbial activity which burns carbon and mineralises nitrogen, creating lush early growth. Once this oxygen is depleted, the soil biology activity crashes and crop activity tails off. In surface tillage or no-till systems this process is far more regulated and controlled.
“If, most recently, you have been practising full inversion or deep non-inversion tillage, you should assess whether installed field drainage is functioning properly. In clay-based soil, good drainage is a prerequisite for a move to surface tillage or no-till.
“Deep tillage temporarily aids rapid ingress of rainfall through the seedbed zone into the lower soil profile via bypass drainage, benefiting the seed by ensuring it doesn’t sit in wet soil. Moving away from this removes the ‘sticking plaster’ of this artificial aid to drainage, but switching to surface tillage or direct drilling in a well-drained soil will replace this with a natural ability to rapidly infiltrate, absorb and store water for when it’s needed during summer.
“That’s why the next area to examine is soil compaction and drainage efficacy. If you’ve already been using deep non-inversion tillage for some years then, while the soil will be somewhat destructured, the effects won’t be as severe as under a plough-based system. With the latter, careful shattering with minimal surface disturbance may be required to alleviate any pan identified via digging holes and looking. If it’s in good condition down to a couple of spades’ depth, don’t worry.”
Moving on to crop establishment, if switching only to shallow non-inversion tillage or using this reduction in soil working depth as a step to no-till, soil must not be overworked simply for cosmetic purposes.
“Many growers come unstuck when moving from ploughing or deep non-inversion tillage to surface tillage as they apply the same seedbed preparation approach, working down land too quickly and aggressively before leaving for late autumn drilling. Too much time for weathering, plus further working if a cultivator drill is used, followed by rainfall on overworked bare soil before crop germination, slows emergence and impedes water infiltration.
“Much of this can be avoided by keeping biologically-active soil on the surface and retaining residue to protect it, before it’s gradually drawn in by worms, evenly distributing it through the soil profile and simultaneously providing soil structure and drainage. If you do remove straw, replace with some other organic material or cover cropping. Light surface incorporation of residue down to 50mm can be performed with a tine cultivator.”
Beyond his agronomic advice, Mr Neale says it is important to ensure farm staff are educated about changes to practices and the reasons for them.
“Headland management is a case in point, as it is here where 90 per cent of crop failures occur. Aside from ensuring chop and spread are good, combine operators should play their part by avoiding sharp turns to prevent uneven straw distribution and excessive cosmetic cultivation passes shouldn’t be made simply to remove wheel marks when surface-tilling. Avoid double-working the headlands at each field pass.
“On the same basis, don’t use the cultivator elements of a cultivator drill unless required. Most times unnecessary cultivation does more harm than good, compromising surface water infiltration.”
Kent farmer Tom Sewell’s family moved gradually to direct drilling over two decades, but he acknowledges recent machinery and knowledge developments mean it should be possible for many to progress faster.
A Nuffield Scholar who studied how cropping systems could be made sustainable and regenerative by moving to no-till, he says his travels showed him an initial focus on improving soil health will naturally lead to reduced establishment costs and potentially help meet future support payment requirements.
“The desire to improve soil health drove us, in the early 1990s, to begin switching from ploughing and combination drilling to shallow discing and using a McConnel Shakaerator, subsoiling where needed,” says Mr Sewell.
“Over time we reduced subsoiling depth and moved to one-pass loosening and seedbed creation with a Sumo Trio. From there we did away with loosening legs, using a disc/roller combination just an inch deep.
“We then felt able to trial direct drilling with a couple of different models before buying a Cross Slot in 2013, chosen for its penetration and slot type, which places seed on a soil shelf, ensuring it doesn’t sit in water at the bottom of a seed furrow.”
One of Mr Sewell’s first tips for those reducing tillage and, in particular, thinking of moving fully to direct drilling, is to make sure fields are level using light surface cultivation if necessary to ensure the accuracy of future operations, particularly drilling, will not be affected by hollows and hills.
“In terms of restructuring the soil as a whole, this is generally best left to natural methods. Reducing soil disturbance should encourage worms, who will do this job for you.
“But using the rooting activity of cover crops ahead of winter and spring cropping can also help, as well as providing ‘armour’ to protect soil from winter rain. We’ve used various mixes, including vetch, phacelia, buckwheat, linseed, oats, clover and radish, and for less than £20 per hectare a blend can bring visible benefits. But target cover crops where they’re most useful. We’re now using them only after oilseed rape before first wheats, and after wheat before spring beans.”
Cover crop destruction can be a challenge, says Mr Sewell, but glyphosate remains the best control.
“Despite breeders’ claims, even good frosts do little to kill off these species. Grazing may work, but I’d be concerned about soil damage if using cattle. Worms are your best form of livestock land managers, gradually pulling dead material into the soil. The tunnel network they create, and the fact minimal soil is moved, helps create a stronger structure, aided by pores created as old plant roots decompose. Coupled with the effects of shallower soil movement, the difference in the ability to travel on the land is staggering, and shallower working also means shallower wheelmarks.”
On the subject of straw management, Mr Sewell echoes Mr Neale’s advice on the necessity of a good chop and spread.
“We’ve recently upgraded our combine to a used Case IH 9230 Axial-Flow, but with a nine-metre header rather than the maximum possible 12m. With this machine, speed of intake is important, so we’re happy to keep the combine full with a smaller header, and benefit from a narrower spread width.
“This negates any need for straw raking, which takes up an operator and can only really be done in the middle of the day when straw is dry, so it doesn’t fit with labour. Our soil-engaging equipment now comprises just the drill, rolls and a subsoiler for areas such as gateways.”
Slug control is another area new min/no-tillers have to address, says Mr Sewell, although he believes this is about more than pellet application.
“Rolling and predator encouragement have a significant part to play, reduced soil movement and non-inversion of weed/volunteer seeds both aiding the latter.
Ferric phosphate use means no buffer requirements. Oilseed rape and cover crops are the biggest harbours, and we counter this by applying 5kg/ha shortly before wheat establishment, and perhaps a further small dose when rolling.
“Rolling is also conducive to ensuring any germinating weeds are shallow-rooted and easily controlled by pre-em herbicides. For the same reason, we get better results from post-em Atlantis.”