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Switching to Min-Till - Dick Neale - Arable Farming

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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? Martin Rickatson gathers some tips.

Switching to min-till

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% to 260,044ha the following year.

Decline

"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 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% clay, most direct drills work best in a tickle of surface soil, more than a simple straw rake creates on these soils.

Transition

"There are an increasing number of tined implements which can work at 30-50mm to create this. 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 bums 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 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. Moving away from this removes 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.

"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.

Disturbance

"With the latter, careful shattering with minimal surface disturbance may be required to alleviate any pan. 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.

"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, 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”.

Educated

Mr Neale says it is important also to ensure farm staff are educated about changes to practices.

“Headland management is a  case in point, as it is here where 90% 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.

“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.”