Soil structure plays a part in direct drilling
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Establishing wheat by direct drilling could be up to four times quicker than plough-based systems, with no long-term detrimental impact on yield.
Worcs farmer Jim Bullock should know – he is in his ninth season of direct drilling on his 320ha (790-acre) farm, near Malvern.
“We first looked at direct drilling as a way of cutting machinery overheads and establishment time and hired a drill for the first year.
It worked well, but the soil got tight and we moved back to a min-till system.”
Since then, soil structure has improved and he now direct drills 30% of the cropped area and expects this to increase further.
But before others race out to buy the latest piece of kit, he strongly urges growers to understand their soil system fully and the implications of direct drilling.
“If your soil structure’s wrong then forget about direct drilling.
Soil needs to be reasonably free draining, dry and free from compaction and/or drainage problems.
We’d like to direct drill everything, but not all soil is suited to it and sometimes the weather doesn’t allow it.”
Closing the slot after the drill is one of the biggest problems, he says.
“If you’re considering direct drilling, you need to start as early as possible – don’t even go there if you’re starting drilling in the second week of October.”
The largest saving growers will make direct drilling is in time establishing crops, says Mr Bullock.
On average this used to take around 150 min/ha under the plough-based system (including spraying off stale seed-beds), but has been cut to just 38 min/ha.
This equates to an establishment cost (including labour) of around 44/ha – a saving of 24/ha over a min-till system involving two passes with a Carrier, some subsoiling and rolling, he notes.
Concerns
While many growers may be put off direct drilling by concerns over grassweed build up, he says this is not an issue, providing you manage them correctly through good rotations, stale seed-beds and chemical control.
“We tend to get a complete flush [from the stale seed-bed], as weeds are only coming up from the top 50mm or so – we can hit these early on with Roundup (glyphosate).”
Couch is no longer a problem, due to the stale seed-bed control, but ryegrass and annual meadowgrass have increased in some fields, possibly due to more focus being given to blackgrass control in previous years, he says.
“We used Atlantis [mesosulfuron-methyl + iodosulfuron-methyl-sodium] last autumn because of the ryegrass and this appears to
have worked well.
Annual meadowgrass is also relatively easy to control with IPU [isoproturon] or Atlantis.”
If there is a problem with resistant blackgrass, it is essential to have a spring crop in the rotation to ease pressure, he notes.
“A good rotation also brings in different types of residues – beans in particular have really helped worm populations.”
Populations of other beneficial insects have also increased and Mr Bullock says he is now very wary of applying insecticides.
“We haven’t needed to spray for aphids in the autumn for four years.”
Higher slug numbers were a problem in the early years, but he says that as soils became more friable, drilling techniques improved and the number of natural predators increased, the threat decreased dramatically.
Slugs are one of several potential problems in the early years of conversion to direct drilling.
“There can be a dramatic drop in yields in years two and three, especially if there are problems with waterlogging, slugs, low organic matter or poor cultivations.”
Once these problems are overcome, yields should be similar to plough-based systems, he says.
“Milling Hereward did 9.5t/ha on some land last harvest and the overall average was 7.5t/ha.”
Straw is no longer baled and removed and he estimates this is worth around 30/ha as a fertiliser and also helps improve soil organic matter and workability.
While nitrogen fertiliser use is similar to the plough-based system, with around 215kg/ha applied to the milling wheat last season, retaining more crop residues near the surface has helped cut P and K use by half, he says.
But getting an even spread of material behind the combine can be a problem.
“If you’ve got a 9m header, you can’t physically throw chaff that far if it’s windy.”
He uses a 6m rake to help spread crop debris, so reducing potential drilling problems and getting more even breakdown.
Disease pressure and fungicide use is no different to the old plough-based system, he notes.
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| Planning Ahead | |
Most failures with direct drilling occur where growers do not plan ahead sufficiently, says Kent-based contractor Simon Chiles, who direct drills 1000ha (2500 acres) in Kent, Surrey and Sussex. “You need to think about everything from traffic and combining to soil structure and weed management in current and previous crops. Direct drilling works better the longer you’ve been doing it. It’s important to give it a chance – the worst thing you can do is resort back to the plough.” Even in wet years direct drilling is feasible, he adds. “The major advantage is its speed – you don’t have to go out there when it’s wet, but can afford to wait.” Mr Chiles reckons his 150hp John Deere 6910 and 750A 4m drill is more than adequate to cover 1000ha (2500 acres) a year. “If you really managed it well, you could do 1600ha (4000 acres).” While direct drilling is possible on nearly any soil type, it is more difficult on sandy or silty soils, which, unlike heavier clays, are less able to correct their own structure, he says. He advises growers on heavy soil looking at direct drilling for the first time to check soil structure and correct problems such as compaction and plough pans with subsoiling first. “Everybody tells you to do away with the plough and buy big kit – some people have been talked into spending a lot of money on cultivators when it may not always be necessary. There is often something that can be adapted on the farm, but drill choice is very important,” he ends. |
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