With black-grass resistance across his fields and winter wheat yields a disaster, Dominic Kilburn speaks to a Cambridgeshire grower and his adviser on how a complete change in their approach literally saved the farm.
Six years ago, everything in the garden was rosy for Fen grower Gary Thacker, who farms 150ha of silty clay loam land at two locations near Benwick in Cambridgeshire.
Wheat was consistently yielding 10/ha, sugar beet and peas were a profitable part of the rotation and some land was let for potatoes.
And then it all began to go wrong.
He started to notice that across the rotation weeds were not being controlled. Chemistry including Atlantis (mesosulfuron + iodosulfuron) in winter wheat, Aramo (tepraloxydim) in peas and Centurion Max (clethodim) in sugar beet was struggling to kill black-grass. "I’ve got to be honest and admit that I didn't realise what black-grass looked like," stresses Mr Thacker, speaking at Marley Farm, Ibbersons Drove. "I'd always deep ploughed every season and there had never been a problem until we started to notice some competition from weeds," he adds.
Mr Thacker had hit the perfect storm. Year after year he had ploughed and then power harrow/drilled all his land, and always without a problem.
But he then got to the point of ploughing up as many black-grass seeds as he was initially trying to bury, and they had developed resistance to herbicides.
Furthermore, it was clear that had transported resistant black-grass seeds via the combine to the other farm nearby which, until that point, had always been ploughed and had always been relatively free of black-grass.
With his winter wheat at best yielding 4.5t/ha, and some as little as 2.5t/ha, Mr Thacker reckons he’d reached a crisis point. And, as has been the case for many growers in the region, Hutchinsons' National Black-grass Centre near Brampton, became a key source of information and advice for him as he faced up to the challenge of literally trying to save his farm.
No more wheat
"The first thing we advised Gary to do was to stop drilling winter wheat," explains Hutchinsons' technical manager, Dick Neale, who has recently helped launch the company’s new 'Healthy Soils' service an initiative borne out of many years of research at the Black-grass Centre.
"We advised him to put the plough and power harrow away, take a 'holiday' from growing sugar beet and, for all cultivations across the farm, shallow till the top 2in of soil only, leaving crop residue on the top," explains Mr Neale.
Both potatoes and sugar beet were removed from the rotation as was winter wheat - replaced by spring barley - and, after careful consideration, a 3m Weaving GD zero till drill was selected for all drilling operations; its angled discs key to achieving good seed placement with minimal soil disturbance, he says.
"There's no doubt that converting to a system like this calls for a big change in mind-set, and patience is certainly needed," adds Mr Neale.
Lower seed return
Five years on the plough remains unused and, according to Mr Thacker, although he still gets a good flush of black-grass each season, there’s not a huge seed return going back in the ground. “we’re just not bringing the seeds up from depth as we used to and the introduction of spring barley really gives us an opportunity to clear as much black-grass out of the seedbank as possible.”
Importantly, where gross margins are concerned, winter wheat has made a return, now accounting for about 20 per cent of the farm's cropping area with yields making a significant recovery and averaging 9.5t/ha in 2017.
Sugar beet and potatoes remain absent from the rotation but there is talk of looking at strip tillage systems for sugar beet if the decision is made to re-introduce it.
"That said, we still have to judge the rotation on the hoof to a certain degree each season by looking at what's in front of us around June time to see the extent of any black-grass seed return," says Mr Thacker.
To add to the armoury in the war on black-grass, whereas in the past all winter wheat was drilled in September, winter cereals (which includes winter wheat and the recent addition of 6-row winter barley) are now drilled from the 25th October at the earliest, giving time for a significant flush of black-grass to be achieved and sprayed off with glyphosate.
Typically, seed rates of 425 seeds/ m2 (winter wheat) and 450 seeds/m2 (winter barley) are ‘cross-drilled’ to provide increased competition for any germinating black-grass.
In addition, Vigon (DFF + flufenacet + flurtamone) is applied to the seedbed at the pre-em timing and, ahead of spring cereal drilling, Mr Thacker will go through once more glyphosate.
“Every year since we changed the system, the condition of our soil has improved, points out Mr Thacker. “Worm counts have increased considerably and because they loosen the soil structure, drilling gets easier each season and more rooting channels are created.
"We've also tried 'Tackle' hot mustard cover crop for the first time this season to add to the overall soil conditioning effect and to see if it makes a difference to black-grass control. It is an additional cost so we'll have to look at it carefully," he says.
Over-wintered stubbles have also created a habitat for ground nesting birds including skylarks and lapwings, whose numbers have increased, as have field mice and shrews, which in turn has increased the number of owls on the farm, he adds.
Dick Neale points out that concerns about crop residue being left on the surface are unfounded. "Plenty of growers are going down the surface tillage route but they worry about the residues left on top of the soil, and so they cultivate again to incorporate more of the residue, then it rains and the soil goes sloppy.
"No two years are the same but growers must look at the weather conditions, see if the straw residue is wet or dry and make an adjustment to the cultivation frequency - raking as an additional cultivation is often all that's needed.
"Gary's fields have seen a 200 per cent increase in the weight of worms over the past 5 years just from using " surface tillage. Deep working anecic worms feed on the surface and take the residue down with them but they are very sensitive to heavy cultivation,” he says.
You will make mistakes when switching to this kind of system, but when you do it's key to understand what's gone wrong so you can learn for next time.
"It's about having the right advice and, often, cultivating less delivers more," he adds.
A good decision
With his soils never looking healthier, black-grass levels under control and crop yields back up to where they should be, Mr Thacker is delighted he made the switch to surface tillage when he did.
In addition, fuel costs are down from fewer passes in the field using less horsepower, while he has more free time on his hands despite being the only full-time person on the farm.
"Other farmers I speak to locally say that there's not much they can do about their black-grass but I can't help thinking that they are going down the same route I was before I did something about it five years ago.
“But when your winter wheat is yielding 2.5t/ha, you have to change your approach to farming and the sooner you do it the better”, concludes Mr Thacker.
Crop protection and advisory business Hutchinsons has recently launched its bespoke Healthy Soils assessment service to farmers to effectively measure soil health - the fundamental part of productivity and sustainability of farms in the UK, it says.
However, compared with standard soil tests, this is a more targeted approach with a full audit and physical assessment to find out exactly what's happening with the soil and to see how biological activity can be improved and, with it, crop performance.
“Soils are still growing perfectly good crops in the UK but they are starting to degrade," explains Hutchinsons' technical manager, Dick Neale. "Where deep cultivations remain the standard operation year after year, in the wrong conditions soils suffer from capping or erosion, while heavy machinery is causing compaction far below cultivation depth, too deep for any mechanical intervention.
"Despite this, farmers are still getting good crops on good land, but another 10 - 15 years down the line there could be a serious problem," warns Mr Neale.
The firms focus on healthy soils and the impact they can have on crop performance has been driven by work at its Black-grass centre at Brampton,
Cambridgeshire which has, for many years, explored the correlation between soil structure management and weed control, leading the way for cultural control developments which are now found in operation on an increasing number of farms.
According to Mr Neale, the audit asks farmers for the commitment of a three-year sign up, giving the necessary time to make any adjustments to operations such as cultivation changes or developments in key performance indicators such as worm counts on the farm following the assessment. l would say that all soil types can benefit from an assessment but it takes two to three years to see the benefits of any changes. One thing that is important though is that farmers must have an agronomist who is sympathetic to the recommendations of the post-assessment report, so that they are acted upon.
We are trying to make this a benchmark as to what your soils are doing and why," he adds.
The Healthy Soils audit incorporates
- Cropping and cultivations review - crop rotations, cultivations, drainage.
- Key soil/field features picked up by aerial images and client knowledge
- VESS Test - visual evaluation of soil structure to 1m depth
- Infiltration assessment - ability of water to permeate through the soil profile indicating any issues with structure, capping etc.
- Soil health and texture test - sand, silt and clay composition, while soil health is assessed using techniques such as a C02 burst and active carbon tests
- Key organisms and earthworm populations
- Nutrients (total and available) in kg/ha measurements - 3 pH assessments: surface; 150mm and 300mm
Mr Neale says that, ideally, a Healthy Soils audit, which costs growers £250, should take place between March and April and in the growing crop, where there is both adequate moisture and the soil is biologically active, as well as growing roots to assess penetration levels and natural aggregation.
Finally, based on the information gathered, Hutchinsons' precision agronomy software Omnia links all the information of the audit to determine yield potential. The variance between this, and what is actually being achieved can then be explored, identifying the critical limiting factors which need to be addressed.