High yielding, profitable early-sown winter wheat crops are once again a regular feature on the heavy land rotations at Lamport AgX, Agrovista’s flagship trials site in Northamptonshire, despite a huge background population of blackgrass.
Speaking at a recent open day, Niall Atkinson, consultant and Lamport AgX trials co-ordinator, said: “Historically, if wheats weren’t drilled by mid October you risked not getting them in at all. But going earlier was asking for trouble – blackgrass populations exceeded 2000 plants/sq m on this site before it was established in 2013.
“Lamport AgX is all about solving this conundrum. We’ve learnt how to do that, using sequences of autumn cover crops and spring break crops such as oats, beans or barley to reduce blackgrass pressure, minimising soil movement when establishing cash crops, and improving soil health to help create a favourable environment for wheat.”
The Lamport concept, backed up by an appropriate herbicide programme, has proved itself over several very different seasons. In 2023 first winter wheats averaged just under 10.5t/ha following a range of different crops, with some plots exceeding 12t/ha, with almost no blackgrass.
“After a run of autumn cover crop/spring breaks, we are now successfully alternating winter wheat with a cover/spring break,” Niall said.
“But you need to choose your fields carefully and stick to the guidelines or risk going backwards. You also need to be reactive – if something goes wrong and blackgrass starts taking hold, you may need to delay your first wheat and grow a further cover crop/spring crop break.”
Integrating SFI into farming systems
Much of the work carried out at Lamport can attract valuable SFI payments. Over-winter cover crops, the mainstay of operations to control blackgrass and improve soil health are currently worth £129/ha, but that’s just the start. Several other options that now attract payments under the scheme are under scrutiny.
Whole field SFI actions are proving difficult to integrate into rotations at Lamport due to the enormous blackgrass challenge.
Winter bird food (AHL2) and legume fallow (CNUM3), look tempting on paper, paying £853 and £593/ha/year respectively. But both plots, which were drilled in April, have been destroyed.
Hamish Wardrop, Agrovista’s rural consultancy national manager, said: “The winter bird food established OK but there was a mass of grass weeds as well, and the pressure was too high to continue with it on this site.
“The legume fallow also established reasonably well, but it suffered badly with slugs, flea beetle and weevil. And we also have grassweed pressure.
“These actions can be a good choice in some situations, but you have to go in with your eyes open. We can’t lose sight of what we are trying to achieve in bringing back first wheats into the rotation.”
Low input cereals
A low-input cereal action (AHW10) aims to create an open-structured cereal crop that encourages wildflower species to grow within it, providing habitat and summer foraging for birds, pollinators and other wildlife.
It pays £354/ha/year under SFI, whilst a further £129/ha is available for a preceding over-winter cover crop.
Technical manager Mark Hemmant said: “Herbicides are restricted and you have to sow the cash crop at a reduced seed rate – we chose spring oats and went at two-thirds rate, or 270 seeds/sq m.
“We have to select carefully where to grow this action at Lamport, but we have achieved the aims; while is a little bit of blackgrass coming through, if you are well on top of grassweeds and have a good rotation, it could be useful.”
Spring wheat and beans
The benefits of adding beans to a spring wheat crop at 10 seeds/sq m are also being assessed. That would attract a £55/ha companion crop payment under SFI for a seed cost of about £15/ha, and could help mitigate take-all.
“The net benefit of what you spend on bean seed compared what you get back looks good, provided there are no adverse effects on blackgrass control or yield,” said Mark.
The beans were destroyed around flag leaf timing as some inputs are not approved for that crop, but the crops appear to have thrived.
“We know at Lamport that black oats in the cover crop aren’t enough to prevent take-all in a wheat-dominated rotation in an autumn like 2023,” he explained. “But if we introduce wheat plus beans in the spring, might the undoubted soil benefits that beans bring change things?”
Does direct drilling affect herbicide choice?
On any farm with a grassweed problem, selecting the best herbicide programme is vital to reinforce the effect of cultural control measures to achieve optimum control.
However, there is little information available on whether different cultivation strategies, particularly direct drilling, affect herbicide efficacy.
In previous years Mark has generally found cinmethylin (as in Luxinum Plus) and aclonifen (as in Proclus) to have similar activity on blackgrass. However, cinmethylin is claimed to have an impact on seed on the surface, so a trial to assess whether it might be a better pre-emergence option was set up at Lamport in 2022/23 and continued this season.
The trial compared blackgrass levels and wheat yields across several cultivation strategies, ranging from direct drilling to deep loosening. These were treated with five pre-emergence regimes – untreated, aclonifen/DFF/flufenacet, and cinmethylin/pendimethalin/picolinafen, both +/- triallate (as in Avadex).
“In two very different years we did not see any significant benefit of cinmethylin over aclonifen-based herbicide options pre-em, even where direct drilling,” Mark said.
“Although not statistically significant, the aclonifen-based herbicide appeared to work better in the dry conditions of autumn 2023 and exhibited better crop safety in the wet autumn of 2024, the latter particularly with establishment systems where less soil was moved and or where shallower drilling took place.
“In addition, consistent benefits of moving less soil in grassweed levels and of including Avadex were seen in both seasons.”
In other trials, best control of blackgrass has consistently come from using both actives in sequence – aclonifen pre-emergence followed by cinmethylin early post-emergence.
“The results from the Lamport trials confirm that this approach, and that the addition of Avadex pre-emergence is appropriate whatever the cultivation method,” said Mark. “And it reiterated the fact that moving less soil reduces grassweed pressure.
“The take-home message is that no herbicide programme is good enough on its own,” he added. “Heavy infestations of blackgrass also require appropriate cultural controls to achieve the desired result.”
Low-pressure tyres on test
The effectiveness of new low-pressure tyre technology in reducing soil compaction was put to the test at Lamport this season.
The trial used a John Deere 6155R tractor with a mounted 3m Weaving direct drill running on Michelin AxioBib 2 VF tyres or and Galileo AgriCup tyres.
The AgriCup is a low-inflation design that, according to the manufacturer, combines the benefits of pneumatic tyres and rubber tracks, producing a 17% larger footprint than a standard tractor tyre.
Tyres were tested on winter wheat and peas drilled after an over-winter cover crop established on soil previously loosened to 15cm.
Independent cultivations consultant Philip Wright said: “The VF tyres were run at 18psi, which is clearly quite extreme, and 11psi, as low as we dare go with the loaded mounted drill. The AgriCups were inflated to 6psi.”
The untrafficked area between the wheelings unsurprisingly looked the best. Of the trafficked areas, the VF at 11psi left the best soil structure and the best crop rooting and canopy for both peas and wheat.
The AgriCup was marginally behind, causing some surface compaction and intermediate rooting but a good canopy. The 18psi VF tyre created the highest surface compaction and poorest rooting.
Earlier work elsewhere carried out by Philip has shown cereal yield losses rising to 30% on heavy soils in areas trafficked by a tractor fitted with VF tyres inflated to 14psi towing a 3m direct drill.
Whilst not pre-judging the Lamport results, he said: “The AgriCup tyre has quite a robust construction, so in damper conditions we could see a slightly greater imprint.
“The biggest markets currently are for skid-steer loaders and irrigation gantry systems, but they could be useful on a crop establishment system that uses quite heavy rear-mounted kit,” he added.
All plots will be taken to yield.
Avoid unnecessary soil loosening
The importance of avoiding unnecessary subsoiling operations was clearly illustrated in results released at the Lamport AgX open day from trials carried out in 2022/23 on Lamport AgX’s difficult silty clay loam.
Loosening an uncompacted plot with a low-disturbance subsoiler to 15cm before direct-drilling winter wheat created an open structure between the subsoiler legs and resulted in good root growth.
However, soil disturbed by the legs was left more fragile and slumped to depth, stifling root growth and creating an inconsistent wheat canopy across the plot.
Yield on this plot dropped to 86% compared with an adjacent uncompacted and unloosened plot, nearly as bad as a compacted plot.
“Less can be more, so check soils carefully,” said Philip. “If they don’t need loosening – they are better left alone.”
