A strategy for better blackgrass control

Ploughing followed by the shallowest cultivation possible for the following few years is just one of a series of measures being used by an eastern counties arable operation to tackle blackgrass.

Cambridgeshire grower Andrew Ramply (pictured left, with brother Richard) says that the number one weed on many farms is all-consuming, with everything they do and most conversations with farming friends in the area dominated by blackgrass.

“But we have to get on top of it – growing wheat and oilseed rape won’t be sustainable if we don’t,” he insists.

See also: Make your soils more resilient to climate change

As if any reminder were needed of the competitive impact of the grassweed, Mr Ramply recalls the stark evidence presented by the combine yield monitor this harvest.

“I was seeing wheat yields of 12-13t/ha driving through blackgrass-free crop plummet to less than 8t/ha in badly infested areas,” he says.

“Overall, the field averaged 11t/ha but it would probably have been over 12t/ha without blackgrass.”

Cousins-Surface-cultivator

Little wonder, then, that a raft of measures have been introduced to achieve better control and deplete the seed bank over time.

Mr Ramply and brother Richard grow 1,300ha of combinable crops across their own and contract-farmed land at Southoe near St Neots, Cambridgeshire, and have the benefit of seeing first-hand the measures developed on their machinery syndicate partner’s farm over the past eight years.

The large-area blackgrass trials conducted by distribution agronomy provider Hutchinsons have covered everything from chemical control, rotations, cultivation techniques and the value of cover crops in helping to restructure soils.

“We were keen to see the trials at Brampton because the farm had a history of blackgrass, probably exacerbated by minimum tillage and a few wet years following a lack of investment in drainage at a time when grain prices were poor,” says Mr Ramply.

“The prospect of having cutting edge cultural and machinery trials on-site was very appealing and they’ve clarified what needs to be done.”


Versatile investment


Laura-Cousins

The Cousins Surface cultivator, developed for shallow cultivation as part of a blackgrass control strategy, is actually a very versatile implement, says Laura Cousins (pictured with the Cousins Surface cultivator).

“In addition to its shallow primary cultivation role, the Surface can be used to work and level ploughed soils, both pre- and post-winter,” she explains. “And with the tines raised, it functions as a seed-bed press, including rolling after strip-till drills.”

The Razor Ring press rollers can have water ballast added to match soils and conditions and, with a power requirement of 45-50hp/m, the Surface is reckoned to be a relatively inexpensive cultivator to operate in terms of fuel consumption.

“If that also means it can be run behind a lighter tractor, then soils will also benefit from reduced compaction,” adds Ms Cousins.

The implement is now available in production form in sizes 3m rigid (£25,500), 4m folding (£48,850) and 6m folding (£68,630).


Commercial scale

Hutchinsons technical director Dick Neale emphasises that the Brampton site has always had a focus on the commercial implementation of grassweed control strategies rather than a reliance on small plot trial results.

“Last autumn, we decided to incorporate all our research experience into commercial practice on the farm, implementing a five-year plan with absolute focus on blackgrass control and seed-bank decline,” he says.

“While some fields entered that plan for the first time, others have been managed for three years with reduced depth cultivation, spring cropping or one year fallow – and the results have been tremendous,” he adds.

“Focused management of blackgrass seed within the top 5cm of soil, coupled with spring cropping in the rotation, has resulted in blackgrass populations of 800 heads/sq m reduced to 120 heads/sq m within two years – and this is in crops untreated with herbicide,” he emphasises.

This approach is now being adopted wholeheartedly, says Mr Ramply, with a significant amount of ploughing added to the autumn schedule this year to target the worst blackgrass infestations. It will account for 15-20% of the cropped area, he estimates, and will be carried out after blackgrass has been encouraged to chit and sprayed off; fields will then be sown to spring barley.

“The objective of ploughing these fields is to bury any seed so that a shallow cultivations regime can begin on a blank canvas,” he explains.

Scratching the surface

The new Surface cultivator devised by local tillage implement manufacturer Cousins of Emneth will be used to perform shallow stubble cultivation at no more than 5cm deep.

It has new-design rigid tines arranged in four rows – two rows are located behind a set of straight cutting discs that slice through trash and are followed by a wide-spaced Razor Ring press. Two more rows of the same tines are deployed ahead of a Razor with narrower-spaced rings to focus consolidation in line with the tines.

“We tried the Surface cultivator last year and have run it again this year having been surprised at how level it remains, with no tines riding out despite working at such a shallow depth,” says Mr Ramply.

“It works best in dry conditions, but was also effective in wetter soils last autumn and after heavy showers this year; we’ve also used it as a levelling tool after ploughing.”

Where blackgrass is not so bad, a single pass with the Surface should create a stale seed-bed that can be sprayed off in due course, then rolled to encourage a further flush before drilling with a Vaderstad Rapid.

While these are changes in detail, they go hand-in-hand with strategic changes in rotation to provide further opportunities to hammer blackgrass.

“Previously, we were on a standard two wheats then oilseed rape rotation, but now, while still using oilseed rape as the main break crop, we’re introducing winter and spring barley as other options.”

Both are more competitive with blackgrass than winter wheat or spring beans, he notes.

“As far as cropping and cultivations are concerned, flexibility is the key word now. We used to block crop for convenience, but now we decide cropping and cultivations on a field-by-field basis according to the blackgrass situation.

“It makes life more complicated and it’s harder to manage,” he adds. “But if that’s what it takes to get on top of blackgrass, then that’s what we’ll do.”


Other anti-blackgrass measures at GT Ramply and Son



  • A drone will map blackgrass patches so they can be targeted with specific measures.
  • Higher seed rate using variable rate technology on the drill to increase crop competition; potentially the same method can be used to apply residual herbicides at a higher rate on the weed patches.
  • Investment in soil improvement aims to eliminate wet, cold conditions that favour blackgrass.

    Cousins-Micro-Wing


  • Improvements to drainage and, organic matter levels. Brampton site trials show the potential for cover crops such as a mixture of ryegrass and black oats, which generates a large root mass to draw out moisture and boost soil structure.
  • Combines are equipped with compressors for a thorough clean up when moving from fields with blackgrass.
  • Contractor balers must be thoroughly blown clean before setting to work.
  • Oilseed rape is established using the Cousins Micro-Wing (pictured), another implement that has emerged from the Hutchinsons work at Brampton.
  • Ultra-narrow legs and points available for Cousins V-Form subsoilers and on a bespoke cultivator are designed to provide soil loosening at depth while creating the least possible seed-bed for blackgrass germination.
  • The resulting low draft also makes it cheaper to run and results in lower blackgrass levels in crops established using the new implement.
  • Inter-row spraying of glyphosate using a Garford hooded sprayer will also be tried this year in an effort to get blackgrass populations down to manageable levels.

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