Strategies for controlling blackgrass

In the first of our winter webinar series we took a deep dive into blackgrass and some of the strategies we can use for controlling it by focusing on soil health. 

As Kyle Richardville, from our mentoring partners Understanding Ag, explains, conventional farming practices have created circumstances which can actually benefit many weeds, including blackgrass. 

“When you think about controlling weeds you have to ask yourself what kind of environment they like the most,” says Kyle.

“They like compact soil, where it’s waterlogged, it's anaerobic, it's bare and there's little competition. 

“This is the kind of situation where they can get off to a quick start and maybe even crowd out everything else. A lot of them love large pools of available nitrate, especially from fertiliser, and they do well in low fungal to bacteria ratio environments.

                    Paying attention to your soil can help to control blackgrass

“The truth is that weeds are actually a symptom of the real disease, which is the environment that we have created that causes them to thrive.

“Tillage is a tool in the toolbox. But chronic tillage can have the effect of breaking aggregates and compacting the soil, leaving it bare. 

“It can increase mineralisation so there could be unnaturally high levels of nitrate and it reduces the fungal to bacteria ratio because the fungi bodies are longer and spindly and more sensitive to that type of event.”

In the webinar, which you can watch in full below, Kyle explains how adopting the Six Principles of Soil Health on your farm will build soils where water and air can cycle freely, reduce compaction and increase organic matter levels to feed beneficial microbes and fungi.

“The important thing is to question everything and use your observations,” he says.

“If there's a patch of blackgrass or a field that's particularly bad, dig into the soil. Look at the aggregation. Smell the soil. Does it smell earthy? Does it smell anaerobic and musty and metallic? 

“This could give you good indications of water cycling and nutrient cycling and whether there is that advantage for the blackgrass to thrive. Then think about ways to create a system where you can change that environment.”

If herbicides are applied, then they will also be more effective on well-structured soil, helping them to infiltrate further and avoiding them being washed away. It is also important to spray before seeds leave the seed head in June.

However, although herbicides can be a useful tool, they have their limitations in the face of blackgrass’ ability to build resistance.

“Unfortunately, there's a high level of herbicide resistance in blackgrass and they produce so quickly and with so many offspring that it increases the chances of mutations that help them survive,” says Kyle

Tips for controlling blackgrass

Cover cropping and spring cropping

Cover cropping in the autumn followed by spring cropping was found to virtually eliminate blackgrass in a study at Agrovista’s Lamport AgX site, with black oats and phacelia the most successful cover crop mix to provide blackgrass cover. 

Grazing herbal leys

Another practice that has proved successful is putting a field down to a herbal lay and grazing it. Oxfordshire farmer Garth Weston saw good results by planting a four-year grass ley which fattened 90 per cent of his lambs and then yielded 10 tonnes of wheat per hectare with little sign of blackgrass. 

Avoid blackgrass contamination

It is very important to ensure equipment which comes onto farm does not have blackgrass attached to it. Work with contractors to make sure they keep machinery clear so it does not have a chance to become established.

Drainage

Drainage infrastructure is vital in maintaining soil health. Although it requires investment, effective drainage is fundamental to building healthy soil and therefore controlling issues such as blackgrass.

Grow profits and produce from healthy soil

Regenerate Outcomes supports farmers to grow profits and food production through one-to-one mentoring with soil health experts.

Download our Programme Handbook to find out how we can work with you.