Sustainably managing troublesome ryegrass

Working with Agrii’s R&D team from Stow Longa near Huntingdon, Roger and Virginia Mills along with their son Mark are exploring a wide range of integrated cultural controls alongside the most effective chemistry to deal with triple R-resistant ryegrass.

Huge variations in weed control are being highlighted across a wide range of tillage regimes, rotations, crop and variety choices. And the work is already extending to finding better ways of managing the health and vitality of soils with some of the highest silt contents in the country.

Resistant ryegrass

“When we first got involved with the Agrii work, our overwhelming need was to deal with the resistant ryegrass that is so problematic locally,” explains self-confessed ‘wheat junky’, Roger who is now growing almost twice as much spring barley as wheat across the 325ha business.

“Too many people will tell you it’s just like black-grass. But, from bitter experience, we know it’s far more serious. It spreads much more rapidly. It’s very much more competitive. It keeps germinating right into the spring. And the physical pressure it puts on cereals can easily destroy them completely, making a promising crop fit for nothing more than silage.

“We’ve learnt an unbelievable amount in recent years. And not just about ryegrass either. The research is utterly transforming the way we think about and manage our ground.

“We made the change to minimum tillage around 20 years ago and brought in much better crops as a result,” he recalls. “But we failed to appreciate how much harder our ground had been getting to work over the years and how much more horsepower, diesel and metal we were having to use.

“Like many, I suspect, the change was too gradual for us to notice. We are getting decent wheat yields, our drains continued to run well and we still had plenty of worms. So, we just put every challenging season down to the weather and got on with it.

“Armed with their spades, full soil analyses and practical soil health understanding, Colin Lloyd and Steve Corbett soon worked with our agronomist, Rob Daniel to put us right. They have opened our eyes to how much more we could make from our cropping by changing our approach. Which we have been doing as fast as we can, and making great progress as a result.”

Waking up ryegrass seed

Amongst other things, regularly soil loosening with wide-winged legs on their Sumo Versadrill Plus as they drilled had helped the Mills family grow good 10t/ha wheat crops when the conditions were right.

Having explored what was actually happening in setting-up the trial site, though, they realised their establishment approach was waking up ryegrass seed at just the wrong time. It was also encouraging silt to run through the profile to pan out, leading to very tight soils without the vertical linkages essential for the best rooting, worm activity and drainage.

Appreciating this, the group designed their initial work to explore a range of cultivation, cropping and rotational approaches. Despite two incredibly wet winters forcing major changes in planting plans, they clearly established that, just like black-grass, ploughing could be a good reset, reducing weed populations approaching 2,000 plants/m2 to virtually zero.

“Our first year’s work with spring crops also showed straw raking and direct drilling was worse for both weed populations and crop performance than a single pass with a set of discs,” Colin Lloyd reports. “Uncropped strips between the spring oats, triticale and spring barley we grew under each regime underlined both this and the extra competitive value of the cropping.

“Of the three crops, oats proved the most and triticale the least effective in reducing ryegrass populations ahead of the six different varieties of winter barley, five winter wheats and three spring barleys we drilled the following season.

“True to black-grass form, ploughing the previously ploughed land just brought-up the weed seed again while ploughing previously min-tilled ground led to the lowest ryegrass counts,” he says.

“Wheats on the ploughed block yielded reasonably at an average of 10.5t/ha but they were the only ones we were able to harvest in 2021. Sky high ryegrass levels in the other wheat blocks meant they had to be foraged.

“The ploughed block gave us reasonable winter and spring barley yields too – around 9.0t/ha and 7.5t/ha respectively. While we were able to harvest them on the other blocks, at near enough 5t/ha in both cases the barleys here were very disappointing. It just underlines how problematic ryegrass can be.”

Even though rotational ploughing stood out for doing by far the best ryegrass control job, the team quickly appreciated they needed to look far beyond it for the most sustainable solution at North Hall Farm. This was mainly because soil analyses revealed a silt content of 49%, together with organic matters at little more than 2.5% and disappointing levels of biological activity.

Soil health focus

Since then the focus on the trial site and across the Mills’ wider Olde Appleton Farms business has, first and foremost, been on building organic matter and soil health – not least with sewage cake and cover cropping. At the same time, their min-till and drilling approach has been adapted to reduce pressure on the ground. And they are exploring a far wider range of rotational options.

“The trials are providing us with the best practical intelligence we can get on improving the health and workability of these difficult silt soils while controlling the ryegrass scourge,” points out Rob Daniel.

“However good it may be at controlling grassweeds, ploughing can create serious problems with silt panning if we are not very careful. So, we have had to look beyond it.

“Spring cropping is particularly important here, which is why Roger and Mark have so much of it in the ground at the moment despite their long-standing preference for winter wheat.

“Delaying winter wheat drilling can help too but later drilling can actually make things worse if it leads to a less competitive crop. Delaying spring drilling until after ryegrass’ normal mid-late March spring flush is probably a better bet for us, providing we have crops and varieties that can take it.

“The trials work has really shown us the value of competitive winter crops like hybrid barley and rye – providing they can be sown early enough – as well as more competitive wheat varieties and spring cereals.

“However, the key to the most competitive crops has to be the best establishment and the healthiest, most resilient soils. These are consequently the focus of so much of our improvement efforts.”

Thoroughly enthused by the trial team’s objective assessments and fresh thinking, Roger and Mark Mills have wasted no time in applying a host of initial learnings to their entire business.

As well as a wholesale change in their tillage and establishment regime over the past two years, they have almost doubled the amount of sewage cake to around 4,000t/year across the farm.

“Dramatic” cover crop difference

They have moved from zero to more than 120ha of cover cropping in a single season. And, having seen the dramatic difference it made to both the soil and ryegrass populations in just a year, are keen to ‘fight fire with fire’ using September-sown Westerwolds ryegrass, cut for silage then direct drilled with wheat the following autumn.

“It’s a huge learning process and we are very far from having all the answers yet,” insists Roger. “As far as we can see, there’s no killer solution. It’s more a matter of putting a multitude of things together in the best possible way.

“Switching to a much lighter and more flexible tillage approach is, however, really helping; especially on our turning headlands.

“Separating the subsoiling from our other operations and employing a 4in wing rather than our previous 14in one means we are using the least possible metal at depth now and only where it’s needed. As well as reducing silt panning, we don’t wake up nearly so much ryegrass at drilling, either.

“We’d love to use FYM but we just can’t get enough of it around here, so sewage cake is our soil health improver of choice. We are looking to marry this with less soil movement, cover cropping and the best crop residue retention to reverse the decline in soil biology and workability as quickly as we can while stabilising the silt in the profile.

“It is working economically too,” he adds. “What we are saving in reducing our cultivations each year pays for our cover cropping. And we should be giving our tractors a longer working life as well as cutting their maintenance bills.”

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