Could a series of research projects looking at the impact of tillage approaches and climate change on cover crop establishment help Scottish farmers to make more of the valuable rotational tool? CPM speaks to the James Hutton Institute to learn more.
“It’s important to understand which cover crops are most appropriate to use when making a transition to no-till.”
By Janine Adamson
Climate change projections suggest Scotland’s weather patterns are changing. As well as an increase in temperature across all seasons, it’s likely growers will face warmer, drier summers and milder, wetter winters.
At the same time, management challenges experienced in the North such as later harvests mean despite best intentions from growers, cover crops haven’t always been a roaring success.
But now, researchers hope to improve the accessibility of the tool by understanding how factors such as tillage techniques and extreme weather conditions impact the success rate of cover crop establishment in Scotland.
Dr Tracy Valentine, research leader for plant: soils interactions at the James Hutton Institute, is involved in two Scottish government-funded projects – ‘Healthy soils for a green recovery (Healthy soils)’ and ‘Crop improvement for sustainable production in a changing environment (Abiotic stress)’. Once collated, she believes the project findings will help growers to make more informed decisions about which cover crop species to use and in which scenarios.
Healthy soils project
The Grieves House tillage trial was first established in 2017 and is currently funded as part of the wider healthy soils project. “This is primarily a tillage trial comparing full inversion with no-till techniques across two cropping approaches, but we began to investigate cover crops within the trial around three years ago,” explains Tracy.
“One half of the trial is a spring-based rotation featuring spring barley, oats and beans, whereas the other is a winter rotation where soils are covered at all times. It’s the winter rotation where we’re able to assess the cover crops,” she continues.
“Research has shown some species are better suited to non-inversion approaches, so our aim is to understand the varietal differences in crops and cover crops across the two tillage systems and what’s driving that.”
Currently, the project is measuring how different cover crops respond to the two methods by assessing plant biomass. “In year one, we observed that cover crop biomass (radish and rye) was significantly reduced in the no-till treatment compared with the full inversion plough.
“To investigate this further, in year two we planted oats and radish – although the radish biomass was again reduced in the no-till, the oats did much better. What this means is it’s important to understand which cover crops are most appropriate to use when making a transition to no-till,” suggests Tracy.
As well as measuring the biomass of the cover crops, the trial also involves quantifying the biomass of the subsequent weed burden. “We know there can be a trade off when implementing a no-till approach, so understanding the relative competitiveness of the cover crops will be valuable insight to add to our findings.”
And although biomass is only an indicator of a plant’s establishment success, reduced effectiveness of certain cover crop species used in these systems is important information. This is because cover crops can be integrated in no-till systems as an approach to climate change mitigation through carbon sequestration and reduced fuel use, explains Tracy.
The next stage of the project will involve assessing a more diverse range of cover crop species, selected based on their rooting-ability.
Crop improvement for sustainable production in a changing environment
According to Tracy, this project explores the impact of abiotic stress and climate change on multiple Scottish crops including cover crops. The cover crop research began three years ago with lab-based experiments.
“We wanted to assess a cover crop seed’s response to water – either drought or water-logging – at the initial germination phase. We did this by looking at seed coat mucilage which researchers believe influences germination through its relationship with seed hydration. We also looked at effects of temperature on germination.
“To ensure a robust sample, we sourced seed for around thirty different species of cover crop from a range of suppliers, some of whom provided the seed in kind,” says Tracy.
The aim of the work is to understand which species – ranging from clovers and radishes to black oats and phacelia – establish best in different environmental conditions. Alongside the lab studies, field work is taking place to evaluate the success of these cover crops live in-situ.
“The trial is untreated, so it very much depends on the weather as it happens each season and comparing year-on-year. Plots were ploughed in the first year but will be direct drilled from the second year onwards.
“We have a weather station in close proximity meaning we can map the results accordingly,” explains Tracy. “And as we progress through the project, we’ll select certain cover crop species to take further through their life cycles beyond just the germination phase.”
Integrated research
The information gathered from these projects will be combined with plant temperature and light growth data in models that link to climate change projections for different regions in Scotland.
“While projections suggest central-eastern areas of Scotland will become warmer, they also propose it to be much drier in the August-September cover crop sowing window, potentially affecting germination rates.
“Further north, projections become much more uncertain, but the issue of quickly fading light for plant growth will still remain whatever the weather brings,” she adds.
Also, because previous James Hutton Institute research has investigated the rooting behaviour of different types of cover crops, this can also be layered onto findings. “The two projects certainly inter-link while being relevant to previous research we’ve undertaken at JHI.
“It’s about helping to improve the access to cover crops in Scotland and the North, so growers can reap the widely publicised benefits that they offer,” concludes Tracy.
This article was taken from the latest issue of CPM. Read the article in full here.
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