Soil science is delivering very real and tangible climate change mitigation measures on behalf of Irish agriculture.
This was the view expressed by Teagasc’s Dr. David Wall, during his presentation to the soils conference which was recently held in Belfast.
The event was jointly hosted by the British Soil Science Society (BSSS) and the Soil Science Society of Ireland (SSSI).
According to Wall, there is no ‘silver bullet’ coming down the track in terms of soil research programmes delivering an overarching response to climate change.
He also recognises that much of the public debate, where farming’s response to climate change is concerned, has centred on methane emission levels from ruminant livestock.
“It’s very easy for farmers to focus on their livestock. For one thing, they are working with their animals on a daily basis. So the issue of developing the likes of a feed additive is a very tangible subject for them to comprehend,” he said.
“Making technologies of this kind work would physically require farmers to include whatever product we might be talking about into a ration on a regular basis.
“Soils, on the other hand, are much more abstract in nature. And, as a result, they tend not to get prominence in terms of farmers’ perception levels on a regular basis.”
Soil science
Wall used his conference presentation to specifically highlight a number of soil-related management choices that will act to mitigate climate change.
Two of these include the tweaking of soil phosphorous levels and pH values.
“We know that nitrous oxide emission levels are linked to available soil phosphate values. And the same principle holds where soil pH values are concerned,” he explained.
The soil scientist said that farmers should aim to have all fields in Index 3 for phosphorus.
He also cited the role of available phosphate as a key constituent of the energy-related pathways that operate within all living organisms.
Teagasc recommends an optimal pH value of 6.3 for grassland, rising to 6.5 for cereal ground.
Research has confirmed that achieving these soil nutrient targets can result in nitrous oxide emissions reducing by up to 20% relative to current figures.
Climate change mitigation
Much of this is already turning out to be a good news story for Irish agriculture. David Wall referenced the significant upturn in lime usage throughout Ireland over the past few years.
Approximately 1.2Mt of agricultural lime was applied in Ireland last year. The comparable figure from a decade ago was 750Kt.
Wall confirmed that the EU is actively working on the development of a soil framework directive, the recommendations within which will have a major impact on Irish agriculture.
One of the reasons why a measure of this nature has not been introduced to this point, according to the Teagasc representative, reflects the very complex nature of soils and the problems of coming up with accurate definitions.
But Wall did confirm that soil management will be at the heart of farming’s response to climate change. This will particularly be the case where issues such as air and water quality are concerned.
Soils will also change with the continuing impact of climate change. This means their ability to withstand and mitigate the extremes of drought and floods – that are already apparent – will be impacted accordingly.
“There are already a wide range of soils to be found across the island of Ireland and beyond,” David Wall explained.
“Different soil types will require differing management priorities into the future.
“Soil health is of fundamental interest to soil scientists. It is the facet of soils that determines their capacity to mitigate the impact of climate change.
“If we fail to protect soil health, this will limit the potential of our land to deliver eco-services on behalf of everyone,” he added.
Sustainability
The soil scientist went on to make the point that soils must also be managed in ways that deliver a financially sustainable future for farmers.
David Wall believes that future soil health assessment policies must be established as part of a top-down process.
As part of this process he wants farmers and the wider agricultural industry to begin to assess the health status of their soils and to inform themselves of what technologies they could implement in order to maintain and enhance soil health in the future.
But, at the end of the day, the focus of future soil management policy to be endorsed by the EU will come down to agreements being reached on a range of very specific definitions.
E.g., soil health is defined as the current capacity of soil to function as a vital living system, within natural or managed ecosystem boundaries, to sustain plant and animal productivity and health, maintain or enhance air or water quality and to provide further ecosystem services (on the long-term) without (increased) trade-offs between ecosystem services.
Soil fertility, on the other hand, is defined as the ability of a soil to sustain plant growth by providing essential plant nutrients, water and favourable chemical, physical and biological properties as a habitat for plant growth.
Two questions then arise from this. Will the forthcoming EU soil framework directive align itself with definitions of this nature? And, if so, what will be the implications for Irish farmers?
Soil
All of these soil-related properties must be quantified into three specific categories moving forward: A reference value; a target value; and a threshold value.
“It is also important that policy makers use the same language and in the right way when deciding on these matters,” Wall continued.
“And then at a national level, there is the issue of how all of this will work out for Irish farmers.”
According to Wall, EU policy makers are currently assessing 40 different soil indicators.
“The physical properties of soils must be considered in this context. But even here there is a range of complications to be addressed e.g., do we restrict our assessments to topsoil layers only? Or do we also include sub-soils?” he said.
“Structure is one of the fundamental issues that determines the overall function of our soils.”
Other soil indicators that determine the functioning of a soil include its chemical and biochemical properties plus the interactions of the soil microbiome and the other organisms that live within this unique habitat.
The conference was told that soils’ ability to sequester carbon will be an important issue within future climate change debates.
Specifically, where future drainage schemes are concerned, David Wall said this matter could well become a trade-off between land’s ability to produce food and the future environmental pressures that may be placed upon it.
Teagasc’s current research programmes recognise that healthy soils are at the heart of meeting challenges around food security, climate adaptation and environmental sustainability.
There is a fundamental principle involved – on the back of healthy soils, Irish agriculture can become more resilient to climate change, reduce input requirements, and reduce its environmental impact.
In turn, this will help to ensure the long-term viability of Ireland’s food production systems.