During this discussion with Professor Jason Rowntree, Katie Evans explores the crucial role of soil carbon storage in mitigating climate change. Professor Jason Rowntree provides an insightful overview of the importance of soil carbon storage, discussing the fundamentals and factors influencing soil carbon levels. The conversation highlights the significant potential for carbon storage in the soil and examines the relationship between livestock systems and carbon sequestration, emphasising the role of soil health. They explore how different grazing practices impact soil structure, microbial activity, and carbon content, and discuss strategies to optimise water infiltration and nutrient recycling for enhanced resilience in agricultural ecosystems. The conversation also delves into the impact of grazing management practices on water retention, nutrient cycling, and carbon sequestration, emphasising the importance of rest periods between grazing events in maximising soil carbon storage in various grazing systems.
Resources:
Great Soils: https://ahdb.org.uk/GREATsoils
Forage for Knowledge Articles: https://ahdb.org.uk/forage-for-knowledge-articles
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Hi I’m Casey Evans senior knowledge exchange manager on the in the beef and lamb team within ahdb today I’m joined by Jason rry from Michigan State University and we’re going to be talking about soil carbon storage in the context of climate change how are you Jason
Great thank you for having me good so to start us off I was wondering if you could give us a quick over rview of the importance of soil carbon sure um soil carbon is obviously very important uh we know that through agriculture practices um much data would suggest
That we’ve lost up to half if not more of our soil carbon in our farmed and and uh grazed soils right and so uh that loss has uh led to problems with uh increased atmospheric CO2 increased acidification of water bodies uh along with uh lower productivity and greater challenges in
Growing food and so unfortunately because of these things carbon has become this huge Target and that’s all we want to talk about right but it’s part of a functioning system where we’ve got water and biodiversity and carbon that are all cycling together to to grow plants and to grow animals yeah
Fantastic so can you take us through some of the fundamentals of soil carbon and what factors actually influence soil carbon into soil sure so um we use often carbon and um soil organic matter which is often 50 to to 72% I think 58 to 72% uh carbon as indicators of well-being of
Of a system and uh in in doing that um you know we we look at these metrics well there’s been this huge push now with Supply chains and others that have said we’re going to lower our carbon footprint and one way of potentially offsetting that carbon in uh footprint
Is by uh sequestering carbon and improving carbon uh in our agriculture soils and it’s important that when we store carbon below ground that it isn’t uh it’s not going to be destroyed by fire it can be a much more permanent um component of our of our um carbon budget
And and so those things are all really important how significant is the potential of carbon storage in our soils the opportunity can can can be very high and uh let’s just say that um most of the data that that I I’ll see uh suggests that you know from a a mineral
Associated or a more perent organic matter uh storage perspective that uh we can see 10 to 12% % yeah of uh carbon storage and mineral Associated organic matter and it begins to plateau and most of our agriculture soils are one to two right so there’s a huge opportunity of
Improving organic matter and soils um most of the farm systems I see today most all of them farm and and and ranch and graze in a way though that probably doesn’t facilitate that occurring and so that’s the big challenge right is how do we um improve the way that we manage
That can begin to see these positive benefits to organic matter in our soils yeah and when we’re talking about soils what about like the soil texture soil like or contents or percentages of sand clay how does that impact us as well yeah generally at at our site we’ve been
Measuring for 15 years and we will generally see greater uh carbon acrel and greater carbon associated with our are LOM to Clay textured soils uh silt silt Loom to to Clay textured soils much less in our sander soils and we are a very Sandy area right and so generally
What you’ll find is there’s going to be more uh carbon associated with heavier soils um we do still see improvements in in those without question um the fact that uh we see less improvement in our Sandy soils it’s just there’s less nutrients there there’s less water hold capacity and other aspects and so
Generally speaking the heavier those soils are um the the more that they can hold and so that’s the hard part then is that what is potentially happening from management versus what’s Just Happening from texture yeah and so when you go out and and do considerable soil sampling uh
You’re going to to learn that you probably need to to to use texture as a covariant in that model that kind of begins to account for teasing out texture for what might have changed with management is there how important are suppose from the soil Health point of view is that an
Area of something that you need to focus on or is it more from the cropping that the soil Health supports healthy crops supports a healthy root system sure or is is there an aspect that it just focuses on soil Health yeah I I think that um when it comes to looking at
Carbon and organic matter it doesn’t matter uh soil health it doesn’t matter if it’s a a cropping or a grazing system it’s all highly important yeah generally our indicators of improved soil Health are going to be uh improved soil respiration which is actually you know CO2 cycling through through that soil uh
Improve microbial activity uh that leads to Greater water uh absorption and utilization as well as more acru of carbon in those soils and so soil health is highly important uh it’s very can be very challenging to measure we have a lot of different recipes for measuring
That uh as as well as as looking at more outcom driven examples of soil Health which would be the the differences and types of soil organic matter yeah we we see it more common now that our farmers are undergoing different soil analysis packages it’s no longer just the
Standard in m m PK magnesium pH we’re now looking at they’re they’re measuring organic mat they measuring carbon you having that data what kind of decisions can they make next based on those figures how do you make use that data in decision making on Farm well I think
That if we make a decision that we’re going to dramatically lower inputs yeah let’s say that might be nitrogen for example that um we are now relying more on our soil biology to deliver nutrients to the r spere of the plant and in doing so that would mean that we have to
Manage to improve that relationship between microbial activity and soil health and the nutrients being delivered and so um the decision that uh is made is is going to drive that so let’s say I am I’m going to lower my inputs I’m going to get rid of nitrogen what does that now look like
Um well it’s going to be a standpoint of not only improving the biodiversity of the plants in my system getting more nitrogen fixing legumes but now because of the fact that uh the higher amounts of nitrogen aren’t negatively impacting soil biology which we know that to be a pretty solid relationship in the
Literature um therefore as I see these improvements uh it it it leads credibility to the management that is now becoming more resilient and less um less Associated and less needy for for those inputs when you speak about the man management side of things how can these different grazing Management Systems
Impact soil carbon I suppose the potential in the sequestration side is there a correlation there yeah and so first of all I just want to say that when it comes to talking about soil carbon in the literature and grazing literature there are many um there’s it’s not decided upon science that there
Are many opinions out there there’s data that uh is is says that it can be substantial there’s other data that would suggest it couldn’t um part part of that is number one uh soil carbon is difficult to measure in time and space okay so that’s one thing um number two
Uh often we just do this in very controlled research type environments versus on the ranch yeah and so there can be definitely differences in management uh across those sites that that can impact that um time and space is just huge when you’re trying to measure something uh so complex yeah I
Don’t know why we pick carbon because it’s like the most challenging thing to to to measure but with that said um we we can see uh opportunities I believe in improved management and improved uh improvements in in organic matter and potentially carbon right and um and and
Even there like putting that aside just overall improv productivity and um what what what the data and what in our context what what we find is that as we have improved our recovery periods as we have uh improved our our and increased our rotations uh we tend to see improved
Productivity uh greater Forge productivity versus say what what I would deem to be more of like a continuously set stocked type of system generally over time those sites can become more mismanaged there’s more stress in in the system which then can begin to erode productivity and in doing
That you’re probably going to begin to see less opportunities for for carbon to be cycling as well and organic matter and then also in terms of overall soil carbon sequestration yeah a really important aspect of it is obviously the walshire filtration side of it and nutrient recycling is that from the
Grazing management point of view how can we manage our systems that bit better to ensure that we’re getting in that filtration side and Nutri inter cyclings yeah so I mean just thinking about this right like if I can show you one system that may only
Infiltrate a half an inch or an inch of rain in an hour yeah and then show you another system that could infiltrate six or eight or 10 inches of rainfall in an hour yeah and you get intense rain events which one would you rather have
And and we know that because of that and through the improved organic matter in these systems that we tend to see continually greater infiltration as well and and by doing that and and to me that is like the match uh lighting the gasoline that that’s the key in this right as
Water improves as water cycling improves a Cascade of great things happen uh we see more carbon built in the soil I I would argue that it it that water begets carbon yeah that improved water cycling but gets greater carbon and overall productivity in that system yeah that as
We infiltrate more water uh we have greater recharge of our below ground aquifers many of our streams yeah are fed by aquifers many of our trout and and salmon depend on cold water to function highly and all of that again um talks about how water cycling through
Our system so if we’ve got a landscape that’s running off water taking nutrients with it water is getting to where it shouldn’t be a lot of negative things begin to happen and we see problems with our stream flows we see problems with drought um in more Aid Landscapes we see problems with
Desertification that’s fantastic Jason we’re going to bring it to a close there is there any La last minute point or anything you’d like to leave our listeners with at this time I think that if if I’m a farmer Rancher right I’ve got to pay my bills
And to me I I think the thing to focus on is improving soil Health not getting caught up in what this carbon number might look like or what the argument in the newspaper may be on if grazing does even impact carbon or not but but what
We all can do is I think look at how we manage and how that impacts organic matter right and and those things are really powerful and and can improve a a producer’s bottom line and so to me focusing on those indicators of soil Health are hugely important important
And um I think over time the other aspects of how much carbon and what kind of management I I think research will begin to to more aply you know show what what can be done and so it’s a um but but for me I think soil health is a real
Key to to focus on thank you Jason that was fantastic thank you for joining us for the second part of our three-part series of Our Roots to resilience module one interviews with Jason rry