Tag: Carbon sequestration

How do we measure peatland?

Posted on December 7, 2023 by - Insights, News

Understanding the carbon dynamics of peatland is a complicated process that is ever-changing for land managers and farmers. Historically, peat soils and habitats have been understood as a carbon store, with peat itself being of extremely high carbon content. However, in the process of carbon footprinting it is required to understand all greenhouse gases associated with peatland (carbon dioxide, methane and nitrous oxide) and the additional storage of carbon into these soils, a process known as sequestration. 

Sequestration is the process of capturing carbon from the air and storing it within the land, through the process of photosynthesis. Within peatland soils there are additional layers of complexity when thinking of carbon storage. The waterlogged conditions of peat soils allow decomposing plants to accumulate, storing the carbon in the form of peat; this means that not only is carbon captured and stored via photosynthesis, but that there are direct carbon additions from the plant structures themselves. 

Consequently, measuring peatland within the Farm Carbon Calculator or any carbon calculator can be complex – knowledge in the scientific community alongside methods of accounting are rapidly developing. However, the following methods can be used:

  • Direct Measurement: soil sampling the peatland soil to understand the carbon content (Soil Organic Matter or Soil Organic Carbon testing) provides a figure of the carbon stock within an area. Carbon stock is the quantity of soil contained within a soil at the time of measurement and is calculated in combination with a Bulk Density sample. To understand if your peatland is sequestering carbon (capturing more, additional carbon) this sampling needs to be repeated to understand whether the figure measured in the first instance is increasing or decreasing. Soil sampling can be conducted annually, but there is often concern around carbon flux so the Farm Carbon Toolkit would usually recommend sampling every 3-5 years. More can be found out about how to sample soil in our free online guide to monitoring soil carbon on the FCT website here.
  • Modelled Measurement: if however direct measurement is unsuitable or you would like a faster indication of the carbon dynamics of your peatland soil you can use modelled figures embedded within the Farm Carbon Calculator. Using data from the Peatland Carbon Code 2.0 there is the ability to account for peatland areas of the landscape through selecting the type of peat you have and the area (hectares). The calculator will then provide a modelled suggestion of the likely dynamics of the different greenhouse gases associated with the different peat classifications. 

Carbon Farmer of the Year Farm Walk at Lockerley Estate, Hampshire – May 2024

Posted on June 6, 2024 by - Carbon Farmer of the Year, Insights

In May 2024, the Farm Carbon Toolkit were delighted to hold a farm walk at Lockerley Estate in Hampshire, home to one of the finalists from our 2023 competition. We would like to thank the Estate Manager Craig Livingstone and one of the owners Sarah Butler- Sloss for being so generous in hosting the farm walk.

Everyone who attended the farm walk heard from Craig and his team on how he has managed to make significant reductions in business greenhouse gas emissions, enhance the farmland biodiversity and enhance business performance.

Introduction

Craig Livingstone took on the role of farm manager at Lockerley Estate, owned by the Sainsbury family, 9 years ago with the challenge to improve biodiversity, sequester carbon, increase the health of the soil, and make a profit. To achieve this, a mission statement was devised with a list of objectives that really helps the whole estate team to work collaboratively to achieve the farm’s goals.

With just under 2,000 ha in Stockbridge, Hampshire, Craig farms Lockerley Estate and Preston Farms as one, which includes arable, grassland, woodland, a veg shed, and pockets of countryside stewardship schemes and SFI options. The farm is also part of a joint venture sheep and cattle enterprise, gaining benefits from grazing and muck which is integrated into the arable rotation. 

Over 9 years, Craig and his team have managed to vastly reduce emissions by transitioning to zero till and reducing artificial fertiliser and chemicals by broadening the rotation and integrating livestock. Specifically, Craig has saved 56,000 litres of red diesel annually and reduced pesticides and N-based fertilisers by 46% and 53% respectively. Soil organic matter has also increased by 1.1%.

Despite focusing on biodiversity, carbon and soils, Craig’s number one priority is profit – every hectare must pay for itself. Where he can, countryside stewardship schemes have been stacked with SFI options to increase profits. In some cases, the options available have encouraged Craig to adopt techniques that, for example, provide integrated pest management because the overall payment in combination with reduced pesticides is more than the potential loss in yield.

Currently, there has been a 17% change in land use, however the farm is still producing 9,000t food (approx. 4.5t/ha). So how has Craig managed to take the farm and reduce its emissions and increase soil organic matter?

Here are some of the highlights from the walk:

Arable

Using a broad and diverse rotation and choosing varieties that require fewer inputs, Craig has managed to halve the farm’s emissions due to vast reductions in fertiliser and pesticides. This in part has been achieved through implementing a mixture of winter and spring cropping interspersed with diverse mixes of cover and catch crops; legumes such as peas and beans; rotating grasses and legume fallow. The farm is also experimenting with clover understories and poly-cropping, prioritising diversity to build fertility and maintaining cover and living roots in the soil at all times.

The farm’s transition to no-till, aided by a zero-tillage seed drill, has also resulted in improved soil health and structure, increasing porosity and facilitating better water infiltration and enhanced soil biological activity through less disturbance. A multi-pronged approach to reducing fuels and fertiliser usage.

Encouraging diversity

As mentioned, the farm has taken advantage of environmental schemes such as winter bird feed (AB9), flower-rich margins and plots (AB8), and nectar flower mix (AB1) for multiple reasons. In short, to connect the woodland and encourage a host of wildlife, provide integrated pest management, and to make land more profitable.

Perhaps most interestingly, the team have implemented 6m assist strips of AB8 within a select few arable fields to encourage pollinators, beneficial insects, and predators. The initial cost of the seed is expensive; however, in this instance, the farm is not looking to reseed any time soon (especially within the duration of the agreement). That combined with savings on pesticides, they have found it far outweighs the cost of seed – it makes business sense. 

Craig has also looked critically at areas that are susceptible to weeds, difficult to graze, areas where the land lies wet, or where the shape of the field is awkward. Here, he has taken land out of production and implemented AB1 or other schemes to benefit wildlife and pocket.

Composting

A big project on the farm is taking cattle FYM and producing a superior product in solid compost and liquid extract using the Johnson-Su methodology. Agricultural soils tend to be bacterially dominated through repeated cultivations and chemical inputs but this process favours fungal communities which are excellent at cycling nutrients, disease suppression and soil aggregation. 

Good quality cattle muck is mixed with clover bales, straw, and woodchip, and through a series of steps breaks down into a fungally dominated compost. 

Once ready, a compost tea is created by placing a mesh bag full of compost into an IBC of water which is left to steep. This produces a highly nutritious and microbially active substrate which can easily be spread during drilling (rip and drip) and goes a lot further than the compost itself as well as reducing reliance on bagged fertiliser.

Veg Shed

Set up three years ago with a strong commitment to benefitting health, community, and the local environment. The veg shed is made up of 2 acres, 3 polytunnels, 40 laying hens and a fruit cage. The garden grows 50 different fruits and vegetables which it sells to local businesses on a wholesale basis but mostly through a local veg box delivery service.

Everything is grown from seed using heritage and heirloom varieties which have more diversity, and from testing, seem to have more nutritional value. They are also more resilient to a changing climate responding better to drought and high rainfall and requiring less inputs than other high yielding varieties.

The garden is designed as a polyculture and receives no artificial inputs, instead utilising compost from the farm and enlisting the help of dynamic accumulators to extract and release nutrients from the soil.

Wood pasture and Woodland

Linking SSSI woodland and calcareous grassland, the farm took advantage of the woodland pasture creation scheme and introduced longhorn cattle to graze instead of taking silage and hay. The aim is to create a large grazing area of species rich grassland and wood pasture that joins with 220ha of woodland improvement.

There is over 300ha of woodland at Lockerley Estate including a portion of semi-natural ancient woodland. The improved woodland is periodically thinned whilst retaining canopy cover to maintain diversity. Timber is harvested and removed with a percentage of profits returned to the estate.

The biggest outcome has been the flourishing biodiversity and wildlife. Diverse grassland is growing out from the hedges and wildflowers are starting to recover, blending into the woodland, and creating a mosaic landscape. Bird surveys see an increase in species year on year and botanical, butterfly and grasshopper surveys with fixed point photography are ongoing.

Hedgerows

Last but not least, Lockerley Estate takes great pride in its hedgerows, planting 12,000 hedgerow plants in the last year. Cutting regimes have also been lengthened to support all wildlife, from insects to birds to small mammals. This is made possible by replacing the hedge cutter with a saw blade to accommodate the thicker branches; the trimmings are then used for ramial woodchip in the composting process.

Summing up

Overall, it was a thoroughly enjoyable day and an interesting insight into how Craig and the team manage to maintain a balance between a thriving farm both in terms of biodiversity and bottom line productivity. Craig has demonstrated that economic resilience can go hand in hand with reduced inputs and tillage without compromising on food production. Entries to this year’s Carbon Farmer of the Year competition close on the 14th June, so  if you believe you are reducing on farm greenhouse gas emissions do enter our competition here

Carbon Farmer of the Year Farm Walk at Durie Farms – November 2023

Posted on December 4, 2023 by - Carbon Farmer of the Year, News

The 21st November 2023 came in as a bright and sunny day, in stark contrast to the near constant rain which had fallen for the previous weeks.

The occasion was the farm walk for FCT’s Carbon Farmer of the Year Competition on the winner’s farm – Doug Christie of Durie Farms, Fife. Durie Farms is a mixed farm combining arable and cattle enterprises, organic and non-organic as well as woodland.

Liz Bowles (Left) CEO of Farm Carbon Toolkit welcoming people to the farm walk

Before we set out on the walk, Doug introduced his farm and explained some of the practices he has adopted which earned him the title of Carbon Farmer of the Year.

Fundamentals include the incorporation of conservation agriculture (minimum till cultivations and more complex arable rotations including peas and legumes within the rotation as standard) and the integration of extensively managed cattle within the whole farm. Central to this has been regular soil analysis with records going back to 2006. These records include soil organic matter which means that Doug is able to track soil carbon changes over time too. Unusually for the time, Doug also measured soil bulk density  which makes carbon stocks estimates more accurate. Alongside measuring soil carbon stocks, Doug also keeps enterprise fuel allocation records which has allowed him to have a much better understanding of hot spot areas. Through doing this he was able to identify the high fuel usage associated with housing cattle in the winter. This knowledge together with his adoption of holistic grazing practices has enabled him to keep cattle out longer,  with some groups of cattle e.g. in calf heifers now not being housed at all.

Our first stop on the farm walk was the large heap of brushwood next to the farm lane (a result of woodland management) and a question posed to the walkers as to how best to deal with this. Burning the pile would release a lot of carbon dioxide, but would that be less than chipping the pile and then burning it as a fuel? Or what about leaving it to break down naturally and possibly combine with farmyard manure and use as a soil amendment?  Now we are starting to look at these things through a number of lenses, these are the sort of questions farmers are increasingly grappling with.

The first field we entered was growing a cover crop, established in mid – late August after a cereal crop.

Doug Christie  (on the right, spade in hand) describing the cover crop

Doug now makes up his own cover crop mixes using farm saved seeds when possible. The cover crop had really motored on since early September and was providing pretty good canopy cover, in flower and up to waist height.  This cover crop will be holding nutrients in the soil, keeping living roots in place and improving soil structure through the varied rooting depths of the different plants in the cover crop.  Doug puts cover crops in place wherever possible and, for cereal harvesting, uses a stripper header leaving straw to rot down and provide food for earthworms. This was evident when inspecting a soil pit where the number of worms was high – worms everywhere. In fact this field which had been harvested with a stripper header, and had been undersown with a grass clover mix, with cattle having been mob grazed across it a few weeks earlier. The cattle had removed some of the straw and helped to break down the rest, and on the day of the farm walk it was clear that the grass clover sward was coming away nicely. Testament to the improving soil health at Durie Farms is the fact that Doug sold his subsoiler some years ago- surplus to requirements!

Doug shared with the group that he has not used insecticides since 2003 and is now working closely with the James Hutton Institute to carry out research on his farm. He has a fantastic site to investigate the impacts of this decision on insect life on the farm.

Arriving at the in calf heifers as we walked across the farm, it was clear they were wondering if it was time to make their move for the day. 

In calf heifers curious to know what we were talking about

Donald Christie, Doug’s son commented that since moving to holistic grazing and generally daily moves the cattle have become much more biddable, and in the move to outdoor wintering the challenge has been to make sure that this group do not carry too much weight as they approach calving. They receive no supplementary feeding when on grass.  One of the group commented that since adopting holistic grazing cattle health has improved and that the growth rate of outwintered animals surpassed that of housed cattle the following spring.

The group asked Doug what he is doing to reduce his reliance on artificial N fertilisers, one of the hot spots for arable farmers. Through improving soil health and bringing pulses and legumes into his cropping rotation Doug has reduced his reliance on granular urea by 30% since 2009. Yields have gone down but net margin is up. When choosing inputs such as fertiliser it is worth noting that different branded products, produced in different parts of the world, may have very different emissions factors. At Farm Carbon Toolkit, we offer Calculator users the ability to choose the product they have used so an accurate figure for emissions will be included.

The group also tackled the topic of cattle and methane, with an acknowledgement of how complex this topic is. The box below discusses the reasons for looking at a better mechanism for accounting for methane, one of the shortest lived greenhouse gases and one which is produced by ruminants as an intrinsic function of rumen function. 

What is becoming clearer is that how cattle are managed will have an impact on their overall impacts on our environment. Certainly Doug is minimising their negative impacts, through minimising their consumption of foods which could be eaten by humans directly, minimising their use of other sources of emissions such as fertiliser and fuel and making sure that their grazing activity has a positive impact on the soils they stand on and sequestering as much carbon as possible in their wake.

Accounting for methane: GWP* and GWP100
GWP (Global Warming Potential) is a measure of how much impact a gas will have on warming the atmosphere. The most common method to evaluate the effect of different greenhouse gases (GHGs) is by comparing them over a 100-year lifetime; this is known as GWP100. This is the internationally agreed metric chosen under the Paris Agreement and the primary tool for emission reduction targets globally. 

Using GWP, it’s possible to compare the impact of different GHGs by converting them to their carbon dioxide equivalent (CO2e) value. The latest research suggests that using GWP100, biogenic methane emissions are 27 times more powerful than CO2; and nitrous oxide (N2O) emissions are 273 times more powerful. However, unlike CO2 and N2O gases that last for hundreds of years in the atmosphere, methane only lasts for an average of 12 years after which most of it is broken down. This means that using GWP100, the impacts of methane could be considered overestimated in the long-term, and underestimated in the short term. 

In an aim to better account for methane, in 2016, a team of researchers proposed a new metric, known as GWP* that works over a 20 year period. Over a 20 year period, emitting a tonne of methane today has 80 times more temperature impact than carbon dioxide. However, the new metric is also designed to reflect the warming impact of ongoing emissions of methane in relation to the current levels of that gas in the atmosphere. The theory is that, over time, ongoing emissions are not adding warming to the atmosphere, but merely replacing old emissions that have degraded. Essentially, GWP* focuses on changes in emissions rather than absolute emissions. This accounting approach has been gathering support within UK agriculture sector, however it does also face some criticism (example).

As we turned for home, and the beckoning hot drinks and cakes, conversation turned to reducing the negative impacts of growing potatoes and the potential for woodland to sequester carbon into trees. On the topic of reducing the harms associated with growing potatoes there is a clear role for keeping living roots in the soil for as much of the year as possible, but to date no alternative has been found to the punishing soil management routine required to grow potatoes, although research is underway.

Liz explaining to the group how woodland is accounted for in the Farm Carbon Calculator

Doug has 50ha of woodland across the farm, with different areas having been in place from 10 -240 years. As his summary carbon footprint report shows, the woodland at Durie Farms alongside soil carbon sequestration offset the business GHG emissions last year. Of the total sequestration, woodland contributed around 50%. It is worth noting that the carbon sequestration associated with woodland depends on the growth rate of the tree. The Woodland Carbon Code has developed “look up tables” for this which the Farm Carbon Calculator  has incorporated into the sequestration area of the Calculator. For users, providing accurate information on the age of the trees as well as their varieties will enable a more accurate assessment of the scale of sequestration to be given. A rule of thumb is that most trees sequester only small amounts of carbon for the first decade or so of life. From the age of around 15 – 30 years carbon sequestration is at its maximum. After that age growth tends to slow down and with it carbon sequestration.

Doug is continually trying new ideas, with pasture cropping a new initiative he has ‘frustratingly’ tried this year. Doug’s long term membership of BASE UK  has supported him in his quest for adopting new and more sustainable farming practices. A quick look at the BASE UK website revealed a number  of fascinating events coming up in the next month including this one:

14/12/23 BASE-UK Member Nick Wall will present his review of the study tour recently taken by 15 members to visit Frederic Thomas and other BASE France members in November 2023 – it wasn’t all good food and drink – there was some learning involved! 

Back in the cattle yard (not in use yet) we finished with a round up of questions, answers and general discussion.

Thank you to our hosts, the Christie Family, for a memorable farm walk and great hospitality.