THE
SOIL SUPPLEMENT F E B R U A RY 2 0 2 2
ISSUE SPONSOR
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WHEN WHERE
Tuesday 15 March 2022 Sandown Park Racecourse Face the future of the UK and play your part
amidst a showcase of future-fuelled products,
WHY
materials and services – all you need to stay
ahead in your landscape business. Powered by
a superb seminar programme, expert panellists with real-life, relatable experiences get ready to tackle the issues you face and challenge
industry norms for a brighter landscape future.
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WELCOME
CONTENTS 05 06
W
e don’t have to tell you how important soil is – it’s been one of the most popular topics at the last two FutureScape events. And as Maylim’s Adam Wraight will tell you within these pages, a lot of time and effort goes into choosing not just the soil for its prolific commercial projects, but the soil supplier too, and logistics is one of the biggest selling points.
WE DON’T HAVE TO TELL YOU HOW IMPORTANT SOIL IS – IT’S BEEN ONE OF THE MOST POPULAR TOPICS AT THE LAST TWO FUTURESCAPE EVENTS But what else is up for discussion when selecting soil? For those who couldn’t attend FutureScape in November – and for those who need a reminder of the wealth of information divulged – we’ve summarised some of the biggest topics raised at The Great Soil Debate.
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WELCOME From provenance to environmental benefits to natural vs manufactured – spoiler alert: there are benefits to both – a few of the industry’s leading suppliers have covered all the bases. One thing they all agreed on is that soil can play a crucial role in helping to tackle climate change and improve biodiversity, which is something you can read more about from soil scientist Tim O’Hare on page 13. To get the most from the soil, though, a soil management plan is needed, says Natural England’s Dr Eleanor Reed. Unsure what this might include? Dr Reed explains, in detail, what landscapers can expect from one and why it’s important to follow. With soil being such a valuable resource, it might cause some alarm when you see the question on page 17: Are we running out of soil? You’ll have to read ahead to find out!
09 13 15 17 19
Barometer Focusing on the trading month of November 2021 for soil suppliers The Great Soil Debate Experts’ deliberation on the topic at FutureScape 2021 Interview: Looking at Logistics Maylim’s succesful method to soil selection and usage The Role of Soil in Combatting Climate Change Soil scientist Tim O’Hare discusses the important role soil plays in climate change Soil Management Plans Dr Eleanor Reed, senior specialist in soils for Natural England shares the benefits of utilising these plans Future Developments We take a look at tackling the issues linked to the potential decline in soil resources Suppliers’ Agenda Experts offer opinions on the British Standards for topsoil
Soil Supplement / February 2022
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BAROMETER
UK LANDSCAPE BAROMETER
FOCUS ON SOIL SUPPLIERS
I
n this issue of the Soil Supplement, the UK Landscaper Barometer is focused on the trading month of November 2021 for soil suppliers. The volume of soil sold went down by an average of -11% in November compared to November 2020. The number of quotes also went down by an average of -25% year on year. Confidence was split evenly between those feeling more confident and the same. This time last year we had just entered into the third national lockdown, so it may appear disappointing to see 50% of soil suppliers are feeling similar levels of confidence compared to the lockdown days. Nevertheless, increases are still
THE VOLUME OF SOIL SOLD WENT DOWN BY AN AVERAGE OF -11% IN NOVEMBER COMPARED TO NOVEMBER 2020
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Barometer.indd 5
apparent for some soil suppliers, with 50% experiencing a higher number of quotes and a higher turnover too. Anecdotal evidence from soil suppliers suggests the industry is looking forward to 2022, one supplier commented: “We’re wasting no time in moving forward with projects
CONFIDENCE
INCREASES ARE STILL APPARENT FOR SOME SOIL SUPPLIERS, WITH 50% EXPERIENCING A HIGHER NUMBER OF QUOTES AND A HIGHER TURNOVER
VO LU M E S O L D
and forward planning, despite COVID-19 interruptions. The industry is buzzing and looking at another big year.” If you would like the full report or would like to contribute to the UK Landscape Barometer moving forward, please send an email to Gemma Lloyd on gemma.lloyd@ eljays44.com or call on 01903 777 594. Please note that all statistics are based on those surveyed and compare November 2021 to November 2020.
MORE 50%
50% SAME
HIGHER 50%
50% LO W E R
QUOTES
HIGHER 50%
50% LO W E R
Soil Supplement / February 2022
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SUMMARY
THE
GREAT SOIL DEBATE
A N I N S I D E LO O K AT W H AT M A D E F U T U R E S C A P E 2 0 2 1 ‘ S G R E AT S O I L D E B AT E S O C O M P E L L I N G
F
utureScape saw some pretty big changes in 2020 when it moved online for the first time ever. 2021 wasn’t without changes for the event, though. Not only did it move to ExCeL London, but it took place over two days, offering visitors even more time to peruse the exhibition stands, more jam-packed seminars, and more award ceremonies. One of the most-watched seminars at FutureScape VIRTUAL, FutureScape 2021 returned with The Great Soil Debate to offer more advice to audience members and to discuss the role it has to play in the fight against climate change. Hosted by Pro Landscaper’s Rachael Forsyth, the hour-long debate opened with something which can all too often be overlooked – the importance of soil. According to the panellists, it’s also the first place any project should start. As one panellist, Andy Spetch put it, it is, after all: “The foundation to any successful project.” It’s therefore the role of any good supplier to help clients choose the right soil for their project. From here, panellists delved into other choices that can be made on site in regard to soil, from sourcing locally to natural vs. manufactured soil. The debate also led to the importance of soil in the fight against climate
change as well as what challenges it might be facing in the future. Here, we summarise some of the advice and expertise given, and the arguments raised during the debate. Natural vs. manufactured soil Put simply, natural soil is just that, taking around 500 to 1,000 years to produce every 1cm of soil, derived from the break down of organic matter. A manufactured soil is a manmade product, or “sand-based soil”, primarily
NATURAL SOIL FILTERS AND CLEANS OUR WATER AND HELPS PREVENT NATURAL HAZARDS SUCH AS FLOODING S I M O N H E D L E Y, M A N AG I N G D I R E C T O R , B O U G H T O N
derived from sand with added compost and other additives to meet a specification, which is “usually BS3882-2015.” This distinction comes from Simon Hedley, who further argued about an important difference between the two: “Natural soil filters and cleans our water and helps prevent natural hazards such as flooding. It contains immense
levels of biodiversity. Natural soil is the place where you will find humus, it is not possible to manufacture this artificially.” But, of course, there are benefits to manufactured soil too, as Simon points out: “Sand-based soils can be very consistent in their physical make up and because they are made to a variety of specific recipes can be favoured by soil specifiers.” Sourcing locally It was made clear that sourcing locally is not always possible. This is down to specification. There could be a clear lack of availability locally, especially if the site requires a very specific mix or it’s a very specific location. Looking at it through an environmental lens, though, it’s very different. Simon argued: “Locally-sourced natural soil would be preferable in most instances, especially as far too many natural soils are underused, which is an environmental concern.” The reduction in carbon footprint is also a key reason, with Andy arguing that sourcing locally would cut down on transport miles, but it also might be what’s best for the site, too. Simon added that financially it could also make sense; “particularly as transport costs never seem to go down.”
THE PANELLISTS
6
A N DY S P E T C H
MARK WOOD
DREW WETHERELL
JOHN COLES
SIMON HEDLEY
TO P S O I L M A N AG E R , B R I T I S H S U G A R TO P S O I L
B U S I N E S S D E V E LO P M E N T D I R E C TO R , G R E E N T E C H LT D
S A L E S M A N AG E R , B O U R N E A M E N I T Y LT D
D I R E C TO R , B U RY H I L L LANDSCAPE SUPPLIES
M A N AG I N G D I R EC TO R , B O U G H TO N
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SUMMARY John Coles, director of Bury Hill Landscape Supplies brought up an important exception,
rather than importing basic materials significant distances.”
though, in high specification materials such as
THE BENEFIT THAT THESE MATERIALS BRING MUST OUTWEIGH THE ENVIRONMENTAL COST OF TRANSPORTING THEM JOHN COLES, DIRECTOR OF BURY HILL LANDSCAPE SUPPLIES
Tree Sands, Bio Retention Soils and Rootzones. “These will often have to travel significant distances as their base ingredients can only be found in certain areas of the country. Therefore, the benefit that these materials bring must outweigh the environmental
Challenges facing soil For Drew there’s one clear challenge – provenance over preference: “We’re starting to see a lot of schemes from major cities replicated into smaller towns across the country, which is great, but some specifications for materials used on one site aren’t always transferable to another due to the geographical location of available materials.” Understanding the environment – from soil type to weather patterns – is crucial, it seems. Advice can always be gained from nurseries to better understand what the plants need and therefore what soil types are required. As Drew put it: “A simple copy and paste isn’t always possible.”
and trees only have a relatively short life and will rot quickly after they die, releasing the carbon – much of which will be re-absorbed by the soil.” Simon also brought up soil’s immense levels of biodiversity: “Only 1% of soil microorganisms have been identified, yet soils are home to over one-quarter of all living species on earth. Soil needs a delicate balance of five key components to be a healthy soil. Healthy soils will deliver the niche to support growth to maintain the terrestrial carbon store, which is the biggest antidote to climate change.”
THE 2015 SUDS MANUAL IS A GREAT GUIDE TO WHAT CAN BE ACHIEVED D R E W W E T H E R E L L , S A L E S M A N AG E R , B O U R N E A M E N I T Y LT D
cost of transporting them.” With the issue of availability but also the benefits in mind, John put the focus on soil science, landscape architects, main contractors – and common sense – arguing that they could all be better utilised; “by understanding the local area’s resources, its soil and mineral profiles, and working together to find viable, economic and environmental
sound solutions – such as on site blending to produce high quality growing media,
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The Great Soil Debate.indd 7
Climate change Simon Hedley put it well when he stated: “Natural soil is the largest terrestrial store of carbon, and therefore helps to regulate the climate.” According to Drew, a football field will sequester around half a ton of carbon each year – which is the equivalent of driving a car over 3,000 miles – while a tree can remove
about 21kg a year. John added that: “Plants
Soil’s role in flood mitigation was also raised, with Drew stating: “The 2015 SuDS Manual is a great guide to what can be achieved. We’re seeing more new builds installing these systems. Rain gardens, swales and bio retention units – Beaulieu Park in Chelmsford is a beautiful example, along with high streets retrofits such as Marylebone High Street.” Drew also reminded that this could help gain BREEAM points, too.
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ADVERTORIAL
When looking to plant sustainably, start with a good quality soil
W
hile it may sound like a no brainer, soil should be one of the first considerations to any growing project when trying to achieve a thriving and sustainable environment for planting. Unfortunately, its importance in growing projects is often overlooked, and soil health considerations as a result can take a back seat on landscape and garden design project planning. With varied BS3882 compliant options for soils on the market, a mixture of natural and man-made variants, each with their own distinct uses, benefits, and occasional shortfalls, it can be difficult to navigate through the available options to land at what matters most – what puts a plants health and longevity first? What’s great about soil? Soil carries out a range of functions and services without which human life would not be possible. It provides an environment for plants, including food crops, to grow in, by anchoring roots and storing nutrients. A good quality nutrient rich soil will be high in microbial activity,
which is crucial to the development and strong growth of flora within a soil. Soil microbes play a key role in essential ecosystem processes such as nutrient acquisition, carbon cycling, nitrogen cycling, soil formation, and disease resistance. In a nutshell, soil filters and cleans our water and helps prevent natural hazards such as flooding. It contains immense levels of biodiversity. Finally, it is the largest terrestrial store of carbon, and therefore helps to regulate the climate. Why does soil health matter? Good soil structure is so important for the biological activity with the larger pores in soil improving air movement and drainage, the smaller pores being able to retain moisture for plants to use, these pores or spaces also give habitats for life, especially soil bacteria which in the right conditions can grow rapidly can have a huge effect on the health of the soil, turning ammonium into useable nitrates. This complex interaction between the physical, chemical and biological properties of the soil has a major influence on soil fertility and health. To give context a good healthy soil with plenty of microbial activity is equivalent to having 12 sheep per hectare living in the soil!
So good soil biology will provide: • Improved cycling of nutrients • Improved resilience to weather i.e. drought and intense rain events • Improved plant growth It is for these reasons that we believe soils, particularly natural soils, as a resource need to be cherished for the many benefits they provides plants and in turn humanity. “Soil is the basis of all terrestrial life. Every living thing on the planet depends on it. We must make sure we manage soil properly and not take it for granted.” Dr Rattan Lal, Professor of Soil Science, Ohio Sate University
Boughton, leading the way in soil A good source of soil is essential to any landscaper or garden designer who is looking to reduce the risk of a nutrient imbalance in the host plants immediately after installation. A well-sourced naturally formed soil is in our opinion the best choice when installing a working soil that could immediately provide an ideal, reliable environment for a host plant rhizosphere and consequently plant health. Boughton are an established company that has been supplying the Amenity, Landscape and Construction Industry since 1985, we pride ourselves in the service and commitment given to each one of our
many customers over the last 30 years of business. We operate from a purposebuilt production facility in Kettering, Northamptonshire, an area well known for its excellent source
of loams and topsoil, we also recover soil from development sites Pre-Construction & Green Field sites in the surrounding neighbouring counties of Leicestershire, Bedfordshire and Hertfordshire. An experienced team with over 30 years’ experience in the landscape, horticulture and sports turf markets include MD Simon Hedley; who has a wealth of technical in-depth product knowledge and more recently Jason Lock who has valuable experience in specifying and delivering projects from a design and build contracting background. Backed by an experienced sales team Boughton are well placed to support all your needs. We have a variety of products including a range of Natural Topsoils, Green Roof Substrates, Urban Trees soils, Composts/Turf Dressings and rootzones all available loose tip, bulk bag and 25kg bags.
www.boughton.co.uk • Tel: 01536 510515 • info@boughton.co.uk Boughton Advertorial.indd 13
13/01/2022 16:56
FEATURE
LOOKING AT
LOGISTICS W
hen it comes to soil for commercial schemes, not many landscaping companies are as well placed to dole out advice as Maylim. The London-based company has built a reputation for successfully delivering some of the biggest and most prolific projects in the capital. Take its involvement in the redevelopment of Battersea Power Station, which is undergoing one of the most impressive transformations the city has seen. More than three years ago, Maylim completed phase one at the Grade II* listed building, into which £9bn is being pumped to turn it into a mixed-use neighbourhood and office district. Maylim was also behind Coal Drops Yard, the
A DA M W R A I G H T , S O F T L A N D S C A P I N G M A N AG E R FO R C O M M E R C I A L E X P E R TS M AY L I M , E X P L A I N S H O W T H E C O M PA N Y S E L EC TS S O I L A N D E N S U R E S S U C C E S S new retail destination which is part of the major development at King’s Cross, and The Tide, a new partly elevated linear park on the Greenwich Peninsula. Its experience is, undoubtedly, vast and varied, and it’s this experience which helps the team to overcome what soft landscaping manager Adam Wraight says is the biggest challenge for soil on commercial sites – logistics. “In terms of number of deliveries, soil is usually one of the biggest, so logistics is one
of the main areas we look at, ensuring we’re efficient in getting it to site. There are a lot of deliveries going in and out, so it can really slow down a project if you’re having to turn anything away or if the soil ends up sitting around and being double handed.” Fortunately, Maylim has built up strong relationships with trusted suppliers and logistics is one of the main discussions it has when choosing a soil supplier for each project, as well as meeting the client’s specifications.
WE’RE SEEING SOIL SCIENTISTS BEING INVOLVED IN PROJECTS FROM AN EARLY STAGE A LOT MORE NOW
COAL DROPS YARD, KINGS CROSS
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Interview Maylim.indd 9
“When we’re going out for pricing, we’ll send the suppliers the spec and we’ll talk to them about the project and the logistics of it. We’ll find out what they can offer in terms of bulk bags or pallets and the different delivery vehicles. This is ensuring they can provide the Soil Supplement / February 2022
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FEATURE
ONE CROWN PLACE
material, as it might be in small loads or maybe 10 a day; so we check from the start that the supplier can achieve what the project needs. It ensures we’re in the right spot from pricing to delivery, which could be a year down the line. “Once priced, we’ll go back to them for the soil test reports and check these against the specs. Quite often, projects require us to carry out our own soil tests too, so we’ll do this at the design stage of the project and, hopefully, they come back within the spec. We’ll upload all of these documents for the client to access.” The detail of the soil specification can differ from client to client, says Adam. “Some ask for
a BS3882 topsoil, for instance, which is a very varied spec; it doesn’t tell you too much, so we’ll select a soil we think is suitable from our supply chain and which meets the standard. Others are far more detailed. They want the reports of every single element of the soil and the variants they need from that, which can result in a bespoke soil. We’re seeing soil scientists being involved in projects from an early stage a lot more now.” So, is it best to stick with one supplier or can you use multiple soil suppliers for one site? This is the decision Maylim is currently making for one of its latest projects, the Park
CAREFULLY LIFTING THE BAGGED SOIL
Basin in the Linear Park which forms part of the Nine Elms masterplan. Landscape architect firm Camlins has designed the 1.5ha open space for client Royal Mail Group, with work on the two-phased project scheduled for completion in summer 2024. Six different types of soil have been specified for the Park Basin, from a highly permeable soil for the swales to aid the SuDS, to a more generic British Standard topsoil for planting, to a well-draining washed sand to provide better structure for tree pits, for example. “From a site perspective, it’s a question of whether one supplier can handle all of the deliveries. Once the project is in full swing, there will be multiple deliveries every day, so can a supplier provide these from the same yard? We’re limited as to when we can book in deliveries on sites such as these too, and you’d rather not be waiting around to unload a couple of bags of soil. “So, on certain jobs, we’d try to go to one supplier, partly to make it easier for our project managers, who liaise with all the suppliers – it removes a layer. On bigger jobs, though, there are certain soils we’d get from multiple suppliers, providing it has all been tested and falls within the same boundaries and pH.” There are rarely rejections when Maylim retests the soil, says Adam, though it’s quite
EAST VILLAGE NO.6 COMPLETED PODIUM GARDEN
DESPITE WHAT THE SPECIFICATION ASKS FOR, WE’LL USE OUR EXPERIENCE TO PUSH THE CLIENT FOR A MORE STANDARDISED APPROACH – IT’S AT THE FRONT OF EVERYONE’S MIND TO CHECK THAT THE RIGHT SOIL HAS BEEN SPECIFIED FOR THE RIGHT AREA
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Soil Supplement / February 2022
Interview Maylim.indd 10
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FEATURE common for one nutrient to fall outside of the specified range. In this case, Maylim will send the findings to the architects and involve a soil scientist to see whether the soil is acceptable. “For one nutrient out of, say, 20 to be slightly out, it is not going to impact the soil too much. It’s good for us to have such strong relationships with the architects so that we can go to them and there is some flexibility, so long as the soil meets the general spec.”
IN TERMS OF NUMBER OF DELIVERIES, SOIL IS USUALLY ONE OF THE BIGGEST, SO LOGISTICS IS ONE OF THE MAIN AREAS WE LOOK AT, ENSURING WE’RE EFFICIENT IN GETTING IT TO SITE One learning curve for the team at Maylim has been laying suitable soils for roof terraces. A few years ago, a soil which was not welldraining was used and, due to the irrigation, became somewhat stagnant. As a result, remediation was required to add more sand to the soil to ensure better drainage. “Despite what the specification asks for, we’ll use
BATTERSEA POWER STATION
our experience to push the client for a more standardised approach – it’s at the front of everyone’s mind to check that the right soil has been specified for the right area.” Another big consideration for roof terraces – and all of its projects, in fact – is compaction. Where there are other trades operating and walking over the soil, compaction can be an issue. Maylim follows the standard soil installation technique to avoid this. Soil is installed in layers of 150mm then lightly
EAST VILLAGE NO.6
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Interview Maylim.indd 11
tamped down, so it’s neither fully compacted nor loose enough that it will settle into pools when it rains. Adam reiterates, though, that the biggest hurdle for soil in commercial schemes is logistics, and this needs to be at the top of the list when selecting and installing soil in order for a project to finish on time. Looking at the long list of successful schemes by Maylim, it’s a piece of advice worth following.
TOPSOIL AT EAST VILLAGE NO.6
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13/01/2022 14:22
FEATURE
T
he climate change predictions for the UK are for warmer and wetter winters and hotter and drier summers. The rainfall events are expected to be heavier and more intense, which will increase the risk of flash flooding. By 2050, heatwaves are expected to happen every other year, which will increase the risk of drought. This in turn could lead to a loss of biodiversity. To reduce the impact of climate change, there are two main objectives to build into the design, construction and maintenance of landscape schemes: 1. Slow down (and reverse) climate change 2. Prepare the soils to respond better to the effects of this change Both objectives are interrelated and even small changes can have large beneficial effects. Not acting now will only exacerbate climate change. In any news piece on the environment or climate change, terms such as nature-based solutions, ecosystem services, carbon sequestration, biodiversity net gain, flood alleviation and sustainable drainage will often feature. But what do they all have in common? They are completely reliant on the soil for delivery. Nature-based solutions (NBS) and ecosystem services NBS are actions to protect, sustainably manage, and restore natural and modified ecosystems. These include: • flood mitigation • improving water resources and quality • improving biodiversity • temperature regulation • reduced noise • improved visual amenity and associated wellbeing. The reliance on natural habitats and created landscape features for these solutions means soils play a vital role in their implementation, both directly and indirectly, by supporting the associated ecosystem services. Soil health Soil health, also referred to as soil quality, is defined as the continued capacity of soil to function as a living ecosystem that sustains plants, animals and humans (Source: The Food and Agriculture Organization of the United Nations). www.prolandscapermagazine.com
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SOILS FULFIL A NUMBER OF ESSENTIAL SERVICES THAT ARE CENTRAL TO SOCIAL , ECONOMIC AND ENVIRONMENTAL SUSTAINABILIT Y. TIM O’HARE E XPLORES SOME OF THE WAYS IN WHICH THESE ‘SERVICES’ ARE DELIVERED IN L ANDSCAPE PROJECTS
Source: Blue Green Solutions (2017), Journal of Water Resource and Protection
Soil properties Soils are made up of a number of physical, chemical and biological properties. These components all influence the health of a soil and its effectiveness in providing the various soil functions. A healthy soil comprises a balance of these properties, a number of which are influenced by their surroundings. This interconnectivity of the soils to their environment mean they are susceptible to rapid deterioration if not managed correctly. Soil functions Soil functions that support nature-based solutions and ecosystem services include: • water regulation and management through storage, aquifer recharge and filtration of polluted water
• temperature control through thermal insulation from podium landscapes and green roofs • carbon capture and storage • provision of habitat for flora and fauna. The role of soils The role soils are able to play in these features can be categorised as direct and indirect. Direct roles • flood mitigation • increasing water resources and improving water quality • temperature regulation • nutrient cycling • carbon sequestration
Indirect roles • growing medium for trees and other landscapes • habitat for flora and fauna to support biodiversity • reduced noise • improved visual amenity and associated wellbeing
Flood mitigation In any landscape environment, soil has a direct influence on rainfall and water interception to reduce the amount of runoff needing to be managed by surface water drainage. Soil Supplement / February 2022
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FEATURE
Water attenuation Soil should be regarded as the biggest component of any sustainable drainage system. Between 25-50% of any healthy soil is made up of void space and these act like a sponge and attenuate water, as well as air. A proportion of this water is stored for plant and animal uptake, and the remainder is slowly released into underlying groundwater reserves. Water filtration Soil acts as a filter for environmental pollutant particulates that infiltrate with surface water. These compounds are encapsulated in the soil matrix where biological and chemical processes break down the compounds to make them harmless. The discharged water is then of a better quality. Thermal insulation Soil used for podium landscapes offers thermal insulation, thereby maintaining more consistent temperatures in the associated building and reducing energy expenditure. Soil microbiology for nutrient cycling A key component to all healthy soil is the balance of soil microbes. One of the major
roles microbes play is nutrient cycling, which provides resources for plant uptake and cycles wastes out of the system. As part of the system, these microbes also play their part in carbon capture and emissions offsetting by locking away carbon from plant photosynthesis and denitrification of nitrous oxide to nitrogen. Soil microbes and microbial diversity are, however, sensitive to their environmental factors, and can be harmed or unbalanced through climatic events, incorrect soil properties for a specific habitat or planting environment, or inappropriate maintenance. Carbon sequestration Soil is the second largest store of carbon on Earth, after the oceans. Approximately 80% of terrestrial carbon is retained in soil. Carbon stored in soil exists in two main forms – inorganic and organic. Soil Inorganic Carbon comprises carbonates and bicarbonates which are abundant in alkaline soils. Soil Organic Carbon is the carbon component of soil organic matter. Soil organic carbon is a diverse group of carbon-based compounds originating from the decomposition of plant material, animal residues, soil fauna and biota and is a key measurement in monitoring changes in the levels of carbon stocks. Soil organic matter As carbon types make up 58% of soil organic matter, it is important to understand the different types. There are two main forms of soil organic matter – particulate organic matter and mineral-associated organic matter – both of which provide important resources and elements to the natural biological processes within soil. Particulate organic matter comprises
partially decomposed plant material and organic fragments, such as leaf litter, humus, animal remains, peat in natural soil habitats, and mulches, grass cuttings, composts and manures in managed landscapes. Use and function is relatively short-term when compared to other carbon inputs. Organic matter is readily available to plants and microbes and can be cycled quickly compared to other forms. Particulate organic matter is not without limitations, including a greater vulnerability to disturbance, releasing carbon back into the atmosphere. This is usually because of cultivation or excavation. In contrast, mineral-associated organic matter is a more stable form, derived naturally from biological processing by soil microbiota, and to some extent artificially through addition of stable materials like biochar. Mineralassociated organic matter is the largest and most persistent pool of carbon in soil. Indirect roles Not all soil functions directly contribute to the goal of a specific nature-based solution, but rather provide the means of facilitating other mechanisms which do. For example, in order to mitigate issues such as the urban heat island effect, planting and habitat creation are often turned to. This may be in the form of tree planting to provide shade and green walls/roofs, helping to regulate temperature and humidity through evapotranspiration. Planting in the urban realm may also provide sound buffers and visual breaks, improving the aesthetics and comfort of the environment. Habitats in which soils are present also provide natural refuges in the ecosystem for flora and fauna, promoting the migration of species and improving biodiversity.
CARBON BALANCE IN SOIL
ABOUT TIM O’HARE Tim O’Hare, principal consultant of Tim O’Hare Associates LLP, has been advising on the use and management of soils for landscaping projects worldwide for more than 20 years. He works with many landscape contractors and architects, garden designers, local authorities, government agencies and soil suppliers to ensure soils are protected and correctly, specified, supplied, used and managed. Source: BSSS adapted from Jenkinson (2010), Rothamsted Research
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www.toha.co.uk
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SOIL S MANAGEMENT
PLANS
D R E L E A N O R R E E D , S E N I O R S P EC I A L I ST I N S O I L S F O R N AT U R A L E N G L A N D , E X P L A I N S TO U S E X AC T LY W H AT L A N D S C A P E R S C A N E X P EC T F R O M A S O I L M A N AG E M E N T P L A N
FEATURE
oil is a finite resource which plays an essential role within sustainable ecosystems, performing an array of functions supporting a range of ecosystem services. In order to safeguard soil resources as part of the overall sustainability of development, it is important to retain as many of its significant functions as possible. This can be achieved through careful soil management and appropriate, beneficial soil re-use on site where possible. Soils are highly variable, with different soil types often found on single development sites. Therefore, a Soil Resource Survey (SRS) undertaken by a competent soil surveyor is essential. The success of soft landscaping and planting schemes are highly dependent on both the appropriate use of each soil type as a planting medium together with appropriate soil handling to avoid soil damage/degradation. When it comes to soil re-use, the terminology and interpretation of survey results can be complex. A Soil Management Plan (SMP) disseminates the
IN ORDER TO SAFEGUARD SOIL RESOURCES AS PART OF THE OVERALL SUSTAINABILITY OF DEVELOPMENT, IT IS IMPORTANT TO RETAIN AS MANY OF ITS IMPORTANT FUNCTIONS AS POSSIBLE information obtained from an SRS, including the characteristics of each soil horizon and soil type, which is vital to inform landscaping and to safeguard the continued delivery of ecosystem services. The early and ongoing communication between landscapers, soil surveyors and the project team will increase the likelihood this soil information is correctly applied. The aim is to achieve positive outcomes such as cost savings, successful landscaping, and enhanced amenity whilst maintaining a healthy natural environment. Ideally, all developments where soil is present on site should have an SRS undertaken and a SMP in place to ensure the sustainable use and management of our precious soil resource in line with the 25 Year Environment Plan objective to ensure all soils are managed sustainably by 2030. But what information can a Soil Management Plan provide to landscapers? www.prolandscapermagazine.com
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FEATURE
This is an important aspect of the SMP which underpins sustainable soil management. The soil balance will identify if there will be a surplus, deficit or a balance of soil resource, including the quantities of each soil type and each soil horizon (e.g., topsoil and subsoil). Where possible, the soil resource (topsoil and subsoil) should be reused on site. This can be a great cost-saving action, rather than importing costly topsoil. Furthermore, where soil materials are exported from a construction site (even temporarily) they are classified as a waste and may require an environmental permit. It’s worth noting at this stage that the criteria set out in the British Standard for Topsoil (BS 3882:2015) and British Standard for Subsoil (BS 8601:2013) only relate to imported soils. Topsoil and subsoil placement thickness will depend on the anticipated rooting depth of the plants to be established, with trees and shrubs requiring a greater rooting depth, and therefore more soil resource, than grasses. Topsoil functionality when placed at depths greater than 300mm can be impeded, with excessive depths increasing the risks of anaerobic soil conditions developing and selfcompaction due to loss of soil structure, resulting in planting failures. Consideration of the soil balance is important at this stage. So now we know how much soil we have, what next?
1. SOIL BALANCE
2. SOIL TYPE Soil type is largely informed from soil texture, which describes the proportion of sand (S), silt (Z) and clay (C). The interactive soil texture triangle provided on LandIS.org.uk provides an easy-touse tool, which defines the texture acronyms. Soil texture influences many soil properties largely driven by surface area of particles. For example, the large surface area of clay typically results in a higher capacity for holding water, nutrients and other chemicals, a greater propensity for soil particles to aggregate, and increased area for microorganisms to colonise. But due to the small, flat shape and packing of clay particles, pore space can be low, leading to poor drainage. The soil texture also influences the soils resilience to handling.
A soil profile specification should be identified, including a subsoil and a topsoil, which can provide different ‘landscape habitats’ – e.g., tree pits, wildflower grassland, amenity grass, rain gardens, etc., based largely on the quantity of soil resource available, but also the soil texture, nutrient status and pH. The plant target community should be tailored to the available soil resource, with different seed mixes available for most different soil types. When considering re-creation or restoration of ecologically valuable habitats often associated with low nutrient, and high pH (alkaline/calcareous) or low pH (acidic) soils, detailed information on soils is necessary to help determine whether a site is suitable, and, if it is, the most appropriate target community to aim for. If topsoil is not present, then it is possible to plant directly into subsoils. However, if a proposed habitat requires removal of the topsoil, this is not a sustainable use of the soil resource. So now we know how we can best re-use the soil on site, what next?
4. SUSTAINABLE SOIL MANAGEMENT DURING CONSTRUCTION To increase the success of soft landscaping, the soil resource needs to be kept in a good condition during construction and through to reinstatement. The SMP will include suitable soil handling and management advice tailored to each identified soil type depending on the soil’s resilience, based on best practice guidance. This will include ensuring the different soil types are stripped and stored separately to each other; the soil is not handled when wet; and soil placement occurs only where the receiving substrate is fit for purpose (i.e. decompacted). Planting should also be in accordance with best practice to avoid damage, including for example avoiding planting clay soils too late in the autumn, to minimise the risk of rotting. Further guidance for protecting soils both during and following development is available in Defra’s Construction Code of Practice for the Sustainable Use of Soils on Construction Sites. The British Society of Soil Science has published the Guidance Note Benefitting from Soil Management in Development and Construction which promotes the protection of soils and the important functions they support within the planning system.
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3. SOIL REUSE
For each soil type identified which can support different landscape habitats, it is appropriate to have a separate soil profile specification. The soil type will also influence the necessary soil handling methodologies to minimise damage and maximise successful reinstatement. A good soil management strategy should be developed and clearly communicated between landscapers, soil surveyors, and the project team to ensure the soils are protected and sustainably managed throughout the development, whilst also supporting successful landscaping schemes. www.prolandscapermagazine.com
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FEATURE
FUTURE DEVELOPMENTS ARE WE RUNNING OUT OF SOIL? W E E X P LO R E W H E T H E R O R N OT WE’RE RUNNING OUT OF SOIL R E S O U R C E S , W H Y T H AT M I G H T B E T H E C A S E , A N D H OW W E C A N TAC K L E T H E I S S U E
T
hroughout this supplement, we’ve explored just how important soil is – to the success of a project and in the fight against climate change. But are we running out of this all-important resource? John Coles, director at Bury Hill Landscape Supplies, reminds us of some startling statements that continue to hit the headlines: “According to Maria Helena Semedo of the UN Food and Agriculture Organisation, the world could run out of topsoil in 60 years. Michael Gove has also suggested that the UK is 30 to 40 years away from losing fertility.” He has argued that these points were unfounded. That was the case, however, until recently. Led by Lancaster University in collaboration with researchers from Chang’an University in China, and KU Leuven in Belgium, a recent study provided the first evidencebacked and globally relevant estimates of soil lifespans – and it’s not a rosiest picture. Dr Dan Evans, soil scientist at Cranfield University, led this study in 2020, pulling together data from 255 locations across 38 countries, by observing how long it would take for the top 30cm of soil to erode at each location. “We found more than www.prolandscapermagazine.com
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90% of the conventionally farmed soils in the study were thinning, and 16% would lose their topsoil in less than a century. And these were found all over the world,” he explains. This topsoil incidentally is rich in nutrients and organic matter, making it important for growing food, fibres, feed, and fuel.”
WE FOUND MORE THAN 90% OF THE CONVENTIONALLY FARMED SOILS IN THE STUDY WERE THINNING, AND 16% WOULD LOSE THEIR TOPSOIL IN LESS THAN A CENTURY D R DA N E VA N S , S O I L S C I E N T I S T AT C R A N F I E L D U N I V E R S I T Y
Dan argues that one of the most prominent forms of soil degradation is erosion. “Globally, soil erosion, which is accelerated by some agricultural activities, is exceeding
the rates at which new soils can form. This imbalance leads to a net loss in soil, i.e., the thinning of the soil profile. In consequence, the productivity of the soil can reduce.” This could easily affect manufactured soils, with many relying on subsoils for mineral material or organic waste products which themselves rely on soils for their production. Certainly, according to Drew Wetherell, sales manager at Bourne Amenity Ltd, it’s becoming increasingly hard to access good volumes of single source material that is BS3882 certified. Grey areas around the classification of ‘as dug’ topsoil with the Environmental Agency (EA) don’t help, as Drew explains: “A greenfield site building new homes will inevitably have an excess of soil left over, sometimes thousands of cubic metres, but two things prohibit it being used on other sites easily – tying up a site that has material available, to a site that can take it at the same time, and the issue of a soil being classed as ‘waste’.” According to Drew, this can be classified by the EA as waste simply because the site doesn’t require it. Of course, the soil may not be Soil Supplement / February 2022
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useable, but this blanket classification could be putting perfectly good soil to waste. And though Dan sees a future where legislation protects natural soils affecting the type of material that is used to make manufactured soils – “for example, a curb on how much subsoil is extracted to provide the necessary minerals for manufactured soils,” he explains, doesn’t yet exist. Simon Hedley, managing director at Boughton agrees that the issues and the solution lie on development sites – “We
I WAGER THOUGH, THE LOSS OF SAND WILL NOT HAVE THE SAME IMPACT AS THE LOSS OF NATURAL SOILS THROUGH BAD SITE MANAGEMENT AND INAPPROPRIATE USAGE S I M O N H E D L E Y, M A N AG I N G D I R E C T O R AT B O U G H T O N
cannot make 20,000m3 tomorrow. It is reliant on both responsible, planned residential and commercial development to enable soil to be correctly harvested for production”. He continues: “Anthropogenic soil will last if we
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have sand quarries. Is it infinite? No, it’s also a finite resource. I wager though, the loss of sand will not have the same impact as the loss of natural soils through bad site management and inappropriate usage.” John agrees that the issue lies on large development sites, but there are things that can be done though – “tighter legislation on stripping virgin sites and encouragement to make better use of brown field sites for housing developments, etc. Perhaps for every hector of soil removed a new area is created of the same size that is legally protected and is either ecologically managed or allowed to rewild.” Drew recommends getting an agronomist at the initial stages of a project, to truly understand what soil is already on site, to see if it can be saved or how it may need to be ameliorated to improve it. “Understanding the soil you have on site is key. Especially on larger residential or commercial sites,” he states. “This can be financially beneficial in the long run, but perhaps slightly trickier for site to implement if you aren’t used to doing so.” The study wasn’t all doom and gloom either; there may be soil at the end of the tunnel. Dan tells us: “We found that soil conservation, either through changes in landuse or management practice, has the potential
to extend soil lifespans. Only 7% of the soils under conservation management in our study would lose their top 30cm in less than a century; in fact, nearly half had lifespans exceeding 5,000 years.”
WE FOUND THAT SOIL CONSERVATION, EITHER THROUGH CHANGES IN LAND-USE OR MANAGEMENT PRACTICE, HAS THE POTENTIAL TO EXTEND SOIL LIFESPANS D R DA N E VA N S , S O I L S C I E N T I S T AT C R A N F I E L D U N I V E R S I T Y
According to Dan, some of the most effective examples of sustainable soil management include converting arable land to forest and grassland; these land-use changes are some of the best for reducing rates of erosion. This does reduce the area of cultivable land, though, so to keep soils in agricultural production, cover cropping is an effective solution. It seems the question needs to not be “are we running out of soil”, but instead should be “what can we do to protect and enhance our soils for future generations?”
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13/01/2022 12:03
N ATH A N F L E TCH E R B U S I N E S S D E V E LO P M E N T M A N AG E R , A H S LT D Here at AHS, we are proud to have achieved BS 3882:2015 on our multipurpose topsoil and feel that it is essential for stringent checks to be in place to ensure the quality of products and the environment is protected during the excavation and production process. However, there needs to be more
SUPPLIERS’
FEATURE
AGENDA
WHAT IS THE ONE THING THAT YOU THINK SHOULD BE ADDED TO THE BRITISH STANDARD TO MAKE IT MORE ROBUST? AND WHY?
education and clarification regarding buying British Standard topsoil. Buyers will quite often just go for a topsoil which has a British Standard, rather than one suitable for purpose or to specification. For instance, a low fertility topsoil could be ordered just they need it to have a British Standard, but the requirement is for a multipurpose topsoil to be used as a growing medium. Ultimately, educating buyers and specifiers would be of benefit to the industry as a whole and ensure that the right product is ordered for the right job and ensure British Standard on topsoil is used correctly.
JASON LOCK
Soil health is not currently featured as a metric within BS 3882; it’s primary focus is on
B U S I N E S S D E V E LO P M E N T compliance rather than ‘how good or healthy’ M A N AG E R , B O U G H TO N the soil is and given
the importance of soil in fighting climate change we believe this should be a key indicator. Soil health is vital for the success of the intended end use of the soil – i.e. whether for vegetable production, wildflower meadow or an extensive planting scheme. The health of a soil is finely balanced between a series of critical linkages and if one of the indicators fail then they all fail, like a house of cards. This is illustrated by the diagram to the right – getting them all right will determine the success of a project.
MIKE JUPP
JOHN COLES
PA U L DAW S O N
C O M M E R C I A L D I R EC TO R , THE WOODHORN GROUP
D I R E C TO R , B U RY H I L L LANDSCAPE SUPPLIES
M A N AG I N G D I R EC TO R , R O L AW N LT D
The British Standard for multi-purpose
The latest updated specification to the
Rolawn recently commissioned an
topsoil (BS 3882: 2015) in its current
British Standard for multi-purpose topsoil
independent organisation to purchase and
format can be easily manipulated by
is BS 3882:2015. Whilst this latest revision
submit for testing a number of bulk bags
suppliers if they wished to do so. The
was a great improvement on the previous
of topsoil from various different suppliers
‘visible contaminants’ and ‘sharps’
BS 3882:2007 specification, we feel that
throughout the UK.
sections should be enough to allow
there is still a need for further changes to
landscapers and groundworkers to
be made as demand grows for soils to
to be suitable for use in general purpose
distinguish a topsoil that is derived
meet increasingly different end uses.
landscaping schemes or residential gardens
from a demolition site to a quality
With this in mind, the current British
Approximately half were found not
and did not meet the British standard for
manufactured soil, but during the
Standard specification covers only the
a number of reasons including pH levels,
sampling process these contaminants
basic soil testing parameters, which are
salt concentration, potassium levels and
can easily be pulled out, thus making
far too wide to ensure that a specific
excessively high sand content. Clearly
a poor-quality soil look good – on paper.
soil meets its required end use whilst
something is wrong here and it raises the
the testing parameters are too broad to
question as to whether there should be
Standard more robust, I would look
guarantee that a soil is actually fully fit for
regular independent testing to ensure
to add a full chemical suite testing
purpose. Whilst changes have been made
products are suitable for use rather than the
including heavy metals, Asbestos, PAH’s,
to the Specific Purpose Topsoil categories,
current requirements for a manufacturer to
TPH. Similar to how NHBC assess the
which we welcome, we feel that additional
submit their own sample for every 5,000 m3
quality of topsoils for building sites.
categories should be created to include
(approximately every 8,300 bulk bags).
By adopting rigorous testing for the
a much broader range of end uses and
The nature of some of the failures also
British Standard, we could ensure
moreover show whether a soil has been
raises the question as to whether elevated
poor quality muck away soils do not
produced from recycled materials, as dug
levels of food waste are ending up in
contaminate future landscaping and
natural soils or manufactured soils using
manufactured topsoils coming through
construction projects.
contaminate, free inert materials.
the compost used and the mixing ratios.
Therefore, to make the British
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