Disclaimer: The views and opinions expressed in this article are those of the author and do not necessarily reflect the views of the Arboricultural Association.

Share this story


#ARBatwork #ArbMatters #PledgeLessPlastic & 12 Faces of Arb 1987 storm 2 Rope 2018 30 Under 30 3ATC 3ATC UK Open 50th annual AA AA award AA Awards Aboricultural Association Accident accreditation advice AFL aftercare AGM Agrilus Biguttatus aid air quality Alert Alex Kirkley All Party Parliamentary Group on Horticulture amenity Amenity Conference Anatomy Ancient Tree Forum Annual Awards Anthropology APF APF 2020 app APPGHG application Appointment apprentice apprenticeship Apprenticeships Approved Approved Contractor Approved Contractors ARB ARB Approved Contractor ARB Approved Contractors ARB at work ARB Magazine ARB Show arb training ArbAC ARBatwork ArbCamp Arbor Day Arboricultural Association Arboricultural Student Arboriculture arborists Arbsafe Ash Ash Archive ash dieback Asian Hornet Assessments atf ATO Australia Autumn Review award Awards Barcham Trees Bark Beetle Bartlett Bartlett Tree Experts bats beetle beyond ism Bill Matthews biochar biodiversity biomechanical biosecurity Book Prize Book Shop Books Bookshop boundaries branch Branches brand Brexit bs5837 Budgeting Tool bursary business Call for Abrstacts Call for papers Campout Canker stain of plane carbon career careers Cavanagh CCS Cellular Confinement Cellular Confinement Systems CEnv CEO Ceratocystis Ceratocystis platani chainsaw chalara charity Charles charter Charter for Trees Chartered Environmentalist chelsea Chelsea Flower Show Claus Mattheck climate climate change climber climbing Cofor Colleges committees competition competiton conference Confor conifers conservation Consultant consultation Continuous Professional Development Contractor Contractors Cornwall Cornwall Branch Coronavirus Coroner Council Countryside Countryside Code Countryside Stewardship Course for beginners COVID-19 CPD cross industry news Crown & Canopy Cryphonectria parasitica Cumbria DART Date for your diary deadwood death debate Debt defra Design Devon Director disease diversity document donate dothistroma downloads draft Dutch elm EAC East Anglia ecology Economic Report economy Ecotricity education EFUF Election elections Electricity Elm yellows Emerald Ash Borer England England Tree Action Plan England Tree Strategy English Elm environment environmental EPF equipment Europe European Arboricultural Council European Forum on Urban Forestry European Wood Pastures Event exeter Exhibitors Fall from Height Fatal Fatality felling Fellow Fellow Members Fera Field Trip Finance Fine firewood First Aid FISA flood flooding for Forest Research forestry Forestry Commission forests freelancers FSC Fund4Trees funding fundraiser fungal fungi Future Flora Futurebuild gardening GDPR Geocells Gold Medal Gov.uk government grant grants Grapple Saws Green Brexit Green Infrastructure Green Infratructure Green Recovery Green Up Guarantee guidance Guidance Note Guidance Note 2 guide guides Hazard Tree Health heart-rot Hedgerow hedges Helliwell Help Henry Girling Henry Kuppen History HMRC HOMED Homeworking Honey Brothers honours Horse Chestnut HortAid horticulture horticulturists HortWeek housing HRH HRH Prince Charles HS2 HSE HTA ICF ICoP identification Immigration import industry Industry Code of Practice industry skills Infographic InfraGreen Initiatives Inspiration Insurance Intermediate Tree Inspection International Urban Forestry Congress International Women’s Day International Year of Plant Health invertebrates Investigating Tree Archaeology Conference Ips typographus Irma irrigation ISA iso i-Tree IUFC IWD21 Job job opportunity jobs judgement JustGiving Karabiner Kew Kit land-based Landsaping Landscape Institute Landscape Show landscaping Lantra law Leaf Minor Lectures legal legislation Letters Liability licence London longevity LTOA Lynne Boddy Magazine Managegement Plan manifesto maple Mayor of London MBE Melbourne Member Benefit Member Survey Membership mentor Midlands moth' motion Myerscough NASA National Geographic National Hedgerow Week National Tree Safety Group National Tree Week NATO Natural England NatureScot Netherlands New Year’s Honours News NHS nominations Northern Northumberland Notice notification NTIS NTOA NTOC NTSG Nurseries oak 'oak Oak Processionary Moth Oak-boring Beetle obituary Observatree occupation online opm Padua Papua parks parliament Perennial Pests & Diseases Pests and Diseases Petersfield petition Petzl photo Phytophthora plan planning Planning Law Plant Health planting Plantsman Pledge Plumpton College policy poll Poster Power PPE Preston Twins Prince Charles Prince of Wales processionary Product Recall Professional Members prosecution Protect and Survive protected tree protection Qualifications Queen’s 70th Jubilee Questionnaire Quotatis ramorum RC Recruitment reference Reg Harris Registered Registered Consultant Registered Consultants Rememberance Day renewal REnvP Report Rescue research Research grant Resilience response results Retirement retrenchment review RFS rhs RHS Chelsea Flower Show Ride for Research Ride4Research rigging Rodney Helliwell rogue tree surgeons Royal Forestry Society RSFS Safe Working Practice Safety Safety Bulletin Safety Guides Safety Notice Saftey Sale school Scotland Scotland Branch Scottish Branch SDG Accord security Seed Gathering Season Seminar seminars Share Sheffield Show Sierra Leone Site Guidance skills skills survey SocEnv Social Benefits of Trees soil soils South East South East Branch South West Speaker spotlight SRT SRWP staff Standards statement Stationary Rope Stationary Rope Technique statutory STIHL Stonehouse strategy student Student Book Prize Student Conference Study Trip Sub-contractors Supporter survey Sustainable Soils Alliance Sweet Chestnut sweet chestnut blight symposium T Level T Levels Tatarian maple TDAG technical guide Technical Guides Technical Officers Technical Team Technician Members Technology Ted Green tender TG3 Thames & Chiltern The Arboricultural Association The Plantsman’s Choice The Queen’s Green Canopy The Woodland Trust Thinking Arbs Thinking Arbs Day Timbersports Tony Kirkham Tools top-handled chainsaws,Elcoat, TPBE4 TPO Trading Standards trailblazer training transport Tree Tree Care Tree Champion Tree Council Tree Fayre Tree Health Tree Health Week Tree Inspection tree loss tree management Tree of the year Tree Officer Tree officers tree planning Tree Planting Tree Production Innovation Fund Tree Protection tree register Tree Risk Tree Shears tree species Tree Supply Tree Surgeon Tree Surgeons Tree Week Tree Work at Height Tree Workers Zone TreeAlert Treeconomics tree-felling TreeRadar trees trees' Trees & Society Trees & Sociey Trees and Society Trees for Cities Trees, People and the Built Environment trust' trustee Trustees TrustMark Two Rope two-rope UAG Uitlity UK favourite ukas UKWAS urban urban forest Urban Forestry Urban Tree Challenge Urban Tree Challenge Fund Urban Tree Cover Urban Tree World Cup urban trees Utility Arboriculture Group UTWC vacancy VETcert veteran trees video Videos Virtual ARB Show volunteer voting VTA WAC Wales Wales Branch Warning Watering watering solutions Webinar webinars website Western Westonbirt Wharton White Paper WIA Witley Women Women in Arb women in arboriculture woodland Woodland Carbon Code Woodland Carbon Guarantee woodland trust woods Work at Height Workshops World Environment Day World Fungi Day Xylella young Young Arboricultural Professional young arborists Young People’s Breakfast Event Young Tree Aftercare zoo

Soil: how do we get things right from the bottom up?

Author:  Ed Baker
Last Updated:  22/06/2017
Article by Ed Baker, Planner (Tree Officer), City of Cardiff Council

The soil is a dark, mysterious world. Until we put a spade into it or look at it under a microscope, we can fail to appreciate its complexity and the kaleidoscope of life it supports. It then becomes ‘muck’ or ‘dirt’, to be shifted, sifted and squashed to support development. So long as we tear it up with a big metal claw and add a bit of muck to it, it will grow us big trees without complaint, won’t it?

Often we are told that trees have died because they have had too little or too much water, when the real problem is soil that has been turned into a lifeless, concrete porridge, into which a pampered nursery tree has been dropped and then, to ‘help it out’, surrounded by a quagmire of compost and fertiliser!

For those of us professionally involved in the care and cultivation of amenity trees, failure to get things right from the bottom up is failure full stop. Arboriculture is no different from agriculture in that it begins and ends with the soil.

Many of our towns and cities are developing fast, and soils untouched by ought but a plough since the end of the last ice age face potentially catastrophic damage. Yet with careful assessment and handling, the best of these soils can be protected so that they support the growth of large trees, giving back to the soil what centuries of farming and more recent development have taken out.

To ensure that the best soils are protected and re-used appropriately, they should be professionally assessed by a soil scientist in accordance with the 2009 Defra ‘Construction Code of Practice for the Sustainable Use of Soils on Construction Sites’. This results in a Soil Resource Survey (SRS) and Soil Resource Plan (SRP) that should inform landscaping specifications and construction environmental management plans. In the same way that an arboriculturist should oversee tree protection on a development site, a soil scientist should oversee soil handling, storage, amelioration and placement, in accordance with the SRP.

Leaving soil handling to groundworks or geotechnical contractors alone may result in a development that satisfies engineering requirements of the soil, but may be less suitable for supporting the establishment and healthy growth of vegetation, particularly large trees. The consequence could be costly in environmental and financial terms, requiring extensive soil amelioration, soil importation and replacement of planting failures.

Relying on generic soil specifications and compliance with British Standards may result in the widespread use of imported, ‘as dug’ or manufactured, ‘multi-purpose’ soils, even when existing in situ or site-won soils could be equally or more effective at supporting the proposed planting.

Different vegetation types such as wildflower grassland, amenity grassland and large, root-balled trees have differing ‘performance’ requirements of the soil, and generic specifications, or those that meet the relatively broad criteria of the British Standards only, may result in poor performance or failures.

Over-specification of topsoil and underspecification of subsoil are common problems with regard to tree planting, with some considering that large trees require a deep hole full of topsoil, compost and fertiliser to grow successfully. The result of this can be oxygen depletion, excessive settlement, spiralling roots and ‘sump’ conditions, so that planting holes become bogs, with the smells to go with it! Anybody who has dug trenches to expose a soil profile knows that in nature ‘topsoil’ depths typically extend no deeper than 400mm, often much less, yet it is still common to see tree pit sections showing topsoil enveloping root-balls to 600mm depth, ‘enriched’ with composts and fertiliser and surrounded by soil of unknown specification.

Subsoil on the other hand is often ignored, or simply proposed for ‘ripping’, without evidence from a soil scientist that this will be necessary or effective, or a description of the methods and equipment to be used. Particularly where larger trees are being planted, subsoil with optimal qualities of aeration and drainage, including under the loading of a large root-ball, is essential to effective establishment. Ensuring that provision is made in practical and financial terms for effective subsoil handling, amelioration or importation is essential, wherever large tree planting is proposed.

Cardiff Council is preparing guidance on soils and development, but this does not seem to be a widespread approach. It will be a learning process, no doubt subject to refinement over time, but the more local authorities develop this sort of guidance, and share knowledge on best practice and local success stories, the better it will be, not only for soils, but in turn for trees and people.

Should you wish to discuss the draft soils and development guidance that is in preparation, please contact treeprotection@cardiff.gov.uk.