#ARBatwork #ArbMatters #PledgeLessPlastic & 1987 storm 2018 3ATC 50th annual AA AA Awards accreditation advice AFL aftercare AGM Agrilus Biguttatus aid air quality Alert Alex Kirkley amenity Amenity Conference Ancient Tree Forum Annual Awards APPGHG apprentice apprenticeship Apprenticeships Approved Approved Contractors ARB ARB Approved Contractor ARB Approved Contractors ARB at work ARB Magazine ARB Show arb training ArbAC Arboricultural Association Arboriculture arborists Arbsafe ash dieback Assessments atf Australia Autumn Review award Awards Barcham Trees Bark Beetle Bartlett Bartlett Tree Experts bats beetle beyond ism Bill Matthews biochar biodiversity biosecurity branch Branches Brexit bs5837 bursary business Call for papers Campout Canker stain of plane carbon CCS Cellular Confinement Systems CEnv Ceratocystis Ceratocystis platani chainsaw chalara Charles charter Charter for Trees chelsea Chelsea Flower Show Claus Mattheck climate climber climbing Colleges committees competiton conference Confor conifers conservation Consultant consultation Contractor Coroner Council Countryside Stewardship cross industry news Cryphonectria parasitica Cumbria DART Date for your diary deadwood death defra Design Devon disease document dothistroma EAC East Anglia ecology Economic Report economy Ecotricity education Electricity England EPF equipment Europe European Arboricultural Council European Wood Pastures exeter Exhibitors Fatality Fera Fine flood flooding Forest Research forestry Forestry Commission forests FSC Fund4Trees funding fundraiser gardening GDPR Geocells government grants Green Brexit Green Infrastructure Green Infratructure guidance Guidance Note 2 guides Hazard Tree Health Helliwell Help Henry Kuppen Horse Chestnut horticulture HRH HRH Prince Charles HS2 HSE ICF Infographic InfraGreen International Urban Forestry Congress Investigating Tree Archaeology Conference Ips typographus Irma irrigation ISA iso i-Tree IUFC Job Karabiner Kew land-based Landscape Institute Landscape Show landscaping Lantra law Leaf Minor Lectures legislation London longevity LTOA Mayor of London Melbourne Member Benefit mentor Midlands moth' NASA National Geographic National Tree Week NATO News nominations Northern Northumberland notification NTIS NTOA NTOC oak 'oak Oak Processionary Moth Oak-boring Beetle obituary Observatree occupation opm Padua parks parliament Perennial Pests and Diseases petition Phytophthora planning Planning Law planting Plumpton College policy poll Power Prince Charles Prince of Wales processionary Protect and Survive protected tree protection Quotatis ramorum Registered Registered Consultant Registered Consultants Rememberance Day Report Rescue research Resilience response retrenchment review RFS rhs Ride4Research rigging Rodney Helliwell rogue tree surgeons RSFS Safety Safety Bulletin Saftey Scotland Scottish Branch SDG Accord security seminars Share Sheffield Show Site Guidance skills SocEnv soil soils South East SRWP staff statement Stationary Rope statutory STIHL strategy student Student Conference survey Sustainable Soils Alliance Sweet Chestnut sweet chestnut blight TDAG Technical Officers tender Thames & Chiltern The Arboricultural Association The Woodland Trust Thinking Arbs Day Timbersports Tools TPO Trading Standards trailblazer training transport Tree Tree Champion Tree Council Tree Health Tree Inspection tree loss tree management Tree of the year Tree Officer Tree officers tree register tree species Tree Surgeons Tree Week tree-felling TreeRadar trees Trees, People and the Built Environment trust' trustee Trustees TrustMark UAG Uitlity UK favourite ukas UKWAS urban forest Urban Forestry Urban Tree Cover urban trees VETcert veteran trees video Videos volunteer VTA Wales watering solutions webinars website Western Westonbirt Wharton women in arboriculture woodland woodland trust woods World Environment Day Xylella young arborists

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

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