Soiltransplantation

Reyerscamp transplantation of heathland soil

How can former arable fields be restored to nature? How can we turn a heavily managed soil into a species-rich grassland or heathland? And what is the role of soil organisms in steering plant communities? This website and film explain soil transplantations for nature restoration and development.

Developed by the Netherlands Institute of Ecology – Royal Netherlands Academy of Arts & Sciences (NIOO-KNAW), in collaboration with the Dutch Society for Nature Preservation (Natuurmonumenten). Funded by the Netherlands Organisation for Scientific Research (NWO).

What is soil transplantation?

Transporting soil from a donor area and spreading this soil over another area is what we call soil transplantation. Soil from a donor area is distributed (transplanted) thinly over the surface of a different area. Soil transplantation is often used to speed up nature development on former arable lands, using soil from nature reserves to kick-start nature in the new location.

Do nothing (left) or with soil transplantation (right)
J. Wubs
Six years after top-soil removal on Reijerscamp former arable field, the Netherlands: without soil transplantation (left) and after transplantation of heathland soil (right).

Why is soil transplantation implemented?

In the Netherlands, new nature reserves are frequently established on former arable fields. Spontaneous nature development is often slow. The target (plant) species don’t establish immediately, because their seeds aren’t present, and because (a)biotic conditions aren’t optimal yet.
Nature managers steer new nature development in different ways. Unwanted plants and seeds are removed by mowing, grazing or excavating. Excavating can also help to reduce the high amounts of nutrients in soil from fertilizers. The groundwater table can be altered to encourage either wetland or dry ecosystems.

The composition of the soil (micro)organisms has been largely neglected in nature development. We know that plants and soil organisms interact and depend on each other. Soil life can thus have a large impact on plants colonising a new area. By transplanting soil from a nature reserve into a newly to be developed area, both the target soil organisms and plant seeds are brought to the new area. This ensures that the target vegetation can develop quicker.

Schematic overview of soil organism's feedback
Schematic overview of soil organisms’ feedback after soil transplantation (above) or doing nothing (below).

Above: after soil transplantation, target soil organisms and plants establish and interact, eventually forming
the desired ecosystem.
Below: If no target soil organisms and plants are brought in, pioneer plants and soil organisms will establish, and
interact, but the target vegetation will not be promoted. Without soil transplantation it is highly unlikely that the
desired ecosystem will establish.

How are soil transplantations applied?

Soil material is excavated from the donor location, and spread in a thin layer over the new area. Different techniques of soil spreading have been tried, such as: soil crumbling, slurry (mixing soil with water), or digging in of intact soil sods. More informational about these methods can be found under “Step-by-step”.

Where can we find examples of soil transplantations?

In the Netherlands, several soil transplantation experiments have been carried out to convert former arable fields to nature reserves. A recent example can be found at Reijerscamp, Gelderland. Under the tab “Map” locations and details of more soil transplantation projects in the Netherlands can be found.

Why this website about soil transplantations?

The Netherlands Institute of Ecology – Royal Netherlands Academy of Arts & Sciences (NIOO-KNAW) in collaboration with the Dutch Society for Nature Preservation (Natuurmonumenten) organised an information day about soil organisms, nature development and soil transplantations on 15 October 2015. This day was attended by many stakeholders and nature restoration practitioners. During the meeting results of the Reijerscamp soil transplantation experiment were presented, as well as the principles of soil transplantation, its use for nature restoration, the practical application of soil transplantations, and ethical questions around soil transplantations. Clearly many practitioners still had questions about how and when soil transplantations can best be used for nature development. To answer those questions NIOO-KNAW created this website, with support of the Netherlands Organisation for Scientific Research (NWO).

Research on soil transplantations at NIOO-KNAW

We study different aspects of soil transplantation, soil organisms, soil fertility, biodiversity and nature restoration. For instance, we found that on former arable fields, sowing of target plant seeds is more effective than removing topsoil for grassland restoration (Kardol et al. 2008), and that soil transplantations decrease the time to establish heathland on former arable fields (Wubs et al. 2016). Martijn Bezemer, Wim van der Putten, and Jasper Wubs are currently working on fundamental and applied soil transplantation research.

Step by step

How to perform a soil transplantation

Common starting points:

  • Former arable fields on sandy soil
  • Forest on sandy soil
  • Built/urban area
Different approaches

1) Preparing for nature

Research
Biotic and abiotic properties of the donor soil should resemble the restoration area as much as possible. To achieve a good match, we need to investigate whether we should perform preparations in the restoration area, and where the donor material can be sourced.

Doing nothing
Soil transplantations don’t necessarily need large-scale preparation. Doing nothing can suffice to start a soil transplantation. The donor material can then be spread onto the restoration area directly.

Topsoil removal
To the ploughing depth of arable fields, the topsoil contains a high amount of nutrients. This hinders the development of (species-rich) grasslands or heathlands. Also, the topsoil doesn’t contain seeds of plant species that we want there, and contains the wrong soil organisms to promote nature restoration.

A first step can be to excavate to the maximum ploughing depth, onto the parent material. This removes the fertilised, nutrient-rich topsoil layer that contains few of the target plant seeds and soil organisms. A new start is made for the development of more natural biotopes.

The depth of topsoil removal varies and depends on the depth of ploughing during previous agricultural practise. Abiotic soil properties need to be taken into account. By excavating too deep, the hydrological environment can change, the organic matter content may become too low to support soil organisms, or soil chemical properties may inhibit colonisation of the specified plants.

Adapt the groundwater table
Sometimes it is necessary to alter the groundwater table, especially for the development of wet, nutrient-poor grasslands that rely on a high groundwater table (e.g. Molinia meadows).

Conserve/apply relief
It may be desirable to preserve cultural-historic landscape remnants such as old dykes, mounds or watercourses. Additions or re-enforcements of local relief create a varied and diverse landscape.

2) Collection and treatment of soil transplantation donor material from nature reserve

Soil material is collected from a nature reserve to spread over the area that will be developed. It is important that as little damage as possible be caused to the existing nature reserve, and that the collection work is done in moderation. Depending on the way the transplantation is performed, intact soil sods can be excavated, or bulk soil material. Intact sods also contain the target plants and their roots.
Intact sods don’t need to be treated and can be transplanted directly.

For the collection of bulk soil material, the top 5-10 cm of the donor site is excavated from 0.5 m2 squares. As long bulk soil is collected from several small patches, the damage is limited. This material is crumbed as much as possible with the help of a spade.
Bulk soil materials from the donor location are easiest to spread onto the new area after homogenisation by crumbing or by mixing with water, creating a slurry.

3) Application of nature reserve soil onto the newly developed area

In smaller areas and when sufficient manpower is available (volunteers), soil from the donor location can be spread manually onto the new area using spades and rakes. Intact soil sods can be manually dug in.

In larger areas, soil from the donor location is spread using a manure spreader onto the newly developed area. This results in spreading approximately 1 liter of soil material per square meter, leading to a thin layer of transplanted soil of on average 1 mm.

4) Continuation

Monitoring of the soil transplantation is needed to observe if and how fast the targeted plant species are establishing, and whether adjustments are needed.

Usually soil transplantations show success within the first years, with the desired plants (grasses, heather) coming up. Sometimes additional measures are needed. This could be another soil transplantation or seeding, in case the targeted plant species don’t start growing. In heathlands it is common practise to manage grass encroachment through mowing, grazing, and eventually excavation if grasses have taken over the heathland.

Locations

Heathland:

Bartokpark Arnhem; Dommeldal; Galderse Heide; Golfclub de Koepel; Heiderijk Nijmegen Mook; Kerckebosch; Kuinderbos; Landgoed de Lage Lier; Loonse en Drunense Duinen; Nieuwe Renkumse Heide; Reijerscamp

Species-rich grassland:

Banisveld; Mantingerveld; Noordenveld, Dwingelderveld; Oudemirdum; Staverden; Wekerom; Wisselse Veen; Wolfsven

Wet, nutrient-poor Grassland (Molinia meadow):

Moerputten - Blues in the Marshes

Dry siliceous grassland Nardetea:

Verlengde Winkelberg

Forest:

Buitenplaats Beekhuizen

Publications

Literature in English:

Literature in Dutch

 

Presentaties

Contact

Koen Verhoeven

k.verhoeven@nioo.knaw.nl
+31 (0)317 473 400

Droevendaalsesteeg 10
6708 PB Wageningen 

Postbus 50 
6700 AB Wageningen