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Setting up paludiculture sites

Conversion to paludiculture may require major operational changes. In drained peatlands, rewetting and maintaining the higher water tables needed for wetland cropping systems to reduce greenhouse gas (GHG) emissions will place new demands on water management systems, as well as requiring new approaches for establishment, management, harvesting, post-harvest processing and marketing. The switch from drainage-based to wetter management may be both time-consuming and costly. In addition, the transport of voluminous raw materials has logistical constraints. Conversion of land to paludiculture should therefore be thought through, developed and implemented together with processing and marketing opportunities. This requires co-operative approaches along value chains and may also require development of intermediary infrastructure and organisations.

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For each site where the potential for paludiculture has been identified, a careful implementation plan will be needed so that alongside the planned structural changes, the funding required also can be estimated robustly. The following questions can help guide this process:

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  • Which areas are suitable for paludiculture (see Identifying suitable sites for paludiculture)? Are there further areas that could be leased or managed jointly within the area for rewetting? Where are these areas located within the wider landscape context?

  • What is the current water level and its seasonal variations? What is the target water level? What water level management structures are already in place? It is very likely that site specific hydrological feasibility studies will be required. Special attention must be paid to the potential impacts of any changes in water management on other areas within the drained catchment. Ideally, hydrological changes should be discussed iteratively (and modelled as required) with all the land owners within a drained catchment. This will enable a more effective catchment-scale plan to be developed.

  • What permits and permissions are required to make the water and land management changes that are proposed? Do you have contacts with the relevant local and national authorities?

  • Are there established uses on the farm or routes to market for paludiculture or other peatland products in the region? What are the amounts and quality of biomass material required for these wider product / processing systems (see Uses of paludiculture crops)? How large is the potential cropping area and can the yield and quality requirements be met from this land? Do you already have contacts with processors? Are there opportunities to expand regional processing?

  • Will new markets need to be developed (see Uses of paludiculture crops)? Do you already have contacts with companies using similar raw materials? Are there suitable sites where regional processing could be initiated?

  • Will additional technology, machinery and infrastructure be required for harvesting and storing, and for drying or compressing the biomass, if required (see Uses of paludiculture crops)?

  • Is adapted technology available for the planned paludiculture? If not, what type of technology is required (see Adaptation of land management equipment)? Can this be procured cost-effectively by the farm or procured jointly and used in co-operation with other farmers? Can machinery be hired regionally or are there local contractors with appropriate technology / machinery in place?

  • How can expertise on wetland management be acquired? Is there a need for inputs from consultants and how can experienced consultants be identified? Is there suitable training available?

  • What are the investment requirements? What is the expected payback period? Are there any constraints arising from for current loans or subsidies that must be taken into account as part of the schedule for change? It is important that the farm’s bank and other financial backers are involved in the planning at an early stage.

  • Which subsidies or funding will remain in place after the changeover, which will be lost and which sources of funding may become newly available as a result of the changes (see relevant government resources)?

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The extent to which these objectives compete with each other should be checked carefully, establishing if there are synergies or conflicts. The main driver for land use change is likely to be the need to reduce greenhouse gas (GHG) emissions from the fossil carbon held within the peat soil, but which is lost steadily from drained soils. Harvest of raw materials is often only a secondary objective or it may be required to achieve a certain vegetation structure (maintenance utilisation) for nature conservation reasons.

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Once sites that have potential for paludiculture are identified, then it is important to consider which paludiculture crops are most appropriate. Given the early market development for paludiculture crops, processing and marketing should also be considered at the earliest stages. Ideally, conversion of land to paludiculture should be thought through, developed and implemented in parallel with development of the processing steps. This will require cooperative approaches along value chains.

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Water Management

Water Management

It is necessary to raise water levels for all forms of paludiculture on previously drained sites. There are many years of experience with rewetting within the field of nature conservation. However, there is no universal strategy to restore drained peatlands as conditions differ widely depending on climate, water and peat chemistry as well as on topography. It is, however, possible to define general principles for the solution of similar problems. The main focus of rewetting is on both raising the level of permanent water saturation and also reducing the amplitude of water level fluctuations by reducing water losses (incl. extraction, surface runoff, sub-surface seepage and evapotranspiration) from the site and from the adjoining catchment. The main challenge is to store enough water during periods of water surplus to prevent drought during periods of water shortage, so successful rewetting requires good planning, knowledge of the area and hydrology as well as accompanying monitoring.

 

The most suitable water management approach will depend on the availability and quality of water, the site conditions, the degree of degradation and the requirements of the crop. Rewetting for nature conservation may seek to minimise ongoing costs and interventions and is often carried out on sites where minimising water loss is the main intervention required. In paludiculture systems, more measures must be taken to mitigate water level fluctuations through active water management. Hydraulic engineering measures for establishing paludiculture systems on previously drained land will require continuous intervention in the water balance in many cases. This conditional "artificiality" serves to restore and maintain water levels close to ground level. Measures that seek to keep water in the area, such as the removal or filling in of drainage ditches, the installation of low weirs and jam flaps or the construction of dams offer few options to control the water level in a targeted manner. Hence a combination of measures that target water retention, together with water supply into the area via irrigation and, if necessary, effective drainage systems ensure that water levels that preserve peat as far as possible are maintained throughout the year. In principle, existing agricultural and water management infrastructure can be used to establish paludiculture systems. Access to water, such as an adjacent receiving watercourse or reservoir, is advantageous. From a technical perspective, the condition and structure of the ditch and drainage systems on the farm and in the wider drained catchment determine whether and how the site can be wetted.

 

Setting up optimal water levels for paludiculture will often require further active rewetting measures as degraded peat soils have altered pore structures that reduce hydraulic conductivity, leading to limited water movement from the ditches into fields. Hence even when the ditch water level is high, the water levels in neighbouring fields drop much lower, especially during the growing season as a result of evapo-transpiration. Water levels of more than 1 metre below ground level have been seen even where the water level in surrounding ditches is at the ground surface.

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Figure 2: An example of modelled water level hydrographs for different initial water levels of a peatland in north-eastern Germany.

With an annual average water level that is at ground level, the water levels are up to 20 cm above ground level in winter and 20 cm below it in summer. An average water level of 20 cm below ground level means that the water level is 10 cm above ground level in winter, is lowered below ground level in spring and thus drops to up to 50 cm below ground level during the vegetation period.

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Therefore, for most paludiculture systems, sufficient additional water will be needed for summer irrigation to meet the additional seasonal demand. If this can be achieved by restoring free inflow, then water inputs may also allow nutrients to be replenished. It is more likely that a range of water management structures will be needed. The construction of new subsurface irrigation / drainage systems may also be necessary to optimise distribution of water across the area. Target water levels can be documented and checked using suitable measuring points at weirs, dams, pumping stations or gauges. However, this would not be possible in areas with water abstraction bans in summer. However, care is needed to take account of the wider catchment as optimising water in some fields for paludiculture could lead to permanent waterlogging and abandonment of the most low-lying areas.

 

Construction and optimisation of water management infrastructure (such as dams, pumping stations, irrigation ditches, sluices, spillways) will be needed at catchment and at farm scale. Energy sources may also be required to operate pumps. All these interventions should be underpinned by hydrological modelling and feasibility studies that allow users to examine various scenarios (e.g. caused by water level fluctuations due to floods, low water, dry summers) from an operational perspective, e.g. along the following lines: What do the scenarios mean for cultivation and management? Where can water management be used and where not? Is additional water available? This can then be followed by practical questions: How is a power supply possible for any necessary pump operation? Possible changes in management and fluctuations in yield, e.g. due to flooding or drought, should be considered from the outset and preventive measures should be developed.

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Picture 1:

Embankment as a boundary for a paludiculture system, which has an outer ditch in front of it forming a boundary with the drained grassland (bottom left edge of the picture). The embankment has a 3 metre wide crown and driveways with flattened banks in several places. The embankment is regularly mowed with the electric fence erected on the embankment to keep out wild animals.

Photo: T. Dahms, 2020).

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Picture 2:  Artificial pond and pump for irrigation, and a spillway used to regulate water levels in a paludiculture system (typha).​

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Picture 3: Pressure pipe outlet on the inside of the area and solar modules in the background for operating the solar pump. In this system, adjustable weirs together with pumps (are required to control the water level.

Other infrastructure

Other infrastructure

Whilst establishing a paludiculture system, it is important to examine whether other infrastructure changes might be beneficial to the overall operation of the system. In particular:

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  • Creation of additional access roads.

  • Construction of paved transport routes and / or transfer points e.g. consolidating gateways.

  • Adaptation of existing transport routes to take account of higher water levels, if necessary upgrading or building new bridges.

  • Improvement of accessibility or workability of the area e.g. by filling in ditches and replacing with sub-surface drainage, adjusting field sizes / shapes to facilitate system operation

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Some of these changes may be implemented together with water management structures e.g. integration of trackways as part of embankments. Where drainage for arable cultivation has occurred, field sizes may be very large and field sub-division may be beneficial as part of the design of the paludiculture system. Systems should be designed so that trafficking on the rewetted peat is kept to a minimum (see The challenges of managing wet peatland soils)

Land Prep

Land preparation

To facilitate active water management for paludiculture systems, levelling, gradient profiling or terracing may be required within the area, depending on the existing relief and slope.  Significant excavation and engineering works may also be required, including the creation of embankments and excavation of external ditches for drainage water (for "island solutions").  Existing drainage systems should have been mapped as part of the implementation plan and much of this existing agricultural and water management infrastructure can be used to establish paludiculture systems. However, some old drainage pipes will need to be capped or disrupted.  These approaches should be planned and scheduled carefully to minimise trafficking on the peatland site and optimise conditions for rewetting. Minor topsoil movement may be necessary to level peatland areas or to obtain soil material to fill ditches or create embankments. Where low nutrient conditions are needed, (e.g. for sphagnum peat moss cultivation) removal of humified and high nutrient peat from the surface can help establishment of the paludiculture system.

 

Once water management systems are in place, the steps required to set up and grow paludiculture crops vary depending on the crop (see Crop establishment and management). Many paludiculture crops are perennial but tillage may be necessary as part of the establishment phase. Tillage may be needed to remove existing vegetative cover, create an appropriate seedbed and as part of weed control measures; however, tillage interventions should be targeted and minimal. Minimal tillage approaches, using adapted machinery, may be possible; for example, approaches to grassland reseeding (e.g. slit sowing) and afforestation on grassland (e.g. strip tiller) could be further developed for paludiculture systems.

Costs of setting up paludiculture sites

Costs

The cost of setting up a paludiculture system and establishing a crop depends on local conditions and the needs of the crop in question, as well as the size of the area. However, for all sites the two main costs are in establishment water management structures and crop establishment. Crop establishment costs are much higher for transplanting compared with direct seeding. For tree crops, planting density and design have a major impact on costs. Rewetting grassland systems to create wet meadows can take place through natural succession, incurring lower costs for establishment of the crop. However, depending on the location, the costs for establishing the required water management structures area can be just as expensive as for other paludiculture systems.

 

Rewetting should ideally be planned at catchment scale to minimise the installation and investment costs.  However, most of the pilot paludiculture systems that have been implemented are a maximum of 10 ha in size and are designed as "wet islands" in a drained environment which increases costs markedly. Therefore, current cost estimates have to be shown with large ranges and are shown as a guide, but it is essential to take the specific conditions of each site into account.

Table 6: Overview of possible cost factors for establishment of paludiculture systems taken from European pilot systems.

Cost type
Costs in € per ha
Construction measures & land preparation
1500 - 15000
Establishing of crops
1) Seeding
60 - 1000
2) Transplanting
3500 - 14000
Investments in irrigation technology
0 - 4000
Total
2000 – 30000

This information is taken from a translation of the Leitfaden Fur Die Umsetzung Von Paludikultur, originally produced in German in 2022.

Nordt, A., Abel, S., Hirschelmann, S., Lechtape, C. & Neubert, J. (2022) Leitfaden für die Umsetzung von Paludikultur. Greifswald Moor Centrum-Schriftenreihe 05/2022 (Selbstverlag, ISSN 2627–910X), 144 S.

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With thanks to the Greifswald Moor Centrum and to funding from the Paludiculture Engagement Fund (within the Nature for Climate Fund).

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Implementation of paludiculture is currently still very much in the pilot stage. Many farmers are aware of the significant climate impact of their peatlands, but they lack specific practical knowledge for conversion alongside specific economic prospects and commercial exploitation partners. Some pioneering farms are already implementing cultivation at high water levels and paludiculture crops are being further developed and tested in research projects. However, large-scale realisation of paludiculture systems in practice is still in its infancy.

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We therefore expect this guide to grow and develop as farmers and researchers provide new information to update it. If you spot errors or want to add material, please contact us at: paludiculture@niab.com.

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