Peatland Agriculture
Agriculture Peatlands
Peatlands make up – 21% of Co. Offaly, 14% of north Tipperary and 12% of Co. Laois.
Peatlands plays an important role economically since they can be drained and reclaimed for agriculture. It is possible to have a peat soil from which all peat-forming vegetation has been completely removed or replaced by human action. In such cases the system is no longer an actively peat-forming mire, but it remains a peatland as it still possesses a peat soil, even though the vegetation it supports is not capable of forming peat. This is because the surface vegetation is just one part of the whole ecosystem – the body of peat beneath the vegetation is the other key component.
Absence of peat-forming vegetation is a widespread condition for peat soils in Irish lowlands as many such peatlands are now farmed as arable cropland, or more typically as the grass pastures. Peatland has also become attractive economically. Shallow peat (<100 cm) can be used to grow food crops including vegetables.
However, peatland on the other side has a number of constraints in terms of greenhouse gas (GHG) emission, especially CO2 emissions in the degraded peatland. CO2 emissions will increase due to acceleration of microbial (heterotropic) decomposition. These arise from decomposition of peat. Common sense suggests three alternatives to manage GHG emissions from degraded peatland:
- Conservation and restoration,
- Natural recovery, and
- Agricultural use.
Wetland Agriculture - Paludiculture
Paludiculture - comes the word palus, the Latin word for swamp.
Paludiculture hence refers to different types of wetland agriculture and forestry for the productive land use of wet and rewetted peatlands closer to their natural permanently wet state.
Paludiculture comprises of various agricultural production systems that target the production of plant- or animal-based commodities ranging from harvesting vegetation on semi-natural sites to establishing specific permanent crops. Paludiculture harvests the above ground biomass while below ground biomass remains for peat formation.
This locks in the carbon by conserving peat-forming or carbon-sequestering conditions. This is a blueprint for peatland carbon farming which still produces food, feed and energy alongside the maintenance and restoration of multiple ecosystem services of water storage and purification, flood control, nutrient retention, local climate moderation and habitat for rare species.
After establishing high water tables near the soil surface throughout the year, wet grasslands may develop by succession of vegetation or permanent crops with specific peatland species being cultivated. The harvested biomass can be used as food, feed, fibres for industrial biochemistry, for production of Construction materials,
High quality liquid or gaseous biofuels, for heat production through direct combustion or for further purposes such as extracting and synthesizing pharmaceuticals and cosmetics.
These diverse options illustrate the great potential that paludiculture offers for future circular bio-economy applications.
Some wetland crops and their uses include:
- Reed canary grass – Fodder, bedding, packaging, energy (combustion & biogas)
- Common reed – Construction, thatching and insulation materials, packaging, fodder, energy
- Sedges – Energy (combustion & biogas), fodder, animal bedding, packaging
- Cattail / Bulrush – Construction materials, fodder, packaging, fodder, energy (biogas)
- Alder – Construction materials, charcoal, furniture, veneer, energy
- Willow – Fodder, weaving material, energy
- Peat mosses (Sphagnum) – Peatland restoration, growing media.
Other Farm Habitats: 1. Meadows
Meadows: These are habitats where the vegetation is either dominated by grasses, or is ‘grassy’ in appearance with abundant small sedges or rushes. There are very few semi-natural grasslands left in Ireland as most have been modified by decades of ploughing, grazing, seeding and fertiliser application. Intensively managed, or highly modified grasslands, involve regular re-seeding to produce a homogeneous crop of fertiliser-dependent rye-grasses.
Where land drainage is poor, peatland pastures will form High Nature Value (HNV) wet grasslands that support some of our prettiest wildflowers which feed pollinators and other invertebrates which in turn feed some of our most threatened birdlife – corncrake, curlew, lapwing, meadow pipit and skylark.
2. Hedgerows
Hedgerows: These are linear strips of shrubs or trees cut low, often with occasional trees, that typically form field or property boundaries. Most Irish hedgerows originate from planting and often occur on raised banks of earth derived from the excavation of associated drainage ditches. Their dimensions vary considerably, depending largely on the species composition and how they are managed, but are generally defined as being shorter than 5 metres high and 4 metres wide.These are habitats where the vegetation is either dominated by grasses, or is ‘grassy’ in appearance with abundant small sedges or rushes.
3. scrub
Scrub: Without management by grazing or mowing, these grasslands would revert to scrub, woodland or heath. Scrublands are dominated by at least 50% cover of shrubs, stunted trees or brambles and have a canopy height that is generally less than 5-metres on dry lands or 4-metres in the case of wetland areas. Scrub typically develops as a precursor to woodland and is often found in inaccessible locations, or abandoned or marginal farmland including cutaway bog. It is very valuable to bird and insect life but when it invades peaty soils it also increases the rate of loss of greenhouse gases.
4. Native Woodlands
Native Woodland: A woodland is any area that is dominated by trees as opposed to shrubs, and where the canopy height is greater than 5 metres on dry lands or 4 metres for woodland in wetland areas or on bogs. The main distinction is between our scarce, semi-natural woodlands and all other woodland types, including commercial plantations. Woods which have invaded damaged bogs are also a common feature of farm sites in the project.
