Mapping of cultivated organic soils for targeting greenhouse gas mitigation

Abstract

Cultivated organic soils can be a major source of GHG emissions in countries with high coverage of peat soils. Targeting mitigation measures based on mapping of cultivated organic soils would reduce these emissions and increase sustainability of agriculture. Different georeferenced datasets were combined to study the area trend and describe current agricultural use of organic soils. The area was also mapped regionally into classes based on intensity of cultivation and organic layer depth, and an example allocation of potential mitigation measures was made at the country scale. The area and proportion of cultivated organic soils have increased in Finland since 1990 but the clearance rate has decreased in recent years. More than half of the area retains a peat layer deeper than 0.6 m indicating long-lasting mitigation potential with measures capable of slowing peat decomposition. Sixty-five percent of the cultivated organic soil area was not considered a priority area for radical management changes, for various reasons, but there are 85,000 ha of field with more realistic potential for GHG mitigation. The mapping method was found to be a practical tool for depicting the GHG mitigation potential of cultivated organic soils. Significant reductions in agricultural GHG emissions can be expected with implementation of the suggested mitigation measures.

Nutrient export from Finnish rivers into the Baltic Sea has not decreased despite water protection measures

“…One possible explanation is that even if the total area of croplands has been quite stable in Finland since 1990, the share of organic soils has increased by 42 900 ha in 1990-2016, predominantly in the catchment area of BOB. Animal production and farm enlargement are more common in the eastern and northern parts of the country where the occurrence of peat soils is also high (Kekkonen et al 2019). Cleared new fields on organic soil types have been shown to have four times higher specific TN loading value than fields on mineral soil, while land clearing was not observed to have any effect on the TP load (Rankinen et al 2016).…”

Farm-Level Effects of Emissions Tax and Adjustable Drainage on Peatlands

“…Recent studies show that one potential source of emissions where reductions could be made effectively is peatlands. Peatlands comprise only 11% of agricultural land, but they produce over 50% of the total GHG emissions from agriculture and 75% of the emissions from agricultural land use in Finland (Kekkonen et al 2019 ; Koljonen et al 2020 ; Lehtonen et al 2020 ).…”

“…Rewetting, i.e., raising the level of the watertable on peatlands, is seen as an effective way of reducing GHG emissions in agriculture in northern conditions (Kekkonen et al 2019 ). Such emissions reductions could be also accounted for in national GHG inventory, which is fully consistent with the United Nations Framework Convention on Climate Change (UNFCCC), the Kyoto Protocol, and the EU greenhouse gas monitoring mechanism that obliges members to monitor and report greenhouse gas emissions on an annual basis.…”

“…Thus, as the opportunity cost of adopting new sustainable practices is high, countries are oriented toward producing conventional crops and livestock products on drained agricultural land (Ferré et al 2019 ). The share of peatland soils is highly variable in Finland (Kekkonen et al 2019 ) and many farms and agriculture in smaller regions in Finland are quite dependent on using drained peatlands for agricultural production. Still, significant reductions in agricultural GHG emissions is not possible without reducing emissions from peatlands.…”

Combining bioenergy and nature conservation: An example in wetlands

“…Without a good management plan, the top layer in these areas experiences continuous mineralisation due to the decreased water table. The consequent greenhouse gas emission should be avoided through the wet cultivation in peatlands of previously selected potential crops [85,160,161]. Such paludiculture systems, if planted with natural, high-yielding plant species under a reasonable and efficient management plan, would constitute an additional agroecological approach to meet both nature-conservation and bio-economy goals.…”