A new national research programme on greenhouse gas emissions from lowland peat meadows in The Netherlands

Following the Paris Agreement (2015) that aims to limit climate warming, the Dutch government presented a National Climate Agreement. The National Climate Agreement allocates the overall ambition of reducing the national greenhouse gas emission by 49% in 2030 (compared to 1990) to different sectors, such as industry, mobility or agriculture and land use. Within the latter sector, the peat meadow areas currently contribute ~4.6 to 7 Mton per year of CO₂ to the national greenhouse gas emission. In the National Climate Agreement, the aim is to reduce the net CO₂ emission from the peat meadow areas with 1 Mton per year by 2030.  

The peat meadows of the Netherlands are drained peatlands for dairy farming. Drainage of peatlands causes land subsidence, and as a result of peat oxidation, greenhouse gas emissions (CO₂, CH₄, N₂O). Critical factors that determine the level of greenhouse gas emissions from the peat meadows are amongst others the groundwater level, peat thickness, macrofossil composition, mineral cover-soil thickness, the level of fertiliser addition. In the National Climate Agreement, the main focus is on raising groundwater levels in the peat meadow area to reduce greenhouse gas emissions and subsidence. This can be either passively achieved by raising the ditch water levels, surface irrigation, reducing transpiration losses or actively by using submerged drainage systems that drain in winter, but infiltrate water in summer.

It is now time to produce regional spatial plans that comprise a compilation of measures that raise groundwater levels enough to reduce the greenhouse emissions with 1 Mton per year by 2030. To do so, it is imperative that the exact effects of the proposed measures on greenhouse gas emissions and subsidence are known, under different environmental conditions. In ongoing and previously executed studies, results so far show mixed outcomes. Therefore, a national research programme commenced autumn 2019, in which the greenhouse gas emission and subsidence is continuously measured in five field sites. The programme focusses on the effects of submerged drainage/irrigation on emissions in the first 2 growing seasons.

The consortium in charge of the national research programme consists of parties in the Netherlands that have ample experience in measuring greenhouse emission and subsidence. Each of the five field sites consists of one measurement plot in an area where the groundwater level is raised and one reference plot where the groundwater level dynamics remained the same. A measurement plot consists of continuously operating gas analyser chambers that rotate within the plot every two weeks. In two field sites, emissions are also measured using the eddy covariance method. In addition, subsidence is measured with extensometers and spirit levelling. Sensors, both in situ and above ground, provide information on relevant parameters such as soil moisture, soil temperature, oxygen availability, and meteorological parameters. Samples are being extracted from the field sites and tested on microbiological assemblages, and soil (mechanical) parameters. The whole programme is designed to run for at least five years, but first results that support policy development, are supposed to be reported in 2021.