No abstract

Greenhouse gas emissions (carbon dioxide, methane, nitrous oxide) from managed organic soils in cropland and grassland is significant part of greenhouse gas (GHG) emission profile of Latvia. Total area of organic soils in grassland and cropland in Latvia is around 8 %, but GHG emissions from this area constitute more than 30 % of the total agricultural GHG emissions (data vary by GHG inventory years and soil data set used). GHG emission measurement data characterizing different agricultural land use practices can support the most appropriate choice of organic soil management that contributes less to the total GHG emission amount. Within the scope of the LIFE REstore project "Sustainable and responsible management and re-use of degraded peatlands in Latvia" research was carried out to assess impact of the management practices to GHG emissions from agricultural land on organic soils. GHG gases from agricultural land were measured in two year cycle in permanent grassland and cropland sites. Ecosystem gas -CO 2 , CH 4 , and N 2 O -exchange measurements were done, using the opaque chamber method and the transparent chamber method. Research results demonstrate the net ecosystem exchange of GHG emissions in relation to different management practices in cropland and grassland on organic soils. Average CO 2 emissions from cropland were 4.8t CO 2 -C ha -1 , but from grassland 4.4t CO 2 -C ha -1 . Study sites in cropland were sink of methane -0.59 kg CH 4 C ha -1 , but source of methane in grassland 57.8 kg CH 4 C ha -1 . Average N 2 O emissions from cropland were 7.1kg N 2 O -N ha -1 , but from grassland 0.3kg N 2 O -N ha -1 . Cumulative GHG emissions from organic soils on cropland and grassland show that cropland annually emits more -20.8 t CO 2 eq ha -1 than grassland -18.1 t CO 2 eq ha -1 thus looking from GHG emission budget perspective, perennial grassland is more advisable for management of organic soils in agriculture.

We determined the magnitude of instantaneous greenhouse gas (GHG) emissions from drainage ditches in hemiboreal peatlands in Latvia during the frost-free period of 2021 and evaluated the main affecting factors. In total, 10 research sites were established in drained peatlands in Latvia, including active and abandoned peat extraction sites and peatland forests. Results demonstrated that in terms of global warming potential, the contribution of CO2 emissions to the total budget of GHG emissions from drainage ditches can exceed the CH4 contribution. The average CO2 and N2O emissions from drainage ditches in peatland forests were significantly higher than those from ditches in peat extraction sites, while there was no difference in average CH4 emissions from ditches between peatland forests and peat extraction sites. Emissions from ditches of all GHGs increased with increasing temperature. In addition, CO2 and N2O emissions from drainage ditches increased with decreasing groundwater (GW) level. They were also negatively correlated with water level in ditches, but positively with potassium (K) and total nitrogen (TN) concentrations in water. By contrast, CH4 emissions from drainage ditches increased with increasing GW level and water level in ditches but were negatively correlated with K and TN concentrations in water.

In the forest land of many European countries, including hemiboreal Latvia, organic soils are considered to be large sources of greenhouse gas (GHG) emissions. At the same time, growing efforts are expected in the near future to decrease emissions from the Land Use, Land Use Change and Forestry sector, including lands with organic soils to achieve enhanced contributions to the emissions and removals balance target set by the Paris Agreement. This paper aims to describe the distribution of organic soil layer thickness in forest land based on national forest inventory data and to evaluate soil organic carbon stock in Latvian forests classified as land with organic soil. The average thickness of the forest floor (organic material consisting of undecomposed or partially decomposed litter, O horizon) was greatest in coniferous forests with wet mineral soil, and decreased with increasing soil fertility. However, forest stand characteristics, including basal area and age, were weak predictors of O horizon thickness. In forests with organic soil, a lower proportion of soil organic matter layer (H horizon) in the top 70 cm soil layer, but a higher soil organic carbon stock both in the 0–30 cm layer and in the 0–100 cm layer was found in drained organic soils than in wet organic soils. Furthermore, the distribution of the soil H horizon thickness across different forest site types highlighted the potential overestimation of area of drained organic soils in Latvian forest land reported within the National GHG Inventory.

Nutrient-rich organic soil management in agriculture is among the critical sources of greenhouse gas (GHG) emissions globally and at the European level, where the most significant effects are observed in Northern, Eastern, and Central Europe. Growing climate change mitigation targets urge the need to assess and analyze current organic soil management patterns and policy planning and look for appropriate future management strategies. The objectives of this research were to assess the nutrient-rich organic soil management patterns in Latvia during the last decade and to conclude whether organic soil management in agriculture has been climate change mitigation targeted and driven by agriculture support policy. We analyzed the complex, two state-level databases based organic soil data set by using the multidimensional approach of the research methods, including graphical, spatial, correlation, factor, and cluster analysis. Our results revealed the lack of purposeful organic soil management planning in light of the climate change policy in Latvia during the research period and the inexpediency of the agriculture support policy in this regard. The research introduced an innovative methodological approach for the analysis of organic soil management patterns and policy impacts, as well as opened the necessity for a revision of the nutrient-rich organic soil management perspective in light of climate change mitigation targets. Doi: 10.28991/CEJ-2022-08-10-017 Full Text: PDF