Impact of land use practices on greenhouse gas emissions from agriculture land on organic soils

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 - CO2, CH4, and N2O - 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 CO2 emissions from cropland were 4.8t CO2 -C ha-1, but from grassland 4.4t CO2 -C ha-1. Study sites in cropland were sink of methane - 0.59 kg CH4 C ha-1, but source of methane in grassland 57.8 kg CH4 C ha-1. Average N2O emissions from cropland were 7.1kg N2O -N ha-1, but from grassland 0.3kg N2O -N ha-1. Cumulative GHG emissions from organic soils on cropland and grassland show that cropland annually emits more - 20.8 t CO2eq ha-1 than grassland - 18.1 t CO2eq ha-1thus looking from GHG emission budget perspective, perennial grassland is more advisable for management of organic soils in agriculture.