CLIMATE SMART MANAGEMENT ALTERNATIVES FOR MANAGEMENT OF ORGANIC SOILS UNDER AGRICULTURAL USE

Abstract

Organic soils in cropland and grassland are absolutely the largest source of greenhouse gas (GHG) emissions in Latvia contributing to output of 3.1 mill. tons CO₂ eq; therefore, it is important, to evaluate different management scenarios and their effect on the GHG emissions. In this study we compared 3 scenarios of management of organic soils used in agriculture: afforestation with birch and retaining of drainage system, afforestation with birch with following rewetting and management these areas as grasslands as a reference scenario. We estimated carbon stock changes in living biomass of trees and forest floor vegetation, litter, dead wood, harvested wood products and soil, substitution effect of forest biofuel, and N₂O and CH₄ emissions from soil. AGM model is used to create forest growth projections. The average annual GHG emissions from grassland is 7.3 tons CO₂ eq ha^-1 yr^-1. In afforested and drained areas average GHG emissions are 2.6 tons CO₂ eq ha^-1 yr^-1, and in afforested and rewetted areas – 3.8 tons CO₂ eq ha^-1 yr^-1. Afforestation of grassland and maintenance of drainage system during 200 years period reduces GHG emissions by 916 tons CO₂ eq ha^-1, while the afforestation and rewetting reduces GHG emissions by 670 tons CO₂ eq. ha^-1. The substitution of fossil fuel has significant role in the climate change mitigation effect. The cost of the emissions' reduction in 2050 reaches 5.8 and 21.3 € ton^-1 CO₂ eq in drained and rewetted areas, accordingly.