Stability of soil organic matter in agro and forest ecosystems in Lithuania

Abstract

Soil organic matter (SOM) is composed of organic and inorganic components. We were seeking to estimate the stability between organic matter inputs and outputs throughout organic matter mineralization. It was an obligatory admire for carbon storage evaluation in soils of agro and forest ecosystems. SOM accumulation have been estimated in a long-term field experiments where were adjusted: (i) arable land with conventional tillage and minimized tillage systems with cereal crop rotation and cover crop treatment in Planosols; (ii) arable land, perennial grassland and forest land in Arenosols and in Luvisols. In first experiment, over the 16 years soil tillage systems with permanent plant rotation and cover crop treatment have influenced the accumulation of SOM via soil organic carbon (SOC) stabilization. However, along the conventional tillage the pools of SOC were not increasing significantly. While shallow rotovating, cover cropping and no-tillage have been processed, the accumulation of SOC has increased on average by 1.5 times in ploughed (0-20 cm) horizon. Therefore, along the minimized tillage the microbial biomass accumulation has been increasing significantly, wherefore, intensified accumulation of SOC as well as humification were ascertained. In second experiment, it was found that in mineral topsoil (0-20 cm) SOC stocks were higher in soils of 50-60-yaer-old deciduous forest plantations than both in arable land and grassland. It was expressed by the decomposition of forest floor, higher content of carbon in microbial biomass and higher rate of humic acids in humus fractional composition and, to a minor extent, by lower intensity of soil respiration. Our observations highlighted the land use specificities to the contribution on the SOM. In agro ecosystems, the process of supplementing the SOM was long-term achieved through adapted tillage practice and the addition of crop and grass as well as microbial biomass organic components