Evaluation of greenhouse gas emissions from fertilized grassland

Abstract

Since the Climate Change Convention (UNFCCC, 1994) and the Kyoto Protocol (1997) intergovernmental mitigation of climate change has become an increasing concern for scientists, public opinion and policy makers. We investigated biosphere-atmosphere interactions on a light loam soil (Calc(ar)i-Endohypogleyic Luvisol) in different managed grassland ecosystems of the training farm of the Lithuanian University of Agriculture in 2009, within the frame of a European COST Project. The objective of this investigation was to determine the impact of fertilizers, their rates and combinations on GHG emissions and productivity of natural and sown grassland. GHG emission measurements were run in June-September, when meteorological conditions were optimal for intensive plant and soil biota physiological processes, in the absence of frost stress. In this study we compared fertilized natural and sown grasslands by using GHG emissions as indicator. This revealed stronger positive correlation (r=0.8) between applied monomial N60-240 fertilizers on GHG fluxes than of complex NPK fertilizers (r=0.7) in both natural and sown grasslands. Our results imply that N2O emissions (0.02 mg h-1 m-2) were the same in natural and sown grasslands. Nonetheless, CO2 and CH4 emissions were less by 3.09 mg h-1 m-1 and 0.01 g h-1 m-1, respectively, in sown grassland, when the same fertilizer rate (N180P41K125) was applied.