EFFECT OF SOIL GRANULOMETRIC COMPOSITION AND MOISTURE ON THE FORMATION OF N2O ISOTOPES

Abstract

Nitrous oxide (N2O) is one of important greenhouse gas (GHG) whose main sources are agricultural soils. N2O forms in soil as a result of microbial processes, reinforced by the use of nitrogen-containing fertilizers. This study will look at how the formation of N2O in soil is affected by soil moisture and soil granulometric composition. Soil N2O isotopes of ?15N? (central nitrogen position) and ?15N? (end nitrogen position) which could help to identify natural and anthropogenic sources of N2O emissions and the involvement of microorganisms in N2O production. N2O isotopes ?15NSP and ?15Nbulk can be traced or N2O produced by nitrification or denitrification. The study used total of 92 soil samples collected in 2020 and 2022. The study uses three types of agricultural soil with a different granulometric compositions. Soil from each agricultural plot was weighted into two samples, each of 1.5 kilograms to provide different humidity conditions � wet aerobic and wet anaerobic. The measurements were performed in a laboratory with the CRDS device Picarro G5131-i. The G5131-i analyzer measures nitrous oxide isotopes ?15N, ?15N?, ?15N?, and ?18O with an accuracy of 0.7 �, and N2O concentration with an accuracy of less than 0.05 ppb (all measurements are averaged over 10 minutes). The data processing did not use all the data obtained from the Picarro G5131-i, but was selected by evaluating the changes in N2O concentrations when the concentrations had stabilized. In this research, three types of soil were used, from which it can be concluded that the type of soil, its inherent physical properties and reaction to the moisture regime play an important role in the formation of N2O isotopes.