Applications of stable carbon isotopes in soil science with special attention to natural 13C abundance approach

Abstract

Since the invention of the isotope ratio mass spectrometer in the late 1930s, isotope analysis has shed light on many key processes in the Earth’s ecosystems. Stable isotope analysis was first applied in the field of chemistry and geochemistry in the 1940s, while the use of isotopic fractionation for various biochemical reactions was elaborated later. The knowledge gained from isotope research led to a better understanding of the dynamics of the biosphere and to the more efficient study of interactions between the geosphere and biosphere. In soil research, stable isotopes are ideally suited to provide a wider insight into the element cycles in soil ecosystems. Stable carbon isotopes, in particular, have been in the focus of soil research, since soil organic matter (SOM) plays an important role not only in soil fertility, soil water management and many other physical, chemical and biological soil functions, but also in the global carbon cycle. If processes connected with these soil functions are isotopically labelled with stable carbon isotopes, the key reactions of C input, exchange and output in the soil and other soil organic matter functions can be studied accurately. The 13C abundance approach is one of the useful methods applying natural stable carbon isotope differences in the atmosphere-plant-soil system to track the stability of organic carbon in these reservoirs. The turnover of SOM, particularly the rate of decomposition and the partitioning of C between the different soil CO2 efflux sources are in the focus of soil science research, which can be studied in detail with the help of natural 13C abundance method. Thus, analysing the isotopic composition of CO2 exchange between the soil and the atmosphere not only helps to gain more information about the impact and role of SOM and its various forms but also to predict ecosystem responses to global changes